1 /*------------------------------------------------------------------------- 2 * 3 * lock.h 4 * POSTGRES low-level lock mechanism 5 * 6 * 7 * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group 8 * Portions Copyright (c) 1994, Regents of the University of California 9 * 10 * src/include/storage/lock.h 11 * 12 *------------------------------------------------------------------------- 13 */ 14 #ifndef LOCK_H_ 15 #define LOCK_H_ 16 17 #ifdef FRONTEND 18 #error "lock.h may not be included from frontend code" 19 #endif 20 21 #include "storage/lockdefs.h" 22 #include "storage/backendid.h" 23 #include "storage/lwlock.h" 24 #include "storage/shmem.h" 25 26 27 /* struct PGPROC is declared in proc.h, but must forward-reference it */ 28 typedef struct PGPROC PGPROC; 29 30 typedef struct PROC_QUEUE 31 { 32 SHM_QUEUE links; /* head of list of PGPROC objects */ 33 int size; /* number of entries in list */ 34 } PROC_QUEUE; 35 36 /* GUC variables */ 37 extern int max_locks_per_xact; 38 39 #ifdef LOCK_DEBUG 40 extern int Trace_lock_oidmin; 41 extern bool Trace_locks; 42 extern bool Trace_userlocks; 43 extern int Trace_lock_table; 44 extern bool Debug_deadlocks; 45 #endif /* LOCK_DEBUG */ 46 47 48 /* 49 * Top-level transactions are identified by VirtualTransactionIDs comprising 50 * the BackendId of the backend running the xact, plus a locally-assigned 51 * LocalTransactionId. These are guaranteed unique over the short term, 52 * but will be reused after a database restart; hence they should never 53 * be stored on disk. 54 * 55 * Note that struct VirtualTransactionId can not be assumed to be atomically 56 * assignable as a whole. However, type LocalTransactionId is assumed to 57 * be atomically assignable, and the backend ID doesn't change often enough 58 * to be a problem, so we can fetch or assign the two fields separately. 59 * We deliberately refrain from using the struct within PGPROC, to prevent 60 * coding errors from trying to use struct assignment with it; instead use 61 * GET_VXID_FROM_PGPROC(). 62 */ 63 typedef struct 64 { 65 BackendId backendId; /* determined at backend startup */ 66 LocalTransactionId localTransactionId; /* backend-local transaction id */ 67 } VirtualTransactionId; 68 69 #define InvalidLocalTransactionId 0 70 #define LocalTransactionIdIsValid(lxid) ((lxid) != InvalidLocalTransactionId) 71 #define VirtualTransactionIdIsValid(vxid) \ 72 (((vxid).backendId != InvalidBackendId) && \ 73 LocalTransactionIdIsValid((vxid).localTransactionId)) 74 #define VirtualTransactionIdEquals(vxid1, vxid2) \ 75 ((vxid1).backendId == (vxid2).backendId && \ 76 (vxid1).localTransactionId == (vxid2).localTransactionId) 77 #define SetInvalidVirtualTransactionId(vxid) \ 78 ((vxid).backendId = InvalidBackendId, \ 79 (vxid).localTransactionId = InvalidLocalTransactionId) 80 #define GET_VXID_FROM_PGPROC(vxid, proc) \ 81 ((vxid).backendId = (proc).backendId, \ 82 (vxid).localTransactionId = (proc).lxid) 83 84 /* MAX_LOCKMODES cannot be larger than the # of bits in LOCKMASK */ 85 #define MAX_LOCKMODES 10 86 87 #define LOCKBIT_ON(lockmode) (1 << (lockmode)) 88 #define LOCKBIT_OFF(lockmode) (~(1 << (lockmode))) 89 90 91 /* 92 * This data structure defines the locking semantics associated with a 93 * "lock method". The semantics specify the meaning of each lock mode 94 * (by defining which lock modes it conflicts with). 95 * All of this data is constant and is kept in const tables. 96 * 97 * numLockModes -- number of lock modes (READ,WRITE,etc) that 98 * are defined in this lock method. Must be less than MAX_LOCKMODES. 99 * 100 * conflictTab -- this is an array of bitmasks showing lock 101 * mode conflicts. conflictTab[i] is a mask with the j-th bit 102 * turned on if lock modes i and j conflict. Lock modes are 103 * numbered 1..numLockModes; conflictTab[0] is unused. 104 * 105 * lockModeNames -- ID strings for debug printouts. 106 * 107 * trace_flag -- pointer to GUC trace flag for this lock method. (The