1 /*-------------------------------------------------------------------------
2 *
3 * reorderbuffer.c
4 * PostgreSQL logical replay/reorder buffer management
5 *
6 *
7 * Copyright (c) 2012-2019, PostgreSQL Global Development Group
8 *
9 *
10 * IDENTIFICATION
11 * src/backend/replication/reorderbuffer.c
12 *
13 * NOTES
14 * This module gets handed individual pieces of transactions in the order
15 * they are written to the WAL and is responsible to reassemble them into
16 * toplevel transaction sized pieces. When a transaction is completely
17 * reassembled - signalled by reading the transaction commit record - it
18 * will then call the output plugin (cf. ReorderBufferCommit()) with the
19 * individual changes. The output plugins rely on snapshots built by
20 * snapbuild.c which hands them to us.
21 *
22 * Transactions and subtransactions/savepoints in postgres are not
23 * immediately linked to each other from outside the performing
24 * backend. Only at commit/abort (or special xact_assignment records) they
25 * are linked together. Which means that we will have to splice together a
26 * toplevel transaction from its subtransactions. To do that efficiently we
27 * build a binary heap indexed by the smallest current lsn of the individual
28 * subtransactions' changestreams. As the individual streams are inherently
29 * ordered by LSN - since that is where we build them from - the transaction
30 * can easily be reassembled by always using the subtransaction with the
31 * smallest current LSN from the heap.
32 *
33 * In order to cope with large transactions - which can be several times as
34 * big as the available memory - this module supports spooling the contents
35 * of a large transactions to disk. When the transaction is replayed the
36 * contents of individual (sub-)transactions will be read from disk in
37 * chunks.
38 *
39 * This module also has to deal with reassembling toast records from the
40 * individual chunks stored in WAL. When a new (or initial) version of a
41 * tuple is stored in WAL it will always be preceded by the toast chunks
42 * emitted for the columns stored out of line. Within a single toplevel
43 * transaction there will be no other data carrying records between a row's
44 * toast chunks and the row data itself. See ReorderBufferToast* for
45 * details.
46 *
47 * ReorderBuffer uses two special memory context types - SlabContext for
48 * allocations of fixed-length structures (changes and transactions), and
49 * GenerationContext for the variable-length transaction data (allocated
50 * and freed in groups with similar lifespan).
51 *
52 * -------------------------------------------------------------------------
53 */
54 #include "postgres.h"
55
56 #include <unistd.h>
57 #include <sys/stat.h>
58
59 #include "access/heapam.h"
60 #include "access/rewriteheap.h"
61 #include "access/transam.h"
62 #include "access/tuptoaster.h"
63 #include "access/xact.h"
64 #include "access/xlog_internal.h"
65 #include "catalog/catalog.h"
66 #include "lib/binaryheap.h"
67 #include "miscadmin.h"
68 #include "pgstat.h"
69 #include "replication/logical.h"
70 #include "replication/reorderbuffer.h"
71 #include "replication/slot.h"
72 #include "replication/snapbuild.h" /* just for SnapBuildSnapDecRefcount */
73 #include "storage/bufmgr.h"
74 #include "storage/fd.h"
75 #include "storage/sinval.h"
76 #include "utils/builtins.h"
77 #include "utils/combocid.h"
78 #include "utils/memdebug.h"
79 #include "utils/memutils.h"
80 #include "utils/rel.h"
81 #include "utils/relfilenodemap.h"
82
83
84 /* entry for a hash table we use to map from xid to our transaction state */
85 typedef struct ReorderBufferTXNByIdEnt
86 {
87 TransactionId xid;
88 ReorderBufferTXN *txn;
89 } ReorderBufferTXNByIdEnt;
90
91 /* data structures for (relfilenode, ctid) => (cmin, cmax) mapping */
92 typedef struct ReorderBufferTupleCidKey
93 {
94 RelFileNode relnode;
95 ItemPointerData tid;
96 } ReorderBufferTupleCidKey;
97
98 typedef struct ReorderBufferTupleCidEnt
99 {
100 ReorderBufferTupleCidKey key;
101 CommandId cmin;
102 CommandId cmax;
103 CommandId combocid; /* just for debugging */
104 } ReorderBufferTupleCidEnt;
105
106 /* Virtual file descriptor with file offset tracking */
107 typedef struct TXNEntryFile
108 {
109 File vfd; /* -1 when the file is closed */
110 off_t curOffset; /* offset for next write or read. Reset to 0
111 * when vfd is opened. */
112 } TXNEntryFile;
113
114 /* k-way in-order change iteration support structures */
115 typedef struct ReorderBufferIterTXNEntry
116 {
117 XLogRecPtr lsn;
118 ReorderBufferChange *change;
119 ReorderBufferTXN *txn;
120 TXNEntryFile file;
121 XLogSegNo segno;
122 } ReorderBufferIterTXNEntry;
123
124 typedef struct ReorderBufferIterTXNState
125 {
126 binaryheap *heap;
127 Size nr_txns;
128 dlist_head old_change;
129 ReorderBufferIterTXNEntry entries[FLEXIBLE_ARRAY_MEMBER];
130 } ReorderBufferIterTXNState;
131
132 /* toast datastructures */
133 typedef struct ReorderBufferToastEnt
134 {
135 Oid chunk_id; /* toast_table.chunk_id */
136 int32 last_chunk_seq; /* toast_table.chunk_seq of the last chunk we
137 * have seen */
138 Size num_chunks; /* number of chunks we've already seen */
139 Size size; /* combined size of chunks seen */
140 dlist_head chunks; /* linked list of chunks */
141 struct varlena *reconstructed; /* reconstructed varlena now pointed to in
142 * main tup */
143 } ReorderBufferToastEnt;
144
145 /* Disk serialization support datastructures */
146 typedef struct ReorderBufferDiskChange
147 {
148 Size size;
149 ReorderBufferChange change;
150 /* data follows */
151 } ReorderBufferDiskChange;
152
153 /*
154 * Maximum number of changes kept in memory, per transaction. After that,
155 * changes are spooled to disk.
156 *
157 * The current value should be sufficient to decode the entire transaction
158 * without hitting disk in OLTP workloads, while starting to spool to disk in
159 * other workloads reasonably fast.
160 *
161 * At some point in the future it probably makes sense to have a more elaborate
162 * resource management here, but it's not entirely clear what that would look
163 * like.
164 */
165 static const Size max_changes_in_memory = 4096;
166
167 /* ---------------------------------------
168 * primary reorderbuffer support routines
169 * ---------------------------------------
170 */
171 static ReorderBufferTXN *ReorderBufferGetTXN(ReorderBuffer *rb);
172 static void ReorderBufferReturnTXN(ReorderBuffer *rb, ReorderBufferTXN *txn);
173 static ReorderBufferTXN *ReorderBufferTXNByXid(ReorderBuffer *rb,
174 TransactionId xid, bool create, bool *is_new,
175 XLogRecPtr lsn, bool create_as_top);
176 static void ReorderBufferTransferSnapToParent(ReorderBufferTXN *txn,
177 ReorderBufferTXN *subtxn);
178
179 static void AssertTXNLsnOrder(ReorderBuffer *rb);
180
181 /* ---------------------------------------
182 * support functions for lsn-order iterating over the ->changes of a
183 * transaction and its subtransactions
184 *
185 * used for iteration over the k-way heap merge of a transaction and its
186 * subtransactions
187 * ---------------------------------------
188 */
189 static void ReorderBufferIterTXNInit(ReorderBuffer *rb, ReorderBufferTXN *txn,
190 ReorderBufferIterTXNState *volatile *iter_state);
191 static ReorderBufferChange *ReorderBufferIterTXNNext(ReorderBuffer *rb, ReorderBufferIterTXNState *state);
192 static void ReorderBufferIterTXNFinish(ReorderBuffer *rb,
193 ReorderBufferIterTXNState *state);
194 static void ReorderBufferExecuteInvalidations(ReorderBuffer *rb, ReorderBufferTXN *txn);
195
196 /*
197 * ---------------------------------------
198 * Disk serialization support functions
199 * ---------------------------------------
200 */
201 static void ReorderBufferCheckSerializeTXN(ReorderBuffer *rb, ReorderBufferTXN *txn);
202 static void ReorderBufferSerializeTXN(ReorderBuffer *rb, ReorderBufferTXN *txn);
203 static void ReorderBufferSerializeChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
204 int fd, ReorderBufferChange *change);
205 static Size ReorderBufferRestoreChanges(ReorderBuffer *rb, ReorderBufferTXN *txn,
206 TXNEntryFile *file, XLogSegNo *segno);
207 static void ReorderBufferRestoreChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
208 char *change);
209 static void ReorderBufferRestoreCleanup(ReorderBuffer *rb, ReorderBufferTXN *txn);
210 static void ReorderBufferCleanupSerializedTXNs(const char *slotname);
211 static void ReorderBufferSerializedPath(char *path, ReplicationSlot *slot,
212 TransactionId xid, XLogSegNo segno);
213
214 static void ReorderBufferFreeSnap(ReorderBuffer *rb, Snapshot snap);
215 static Snapshot ReorderBufferCopySnap(ReorderBuffer *rb, Snapshot orig_snap,
216 ReorderBufferTXN *txn, CommandId cid);
217
218 /* ---------------------------------------
219 * toast reassembly support
220 * ---------------------------------------
221 */
222 static void ReorderBufferToastInitHash(ReorderBuffer *rb, ReorderBufferTXN *txn);
223 static void ReorderBufferToastReset(ReorderBuffer *rb, ReorderBufferTXN *txn);
224 static void ReorderBufferToastReplace(ReorderBuffer *rb, ReorderBufferTXN *txn,
225 Relation relation, ReorderBufferChange *change);
226 static void ReorderBufferToastAppendChunk(ReorderBuffer *rb, ReorderBufferTXN *txn,
227 Relation relation, ReorderBufferChange *change);
228
229
230 /*
231 * Allocate a new ReorderBuffer and clean out any old serialized state from
232 * prior ReorderBuffer instances for the same slot.
233 */
234 ReorderBuffer *
ReorderBufferAllocate(void)235 ReorderBufferAllocate(void)
236 {
237 ReorderBuffer *buffer;
238 HASHCTL hash_ctl;
239 MemoryContext new_ctx;
240
241 Assert(MyReplicationSlot != NULL);
242
243 /* allocate memory in own context, to have better accountability */
244 new_ctx = AllocSetContextCreate(CurrentMemoryContext,
245 "ReorderBuffer",
246 ALLOCSET_DEFAULT_SIZES);
247
248 buffer =
249 (ReorderBuffer *) MemoryContextAlloc(new_ctx, sizeof(ReorderBuffer));
250
251 memset(&hash_ctl, 0, sizeof(hash_ctl));
252
253 buffer->context = new_ctx;
254
255 buffer->change_context = SlabContextCreate(new_ctx,
256 "Change",
257 SLAB_DEFAULT_BLOCK_SIZE,
258 sizeof(ReorderBufferChange));
259
260 buffer->txn_context = SlabContextCreate(new_ctx,
261 "TXN",
262 SLAB_DEFAULT_BLOCK_SIZE,
263 sizeof(ReorderBufferTXN));
264
265 buffer->tup_context = GenerationContextCreate(new_ctx,
266 "Tuples",
267 SLAB_LARGE_BLOCK_SIZE);
268
269 hash_ctl.keysize = sizeof(TransactionId);
270 hash_ctl.entrysize = sizeof(ReorderBufferTXNByIdEnt);
271 hash_ctl.hcxt = buffer->context;
272
273 buffer->by_txn = hash_create("ReorderBufferByXid", 1000, &hash_ctl,
274 HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
275
276 buffer->by_txn_last_xid = InvalidTransactionId;
277 buffer->by_txn_last_txn = NULL;
278
279 buffer->outbuf = NULL;
280 buffer->outbufsize = 0;
281
282 buffer->current_restart_decoding_lsn = InvalidXLogRecPtr;
283
284 dlist_init(&buffer->toplevel_by_lsn);
285 dlist_init(&buffer->txns_by_base_snapshot_lsn);
286
287 /*
288 * Ensure there's no stale data from prior uses of this slot, in case some
289 * prior exit avoided calling ReorderBufferFree. Failure to do this can
290 * produce duplicated txns, and it's very cheap if there's nothing there.
291 */
292 ReorderBufferCleanupSerializedTXNs(NameStr(MyReplicationSlot->data.name));
293
294 return buffer;
295 }
296
297 /*
298 * Free a ReorderBuffer
299 */
300 void
ReorderBufferFree(ReorderBuffer * rb)301 ReorderBufferFree(ReorderBuffer *rb)
302 {
303 MemoryContext context = rb->context;
304
305 /*
306 * We free separately allocated data by entirely scrapping reorderbuffer's
307 * memory context.
308 */
309 MemoryContextDelete(context);
310
311 /* Free disk space used by unconsumed reorder buffers */
312 ReorderBufferCleanupSerializedTXNs(NameStr(MyReplicationSlot->data.name));
313 }
314
315 /*
316 * Get an unused, possibly preallocated, ReorderBufferTXN.
317 */
318 static ReorderBufferTXN *
ReorderBufferGetTXN(ReorderBuffer * rb)319 ReorderBufferGetTXN(ReorderBuffer *rb)
320 {
321 ReorderBufferTXN *txn;
322
323 txn = (ReorderBufferTXN *)
324 MemoryContextAlloc(rb->txn_context, sizeof(ReorderBufferTXN));
325
326 memset(txn, 0, sizeof(ReorderBufferTXN));
327
328 dlist_init(&txn->changes);
329 dlist_init(&txn->tuplecids);
330 dlist_init(&txn->subtxns);
331
332 return txn;
333 }
334
335 /*
336 * Free a ReorderBufferTXN.
337 */
338 static void
ReorderBufferReturnTXN(ReorderBuffer * rb,ReorderBufferTXN * txn)339 ReorderBufferReturnTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
340 {
341 /* clean the lookup cache if we were cached (quite likely) */
342 if (rb->by_txn_last_xid == txn->xid)
343 {
344 rb->by_txn_last_xid = InvalidTransactionId;
345 rb->by_txn_last_txn = NULL;
346 }
347
348 /* free data that's contained */
349
350 if (txn->tuplecid_hash != NULL)
351 {
352 hash_destroy(txn->tuplecid_hash);
353 txn->tuplecid_hash = NULL;
354 }
355
356 if (txn->invalidations)
357 {
358 pfree(txn->invalidations);
359 txn->invalidations = NULL;
360 }
361
362 /* Reset the toast hash */
363 ReorderBufferToastReset(rb, txn);
364
365 pfree(txn);
366 }
367
368 /*
369 * Get an fresh ReorderBufferChange.
370 */
371 ReorderBufferChange *
ReorderBufferGetChange(ReorderBuffer * rb)372 ReorderBufferGetChange(ReorderBuffer *rb)
373 {
374 ReorderBufferChange *change;
375
376 change = (ReorderBufferChange *)
377 MemoryContextAlloc(rb->change_context, sizeof(ReorderBufferChange));
378
379 memset(change, 0, sizeof(ReorderBufferChange));
380 return change;
381 }
382
383 /*
384 * Free an ReorderBufferChange.
385 */
386 void
ReorderBufferReturnChange(ReorderBuffer * rb,ReorderBufferChange * change)387 ReorderBufferReturnChange(ReorderBuffer *rb, ReorderBufferChange *change)
388 {
389 /* free contained data */
390 switch (change->action)
391 {
392 case REORDER_BUFFER_CHANGE_INSERT:
393 case REORDER_BUFFER_CHANGE_UPDATE:
394 case REORDER_BUFFER_CHANGE_DELETE:
395 case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_INSERT:
396 if (change->data.tp.newtuple)
397 {
398 ReorderBufferReturnTupleBuf(rb, change->data.tp.newtuple);
399 change->data.tp.newtuple = NULL;
400 }
401
402 if (change->data.tp.oldtuple)
403 {
404 ReorderBufferReturnTupleBuf(rb, change->data.tp.oldtuple);
405 change->data.tp.oldtuple = NULL;
406 }
407 break;
408 case REORDER_BUFFER_CHANGE_MESSAGE:
409 if (change->data.msg.prefix != NULL)
410 pfree(change->data.msg.prefix);
411 change->data.msg.prefix = NULL;
412 if (change->data.msg.message != NULL)
413 pfree(change->data.msg.message);
414 change->data.msg.message = NULL;
415 break;
416 case REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT:
417 if (change->data.snapshot)
418 {
419 ReorderBufferFreeSnap(rb, change->data.snapshot);
420 change->data.snapshot = NULL;
421 }
422 break;
423 /* no data in addition to the struct itself */
424 case REORDER_BUFFER_CHANGE_TRUNCATE:
425 if (change->data.truncate.relids != NULL)
426 {
427 ReorderBufferReturnRelids(rb, change->data.truncate.relids);
428 change->data.truncate.relids = NULL;
429 }
430 break;
431 case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_CONFIRM:
432 case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_ABORT:
433 case REORDER_BUFFER_CHANGE_INTERNAL_COMMAND_ID:
434 case REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID:
435 break;
436 }
437
438 pfree(change);
439 }
440
441 /*
442 * Get a fresh ReorderBufferTupleBuf fitting at least a tuple of size
443 * tuple_len (excluding header overhead).
444 */
445 ReorderBufferTupleBuf *
ReorderBufferGetTupleBuf(ReorderBuffer * rb,Size tuple_len)446 ReorderBufferGetTupleBuf(ReorderBuffer *rb, Size tuple_len)
447 {
448 ReorderBufferTupleBuf *tuple;
449 Size alloc_len;
450
451 alloc_len = tuple_len + SizeofHeapTupleHeader;
452
453 tuple = (ReorderBufferTupleBuf *)
454 MemoryContextAlloc(rb->tup_context,
455 sizeof(ReorderBufferTupleBuf) +
456 MAXIMUM_ALIGNOF + alloc_len);
457 tuple->alloc_tuple_size = alloc_len;
458 tuple->tuple.t_data = ReorderBufferTupleBufData(tuple);
459
460 return tuple;
461 }
462
463 /*
464 * Free an ReorderBufferTupleBuf.
465 */
466 void
ReorderBufferReturnTupleBuf(ReorderBuffer * rb,ReorderBufferTupleBuf * tuple)467 ReorderBufferReturnTupleBuf(ReorderBuffer *rb, ReorderBufferTupleBuf *tuple)
468 {
469 pfree(tuple);
470 }
471
472 /*
473 * Get an array for relids of truncated relations.
474 *
475 * We use the global memory context (for the whole reorder buffer), because
476 * none of the existing ones seems like a good match (some are SLAB, so we
477 * can't use those, and tup_context is meant for tuple data, not relids). We
478 * could add yet another context, but it seems like an overkill - TRUNCATE is
479 * not particularly common operation, so it does not seem worth it.
480 */
481 Oid *
ReorderBufferGetRelids(ReorderBuffer * rb,int nrelids)482 ReorderBufferGetRelids(ReorderBuffer *rb, int nrelids)
483 {
484 Oid *relids;
485 Size alloc_len;
486
487 alloc_len = sizeof(Oid) * nrelids;
488
489 relids = (Oid *) MemoryContextAlloc(rb->context, alloc_len);
490
491 return relids;
492 }
493
494 /*
495 * Free an array of relids.
496 */
497 void
ReorderBufferReturnRelids(ReorderBuffer * rb,Oid * relids)498 ReorderBufferReturnRelids(ReorderBuffer *rb, Oid *relids)
499 {
500 pfree(relids);
501 }
502
503 /*
504 * Return the ReorderBufferTXN from the given buffer, specified by Xid.
505 * If create is true, and a transaction doesn't already exist, create it
506 * (with the given LSN, and as top transaction if that's specified);
507 * when this happens, is_new is set to true.
508 */
509 static ReorderBufferTXN *
ReorderBufferTXNByXid(ReorderBuffer * rb,TransactionId xid,bool create,bool * is_new,XLogRecPtr lsn,bool create_as_top)510 ReorderBufferTXNByXid(ReorderBuffer *rb, TransactionId xid, bool create,
511 bool *is_new, XLogRecPtr lsn, bool create_as_top)
512 {
513 ReorderBufferTXN *txn;
514 ReorderBufferTXNByIdEnt *ent;
515 bool found;
516
517 Assert(TransactionIdIsValid(xid));
518
519 /*
520 * Check the one-entry lookup cache first
521 */
522 if (TransactionIdIsValid(rb->by_txn_last_xid) &&
523 rb->by_txn_last_xid == xid)
524 {
525 txn = rb->by_txn_last_txn;
526
527 if (txn != NULL)
528 {
529 /* found it, and it's valid */
530 if (is_new)
531 *is_new = false;
532 return txn;
533 }
534
535 /*
536 * cached as non-existent, and asked not to create? Then nothing else
537 * to do.
538 */
539 if (!create)
540 return NULL;
541 /* otherwise fall through to create it */
542 }
543
544 /*
545 * If the cache wasn't hit or it yielded an "does-not-exist" and we want
546 * to create an entry.
547 */
548
549 /* search the lookup table */
550 ent = (ReorderBufferTXNByIdEnt *)
551 hash_search(rb->by_txn,
552 (void *) &xid,
553 create ? HASH_ENTER : HASH_FIND,
554 &found);
555 if (found)
556 txn = ent->txn;
557 else if (create)
558 {
559 /* initialize the new entry, if creation was requested */
560 Assert(ent != NULL);
561 Assert(lsn != InvalidXLogRecPtr);
562
563 ent->txn = ReorderBufferGetTXN(rb);
564 ent->txn->xid = xid;
565 txn = ent->txn;
566 txn->first_lsn = lsn;
567 txn->restart_decoding_lsn = rb->current_restart_decoding_lsn;
568
569 if (create_as_top)
570 {
571 dlist_push_tail(&rb->toplevel_by_lsn, &txn->node);
572 AssertTXNLsnOrder(rb);
573 }
574 }
575 else
576 txn = NULL; /* not found and not asked to create */
577
578 /* update cache */
579 rb->by_txn_last_xid = xid;
580 rb->by_txn_last_txn = txn;
581
582 if (is_new)
583 *is_new = !found;
584
585 Assert(!create || txn != NULL);
586 return txn;
587 }
588
589 /*
590 * Queue a change into a transaction so it can be replayed upon commit.
591 */
592 void
ReorderBufferQueueChange(ReorderBuffer * rb,TransactionId xid,XLogRecPtr lsn,ReorderBufferChange * change)593 ReorderBufferQueueChange(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn,
594 ReorderBufferChange *change)
595 {
596 ReorderBufferTXN *txn;
597
598 txn = ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
599
600 change->lsn = lsn;
601 Assert(InvalidXLogRecPtr != lsn);
602 dlist_push_tail(&txn->changes, &change->node);
603 txn->nentries++;
604 txn->nentries_mem++;
605
606 ReorderBufferCheckSerializeTXN(rb, txn);
607 }
608
609 /*
610 * Queue message into a transaction so it can be processed upon commit.
611 */
612 void
ReorderBufferQueueMessage(ReorderBuffer * rb,TransactionId xid,Snapshot snapshot,XLogRecPtr lsn,bool transactional,const char * prefix,Size message_size,const char * message)613 ReorderBufferQueueMessage(ReorderBuffer *rb, TransactionId xid,
614 Snapshot snapshot, XLogRecPtr lsn,
615 bool transactional, const char *prefix,
616 Size message_size, const char *message)
617 {
618 if (transactional)
619 {
620 MemoryContext oldcontext;
621 ReorderBufferChange *change;
622
623 Assert(xid != InvalidTransactionId);
624
625 oldcontext = MemoryContextSwitchTo(rb->context);
626
627 change = ReorderBufferGetChange(rb);
628 change->action = REORDER_BUFFER_CHANGE_MESSAGE;
629 change->data.msg.prefix = pstrdup(prefix);
630 change->data.msg.message_size = message_size;
631 change->data.msg.message = palloc(message_size);
632 memcpy(change->data.msg.message, message, message_size);
633
634 ReorderBufferQueueChange(rb, xid, lsn, change);
635
636 MemoryContextSwitchTo(oldcontext);
637 }
638 else
639 {
640 ReorderBufferTXN *txn = NULL;
641 volatile Snapshot snapshot_now = snapshot;
642
643 if (xid != InvalidTransactionId)
644 txn = ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
645
646 /* setup snapshot to allow catalog access */
647 SetupHistoricSnapshot(snapshot_now, NULL);
648 PG_TRY();
649 {
650 rb->message(rb, txn, lsn, false, prefix, message_size, message);
651
652 TeardownHistoricSnapshot(false);
653 }
654 PG_CATCH();
655 {
656 TeardownHistoricSnapshot(true);
657 PG_RE_THROW();
658 }
659 PG_END_TRY();
660 }
661 }
662
663 /*
664 * AssertTXNLsnOrder
665 * Verify LSN ordering of transaction lists in the reorderbuffer
666 *
667 * Other LSN-related invariants are checked too.
668 *
669 * No-op if assertions are not in use.
670 */
671 static void
AssertTXNLsnOrder(ReorderBuffer * rb)672 AssertTXNLsnOrder(ReorderBuffer *rb)
673 {
674 #ifdef USE_ASSERT_CHECKING
675 dlist_iter iter;
676 XLogRecPtr prev_first_lsn = InvalidXLogRecPtr;
677 XLogRecPtr prev_base_snap_lsn = InvalidXLogRecPtr;
678
679 dlist_foreach(iter, &rb->toplevel_by_lsn)
680 {
681 ReorderBufferTXN *cur_txn = dlist_container(ReorderBufferTXN, node,
682 iter.cur);
683
684 /* start LSN must be set */
685 Assert(cur_txn->first_lsn != InvalidXLogRecPtr);
686
687 /* If there is an end LSN, it must be higher than start LSN */
688 if (cur_txn->end_lsn != InvalidXLogRecPtr)
689 Assert(cur_txn->first_lsn <= cur_txn->end_lsn);
690
691 /* Current initial LSN must be strictly higher than previous */
692 if (prev_first_lsn != InvalidXLogRecPtr)
693 Assert(prev_first_lsn < cur_txn->first_lsn);
694
695 /* known-as-subtxn txns must not be listed */
696 Assert(!cur_txn->is_known_as_subxact);
697
698 prev_first_lsn = cur_txn->first_lsn;
699 }
700
701 dlist_foreach(iter, &rb->txns_by_base_snapshot_lsn)
702 {
703 ReorderBufferTXN *cur_txn = dlist_container(ReorderBufferTXN,
704 base_snapshot_node,
705 iter.cur);
706
707 /* base snapshot (and its LSN) must be set */
708 Assert(cur_txn->base_snapshot != NULL);
709 Assert(cur_txn->base_snapshot_lsn != InvalidXLogRecPtr);
710
711 /* current LSN must be strictly higher than previous */
712 if (prev_base_snap_lsn != InvalidXLogRecPtr)
713 Assert(prev_base_snap_lsn < cur_txn->base_snapshot_lsn);
714
715 /* known-as-subtxn txns must not be listed */
716 Assert(!cur_txn->is_known_as_subxact);
717
718 prev_base_snap_lsn = cur_txn->base_snapshot_lsn;
719 }
720 #endif
721 }
722
723 /*
724 * ReorderBufferGetOldestTXN
725 * Return oldest transaction in reorderbuffer
726 */
727 ReorderBufferTXN *
ReorderBufferGetOldestTXN(ReorderBuffer * rb)728 ReorderBufferGetOldestTXN(ReorderBuffer *rb)
729 {
730 ReorderBufferTXN *txn;
731
732 AssertTXNLsnOrder(rb);
733
734 if (dlist_is_empty(&rb->toplevel_by_lsn))
735 return NULL;
736
737 txn = dlist_head_element(ReorderBufferTXN, node, &rb->toplevel_by_lsn);
738
739 Assert(!txn->is_known_as_subxact);
740 Assert(txn->first_lsn != InvalidXLogRecPtr);
741 return txn;
742 }
743
744 /*
745 * ReorderBufferGetOldestXmin
746 * Return oldest Xmin in reorderbuffer
747 *
748 * Returns oldest possibly running Xid from the point of view of snapshots
749 * used in the transactions kept by reorderbuffer, or InvalidTransactionId if
750 * there are none.
751 *
752 * Since snapshots are assigned monotonically, this equals the Xmin of the
753 * base snapshot with minimal base_snapshot_lsn.
754 */
755 TransactionId
ReorderBufferGetOldestXmin(ReorderBuffer * rb)756 ReorderBufferGetOldestXmin(ReorderBuffer *rb)
757 {
758 ReorderBufferTXN *txn;
759
760 AssertTXNLsnOrder(rb);
761
762 if (dlist_is_empty(&rb->txns_by_base_snapshot_lsn))
763 return InvalidTransactionId;
764
765 txn = dlist_head_element(ReorderBufferTXN, base_snapshot_node,
766 &rb->txns_by_base_snapshot_lsn);
767 return txn->base_snapshot->xmin;
768 }
769
770 void
ReorderBufferSetRestartPoint(ReorderBuffer * rb,XLogRecPtr ptr)771 ReorderBufferSetRestartPoint(ReorderBuffer *rb, XLogRecPtr ptr)
772 {
773 rb->current_restart_decoding_lsn = ptr;
774 }
775
776 /*
777 * ReorderBufferAssignChild
778 *
779 * Make note that we know that subxid is a subtransaction of xid, seen as of
780 * the given lsn.
781 */
782 void
ReorderBufferAssignChild(ReorderBuffer * rb,TransactionId xid,TransactionId subxid,XLogRecPtr lsn)783 ReorderBufferAssignChild(ReorderBuffer *rb, TransactionId xid,
784 TransactionId subxid, XLogRecPtr lsn)
785 {
786 ReorderBufferTXN *txn;
787 ReorderBufferTXN *subtxn;
788 bool new_top;
789 bool new_sub;
790
791 txn = ReorderBufferTXNByXid(rb, xid, true, &new_top, lsn, true);
792 subtxn = ReorderBufferTXNByXid(rb, subxid, true, &new_sub, lsn, false);
793
794 if (!new_sub)
795 {
796 if (subtxn->is_known_as_subxact)
797 {
798 /* already associated, nothing to do */
799 return;
800 }
801 else
802 {
803 /*
804 * We already saw this transaction, but initially added it to the
805 * list of top-level txns. Now that we know it's not top-level,
806 * remove it from there.
807 */
808 dlist_delete(&subtxn->node);
809 }
810 }
811
812 subtxn->is_known_as_subxact = true;
813 subtxn->toplevel_xid = xid;
814 Assert(subtxn->nsubtxns == 0);
815
816 /* add to subtransaction list */
817 dlist_push_tail(&txn->subtxns, &subtxn->node);
818 txn->nsubtxns++;
819
820 /* Possibly transfer the subtxn's snapshot to its top-level txn. */
821 ReorderBufferTransferSnapToParent(txn, subtxn);
822
823 /* Verify LSN-ordering invariant */
824 AssertTXNLsnOrder(rb);
825 }
826
827 /*
828 * ReorderBufferTransferSnapToParent
829 * Transfer base snapshot from subtxn to top-level txn, if needed
830 *
831 * This is done if the top-level txn doesn't have a base snapshot, or if the
832 * subtxn's base snapshot has an earlier LSN than the top-level txn's base
833 * snapshot's LSN. This can happen if there are no changes in the toplevel
834 * txn but there are some in the subtxn, or the first change in subtxn has
835 * earlier LSN than first change in the top-level txn and we learned about
836 * their kinship only now.
837 *
838 * The subtransaction's snapshot is cleared regardless of the transfer
839 * happening, since it's not needed anymore in either case.
840 *
841 * We do this as soon as we become aware of their kinship, to avoid queueing
842 * extra snapshots to txns known-as-subtxns -- only top-level txns will
843 * receive further snapshots.
844 */
845 static void
ReorderBufferTransferSnapToParent(ReorderBufferTXN * txn,ReorderBufferTXN * subtxn)846 ReorderBufferTransferSnapToParent(ReorderBufferTXN *txn,
847 ReorderBufferTXN *subtxn)
848 {
849 Assert(subtxn->toplevel_xid == txn->xid);
850
851 if (subtxn->base_snapshot != NULL)
852 {
853 if (txn->base_snapshot == NULL ||
854 subtxn->base_snapshot_lsn < txn->base_snapshot_lsn)
855 {
856 /*
857 * If the toplevel transaction already has a base snapshot but
858 * it's newer than the subxact's, purge it.
859 */
860 if (txn->base_snapshot != NULL)
861 {
862 SnapBuildSnapDecRefcount(txn->base_snapshot);
863 dlist_delete(&txn->base_snapshot_node);
864 }
865
866 /*
867 * The snapshot is now the top transaction's; transfer it, and
868 * adjust the list position of the top transaction in the list by
869 * moving it to where the subtransaction is.
870 */
871 txn->base_snapshot = subtxn->base_snapshot;
872 txn->base_snapshot_lsn = subtxn->base_snapshot_lsn;
873 dlist_insert_before(&subtxn->base_snapshot_node,
874 &txn->base_snapshot_node);
875
876 /*
877 * The subtransaction doesn't have a snapshot anymore (so it
878 * mustn't be in the list.)
879 */
880 subtxn->base_snapshot = NULL;
881 subtxn->base_snapshot_lsn = InvalidXLogRecPtr;
882 dlist_delete(&subtxn->base_snapshot_node);
883 }
884 else
885 {
886 /* Base snap of toplevel is fine, so subxact's is not needed */
887 SnapBuildSnapDecRefcount(subtxn->base_snapshot);
888 dlist_delete(&subtxn->base_snapshot_node);
889 subtxn->base_snapshot = NULL;
890 subtxn->base_snapshot_lsn = InvalidXLogRecPtr;
891 }
892 }
893 }
894
895 /*
896 * Associate a subtransaction with its toplevel transaction at commit
897 * time. There may be no further changes added after this.
898 */
899 void
ReorderBufferCommitChild(ReorderBuffer * rb,TransactionId xid,TransactionId subxid,XLogRecPtr commit_lsn,XLogRecPtr end_lsn)900 ReorderBufferCommitChild(ReorderBuffer *rb, TransactionId xid,
901 TransactionId subxid, XLogRecPtr commit_lsn,
902 XLogRecPtr end_lsn)
903 {
904 ReorderBufferTXN *subtxn;
905
906 subtxn = ReorderBufferTXNByXid(rb, subxid, false, NULL,
907 InvalidXLogRecPtr, false);
908
909 /*
910 * No need to do anything if that subtxn didn't contain any changes
911 */
912 if (!subtxn)
913 return;
914
915 subtxn->final_lsn = commit_lsn;
916 subtxn->end_lsn = end_lsn;
917
918 /*
919 * Assign this subxact as a child of the toplevel xact (no-op if already
920 * done.)
921 */
922 ReorderBufferAssignChild(rb, xid, subxid, InvalidXLogRecPtr);
923 }
924
925
926 /*
927 * Support for efficiently iterating over a transaction's and its
928 * subtransactions' changes.
929 *
930 * We do by doing a k-way merge between transactions/subtransactions. For that
931 * we model the current heads of the different transactions as a binary heap
932 * so we easily know which (sub-)transaction has the change with the smallest
933 * lsn next.
934 *
935 * We assume the changes in individual transactions are already sorted by LSN.
936 */
937
938 /*
939 * Binary heap comparison function.
940 */
941 static int
ReorderBufferIterCompare(Datum a,Datum b,void * arg)942 ReorderBufferIterCompare(Datum a, Datum b, void *arg)
943 {
944 ReorderBufferIterTXNState *state = (ReorderBufferIterTXNState *) arg;
945 XLogRecPtr pos_a = state->entries[DatumGetInt32(a)].lsn;
946 XLogRecPtr pos_b = state->entries[DatumGetInt32(b)].lsn;
947
948 if (pos_a < pos_b)
949 return 1;
950 else if (pos_a == pos_b)
951 return 0;
952 return -1;
953 }
954
955 /*
956 * Allocate & initialize an iterator which iterates in lsn order over a
957 * transaction and all its subtransactions.
958 *
959 * Note: The iterator state is returned through iter_state parameter rather
960 * than the function's return value. This is because the state gets cleaned up
961 * in a PG_CATCH block in the caller, so we want to make sure the caller gets
962 * back the state even if this function throws an exception.
963 */
964 static void
ReorderBufferIterTXNInit(ReorderBuffer * rb,ReorderBufferTXN * txn,ReorderBufferIterTXNState * volatile * iter_state)965 ReorderBufferIterTXNInit(ReorderBuffer *rb, ReorderBufferTXN *txn,
966 ReorderBufferIterTXNState *volatile *iter_state)
967 {
968 Size nr_txns = 0;
969 ReorderBufferIterTXNState *state;
970 dlist_iter cur_txn_i;
971 int32 off;
972
973 *iter_state = NULL;
974
975 /*
976 * Calculate the size of our heap: one element for every transaction that
977 * contains changes. (Besides the transactions already in the reorder
978 * buffer, we count the one we were directly passed.)
979 */
980 if (txn->nentries > 0)
981 nr_txns++;
982
983 dlist_foreach(cur_txn_i, &txn->subtxns)
984 {
985 ReorderBufferTXN *cur_txn;
986
987 cur_txn = dlist_container(ReorderBufferTXN, node, cur_txn_i.cur);
988
989 if (cur_txn->nentries > 0)
990 nr_txns++;
991 }
992
993 /*
994 * TODO: Consider adding fastpath for the rather common nr_txns=1 case, no
995 * need to allocate/build a heap then.
996 */
997
998 /* allocate iteration state */
999 state = (ReorderBufferIterTXNState *)
1000 MemoryContextAllocZero(rb->context,
1001 sizeof(ReorderBufferIterTXNState) +
1002 sizeof(ReorderBufferIterTXNEntry) * nr_txns);
1003
1004 state->nr_txns = nr_txns;
1005 dlist_init(&state->old_change);
1006
1007 for (off = 0; off < state->nr_txns; off++)
1008 {
1009 state->entries[off].file.vfd = -1;
1010 state->entries[off].segno = 0;
1011 }
1012
1013 /* allocate heap */
1014 state->heap = binaryheap_allocate(state->nr_txns,
1015 ReorderBufferIterCompare,
1016 state);
1017
1018 /* Now that the state fields are initialized, it is safe to return it. */
1019 *iter_state = state;
1020
1021 /*
1022 * Now insert items into the binary heap, in an unordered fashion. (We
1023 * will run a heap assembly step at the end; this is more efficient.)
1024 */
1025
1026 off = 0;
1027
1028 /* add toplevel transaction if it contains changes */
1029 if (txn->nentries > 0)
1030 {
1031 ReorderBufferChange *cur_change;
1032
1033 if (txn->serialized)
1034 {
1035 /* serialize remaining changes */
1036 ReorderBufferSerializeTXN(rb, txn);
1037 ReorderBufferRestoreChanges(rb, txn, &state->entries[off].file,
1038 &state->entries[off].segno);
1039 }
1040
1041 cur_change = dlist_head_element(ReorderBufferChange, node,
1042 &txn->changes);
1043
1044 state->entries[off].lsn = cur_change->lsn;
1045 state->entries[off].change = cur_change;
1046 state->entries[off].txn = txn;
1047
1048 binaryheap_add_unordered(state->heap, Int32GetDatum(off++));
1049 }
1050
1051 /* add subtransactions if they contain changes */
1052 dlist_foreach(cur_txn_i, &txn->subtxns)
1053 {
1054 ReorderBufferTXN *cur_txn;
1055
1056 cur_txn = dlist_container(ReorderBufferTXN, node, cur_txn_i.cur);
1057
1058 if (cur_txn->nentries > 0)
1059 {
1060 ReorderBufferChange *cur_change;
1061
1062 if (cur_txn->serialized)
1063 {
1064 /* serialize remaining changes */
1065 ReorderBufferSerializeTXN(rb, cur_txn);
1066 ReorderBufferRestoreChanges(rb, cur_txn,
1067 &state->entries[off].file,
1068 &state->entries[off].segno);
1069 }
1070 cur_change = dlist_head_element(ReorderBufferChange, node,
1071 &cur_txn->changes);
1072
1073 state->entries[off].lsn = cur_change->lsn;
1074 state->entries[off].change = cur_change;
1075 state->entries[off].txn = cur_txn;
1076
1077 binaryheap_add_unordered(state->heap, Int32GetDatum(off++));
1078 }
1079 }
1080
1081 /* assemble a valid binary heap */
1082 binaryheap_build(state->heap);
1083 }
1084
1085 /*
1086 * Return the next change when iterating over a transaction and its
1087 * subtransactions.
1088 *
1089 * Returns NULL when no further changes exist.
1090 */
1091 static ReorderBufferChange *
ReorderBufferIterTXNNext(ReorderBuffer * rb,ReorderBufferIterTXNState * state)1092 ReorderBufferIterTXNNext(ReorderBuffer *rb, ReorderBufferIterTXNState *state)
1093 {
1094 ReorderBufferChange *change;
1095 ReorderBufferIterTXNEntry *entry;
1096 int32 off;
1097
1098 /* nothing there anymore */
1099 if (state->heap->bh_size == 0)
1100 return NULL;
1101
1102 off = DatumGetInt32(binaryheap_first(state->heap));
1103 entry = &state->entries[off];
1104
1105 /* free memory we might have "leaked" in the previous *Next call */
1106 if (!dlist_is_empty(&state->old_change))
1107 {
1108 change = dlist_container(ReorderBufferChange, node,
1109 dlist_pop_head_node(&state->old_change));
1110 ReorderBufferReturnChange(rb, change);
1111 Assert(dlist_is_empty(&state->old_change));
1112 }
1113
1114 change = entry->change;
1115
1116 /*
1117 * update heap with information about which transaction has the next
1118 * relevant change in LSN order
1119 */
1120
1121 /* there are in-memory changes */
1122 if (dlist_has_next(&entry->txn->changes, &entry->change->node))
1123 {
1124 dlist_node *next = dlist_next_node(&entry->txn->changes, &change->node);
1125 ReorderBufferChange *next_change =
1126 dlist_container(ReorderBufferChange, node, next);
1127
1128 /* txn stays the same */
1129 state->entries[off].lsn = next_change->lsn;
1130 state->entries[off].change = next_change;
1131
1132 binaryheap_replace_first(state->heap, Int32GetDatum(off));
1133 return change;
1134 }
1135
1136 /* try to load changes from disk */
1137 if (entry->txn->nentries != entry->txn->nentries_mem)
1138 {
1139 /*
1140 * Ugly: restoring changes will reuse *Change records, thus delete the
1141 * current one from the per-tx list and only free in the next call.
1142 */
1143 dlist_delete(&change->node);
1144 dlist_push_tail(&state->old_change, &change->node);
1145
1146 if (ReorderBufferRestoreChanges(rb, entry->txn, &entry->file,
1147 &state->entries[off].segno))
1148 {
1149 /* successfully restored changes from disk */
1150 ReorderBufferChange *next_change =
1151 dlist_head_element(ReorderBufferChange, node,
1152 &entry->txn->changes);
1153
1154 elog(DEBUG2, "restored %u/%u changes from disk",
1155 (uint32) entry->txn->nentries_mem,
1156 (uint32) entry->txn->nentries);
1157
1158 Assert(entry->txn->nentries_mem);
1159 /* txn stays the same */
1160 state->entries[off].lsn = next_change->lsn;
1161 state->entries[off].change = next_change;
1162 binaryheap_replace_first(state->heap, Int32GetDatum(off));
1163
1164 return change;
1165 }
1166 }
1167
1168 /* ok, no changes there anymore, remove */
1169 binaryheap_remove_first(state->heap);
1170
1171 return change;
1172 }
1173
1174 /*
1175 * Deallocate the iterator
1176 */
1177 static void
ReorderBufferIterTXNFinish(ReorderBuffer * rb,ReorderBufferIterTXNState * state)1178 ReorderBufferIterTXNFinish(ReorderBuffer *rb,
1179 ReorderBufferIterTXNState *state)
1180 {
1181 int32 off;
1182
1183 for (off = 0; off < state->nr_txns; off++)
1184 {
1185 if (state->entries[off].file.vfd != -1)
1186 FileClose(state->entries[off].file.vfd);
1187 }
1188
1189 /* free memory we might have "leaked" in the last *Next call */
1190 if (!dlist_is_empty(&state->old_change))
1191 {
1192 ReorderBufferChange *change;
1193
1194 change = dlist_container(ReorderBufferChange, node,
1195 dlist_pop_head_node(&state->old_change));
1196 ReorderBufferReturnChange(rb, change);
1197 Assert(dlist_is_empty(&state->old_change));
1198 }
1199
1200 binaryheap_free(state->heap);
1201 pfree(state);
1202 }
1203
1204 /*
1205 * Cleanup the contents of a transaction, usually after the transaction
1206 * committed or aborted.
1207 */
1208 static void
ReorderBufferCleanupTXN(ReorderBuffer * rb,ReorderBufferTXN * txn)1209 ReorderBufferCleanupTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
1210 {
1211 bool found;
1212 dlist_mutable_iter iter;
1213
1214 /* cleanup subtransactions & their changes */
1215 dlist_foreach_modify(iter, &txn->subtxns)
1216 {
1217 ReorderBufferTXN *subtxn;
1218
1219 subtxn = dlist_container(ReorderBufferTXN, node, iter.cur);
1220
1221 /*
1222 * Subtransactions are always associated to the toplevel TXN, even if
1223 * they originally were happening inside another subtxn, so we won't
1224 * ever recurse more than one level deep here.
1225 */
1226 Assert(subtxn->is_known_as_subxact);
1227 Assert(subtxn->nsubtxns == 0);
1228
1229 ReorderBufferCleanupTXN(rb, subtxn);
1230 }
1231
1232 /* cleanup changes in the toplevel txn */
1233 dlist_foreach_modify(iter, &txn->changes)
1234 {
1235 ReorderBufferChange *change;
1236
1237 change = dlist_container(ReorderBufferChange, node, iter.cur);
1238
1239 ReorderBufferReturnChange(rb, change);
1240 }
1241
1242 /*
1243 * Cleanup the tuplecids we stored for decoding catalog snapshot access.
1244 * They are always stored in the toplevel transaction.
1245 */
1246 dlist_foreach_modify(iter, &txn->tuplecids)
1247 {
1248 ReorderBufferChange *change;
1249
1250 change = dlist_container(ReorderBufferChange, node, iter.cur);
1251 Assert(change->action == REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID);
1252 ReorderBufferReturnChange(rb, change);
1253 }
1254
1255 /*
1256 * Cleanup the base snapshot, if set.
1257 */
1258 if (txn->base_snapshot != NULL)
1259 {
1260 SnapBuildSnapDecRefcount(txn->base_snapshot);
1261 dlist_delete(&txn->base_snapshot_node);
1262 }
1263
1264 /*
1265 * Remove TXN from its containing list.
1266 *
1267 * Note: if txn->is_known_as_subxact, we are deleting the TXN from its
1268 * parent's list of known subxacts; this leaves the parent's nsubxacts
1269 * count too high, but we don't care. Otherwise, we are deleting the TXN
1270 * from the LSN-ordered list of toplevel TXNs.
1271 */
1272 dlist_delete(&txn->node);
1273
1274 /* now remove reference from buffer */
1275 hash_search(rb->by_txn,
1276 (void *) &txn->xid,
1277 HASH_REMOVE,
1278 &found);
1279 Assert(found);
1280
1281 /* remove entries spilled to disk */
1282 if (txn->serialized)
1283 ReorderBufferRestoreCleanup(rb, txn);
1284
1285 /* deallocate */
1286 ReorderBufferReturnTXN(rb, txn);
1287 }
1288
1289 /*
1290 * Build a hash with a (relfilenode, ctid) -> (cmin, cmax) mapping for use by
1291 * HeapTupleSatisfiesHistoricMVCC.
1292 */
1293 static void
ReorderBufferBuildTupleCidHash(ReorderBuffer * rb,ReorderBufferTXN * txn)1294 ReorderBufferBuildTupleCidHash(ReorderBuffer *rb, ReorderBufferTXN *txn)
1295 {
1296 dlist_iter iter;
1297 HASHCTL hash_ctl;
1298
1299 if (!txn->has_catalog_changes || dlist_is_empty(&txn->tuplecids))
1300 return;
1301
1302 memset(&hash_ctl, 0, sizeof(hash_ctl));
1303
1304 hash_ctl.keysize = sizeof(ReorderBufferTupleCidKey);
1305 hash_ctl.entrysize = sizeof(ReorderBufferTupleCidEnt);
1306 hash_ctl.hcxt = rb->context;
1307
1308 /*
1309 * create the hash with the exact number of to-be-stored tuplecids from
1310 * the start
1311 */
1312 txn->tuplecid_hash =
1313 hash_create("ReorderBufferTupleCid", txn->ntuplecids, &hash_ctl,
1314 HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
1315
1316 dlist_foreach(iter, &txn->tuplecids)
1317 {
1318 ReorderBufferTupleCidKey key;
1319 ReorderBufferTupleCidEnt *ent;
1320 bool found;
1321 ReorderBufferChange *change;
1322
1323 change = dlist_container(ReorderBufferChange, node, iter.cur);
1324
1325 Assert(change->action == REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID);
1326
1327 /* be careful about padding */
1328 memset(&key, 0, sizeof(ReorderBufferTupleCidKey));
1329
1330 key.relnode = change->data.tuplecid.node;
1331
1332 ItemPointerCopy(&change->data.tuplecid.tid,
1333 &key.tid);
1334
1335 ent = (ReorderBufferTupleCidEnt *)
1336 hash_search(txn->tuplecid_hash,
1337 (void *) &key,
1338 HASH_ENTER,
1339 &found);
1340 if (!found)
1341 {
1342 ent->cmin = change->data.tuplecid.cmin;
1343 ent->cmax = change->data.tuplecid.cmax;
1344 ent->combocid = change->data.tuplecid.combocid;
1345 }
1346 else
1347 {
1348 /*
1349 * Maybe we already saw this tuple before in this transaction, but
1350 * if so it must have the same cmin.
1351 */
1352 Assert(ent->cmin == change->data.tuplecid.cmin);
1353
1354 /*
1355 * cmax may be initially invalid, but once set it can only grow,
1356 * and never become invalid again.
1357 */
1358 Assert((ent->cmax == InvalidCommandId) ||
1359 ((change->data.tuplecid.cmax != InvalidCommandId) &&
1360 (change->data.tuplecid.cmax > ent->cmax)));
1361 ent->cmax = change->data.tuplecid.cmax;
1362 }
1363 }
1364 }
1365
1366 /*
1367 * Copy a provided snapshot so we can modify it privately. This is needed so
1368 * that catalog modifying transactions can look into intermediate catalog
1369 * states.
1370 */
1371 static Snapshot
ReorderBufferCopySnap(ReorderBuffer * rb,Snapshot orig_snap,ReorderBufferTXN * txn,CommandId cid)1372 ReorderBufferCopySnap(ReorderBuffer *rb, Snapshot orig_snap,
1373 ReorderBufferTXN *txn, CommandId cid)
1374 {
1375 Snapshot snap;
1376 dlist_iter iter;
1377 int i = 0;
1378 Size size;
1379
1380 size = sizeof(SnapshotData) +
1381 sizeof(TransactionId) * orig_snap->xcnt +
1382 sizeof(TransactionId) * (txn->nsubtxns + 1);
1383
1384 snap = MemoryContextAllocZero(rb->context, size);
1385 memcpy(snap, orig_snap, sizeof(SnapshotData));
1386
1387 snap->copied = true;
1388 snap->active_count = 1; /* mark as active so nobody frees it */
1389 snap->regd_count = 0;
1390 snap->xip = (TransactionId *) (snap + 1);
1391
1392 memcpy(snap->xip, orig_snap->xip, sizeof(TransactionId) * snap->xcnt);
1393
1394 /*
1395 * snap->subxip contains all txids that belong to our transaction which we
1396 * need to check via cmin/cmax. That's why we store the toplevel
1397 * transaction in there as well.
1398 */
1399 snap->subxip = snap->xip + snap->xcnt;
1400 snap->subxip[i++] = txn->xid;
1401
1402 /*
1403 * nsubxcnt isn't decreased when subtransactions abort, so count manually.
1404 * Since it's an upper boundary it is safe to use it for the allocation
1405 * above.
1406 */
1407 snap->subxcnt = 1;
1408
1409 dlist_foreach(iter, &txn->subtxns)
1410 {
1411 ReorderBufferTXN *sub_txn;
1412
1413 sub_txn = dlist_container(ReorderBufferTXN, node, iter.cur);
1414 snap->subxip[i++] = sub_txn->xid;
1415 snap->subxcnt++;
1416 }
1417
1418 /* sort so we can bsearch() later */
1419 qsort(snap->subxip, snap->subxcnt, sizeof(TransactionId), xidComparator);
1420
1421 /* store the specified current CommandId */
1422 snap->curcid = cid;
1423
1424 return snap;
1425 }
1426
1427 /*
1428 * Free a previously ReorderBufferCopySnap'ed snapshot
1429 */
1430 static void
ReorderBufferFreeSnap(ReorderBuffer * rb,Snapshot snap)1431 ReorderBufferFreeSnap(ReorderBuffer *rb, Snapshot snap)
1432 {
1433 if (snap->copied)
1434 pfree(snap);
1435 else
1436 SnapBuildSnapDecRefcount(snap);
1437 }
1438
1439 /*
1440 * Perform the replay of a transaction and its non-aborted subtransactions.
1441 *
1442 * Subtransactions previously have to be processed by
1443 * ReorderBufferCommitChild(), even if previously assigned to the toplevel
1444 * transaction with ReorderBufferAssignChild.
1445 *
1446 * We currently can only decode a transaction's contents when its commit
1447 * record is read because that's the only place where we know about cache
1448 * invalidations. Thus, once a toplevel commit is read, we iterate over the top
1449 * and subtransactions (using a k-way merge) and replay the changes in lsn
1450 * order.
1451 */
1452 void
ReorderBufferCommit(ReorderBuffer * rb,TransactionId xid,XLogRecPtr commit_lsn,XLogRecPtr end_lsn,TimestampTz commit_time,RepOriginId origin_id,XLogRecPtr origin_lsn)1453 ReorderBufferCommit(ReorderBuffer *rb, TransactionId xid,
1454 XLogRecPtr commit_lsn, XLogRecPtr end_lsn,
1455 TimestampTz commit_time,
1456 RepOriginId origin_id, XLogRecPtr origin_lsn)
1457 {
1458 ReorderBufferTXN *txn;
1459 volatile Snapshot snapshot_now;
1460 volatile CommandId command_id = FirstCommandId;
1461 bool using_subtxn;
1462 ReorderBufferIterTXNState *volatile iterstate = NULL;
1463
1464 txn = ReorderBufferTXNByXid(rb, xid, false, NULL, InvalidXLogRecPtr,
1465 false);
1466
1467 /* unknown transaction, nothing to replay */
1468 if (txn == NULL)
1469 return;
1470
1471 txn->final_lsn = commit_lsn;
1472 txn->end_lsn = end_lsn;
1473 txn->commit_time = commit_time;
1474 txn->origin_id = origin_id;
1475 txn->origin_lsn = origin_lsn;
1476
1477 /*
1478 * If this transaction has no snapshot, it didn't make any changes to the
1479 * database, so there's nothing to decode. Note that
1480 * ReorderBufferCommitChild will have transferred any snapshots from
1481 * subtransactions if there were any.
1482 */
1483 if (txn->base_snapshot == NULL)
1484 {
1485 Assert(txn->ninvalidations == 0);
1486 ReorderBufferCleanupTXN(rb, txn);
1487 return;
1488 }
1489
1490 snapshot_now = txn->base_snapshot;
1491
1492 /* build data to be able to lookup the CommandIds of catalog tuples */
1493 ReorderBufferBuildTupleCidHash(rb, txn);
1494
1495 /* setup the initial snapshot */
1496 SetupHistoricSnapshot(snapshot_now, txn->tuplecid_hash);
1497
1498 /*
1499 * Decoding needs access to syscaches et al., which in turn use
1500 * heavyweight locks and such. Thus we need to have enough state around to
1501 * keep track of those. The easiest way is to simply use a transaction
1502 * internally. That also allows us to easily enforce that nothing writes
1503 * to the database by checking for xid assignments.
1504 *
1505 * When we're called via the SQL SRF there's already a transaction
1506 * started, so start an explicit subtransaction there.
1507 */
1508 using_subtxn = IsTransactionOrTransactionBlock();
1509
1510 PG_TRY();
1511 {
1512 ReorderBufferChange *change;
1513 ReorderBufferChange *specinsert = NULL;
1514
1515 if (using_subtxn)
1516 BeginInternalSubTransaction("replay");
1517 else
1518 StartTransactionCommand();
1519
1520 rb->begin(rb, txn);
1521
1522 ReorderBufferIterTXNInit(rb, txn, &iterstate);
1523 while ((change = ReorderBufferIterTXNNext(rb, iterstate)) != NULL)
1524 {
1525 Relation relation = NULL;
1526 Oid reloid;
1527
1528 switch (change->action)
1529 {
1530 case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_CONFIRM:
1531
1532 /*
1533 * Confirmation for speculative insertion arrived. Simply
1534 * use as a normal record. It'll be cleaned up at the end
1535 * of INSERT processing.
1536 */
1537 if (specinsert == NULL)
1538 elog(ERROR, "invalid ordering of speculative insertion changes");
1539 Assert(specinsert->data.tp.oldtuple == NULL);
1540 change = specinsert;
1541 change->action = REORDER_BUFFER_CHANGE_INSERT;
1542
1543 /* intentionally fall through */
1544 case REORDER_BUFFER_CHANGE_INSERT:
1545 case REORDER_BUFFER_CHANGE_UPDATE:
1546 case REORDER_BUFFER_CHANGE_DELETE:
1547 Assert(snapshot_now);
1548
1549 reloid = RelidByRelfilenode(change->data.tp.relnode.spcNode,
1550 change->data.tp.relnode.relNode);
1551
1552 /*
1553 * Mapped catalog tuple without data, emitted while
1554 * catalog table was in the process of being rewritten. We
1555 * can fail to look up the relfilenode, because the
1556 * relmapper has no "historic" view, in contrast to normal
1557 * the normal catalog during decoding. Thus repeated
1558 * rewrites can cause a lookup failure. That's OK because
1559 * we do not decode catalog changes anyway. Normally such
1560 * tuples would be skipped over below, but we can't
1561 * identify whether the table should be logically logged
1562 * without mapping the relfilenode to the oid.
1563 */
1564 if (reloid == InvalidOid &&
1565 change->data.tp.newtuple == NULL &&
1566 change->data.tp.oldtuple == NULL)
1567 goto change_done;
1568 else if (reloid == InvalidOid)
1569 elog(ERROR, "could not map filenode \"%s\" to relation OID",
1570 relpathperm(change->data.tp.relnode,
1571 MAIN_FORKNUM));
1572
1573 relation = RelationIdGetRelation(reloid);
1574
1575 if (!RelationIsValid(relation))
1576 elog(ERROR, "could not open relation with OID %u (for filenode \"%s\")",
1577 reloid,
1578 relpathperm(change->data.tp.relnode,
1579 MAIN_FORKNUM));
1580
1581 if (!RelationIsLogicallyLogged(relation))
1582 goto change_done;
1583
1584 /*
1585 * Ignore temporary heaps created during DDL unless the
1586 * plugin has asked for them.
1587 */
1588 if (relation->rd_rel->relrewrite && !rb->output_rewrites)
1589 goto change_done;
1590
1591 /*
1592 * For now ignore sequence changes entirely. Most of the
1593 * time they don't log changes using records we
1594 * understand, so it doesn't make sense to handle the few
1595 * cases we do.
1596 */
1597 if (relation->rd_rel->relkind == RELKIND_SEQUENCE)
1598 goto change_done;
1599
1600 /* user-triggered change */
1601 if (!IsToastRelation(relation))
1602 {
1603 ReorderBufferToastReplace(rb, txn, relation, change);
1604 rb->apply_change(rb, txn, relation, change);
1605
1606 /*
1607 * Only clear reassembled toast chunks if we're sure
1608 * they're not required anymore. The creator of the
1609 * tuple tells us.
1610 */
1611 if (change->data.tp.clear_toast_afterwards)
1612 ReorderBufferToastReset(rb, txn);
1613 }
1614 /* we're not interested in toast deletions */
1615 else if (change->action == REORDER_BUFFER_CHANGE_INSERT)
1616 {
1617 /*
1618 * Need to reassemble the full toasted Datum in
1619 * memory, to ensure the chunks don't get reused till
1620 * we're done remove it from the list of this
1621 * transaction's changes. Otherwise it will get
1622 * freed/reused while restoring spooled data from
1623 * disk.
1624 */
1625 Assert(change->data.tp.newtuple != NULL);
1626
1627 dlist_delete(&change->node);
1628 ReorderBufferToastAppendChunk(rb, txn, relation,
1629 change);
1630 }
1631
1632 change_done:
1633
1634 /*
1635 * If speculative insertion was confirmed, the record isn't
1636 * needed anymore.
1637 */
1638 if (specinsert != NULL)
1639 {
1640 ReorderBufferReturnChange(rb, specinsert);
1641 specinsert = NULL;
1642 }
1643
1644 if (relation != NULL)
1645 {
1646 RelationClose(relation);
1647 relation = NULL;
1648 }
1649 break;
1650
1651 case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_INSERT:
1652
1653 /*
1654 * Speculative insertions are dealt with by delaying the
1655 * processing of the insert until the confirmation record
1656 * arrives. For that we simply unlink the record from the
1657 * chain, so it does not get freed/reused while restoring
1658 * spooled data from disk.
1659 *
1660 * This is safe in the face of concurrent catalog changes
1661 * because the relevant relation can't be changed between
1662 * speculative insertion and confirmation due to
1663 * CheckTableNotInUse() and locking.
1664 */
1665
1666 /* clear out a pending (and thus failed) speculation */
1667 if (specinsert != NULL)
1668 {
1669 ReorderBufferReturnChange(rb, specinsert);
1670 specinsert = NULL;
1671 }
1672
1673 /* and memorize the pending insertion */
1674 dlist_delete(&change->node);
1675 specinsert = change;
1676 break;
1677
1678 case REORDER_BUFFER_CHANGE_TRUNCATE:
1679 {
1680 int i;
1681 int nrelids = change->data.truncate.nrelids;
1682 int nrelations = 0;
1683 Relation *relations;
1684
1685 relations = palloc0(nrelids * sizeof(Relation));
1686 for (i = 0; i < nrelids; i++)
1687 {
1688 Oid relid = change->data.truncate.relids[i];
1689 Relation relation;
1690
1691 relation = RelationIdGetRelation(relid);
1692
1693 if (!RelationIsValid(relation))
1694 elog(ERROR, "could not open relation with OID %u", relid);
1695
1696 if (!RelationIsLogicallyLogged(relation))
1697 continue;
1698
1699 relations[nrelations++] = relation;
1700 }
1701
1702 rb->apply_truncate(rb, txn, nrelations, relations, change);
1703
1704 for (i = 0; i < nrelations; i++)
1705 RelationClose(relations[i]);
1706
1707 break;
1708 }
1709
1710 case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_ABORT:
1711
1712 /*
1713 * Abort for speculative insertion arrived. So cleanup the
1714 * specinsert tuple and toast hash.
1715 *
1716 * Note that we get the spec abort change for each toast
1717 * entry but we need to perform the cleanup only the first
1718 * time we get it for the main table.
1719 */
1720 if (specinsert != NULL)
1721 {
1722 /*
1723 * We must clean the toast hash before processing a
1724 * completely new tuple to avoid confusion about the
1725 * previous tuple's toast chunks.
1726 */
1727 Assert(change->data.tp.clear_toast_afterwards);
1728 ReorderBufferToastReset(rb, txn);
1729
1730 /* We don't need this record anymore. */
1731 ReorderBufferReturnChange(rb, specinsert);
1732 specinsert = NULL;
1733 }
1734 break;
1735
1736 case REORDER_BUFFER_CHANGE_MESSAGE:
1737 rb->message(rb, txn, change->lsn, true,
1738 change->data.msg.prefix,
1739 change->data.msg.message_size,
1740 change->data.msg.message);
1741 break;
1742
1743 case REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT:
1744 /* get rid of the old */
1745 TeardownHistoricSnapshot(false);
1746
1747 if (snapshot_now->copied)
1748 {
1749 ReorderBufferFreeSnap(rb, snapshot_now);
1750 snapshot_now =
1751 ReorderBufferCopySnap(rb, change->data.snapshot,
1752 txn, command_id);
1753 }
1754
1755 /*
1756 * Restored from disk, need to be careful not to double
1757 * free. We could introduce refcounting for that, but for
1758 * now this seems infrequent enough not to care.
1759 */
1760 else if (change->data.snapshot->copied)
1761 {
1762 snapshot_now =
1763 ReorderBufferCopySnap(rb, change->data.snapshot,
1764 txn, command_id);
1765 }
1766 else
1767 {
1768 snapshot_now = change->data.snapshot;
1769 }
1770
1771
1772 /* and continue with the new one */
1773 SetupHistoricSnapshot(snapshot_now, txn->tuplecid_hash);
1774 break;
1775
1776 case REORDER_BUFFER_CHANGE_INTERNAL_COMMAND_ID:
1777 Assert(change->data.command_id != InvalidCommandId);
1778
1779 if (command_id < change->data.command_id)
1780 {
1781 command_id = change->data.command_id;
1782
1783 if (!snapshot_now->copied)
1784 {
1785 /* we don't use the global one anymore */
1786 snapshot_now = ReorderBufferCopySnap(rb, snapshot_now,
1787 txn, command_id);
1788 }
1789
1790 snapshot_now->curcid = command_id;
1791
1792 TeardownHistoricSnapshot(false);
1793 SetupHistoricSnapshot(snapshot_now, txn->tuplecid_hash);
1794
1795 /*
1796 * Every time the CommandId is incremented, we could
1797 * see new catalog contents, so execute all
1798 * invalidations.
1799 */
1800 ReorderBufferExecuteInvalidations(rb, txn);
1801 }
1802
1803 break;
1804
1805 case REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID:
1806 elog(ERROR, "tuplecid value in changequeue");
1807 break;
1808 }
1809 }
1810
1811 /* speculative insertion record must be freed by now */
1812 Assert(!specinsert);
1813
1814 /* clean up the iterator */
1815 ReorderBufferIterTXNFinish(rb, iterstate);
1816 iterstate = NULL;
1817
1818 /* call commit callback */
1819 rb->commit(rb, txn, commit_lsn);
1820
1821 /* this is just a sanity check against bad output plugin behaviour */
1822 if (GetCurrentTransactionIdIfAny() != InvalidTransactionId)
1823 elog(ERROR, "output plugin used XID %u",
1824 GetCurrentTransactionId());
1825
1826 /* cleanup */
1827 TeardownHistoricSnapshot(false);
1828
1829 /*
1830 * Aborting the current (sub-)transaction as a whole has the right
1831 * semantics. We want all locks acquired in here to be released, not
1832 * reassigned to the parent and we do not want any database access
1833 * have persistent effects.
1834 */
1835 AbortCurrentTransaction();
1836
1837 /* make sure there's no cache pollution */
1838 ReorderBufferExecuteInvalidations(rb, txn);
1839
1840 if (using_subtxn)
1841 RollbackAndReleaseCurrentSubTransaction();
1842
1843 if (snapshot_now->copied)
1844 ReorderBufferFreeSnap(rb, snapshot_now);
1845
1846 /* remove potential on-disk data, and deallocate */
1847 ReorderBufferCleanupTXN(rb, txn);
1848 }
1849 PG_CATCH();
1850 {
1851 /* TODO: Encapsulate cleanup from the PG_TRY and PG_CATCH blocks */
1852 if (iterstate)
1853 ReorderBufferIterTXNFinish(rb, iterstate);
1854
1855 TeardownHistoricSnapshot(true);
1856
1857 /*
1858 * Force cache invalidation to happen outside of a valid transaction
1859 * to prevent catalog access as we just caught an error.
1860 */
1861 AbortCurrentTransaction();
1862
1863 /* make sure there's no cache pollution */
1864 ReorderBufferExecuteInvalidations(rb, txn);
1865
1866 if (using_subtxn)
1867 RollbackAndReleaseCurrentSubTransaction();
1868
1869 if (snapshot_now->copied)
1870 ReorderBufferFreeSnap(rb, snapshot_now);
1871
1872 /* remove potential on-disk data, and deallocate */
1873 ReorderBufferCleanupTXN(rb, txn);
1874
1875 PG_RE_THROW();
1876 }
1877 PG_END_TRY();
1878 }
1879
1880 /*
1881 * Abort a transaction that possibly has previous changes. Needs to be first
1882 * called for subtransactions and then for the toplevel xid.
1883 *
1884 * NB: Transactions handled here have to have actively aborted (i.e. have
1885 * produced an abort record). Implicitly aborted transactions are handled via
1886 * ReorderBufferAbortOld(); transactions we're just not interested in, but
1887 * which have committed are handled in ReorderBufferForget().
1888 *
1889 * This function purges this transaction and its contents from memory and
1890 * disk.
1891 */
1892 void
ReorderBufferAbort(ReorderBuffer * rb,TransactionId xid,XLogRecPtr lsn)1893 ReorderBufferAbort(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn)
1894 {
1895 ReorderBufferTXN *txn;
1896
1897 txn = ReorderBufferTXNByXid(rb, xid, false, NULL, InvalidXLogRecPtr,
1898 false);
1899
1900 /* unknown, nothing to remove */
1901 if (txn == NULL)
1902 return;
1903
1904 /* cosmetic... */
1905 txn->final_lsn = lsn;
1906
1907 /* remove potential on-disk data, and deallocate */
1908 ReorderBufferCleanupTXN(rb, txn);
1909 }
1910
1911 /*
1912 * Abort all transactions that aren't actually running anymore because the
1913 * server restarted.
1914 *
1915 * NB: These really have to be transactions that have aborted due to a server
1916 * crash/immediate restart, as we don't deal with invalidations here.
1917 */
1918 void
ReorderBufferAbortOld(ReorderBuffer * rb,TransactionId oldestRunningXid)1919 ReorderBufferAbortOld(ReorderBuffer *rb, TransactionId oldestRunningXid)
1920 {
1921 dlist_mutable_iter it;
1922
1923 /*
1924 * Iterate through all (potential) toplevel TXNs and abort all that are
1925 * older than what possibly can be running. Once we've found the first
1926 * that is alive we stop, there might be some that acquired an xid earlier
1927 * but started writing later, but it's unlikely and they will be cleaned
1928 * up in a later call to this function.
1929 */
1930 dlist_foreach_modify(it, &rb->toplevel_by_lsn)
1931 {
1932 ReorderBufferTXN *txn;
1933
1934 txn = dlist_container(ReorderBufferTXN, node, it.cur);
1935
1936 if (TransactionIdPrecedes(txn->xid, oldestRunningXid))
1937 {
1938 elog(DEBUG2, "aborting old transaction %u", txn->xid);
1939
1940 /* remove potential on-disk data, and deallocate this tx */
1941 ReorderBufferCleanupTXN(rb, txn);
1942 }
1943 else
1944 return;
1945 }
1946 }
1947
1948 /*
1949 * Forget the contents of a transaction if we aren't interested in its
1950 * contents. Needs to be first called for subtransactions and then for the
1951 * toplevel xid.
1952 *
1953 * This is significantly different to ReorderBufferAbort() because
1954 * transactions that have committed need to be treated differently from aborted
1955 * ones since they may have modified the catalog.
1956 *
1957 * Note that this is only allowed to be called in the moment a transaction
1958 * commit has just been read, not earlier; otherwise later records referring
1959 * to this xid might re-create the transaction incompletely.
1960 */
1961 void
ReorderBufferForget(ReorderBuffer * rb,TransactionId xid,XLogRecPtr lsn)1962 ReorderBufferForget(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn)
1963 {
1964 ReorderBufferTXN *txn;
1965
1966 txn = ReorderBufferTXNByXid(rb, xid, false, NULL, InvalidXLogRecPtr,
1967 false);
1968
1969 /* unknown, nothing to forget */
1970 if (txn == NULL)
1971 return;
1972
1973 /* cosmetic... */
1974 txn->final_lsn = lsn;
1975
1976 /*
1977 * Process cache invalidation messages if there are any. Even if we're not
1978 * interested in the transaction's contents, it could have manipulated the
1979 * catalog and we need to update the caches according to that.
1980 */
1981 if (txn->base_snapshot != NULL && txn->ninvalidations > 0)
1982 ReorderBufferImmediateInvalidation(rb, txn->ninvalidations,
1983 txn->invalidations);
1984 else
1985 Assert(txn->ninvalidations == 0);
1986
1987 /* remove potential on-disk data, and deallocate */
1988 ReorderBufferCleanupTXN(rb, txn);
1989 }
1990
1991 /*
1992 * Execute invalidations happening outside the context of a decoded
1993 * transaction. That currently happens either for xid-less commits
1994 * (cf. RecordTransactionCommit()) or for invalidations in uninteresting
1995 * transactions (via ReorderBufferForget()).
1996 */
1997 void
ReorderBufferImmediateInvalidation(ReorderBuffer * rb,uint32 ninvalidations,SharedInvalidationMessage * invalidations)1998 ReorderBufferImmediateInvalidation(ReorderBuffer *rb, uint32 ninvalidations,
1999 SharedInvalidationMessage *invalidations)
2000 {
2001 bool use_subtxn = IsTransactionOrTransactionBlock();
2002 int i;
2003
2004 if (use_subtxn)
2005 BeginInternalSubTransaction("replay");
2006
2007 /*
2008 * Force invalidations to happen outside of a valid transaction - that way
2009 * entries will just be marked as invalid without accessing the catalog.
2010 * That's advantageous because we don't need to setup the full state
2011 * necessary for catalog access.
2012 */
2013 if (use_subtxn)
2014 AbortCurrentTransaction();
2015
2016 for (i = 0; i < ninvalidations; i++)
2017 LocalExecuteInvalidationMessage(&invalidations[i]);
2018
2019 if (use_subtxn)
2020 RollbackAndReleaseCurrentSubTransaction();
2021 }
2022
2023 /*
2024 * Tell reorderbuffer about an xid seen in the WAL stream. Has to be called at
2025 * least once for every xid in XLogRecord->xl_xid (other places in records
2026 * may, but do not have to be passed through here).
2027 *
2028 * Reorderbuffer keeps some datastructures about transactions in LSN order,
2029 * for efficiency. To do that it has to know about when transactions are seen
2030 * first in the WAL. As many types of records are not actually interesting for
2031 * logical decoding, they do not necessarily pass though here.
2032 */
2033 void
ReorderBufferProcessXid(ReorderBuffer * rb,TransactionId xid,XLogRecPtr lsn)2034 ReorderBufferProcessXid(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn)
2035 {
2036 /* many records won't have an xid assigned, centralize check here */
2037 if (xid != InvalidTransactionId)
2038 ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
2039 }
2040
2041 /*
2042 * Add a new snapshot to this transaction that may only used after lsn 'lsn'
2043 * because the previous snapshot doesn't describe the catalog correctly for
2044 * following rows.
2045 */
2046 void
ReorderBufferAddSnapshot(ReorderBuffer * rb,TransactionId xid,XLogRecPtr lsn,Snapshot snap)2047 ReorderBufferAddSnapshot(ReorderBuffer *rb, TransactionId xid,
2048 XLogRecPtr lsn, Snapshot snap)
2049 {
2050 ReorderBufferChange *change = ReorderBufferGetChange(rb);
2051
2052 change->data.snapshot = snap;
2053 change->action = REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT;
2054
2055 ReorderBufferQueueChange(rb, xid, lsn, change);
2056 }
2057
2058 /*
2059 * Set up the transaction's base snapshot.
2060 *
2061 * If we know that xid is a subtransaction, set the base snapshot on the
2062 * top-level transaction instead.
2063 */
2064 void
ReorderBufferSetBaseSnapshot(ReorderBuffer * rb,TransactionId xid,XLogRecPtr lsn,Snapshot snap)2065 ReorderBufferSetBaseSnapshot(ReorderBuffer *rb, TransactionId xid,
2066 XLogRecPtr lsn, Snapshot snap)
2067 {
2068 ReorderBufferTXN *txn;
2069 bool is_new;
2070
2071 AssertArg(snap != NULL);
2072
2073 /*
2074 * Fetch the transaction to operate on. If we know it's a subtransaction,
2075 * operate on its top-level transaction instead.
2076 */
2077 txn = ReorderBufferTXNByXid(rb, xid, true, &is_new, lsn, true);
2078 if (txn->is_known_as_subxact)
2079 txn = ReorderBufferTXNByXid(rb, txn->toplevel_xid, false,
2080 NULL, InvalidXLogRecPtr, false);
2081 Assert(txn->base_snapshot == NULL);
2082
2083 txn->base_snapshot = snap;
2084 txn->base_snapshot_lsn = lsn;
2085 dlist_push_tail(&rb->txns_by_base_snapshot_lsn, &txn->base_snapshot_node);
2086
2087 AssertTXNLsnOrder(rb);
2088 }
2089
2090 /*
2091 * Access the catalog with this CommandId at this point in the changestream.
2092 *
2093 * May only be called for command ids > 1
2094 */
2095 void
ReorderBufferAddNewCommandId(ReorderBuffer * rb,TransactionId xid,XLogRecPtr lsn,CommandId cid)2096 ReorderBufferAddNewCommandId(ReorderBuffer *rb, TransactionId xid,
2097 XLogRecPtr lsn, CommandId cid)
2098 {
2099 ReorderBufferChange *change = ReorderBufferGetChange(rb);
2100
2101 change->data.command_id = cid;
2102 change->action = REORDER_BUFFER_CHANGE_INTERNAL_COMMAND_ID;
2103
2104 ReorderBufferQueueChange(rb, xid, lsn, change);
2105 }
2106
2107
2108 /*
2109 * Add new (relfilenode, tid) -> (cmin, cmax) mappings.
2110 */
2111 void
ReorderBufferAddNewTupleCids(ReorderBuffer * rb,TransactionId xid,XLogRecPtr lsn,RelFileNode node,ItemPointerData tid,CommandId cmin,CommandId cmax,CommandId combocid)2112 ReorderBufferAddNewTupleCids(ReorderBuffer *rb, TransactionId xid,
2113 XLogRecPtr lsn, RelFileNode node,
2114 ItemPointerData tid, CommandId cmin,
2115 CommandId cmax, CommandId combocid)
2116 {
2117 ReorderBufferChange *change = ReorderBufferGetChange(rb);
2118 ReorderBufferTXN *txn;
2119
2120 txn = ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
2121
2122 change->data.tuplecid.node = node;
2123 change->data.tuplecid.tid = tid;
2124 change->data.tuplecid.cmin = cmin;
2125 change->data.tuplecid.cmax = cmax;
2126 change->data.tuplecid.combocid = combocid;
2127 change->lsn = lsn;
2128 change->action = REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID;
2129
2130 dlist_push_tail(&txn->tuplecids, &change->node);
2131 txn->ntuplecids++;
2132 }
2133
2134 /*
2135 * Setup the invalidation of the toplevel transaction.
2136 *
2137 * This needs to be done before ReorderBufferCommit is called!
2138 */
2139 void
ReorderBufferAddInvalidations(ReorderBuffer * rb,TransactionId xid,XLogRecPtr lsn,Size nmsgs,SharedInvalidationMessage * msgs)2140 ReorderBufferAddInvalidations(ReorderBuffer *rb, TransactionId xid,
2141 XLogRecPtr lsn, Size nmsgs,
2142 SharedInvalidationMessage *msgs)
2143 {
2144 ReorderBufferTXN *txn;
2145
2146 txn = ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
2147
2148 if (txn->ninvalidations != 0)
2149 elog(ERROR, "only ever add one set of invalidations");
2150
2151 Assert(nmsgs > 0);
2152
2153 txn->ninvalidations = nmsgs;
2154 txn->invalidations = (SharedInvalidationMessage *)
2155 MemoryContextAlloc(rb->context,
2156 sizeof(SharedInvalidationMessage) * nmsgs);
2157 memcpy(txn->invalidations, msgs,
2158 sizeof(SharedInvalidationMessage) * nmsgs);
2159 }
2160
2161 /*
2162 * Apply all invalidations we know. Possibly we only need parts at this point
2163 * in the changestream but we don't know which those are.
2164 */
2165 static void
ReorderBufferExecuteInvalidations(ReorderBuffer * rb,ReorderBufferTXN * txn)2166 ReorderBufferExecuteInvalidations(ReorderBuffer *rb, ReorderBufferTXN *txn)
2167 {
2168 int i;
2169
2170 for (i = 0; i < txn->ninvalidations; i++)
2171 LocalExecuteInvalidationMessage(&txn->invalidations[i]);
2172 }
2173
2174 /*
2175 * Mark a transaction as containing catalog changes
2176 */
2177 void
ReorderBufferXidSetCatalogChanges(ReorderBuffer * rb,TransactionId xid,XLogRecPtr lsn)2178 ReorderBufferXidSetCatalogChanges(ReorderBuffer *rb, TransactionId xid,
2179 XLogRecPtr lsn)
2180 {
2181 ReorderBufferTXN *txn;
2182
2183 txn = ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
2184
2185 txn->has_catalog_changes = true;
2186 }
2187
2188 /*
2189 * Query whether a transaction is already *known* to contain catalog
2190 * changes. This can be wrong until directly before the commit!
2191 */
2192 bool
ReorderBufferXidHasCatalogChanges(ReorderBuffer * rb,TransactionId xid)2193 ReorderBufferXidHasCatalogChanges(ReorderBuffer *rb, TransactionId xid)
2194 {
2195 ReorderBufferTXN *txn;
2196
2197 txn = ReorderBufferTXNByXid(rb, xid, false, NULL, InvalidXLogRecPtr,
2198 false);
2199 if (txn == NULL)
2200 return false;
2201
2202 return txn->has_catalog_changes;
2203 }
2204
2205 /*
2206 * ReorderBufferXidHasBaseSnapshot
2207 * Have we already set the base snapshot for the given txn/subtxn?
2208 */
2209 bool
ReorderBufferXidHasBaseSnapshot(ReorderBuffer * rb,TransactionId xid)2210 ReorderBufferXidHasBaseSnapshot(ReorderBuffer *rb, TransactionId xid)
2211 {
2212 ReorderBufferTXN *txn;
2213
2214 txn = ReorderBufferTXNByXid(rb, xid, false,
2215 NULL, InvalidXLogRecPtr, false);
2216
2217 /* transaction isn't known yet, ergo no snapshot */
2218 if (txn == NULL)
2219 return false;
2220
2221 /* a known subtxn? operate on top-level txn instead */
2222 if (txn->is_known_as_subxact)
2223 txn = ReorderBufferTXNByXid(rb, txn->toplevel_xid, false,
2224 NULL, InvalidXLogRecPtr, false);
2225
2226 return txn->base_snapshot != NULL;
2227 }
2228
2229
2230 /*
2231 * ---------------------------------------
2232 * Disk serialization support
2233 * ---------------------------------------
2234 */
2235
2236 /*
2237 * Ensure the IO buffer is >= sz.
2238 */
2239 static void
ReorderBufferSerializeReserve(ReorderBuffer * rb,Size sz)2240 ReorderBufferSerializeReserve(ReorderBuffer *rb, Size sz)
2241 {
2242 if (!rb->outbufsize)
2243 {
2244 rb->outbuf = MemoryContextAlloc(rb->context, sz);
2245 rb->outbufsize = sz;
2246 }
2247 else if (rb->outbufsize < sz)
2248 {
2249 rb->outbuf = repalloc(rb->outbuf, sz);
2250 rb->outbufsize = sz;
2251 }
2252 }
2253
2254 /*
2255 * Check whether the transaction tx should spill its data to disk.
2256 */
2257 static void
ReorderBufferCheckSerializeTXN(ReorderBuffer * rb,ReorderBufferTXN * txn)2258 ReorderBufferCheckSerializeTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
2259 {
2260 /*
2261 * TODO: improve accounting so we cheaply can take subtransactions into
2262 * account here.
2263 */
2264 if (txn->nentries_mem >= max_changes_in_memory)
2265 {
2266 ReorderBufferSerializeTXN(rb, txn);
2267 Assert(txn->nentries_mem == 0);
2268 }
2269 }
2270
2271 /*
2272 * Spill data of a large transaction (and its subtransactions) to disk.
2273 */
2274 static void
ReorderBufferSerializeTXN(ReorderBuffer * rb,ReorderBufferTXN * txn)2275 ReorderBufferSerializeTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
2276 {
2277 dlist_iter subtxn_i;
2278 dlist_mutable_iter change_i;
2279 int fd = -1;
2280 XLogSegNo curOpenSegNo = 0;
2281 Size spilled = 0;
2282
2283 elog(DEBUG2, "spill %u changes in XID %u to disk",
2284 (uint32) txn->nentries_mem, txn->xid);
2285
2286 /* do the same to all child TXs */
2287 dlist_foreach(subtxn_i, &txn->subtxns)
2288 {
2289 ReorderBufferTXN *subtxn;
2290
2291 subtxn = dlist_container(ReorderBufferTXN, node, subtxn_i.cur);
2292 ReorderBufferSerializeTXN(rb, subtxn);
2293 }
2294
2295 /* serialize changestream */
2296 dlist_foreach_modify(change_i, &txn->changes)
2297 {
2298 ReorderBufferChange *change;
2299
2300 change = dlist_container(ReorderBufferChange, node, change_i.cur);
2301
2302 /*
2303 * store in segment in which it belongs by start lsn, don't split over
2304 * multiple segments tho
2305 */
2306 if (fd == -1 ||
2307 !XLByteInSeg(change->lsn, curOpenSegNo, wal_segment_size))
2308 {
2309 char path[MAXPGPATH];
2310
2311 if (fd != -1)
2312 CloseTransientFile(fd);
2313
2314 XLByteToSeg(change->lsn, curOpenSegNo, wal_segment_size);
2315
2316 /*
2317 * No need to care about TLIs here, only used during a single run,
2318 * so each LSN only maps to a specific WAL record.
2319 */
2320 ReorderBufferSerializedPath(path, MyReplicationSlot, txn->xid,
2321 curOpenSegNo);
2322
2323 /* open segment, create it if necessary */
2324 fd = OpenTransientFile(path,
2325 O_CREAT | O_WRONLY | O_APPEND | PG_BINARY);
2326
2327 if (fd < 0)
2328 ereport(ERROR,
2329 (errcode_for_file_access(),
2330 errmsg("could not open file \"%s\": %m", path)));
2331 }
2332
2333 ReorderBufferSerializeChange(rb, txn, fd, change);
2334 dlist_delete(&change->node);
2335 ReorderBufferReturnChange(rb, change);
2336
2337 spilled++;
2338 }
2339
2340 Assert(spilled == txn->nentries_mem);
2341 Assert(dlist_is_empty(&txn->changes));
2342 txn->nentries_mem = 0;
2343 txn->serialized = true;
2344
2345 if (fd != -1)
2346 CloseTransientFile(fd);
2347 }
2348
2349 /*
2350 * Serialize individual change to disk.
2351 */
2352 static void
ReorderBufferSerializeChange(ReorderBuffer * rb,ReorderBufferTXN * txn,int fd,ReorderBufferChange * change)2353 ReorderBufferSerializeChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
2354 int fd, ReorderBufferChange *change)
2355 {
2356 ReorderBufferDiskChange *ondisk;
2357 Size sz = sizeof(ReorderBufferDiskChange);
2358
2359 ReorderBufferSerializeReserve(rb, sz);
2360
2361 ondisk = (ReorderBufferDiskChange *) rb->outbuf;
2362 memcpy(&ondisk->change, change, sizeof(ReorderBufferChange));
2363
2364 switch (change->action)
2365 {
2366 /* fall through these, they're all similar enough */
2367 case REORDER_BUFFER_CHANGE_INSERT:
2368 case REORDER_BUFFER_CHANGE_UPDATE:
2369 case REORDER_BUFFER_CHANGE_DELETE:
2370 case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_INSERT:
2371 {
2372 char *data;
2373 ReorderBufferTupleBuf *oldtup,
2374 *newtup;
2375 Size oldlen = 0;
2376 Size newlen = 0;
2377
2378 oldtup = change->data.tp.oldtuple;
2379 newtup = change->data.tp.newtuple;
2380
2381 if (oldtup)
2382 {
2383 sz += sizeof(HeapTupleData);
2384 oldlen = oldtup->tuple.t_len;
2385 sz += oldlen;
2386 }
2387
2388 if (newtup)
2389 {
2390 sz += sizeof(HeapTupleData);
2391 newlen = newtup->tuple.t_len;
2392 sz += newlen;
2393 }
2394
2395 /* make sure we have enough space */
2396 ReorderBufferSerializeReserve(rb, sz);
2397
2398 data = ((char *) rb->outbuf) + sizeof(ReorderBufferDiskChange);
2399 /* might have been reallocated above */
2400 ondisk = (ReorderBufferDiskChange *) rb->outbuf;
2401
2402 if (oldlen)
2403 {
2404 memcpy(data, &oldtup->tuple, sizeof(HeapTupleData));
2405 data += sizeof(HeapTupleData);
2406
2407 memcpy(data, oldtup->tuple.t_data, oldlen);
2408 data += oldlen;
2409 }
2410
2411 if (newlen)
2412 {
2413 memcpy(data, &newtup->tuple, sizeof(HeapTupleData));
2414 data += sizeof(HeapTupleData);
2415
2416 memcpy(data, newtup->tuple.t_data, newlen);
2417 data += newlen;
2418 }
2419 break;
2420 }
2421 case REORDER_BUFFER_CHANGE_MESSAGE:
2422 {
2423 char *data;
2424 Size prefix_size = strlen(change->data.msg.prefix) + 1;
2425
2426 sz += prefix_size + change->data.msg.message_size +
2427 sizeof(Size) + sizeof(Size);
2428 ReorderBufferSerializeReserve(rb, sz);
2429
2430 data = ((char *) rb->outbuf) + sizeof(ReorderBufferDiskChange);
2431
2432 /* might have been reallocated above */
2433 ondisk = (ReorderBufferDiskChange *) rb->outbuf;
2434
2435 /* write the prefix including the size */
2436 memcpy(data, &prefix_size, sizeof(Size));
2437 data += sizeof(Size);
2438 memcpy(data, change->data.msg.prefix,
2439 prefix_size);
2440 data += prefix_size;
2441
2442 /* write the message including the size */
2443 memcpy(data, &change->data.msg.message_size, sizeof(Size));
2444 data += sizeof(Size);
2445 memcpy(data, change->data.msg.message,
2446 change->data.msg.message_size);
2447 data += change->data.msg.message_size;
2448
2449 break;
2450 }
2451 case REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT:
2452 {
2453 Snapshot snap;
2454 char *data;
2455
2456 snap = change->data.snapshot;
2457
2458 sz += sizeof(SnapshotData) +
2459 sizeof(TransactionId) * snap->xcnt +
2460 sizeof(TransactionId) * snap->subxcnt;
2461
2462 /* make sure we have enough space */
2463 ReorderBufferSerializeReserve(rb, sz);
2464 data = ((char *) rb->outbuf) + sizeof(ReorderBufferDiskChange);
2465 /* might have been reallocated above */
2466 ondisk = (ReorderBufferDiskChange *) rb->outbuf;
2467
2468 memcpy(data, snap, sizeof(SnapshotData));
2469 data += sizeof(SnapshotData);
2470
2471 if (snap->xcnt)
2472 {
2473 memcpy(data, snap->xip,
2474 sizeof(TransactionId) * snap->xcnt);
2475 data += sizeof(TransactionId) * snap->xcnt;
2476 }
2477
2478 if (snap->subxcnt)
2479 {
2480 memcpy(data, snap->subxip,
2481 sizeof(TransactionId) * snap->subxcnt);
2482 data += sizeof(TransactionId) * snap->subxcnt;
2483 }
2484 break;
2485 }
2486 case REORDER_BUFFER_CHANGE_TRUNCATE:
2487 {
2488 Size size;
2489 char *data;
2490
2491 /* account for the OIDs of truncated relations */
2492 size = sizeof(Oid) * change->data.truncate.nrelids;
2493 sz += size;
2494
2495 /* make sure we have enough space */
2496 ReorderBufferSerializeReserve(rb, sz);
2497
2498 data = ((char *) rb->outbuf) + sizeof(ReorderBufferDiskChange);
2499 /* might have been reallocated above */
2500 ondisk = (ReorderBufferDiskChange *) rb->outbuf;
2501
2502 memcpy(data, change->data.truncate.relids, size);
2503 data += size;
2504
2505 break;
2506 }
2507 case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_CONFIRM:
2508 case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_ABORT:
2509 case REORDER_BUFFER_CHANGE_INTERNAL_COMMAND_ID:
2510 case REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID:
2511 /* ReorderBufferChange contains everything important */
2512 break;
2513 }
2514
2515 ondisk->size = sz;
2516
2517 errno = 0;
2518 pgstat_report_wait_start(WAIT_EVENT_REORDER_BUFFER_WRITE);
2519 if (write(fd, rb->outbuf, ondisk->size) != ondisk->size)
2520 {
2521 int save_errno = errno;
2522
2523 CloseTransientFile(fd);
2524
2525 /* if write didn't set errno, assume problem is no disk space */
2526 errno = save_errno ? save_errno : ENOSPC;
2527 ereport(ERROR,
2528 (errcode_for_file_access(),
2529 errmsg("could not write to data file for XID %u: %m",
2530 txn->xid)));
2531 }
2532 pgstat_report_wait_end();
2533
2534 /*
2535 * Keep the transaction's final_lsn up to date with each change we send to
2536 * disk, so that ReorderBufferRestoreCleanup works correctly. (We used to
2537 * only do this on commit and abort records, but that doesn't work if a
2538 * system crash leaves a transaction without its abort record).
2539 *
2540 * Make sure not to move it backwards.
2541 */
2542 if (txn->final_lsn < change->lsn)
2543 txn->final_lsn = change->lsn;
2544
2545 Assert(ondisk->change.action == change->action);
2546 }
2547
2548 /*
2549 * Restore a number of changes spilled to disk back into memory.
2550 */
2551 static Size
ReorderBufferRestoreChanges(ReorderBuffer * rb,ReorderBufferTXN * txn,TXNEntryFile * file,XLogSegNo * segno)2552 ReorderBufferRestoreChanges(ReorderBuffer *rb, ReorderBufferTXN *txn,
2553 TXNEntryFile *file, XLogSegNo *segno)
2554 {
2555 Size restored = 0;
2556 XLogSegNo last_segno;
2557 dlist_mutable_iter cleanup_iter;
2558 File *fd = &file->vfd;
2559
2560 Assert(txn->first_lsn != InvalidXLogRecPtr);
2561 Assert(txn->final_lsn != InvalidXLogRecPtr);
2562
2563 /* free current entries, so we have memory for more */
2564 dlist_foreach_modify(cleanup_iter, &txn->changes)
2565 {
2566 ReorderBufferChange *cleanup =
2567 dlist_container(ReorderBufferChange, node, cleanup_iter.cur);
2568
2569 dlist_delete(&cleanup->node);
2570 ReorderBufferReturnChange(rb, cleanup);
2571 }
2572 txn->nentries_mem = 0;
2573 Assert(dlist_is_empty(&txn->changes));
2574
2575 XLByteToSeg(txn->final_lsn, last_segno, wal_segment_size);
2576
2577 while (restored < max_changes_in_memory && *segno <= last_segno)
2578 {
2579 int readBytes;
2580 ReorderBufferDiskChange *ondisk;
2581
2582 if (*fd == -1)
2583 {
2584 char path[MAXPGPATH];
2585
2586 /* first time in */
2587 if (*segno == 0)
2588 XLByteToSeg(txn->first_lsn, *segno, wal_segment_size);
2589
2590 Assert(*segno != 0 || dlist_is_empty(&txn->changes));
2591
2592 /*
2593 * No need to care about TLIs here, only used during a single run,
2594 * so each LSN only maps to a specific WAL record.
2595 */
2596 ReorderBufferSerializedPath(path, MyReplicationSlot, txn->xid,
2597 *segno);
2598
2599 *fd = PathNameOpenFile(path, O_RDONLY | PG_BINARY);
2600
2601 /* No harm in resetting the offset even in case of failure */
2602 file->curOffset = 0;
2603
2604 if (*fd < 0 && errno == ENOENT)
2605 {
2606 *fd = -1;
2607 (*segno)++;
2608 continue;
2609 }
2610 else if (*fd < 0)
2611 ereport(ERROR,
2612 (errcode_for_file_access(),
2613 errmsg("could not open file \"%s\": %m",
2614 path)));
2615 }
2616
2617 /*
2618 * Read the statically sized part of a change which has information
2619 * about the total size. If we couldn't read a record, we're at the
2620 * end of this file.
2621 */
2622 ReorderBufferSerializeReserve(rb, sizeof(ReorderBufferDiskChange));
2623 readBytes = FileRead(file->vfd, rb->outbuf,
2624 sizeof(ReorderBufferDiskChange),
2625 file->curOffset, WAIT_EVENT_REORDER_BUFFER_READ);
2626
2627 /* eof */
2628 if (readBytes == 0)
2629 {
2630 FileClose(*fd);
2631 *fd = -1;
2632 (*segno)++;
2633 continue;
2634 }
2635 else if (readBytes < 0)
2636 ereport(ERROR,
2637 (errcode_for_file_access(),
2638 errmsg("could not read from reorderbuffer spill file: %m")));
2639 else if (readBytes != sizeof(ReorderBufferDiskChange))
2640 ereport(ERROR,
2641 (errcode_for_file_access(),
2642 errmsg("could not read from reorderbuffer spill file: read %d instead of %u bytes",
2643 readBytes,
2644 (uint32) sizeof(ReorderBufferDiskChange))));
2645
2646 file->curOffset += readBytes;
2647
2648 ondisk = (ReorderBufferDiskChange *) rb->outbuf;
2649
2650 ReorderBufferSerializeReserve(rb,
2651 sizeof(ReorderBufferDiskChange) + ondisk->size);
2652 ondisk = (ReorderBufferDiskChange *) rb->outbuf;
2653
2654 readBytes = FileRead(file->vfd,
2655 rb->outbuf + sizeof(ReorderBufferDiskChange),
2656 ondisk->size - sizeof(ReorderBufferDiskChange),
2657 file->curOffset,
2658 WAIT_EVENT_REORDER_BUFFER_READ);
2659
2660 if (readBytes < 0)
2661 ereport(ERROR,
2662 (errcode_for_file_access(),
2663 errmsg("could not read from reorderbuffer spill file: %m")));
2664 else if (readBytes != ondisk->size - sizeof(ReorderBufferDiskChange))
2665 ereport(ERROR,
2666 (errcode_for_file_access(),
2667 errmsg("could not read from reorderbuffer spill file: read %d instead of %u bytes",
2668 readBytes,
2669 (uint32) (ondisk->size - sizeof(ReorderBufferDiskChange)))));
2670
2671 file->curOffset += readBytes;
2672
2673 /*
2674 * ok, read a full change from disk, now restore it into proper
2675 * in-memory format
2676 */
2677 ReorderBufferRestoreChange(rb, txn, rb->outbuf);
2678 restored++;
2679 }
2680
2681 return restored;
2682 }
2683
2684 /*
2685 * Convert change from its on-disk format to in-memory format and queue it onto
2686 * the TXN's ->changes list.
2687 *
2688 * Note: although "data" is declared char*, at entry it points to a
2689 * maxalign'd buffer, making it safe in most of this function to assume
2690 * that the pointed-to data is suitably aligned for direct access.
2691 */
2692 static void
ReorderBufferRestoreChange(ReorderBuffer * rb,ReorderBufferTXN * txn,char * data)2693 ReorderBufferRestoreChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
2694 char *data)
2695 {
2696 ReorderBufferDiskChange *ondisk;
2697 ReorderBufferChange *change;
2698
2699 ondisk = (ReorderBufferDiskChange *) data;
2700
2701 change = ReorderBufferGetChange(rb);
2702
2703 /* copy static part */
2704 memcpy(change, &ondisk->change, sizeof(ReorderBufferChange));
2705
2706 data += sizeof(ReorderBufferDiskChange);
2707
2708 /* restore individual stuff */
2709 switch (change->action)
2710 {
2711 /* fall through these, they're all similar enough */
2712 case REORDER_BUFFER_CHANGE_INSERT:
2713 case REORDER_BUFFER_CHANGE_UPDATE:
2714 case REORDER_BUFFER_CHANGE_DELETE:
2715 case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_INSERT:
2716 if (change->data.tp.oldtuple)
2717 {
2718 uint32 tuplelen = ((HeapTuple) data)->t_len;
2719
2720 change->data.tp.oldtuple =
2721 ReorderBufferGetTupleBuf(rb, tuplelen - SizeofHeapTupleHeader);
2722
2723 /* restore ->tuple */
2724 memcpy(&change->data.tp.oldtuple->tuple, data,
2725 sizeof(HeapTupleData));
2726 data += sizeof(HeapTupleData);
2727
2728 /* reset t_data pointer into the new tuplebuf */
2729 change->data.tp.oldtuple->tuple.t_data =
2730 ReorderBufferTupleBufData(change->data.tp.oldtuple);
2731
2732 /* restore tuple data itself */
2733 memcpy(change->data.tp.oldtuple->tuple.t_data, data, tuplelen);
2734 data += tuplelen;
2735 }
2736
2737 if (change->data.tp.newtuple)
2738 {
2739 /* here, data might not be suitably aligned! */
2740 uint32 tuplelen;
2741
2742 memcpy(&tuplelen, data + offsetof(HeapTupleData, t_len),
2743 sizeof(uint32));
2744
2745 change->data.tp.newtuple =
2746 ReorderBufferGetTupleBuf(rb, tuplelen - SizeofHeapTupleHeader);
2747
2748 /* restore ->tuple */
2749 memcpy(&change->data.tp.newtuple->tuple, data,
2750 sizeof(HeapTupleData));
2751 data += sizeof(HeapTupleData);
2752
2753 /* reset t_data pointer into the new tuplebuf */
2754 change->data.tp.newtuple->tuple.t_data =
2755 ReorderBufferTupleBufData(change->data.tp.newtuple);
2756
2757 /* restore tuple data itself */
2758 memcpy(change->data.tp.newtuple->tuple.t_data, data, tuplelen);
2759 data += tuplelen;
2760 }
2761
2762 break;
2763 case REORDER_BUFFER_CHANGE_MESSAGE:
2764 {
2765 Size prefix_size;
2766
2767 /* read prefix */
2768 memcpy(&prefix_size, data, sizeof(Size));
2769 data += sizeof(Size);
2770 change->data.msg.prefix = MemoryContextAlloc(rb->context,
2771 prefix_size);
2772 memcpy(change->data.msg.prefix, data, prefix_size);
2773 Assert(change->data.msg.prefix[prefix_size - 1] == '\0');
2774 data += prefix_size;
2775
2776 /* read the message */
2777 memcpy(&change->data.msg.message_size, data, sizeof(Size));
2778 data += sizeof(Size);
2779 change->data.msg.message = MemoryContextAlloc(rb->context,
2780 change->data.msg.message_size);
2781 memcpy(change->data.msg.message, data,
2782 change->data.msg.message_size);
2783 data += change->data.msg.message_size;
2784
2785 break;
2786 }
2787 case REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT:
2788 {
2789 Snapshot oldsnap;
2790 Snapshot newsnap;
2791 Size size;
2792
2793 oldsnap = (Snapshot) data;
2794
2795 size = sizeof(SnapshotData) +
2796 sizeof(TransactionId) * oldsnap->xcnt +
2797 sizeof(TransactionId) * (oldsnap->subxcnt + 0);
2798
2799 change->data.snapshot = MemoryContextAllocZero(rb->context, size);
2800
2801 newsnap = change->data.snapshot;
2802
2803 memcpy(newsnap, data, size);
2804 newsnap->xip = (TransactionId *)
2805 (((char *) newsnap) + sizeof(SnapshotData));
2806 newsnap->subxip = newsnap->xip + newsnap->xcnt;
2807 newsnap->copied = true;
2808 break;
2809 }
2810 /* the base struct contains all the data, easy peasy */
2811 case REORDER_BUFFER_CHANGE_TRUNCATE:
2812 {
2813 Oid *relids;
2814
2815 relids = ReorderBufferGetRelids(rb,
2816 change->data.truncate.nrelids);
2817 memcpy(relids, data, change->data.truncate.nrelids * sizeof(Oid));
2818 change->data.truncate.relids = relids;
2819
2820 break;
2821 }
2822 case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_CONFIRM:
2823 case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_ABORT:
2824 case REORDER_BUFFER_CHANGE_INTERNAL_COMMAND_ID:
2825 case REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID:
2826 break;
2827 }
2828
2829 dlist_push_tail(&txn->changes, &change->node);
2830 txn->nentries_mem++;
2831 }
2832
2833 /*
2834 * Remove all on-disk stored for the passed in transaction.
2835 */
2836 static void
ReorderBufferRestoreCleanup(ReorderBuffer * rb,ReorderBufferTXN * txn)2837 ReorderBufferRestoreCleanup(ReorderBuffer *rb, ReorderBufferTXN *txn)
2838 {
2839 XLogSegNo first;
2840 XLogSegNo cur;
2841 XLogSegNo last;
2842
2843 Assert(txn->first_lsn != InvalidXLogRecPtr);
2844 Assert(txn->final_lsn != InvalidXLogRecPtr);
2845
2846 XLByteToSeg(txn->first_lsn, first, wal_segment_size);
2847 XLByteToSeg(txn->final_lsn, last, wal_segment_size);
2848
2849 /* iterate over all possible filenames, and delete them */
2850 for (cur = first; cur <= last; cur++)
2851 {
2852 char path[MAXPGPATH];
2853
2854 ReorderBufferSerializedPath(path, MyReplicationSlot, txn->xid, cur);
2855 if (unlink(path) != 0 && errno != ENOENT)
2856 ereport(ERROR,
2857 (errcode_for_file_access(),
2858 errmsg("could not remove file \"%s\": %m", path)));
2859 }
2860 }
2861
2862 /*
2863 * Remove any leftover serialized reorder buffers from a slot directory after a
2864 * prior crash or decoding session exit.
2865 */
2866 static void
ReorderBufferCleanupSerializedTXNs(const char * slotname)2867 ReorderBufferCleanupSerializedTXNs(const char *slotname)
2868 {
2869 DIR *spill_dir;
2870 struct dirent *spill_de;
2871 struct stat statbuf;
2872 char path[MAXPGPATH * 2 + 12];
2873
2874 sprintf(path, "pg_replslot/%s", slotname);
2875
2876 /* we're only handling directories here, skip if it's not ours */
2877 if (lstat(path, &statbuf) == 0 && !S_ISDIR(statbuf.st_mode))
2878 return;
2879
2880 spill_dir = AllocateDir(path);
2881 while ((spill_de = ReadDirExtended(spill_dir, path, INFO)) != NULL)
2882 {
2883 /* only look at names that can be ours */
2884 if (strncmp(spill_de->d_name, "xid", 3) == 0)
2885 {
2886 snprintf(path, sizeof(path),
2887 "pg_replslot/%s/%s", slotname,
2888 spill_de->d_name);
2889
2890 if (unlink(path) != 0)
2891 ereport(ERROR,
2892 (errcode_for_file_access(),
2893 errmsg("could not remove file \"%s\" during removal of pg_replslot/%s/xid*: %m",
2894 path, slotname)));
2895 }
2896 }
2897 FreeDir(spill_dir);
2898 }
2899
2900 /*
2901 * Given a replication slot, transaction ID and segment number, fill in the
2902 * corresponding spill file into 'path', which is a caller-owned buffer of size
2903 * at least MAXPGPATH.
2904 */
2905 static void
ReorderBufferSerializedPath(char * path,ReplicationSlot * slot,TransactionId xid,XLogSegNo segno)2906 ReorderBufferSerializedPath(char *path, ReplicationSlot *slot, TransactionId xid,
2907 XLogSegNo segno)
2908 {
2909 XLogRecPtr recptr;
2910
2911 XLogSegNoOffsetToRecPtr(segno, 0, wal_segment_size, recptr);
2912
2913 snprintf(path, MAXPGPATH, "pg_replslot/%s/xid-%u-lsn-%X-%X.spill",
2914 NameStr(MyReplicationSlot->data.name),
2915 xid,
2916 (uint32) (recptr >> 32), (uint32) recptr);
2917 }
2918
2919 /*
2920 * Delete all data spilled to disk after we've restarted/crashed. It will be
2921 * recreated when the respective slots are reused.
2922 */
2923 void
StartupReorderBuffer(void)2924 StartupReorderBuffer(void)
2925 {
2926 DIR *logical_dir;
2927 struct dirent *logical_de;
2928
2929 logical_dir = AllocateDir("pg_replslot");
2930 while ((logical_de = ReadDir(logical_dir, "pg_replslot")) != NULL)
2931 {
2932 if (strcmp(logical_de->d_name, ".") == 0 ||
2933 strcmp(logical_de->d_name, "..") == 0)
2934 continue;
2935
2936 /* if it cannot be a slot, skip the directory */
2937 if (!ReplicationSlotValidateName(logical_de->d_name, DEBUG2))
2938 continue;
2939
2940 /*
2941 * ok, has to be a surviving logical slot, iterate and delete
2942 * everything starting with xid-*
2943 */
2944 ReorderBufferCleanupSerializedTXNs(logical_de->d_name);
2945 }
2946 FreeDir(logical_dir);
2947 }
2948
2949 /* ---------------------------------------
2950 * toast reassembly support
2951 * ---------------------------------------
2952 */
2953
2954 /*
2955 * Initialize per tuple toast reconstruction support.
2956 */
2957 static void
ReorderBufferToastInitHash(ReorderBuffer * rb,ReorderBufferTXN * txn)2958 ReorderBufferToastInitHash(ReorderBuffer *rb, ReorderBufferTXN *txn)
2959 {
2960 HASHCTL hash_ctl;
2961
2962 Assert(txn->toast_hash == NULL);
2963
2964 memset(&hash_ctl, 0, sizeof(hash_ctl));
2965 hash_ctl.keysize = sizeof(Oid);
2966 hash_ctl.entrysize = sizeof(ReorderBufferToastEnt);
2967 hash_ctl.hcxt = rb->context;
2968 txn->toast_hash = hash_create("ReorderBufferToastHash", 5, &hash_ctl,
2969 HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
2970 }
2971
2972 /*
2973 * Per toast-chunk handling for toast reconstruction
2974 *
2975 * Appends a toast chunk so we can reconstruct it when the tuple "owning" the
2976 * toasted Datum comes along.
2977 */
2978 static void
ReorderBufferToastAppendChunk(ReorderBuffer * rb,ReorderBufferTXN * txn,Relation relation,ReorderBufferChange * change)2979 ReorderBufferToastAppendChunk(ReorderBuffer *rb, ReorderBufferTXN *txn,
2980 Relation relation, ReorderBufferChange *change)
2981 {
2982 ReorderBufferToastEnt *ent;
2983 ReorderBufferTupleBuf *newtup;
2984 bool found;
2985 int32 chunksize;
2986 bool isnull;
2987 Pointer chunk;
2988 TupleDesc desc = RelationGetDescr(relation);
2989 Oid chunk_id;
2990 int32 chunk_seq;
2991
2992 if (txn->toast_hash == NULL)
2993 ReorderBufferToastInitHash(rb, txn);
2994
2995 Assert(IsToastRelation(relation));
2996
2997 newtup = change->data.tp.newtuple;
2998 chunk_id = DatumGetObjectId(fastgetattr(&newtup->tuple, 1, desc, &isnull));
2999 Assert(!isnull);
3000 chunk_seq = DatumGetInt32(fastgetattr(&newtup->tuple, 2, desc, &isnull));
3001 Assert(!isnull);
3002
3003 ent = (ReorderBufferToastEnt *)
3004 hash_search(txn->toast_hash,
3005 (void *) &chunk_id,
3006 HASH_ENTER,
3007 &found);
3008
3009 if (!found)
3010 {
3011 Assert(ent->chunk_id == chunk_id);
3012 ent->num_chunks = 0;
3013 ent->last_chunk_seq = 0;
3014 ent->size = 0;
3015 ent->reconstructed = NULL;
3016 dlist_init(&ent->chunks);
3017
3018 if (chunk_seq != 0)
3019 elog(ERROR, "got sequence entry %d for toast chunk %u instead of seq 0",
3020 chunk_seq, chunk_id);
3021 }
3022 else if (found && chunk_seq != ent->last_chunk_seq + 1)
3023 elog(ERROR, "got sequence entry %d for toast chunk %u instead of seq %d",
3024 chunk_seq, chunk_id, ent->last_chunk_seq + 1);
3025
3026 chunk = DatumGetPointer(fastgetattr(&newtup->tuple, 3, desc, &isnull));
3027 Assert(!isnull);
3028
3029 /* calculate size so we can allocate the right size at once later */
3030 if (!VARATT_IS_EXTENDED(chunk))
3031 chunksize = VARSIZE(chunk) - VARHDRSZ;
3032 else if (VARATT_IS_SHORT(chunk))
3033 /* could happen due to heap_form_tuple doing its thing */
3034 chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
3035 else
3036 elog(ERROR, "unexpected type of toast chunk");
3037
3038 ent->size += chunksize;
3039 ent->last_chunk_seq = chunk_seq;
3040 ent->num_chunks++;
3041 dlist_push_tail(&ent->chunks, &change->node);
3042 }
3043
3044 /*
3045 * Rejigger change->newtuple to point to in-memory toast tuples instead to
3046 * on-disk toast tuples that may not longer exist (think DROP TABLE or VACUUM).
3047 *
3048 * We cannot replace unchanged toast tuples though, so those will still point
3049 * to on-disk toast data.
3050 */
3051 static void
ReorderBufferToastReplace(ReorderBuffer * rb,ReorderBufferTXN * txn,Relation relation,ReorderBufferChange * change)3052 ReorderBufferToastReplace(ReorderBuffer *rb, ReorderBufferTXN *txn,
3053 Relation relation, ReorderBufferChange *change)
3054 {
3055 TupleDesc desc;
3056 int natt;
3057 Datum *attrs;
3058 bool *isnull;
3059 bool *free;
3060 HeapTuple tmphtup;
3061 Relation toast_rel;
3062 TupleDesc toast_desc;
3063 MemoryContext oldcontext;
3064 ReorderBufferTupleBuf *newtup;
3065
3066 /* no toast tuples changed */
3067 if (txn->toast_hash == NULL)
3068 return;
3069
3070 oldcontext = MemoryContextSwitchTo(rb->context);
3071
3072 /* we should only have toast tuples in an INSERT or UPDATE */
3073 Assert(change->data.tp.newtuple);
3074
3075 desc = RelationGetDescr(relation);
3076
3077 toast_rel = RelationIdGetRelation(relation->rd_rel->reltoastrelid);
3078 if (!RelationIsValid(toast_rel))
3079 elog(ERROR, "could not open toast relation with OID %u (base relation \"%s\")",
3080 relation->rd_rel->reltoastrelid, RelationGetRelationName(relation));
3081
3082 toast_desc = RelationGetDescr(toast_rel);
3083
3084 /* should we allocate from stack instead? */
3085 attrs = palloc0(sizeof(Datum) * desc->natts);
3086 isnull = palloc0(sizeof(bool) * desc->natts);
3087 free = palloc0(sizeof(bool) * desc->natts);
3088
3089 newtup = change->data.tp.newtuple;
3090
3091 heap_deform_tuple(&newtup->tuple, desc, attrs, isnull);
3092
3093 for (natt = 0; natt < desc->natts; natt++)
3094 {
3095 Form_pg_attribute attr = TupleDescAttr(desc, natt);
3096 ReorderBufferToastEnt *ent;
3097 struct varlena *varlena;
3098
3099 /* va_rawsize is the size of the original datum -- including header */
3100 struct varatt_external toast_pointer;
3101 struct varatt_indirect redirect_pointer;
3102 struct varlena *new_datum = NULL;
3103 struct varlena *reconstructed;
3104 dlist_iter it;
3105 Size data_done = 0;
3106
3107 /* system columns aren't toasted */
3108 if (attr->attnum < 0)
3109 continue;
3110
3111 if (attr->attisdropped)
3112 continue;
3113
3114 /* not a varlena datatype */
3115 if (attr->attlen != -1)
3116 continue;
3117
3118 /* no data */
3119 if (isnull[natt])
3120 continue;
3121
3122 /* ok, we know we have a toast datum */
3123 varlena = (struct varlena *) DatumGetPointer(attrs[natt]);
3124
3125 /* no need to do anything if the tuple isn't external */
3126 if (!VARATT_IS_EXTERNAL(varlena))
3127 continue;
3128
3129 VARATT_EXTERNAL_GET_POINTER(toast_pointer, varlena);
3130
3131 /*
3132 * Check whether the toast tuple changed, replace if so.
3133 */
3134 ent = (ReorderBufferToastEnt *)
3135 hash_search(txn->toast_hash,
3136 (void *) &toast_pointer.va_valueid,
3137 HASH_FIND,
3138 NULL);
3139 if (ent == NULL)
3140 continue;
3141
3142 new_datum =
3143 (struct varlena *) palloc0(INDIRECT_POINTER_SIZE);
3144
3145 free[natt] = true;
3146
3147 reconstructed = palloc0(toast_pointer.va_rawsize);
3148
3149 ent->reconstructed = reconstructed;
3150
3151 /* stitch toast tuple back together from its parts */
3152 dlist_foreach(it, &ent->chunks)
3153 {
3154 bool isnull;
3155 ReorderBufferChange *cchange;
3156 ReorderBufferTupleBuf *ctup;
3157 Pointer chunk;
3158
3159 cchange = dlist_container(ReorderBufferChange, node, it.cur);
3160 ctup = cchange->data.tp.newtuple;
3161 chunk = DatumGetPointer(
3162 fastgetattr(&ctup->tuple, 3, toast_desc, &isnull));
3163
3164 Assert(!isnull);
3165 Assert(!VARATT_IS_EXTERNAL(chunk));
3166 Assert(!VARATT_IS_SHORT(chunk));
3167
3168 memcpy(VARDATA(reconstructed) + data_done,
3169 VARDATA(chunk),
3170 VARSIZE(chunk) - VARHDRSZ);
3171 data_done += VARSIZE(chunk) - VARHDRSZ;
3172 }
3173 Assert(data_done == toast_pointer.va_extsize);
3174
3175 /* make sure its marked as compressed or not */
3176 if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
3177 SET_VARSIZE_COMPRESSED(reconstructed, data_done + VARHDRSZ);
3178 else
3179 SET_VARSIZE(reconstructed, data_done + VARHDRSZ);
3180
3181 memset(&redirect_pointer, 0, sizeof(redirect_pointer));
3182 redirect_pointer.pointer = reconstructed;
3183
3184 SET_VARTAG_EXTERNAL(new_datum, VARTAG_INDIRECT);
3185 memcpy(VARDATA_EXTERNAL(new_datum), &redirect_pointer,
3186 sizeof(redirect_pointer));
3187
3188 attrs[natt] = PointerGetDatum(new_datum);
3189 }
3190
3191 /*
3192 * Build tuple in separate memory & copy tuple back into the tuplebuf
3193 * passed to the output plugin. We can't directly heap_fill_tuple() into
3194 * the tuplebuf because attrs[] will point back into the current content.
3195 */
3196 tmphtup = heap_form_tuple(desc, attrs, isnull);
3197 Assert(newtup->tuple.t_len <= MaxHeapTupleSize);
3198 Assert(ReorderBufferTupleBufData(newtup) == newtup->tuple.t_data);
3199
3200 memcpy(newtup->tuple.t_data, tmphtup->t_data, tmphtup->t_len);
3201 newtup->tuple.t_len = tmphtup->t_len;
3202
3203 /*
3204 * free resources we won't further need, more persistent stuff will be
3205 * free'd in ReorderBufferToastReset().
3206 */
3207 RelationClose(toast_rel);
3208 pfree(tmphtup);
3209 for (natt = 0; natt < desc->natts; natt++)
3210 {
3211 if (free[natt])
3212 pfree(DatumGetPointer(attrs[natt]));
3213 }
3214 pfree(attrs);
3215 pfree(free);
3216 pfree(isnull);
3217
3218 MemoryContextSwitchTo(oldcontext);
3219 }
3220
3221 /*
3222 * Free all resources allocated for toast reconstruction.
3223 */
3224 static void
ReorderBufferToastReset(ReorderBuffer * rb,ReorderBufferTXN * txn)3225 ReorderBufferToastReset(ReorderBuffer *rb, ReorderBufferTXN *txn)
3226 {
3227 HASH_SEQ_STATUS hstat;
3228 ReorderBufferToastEnt *ent;
3229
3230 if (txn->toast_hash == NULL)
3231 return;
3232
3233 /* sequentially walk over the hash and free everything */
3234 hash_seq_init(&hstat, txn->toast_hash);
3235 while ((ent = (ReorderBufferToastEnt *) hash_seq_search(&hstat)) != NULL)
3236 {
3237 dlist_mutable_iter it;
3238
3239 if (ent->reconstructed != NULL)
3240 pfree(ent->reconstructed);
3241
3242 dlist_foreach_modify(it, &ent->chunks)
3243 {
3244 ReorderBufferChange *change =
3245 dlist_container(ReorderBufferChange, node, it.cur);
3246
3247 dlist_delete(&change->node);
3248 ReorderBufferReturnChange(rb, change);
3249 }
3250 }
3251
3252 hash_destroy(txn->toast_hash);
3253 txn->toast_hash = NULL;
3254 }
3255
3256
3257 /* ---------------------------------------
3258 * Visibility support for logical decoding
3259 *
3260 *
3261 * Lookup actual cmin/cmax values when using decoding snapshot. We can't
3262 * always rely on stored cmin/cmax values because of two scenarios:
3263 *
3264 * * A tuple got changed multiple times during a single transaction and thus
3265 * has got a combocid. Combocid's are only valid for the duration of a
3266 * single transaction.
3267 * * A tuple with a cmin but no cmax (and thus no combocid) got
3268 * deleted/updated in another transaction than the one which created it
3269 * which we are looking at right now. As only one of cmin, cmax or combocid
3270 * is actually stored in the heap we don't have access to the value we
3271 * need anymore.
3272 *
3273 * To resolve those problems we have a per-transaction hash of (cmin,
3274 * cmax) tuples keyed by (relfilenode, ctid) which contains the actual
3275 * (cmin, cmax) values. That also takes care of combocids by simply
3276 * not caring about them at all. As we have the real cmin/cmax values
3277 * combocids aren't interesting.
3278 *
3279 * As we only care about catalog tuples here the overhead of this
3280 * hashtable should be acceptable.
3281 *
3282 * Heap rewrites complicate this a bit, check rewriteheap.c for
3283 * details.
3284 * -------------------------------------------------------------------------
3285 */
3286
3287 /* struct for qsort()ing mapping files by lsn somewhat efficiently */
3288 typedef struct RewriteMappingFile
3289 {
3290 XLogRecPtr lsn;
3291 char fname[MAXPGPATH];
3292 } RewriteMappingFile;
3293
3294 #if NOT_USED
3295 static void
DisplayMapping(HTAB * tuplecid_data)3296 DisplayMapping(HTAB *tuplecid_data)
3297 {
3298 HASH_SEQ_STATUS hstat;
3299 ReorderBufferTupleCidEnt *ent;
3300
3301 hash_seq_init(&hstat, tuplecid_data);
3302 while ((ent = (ReorderBufferTupleCidEnt *) hash_seq_search(&hstat)) != NULL)
3303 {
3304 elog(DEBUG3, "mapping: node: %u/%u/%u tid: %u/%u cmin: %u, cmax: %u",
3305 ent->key.relnode.dbNode,
3306 ent->key.relnode.spcNode,
3307 ent->key.relnode.relNode,
3308 ItemPointerGetBlockNumber(&ent->key.tid),
3309 ItemPointerGetOffsetNumber(&ent->key.tid),
3310 ent->cmin,
3311 ent->cmax
3312 );
3313 }
3314 }
3315 #endif
3316
3317 /*
3318 * Apply a single mapping file to tuplecid_data.
3319 *
3320 * The mapping file has to have been verified to be a) committed b) for our
3321 * transaction c) applied in LSN order.
3322 */
3323 static void
ApplyLogicalMappingFile(HTAB * tuplecid_data,Oid relid,const char * fname)3324 ApplyLogicalMappingFile(HTAB *tuplecid_data, Oid relid, const char *fname)
3325 {
3326 char path[MAXPGPATH];
3327 int fd;
3328 int readBytes;
3329 LogicalRewriteMappingData map;
3330
3331 sprintf(path, "pg_logical/mappings/%s", fname);
3332 fd = OpenTransientFile(path, O_RDONLY | PG_BINARY);
3333 if (fd < 0)
3334 ereport(ERROR,
3335 (errcode_for_file_access(),
3336 errmsg("could not open file \"%s\": %m", path)));
3337
3338 while (true)
3339 {
3340 ReorderBufferTupleCidKey key;
3341 ReorderBufferTupleCidEnt *ent;
3342 ReorderBufferTupleCidEnt *new_ent;
3343 bool found;
3344
3345 /* be careful about padding */
3346 memset(&key, 0, sizeof(ReorderBufferTupleCidKey));
3347
3348 /* read all mappings till the end of the file */
3349 pgstat_report_wait_start(WAIT_EVENT_REORDER_LOGICAL_MAPPING_READ);
3350 readBytes = read(fd, &map, sizeof(LogicalRewriteMappingData));
3351 pgstat_report_wait_end();
3352
3353 if (readBytes < 0)
3354 ereport(ERROR,
3355 (errcode_for_file_access(),
3356 errmsg("could not read file \"%s\": %m",
3357 path)));
3358 else if (readBytes == 0) /* EOF */
3359 break;
3360 else if (readBytes != sizeof(LogicalRewriteMappingData))
3361 ereport(ERROR,
3362 (errcode_for_file_access(),
3363 errmsg("could not read from file \"%s\": read %d instead of %d bytes",
3364 path, readBytes,
3365 (int32) sizeof(LogicalRewriteMappingData))));
3366
3367 key.relnode = map.old_node;
3368 ItemPointerCopy(&map.old_tid,
3369 &key.tid);
3370
3371
3372 ent = (ReorderBufferTupleCidEnt *)
3373 hash_search(tuplecid_data,
3374 (void *) &key,
3375 HASH_FIND,
3376 NULL);
3377
3378 /* no existing mapping, no need to update */
3379 if (!ent)
3380 continue;
3381
3382 key.relnode = map.new_node;
3383 ItemPointerCopy(&map.new_tid,
3384 &key.tid);
3385
3386 new_ent = (ReorderBufferTupleCidEnt *)
3387 hash_search(tuplecid_data,
3388 (void *) &key,
3389 HASH_ENTER,
3390 &found);
3391
3392 if (found)
3393 {
3394 /*
3395 * Make sure the existing mapping makes sense. We sometime update
3396 * old records that did not yet have a cmax (e.g. pg_class' own
3397 * entry while rewriting it) during rewrites, so allow that.
3398 */
3399 Assert(ent->cmin == InvalidCommandId || ent->cmin == new_ent->cmin);
3400 Assert(ent->cmax == InvalidCommandId || ent->cmax == new_ent->cmax);
3401 }
3402 else
3403 {
3404 /* update mapping */
3405 new_ent->cmin = ent->cmin;
3406 new_ent->cmax = ent->cmax;
3407 new_ent->combocid = ent->combocid;
3408 }
3409 }
3410
3411 if (CloseTransientFile(fd))
3412 ereport(ERROR,
3413 (errcode_for_file_access(),
3414 errmsg("could not close file \"%s\": %m", path)));
3415 }
3416
3417
3418 /*
3419 * Check whether the TransactionOid 'xid' is in the pre-sorted array 'xip'.
3420 */
3421 static bool
TransactionIdInArray(TransactionId xid,TransactionId * xip,Size num)3422 TransactionIdInArray(TransactionId xid, TransactionId *xip, Size num)
3423 {
3424 return bsearch(&xid, xip, num,
3425 sizeof(TransactionId), xidComparator) != NULL;
3426 }
3427
3428 /*
3429 * qsort() comparator for sorting RewriteMappingFiles in LSN order.
3430 */
3431 static int
file_sort_by_lsn(const void * a_p,const void * b_p)3432 file_sort_by_lsn(const void *a_p, const void *b_p)
3433 {
3434 RewriteMappingFile *a = *(RewriteMappingFile **) a_p;
3435 RewriteMappingFile *b = *(RewriteMappingFile **) b_p;
3436
3437 if (a->lsn < b->lsn)
3438 return -1;
3439 else if (a->lsn > b->lsn)
3440 return 1;
3441 return 0;
3442 }
3443
3444 /*
3445 * Apply any existing logical remapping files if there are any targeted at our
3446 * transaction for relid.
3447 */
3448 static void
UpdateLogicalMappings(HTAB * tuplecid_data,Oid relid,Snapshot snapshot)3449 UpdateLogicalMappings(HTAB *tuplecid_data, Oid relid, Snapshot snapshot)
3450 {
3451 DIR *mapping_dir;
3452 struct dirent *mapping_de;
3453 List *files = NIL;
3454 ListCell *file;
3455 RewriteMappingFile **files_a;
3456 size_t off;
3457 Oid dboid = IsSharedRelation(relid) ? InvalidOid : MyDatabaseId;
3458
3459 mapping_dir = AllocateDir("pg_logical/mappings");
3460 while ((mapping_de = ReadDir(mapping_dir, "pg_logical/mappings")) != NULL)
3461 {
3462 Oid f_dboid;
3463 Oid f_relid;
3464 TransactionId f_mapped_xid;
3465 TransactionId f_create_xid;
3466 XLogRecPtr f_lsn;
3467 uint32 f_hi,
3468 f_lo;
3469 RewriteMappingFile *f;
3470
3471 if (strcmp(mapping_de->d_name, ".") == 0 ||
3472 strcmp(mapping_de->d_name, "..") == 0)
3473 continue;
3474
3475 /* Ignore files that aren't ours */
3476 if (strncmp(mapping_de->d_name, "map-", 4) != 0)
3477 continue;
3478
3479 if (sscanf(mapping_de->d_name, LOGICAL_REWRITE_FORMAT,
3480 &f_dboid, &f_relid, &f_hi, &f_lo,
3481 &f_mapped_xid, &f_create_xid) != 6)
3482 elog(ERROR, "could not parse filename \"%s\"", mapping_de->d_name);
3483
3484 f_lsn = ((uint64) f_hi) << 32 | f_lo;
3485
3486 /* mapping for another database */
3487 if (f_dboid != dboid)
3488 continue;
3489
3490 /* mapping for another relation */
3491 if (f_relid != relid)
3492 continue;
3493
3494 /* did the creating transaction abort? */
3495 if (!TransactionIdDidCommit(f_create_xid))
3496 continue;
3497
3498 /* not for our transaction */
3499 if (!TransactionIdInArray(f_mapped_xid, snapshot->subxip, snapshot->subxcnt))
3500 continue;
3501
3502 /* ok, relevant, queue for apply */
3503 f = palloc(sizeof(RewriteMappingFile));
3504 f->lsn = f_lsn;
3505 strcpy(f->fname, mapping_de->d_name);
3506 files = lappend(files, f);
3507 }
3508 FreeDir(mapping_dir);
3509
3510 /* build array we can easily sort */
3511 files_a = palloc(list_length(files) * sizeof(RewriteMappingFile *));
3512 off = 0;
3513 foreach(file, files)
3514 {
3515 files_a[off++] = lfirst(file);
3516 }
3517
3518 /* sort files so we apply them in LSN order */
3519 qsort(files_a, list_length(files), sizeof(RewriteMappingFile *),
3520 file_sort_by_lsn);
3521
3522 for (off = 0; off < list_length(files); off++)
3523 {
3524 RewriteMappingFile *f = files_a[off];
3525
3526 elog(DEBUG1, "applying mapping: \"%s\" in %u", f->fname,
3527 snapshot->subxip[0]);
3528 ApplyLogicalMappingFile(tuplecid_data, relid, f->fname);
3529 pfree(f);
3530 }
3531 }
3532
3533 /*
3534 * Lookup cmin/cmax of a tuple, during logical decoding where we can't rely on
3535 * combocids.
3536 */
3537 bool
ResolveCminCmaxDuringDecoding(HTAB * tuplecid_data,Snapshot snapshot,HeapTuple htup,Buffer buffer,CommandId * cmin,CommandId * cmax)3538 ResolveCminCmaxDuringDecoding(HTAB *tuplecid_data,
3539 Snapshot snapshot,
3540 HeapTuple htup, Buffer buffer,
3541 CommandId *cmin, CommandId *cmax)
3542 {
3543 ReorderBufferTupleCidKey key;
3544 ReorderBufferTupleCidEnt *ent;
3545 ForkNumber forkno;
3546 BlockNumber blockno;
3547 bool updated_mapping = false;
3548
3549 /* be careful about padding */
3550 memset(&key, 0, sizeof(key));
3551
3552 Assert(!BufferIsLocal(buffer));
3553
3554 /*
3555 * get relfilenode from the buffer, no convenient way to access it other
3556 * than that.
3557 */
3558 BufferGetTag(buffer, &key.relnode, &forkno, &blockno);
3559
3560 /* tuples can only be in the main fork */
3561 Assert(forkno == MAIN_FORKNUM);
3562 Assert(blockno == ItemPointerGetBlockNumber(&htup->t_self));
3563
3564 ItemPointerCopy(&htup->t_self,
3565 &key.tid);
3566
3567 restart:
3568 ent = (ReorderBufferTupleCidEnt *)
3569 hash_search(tuplecid_data,
3570 (void *) &key,
3571 HASH_FIND,
3572 NULL);
3573
3574 /*
3575 * failed to find a mapping, check whether the table was rewritten and
3576 * apply mapping if so, but only do that once - there can be no new
3577 * mappings while we are in here since we have to hold a lock on the
3578 * relation.
3579 */
3580 if (ent == NULL && !updated_mapping)
3581 {
3582 UpdateLogicalMappings(tuplecid_data, htup->t_tableOid, snapshot);
3583 /* now check but don't update for a mapping again */
3584 updated_mapping = true;
3585 goto restart;
3586 }
3587 else if (ent == NULL)
3588 return false;
3589
3590 if (cmin)
3591 *cmin = ent->cmin;
3592 if (cmax)
3593 *cmax = ent->cmax;
3594 return true;
3595 }
3596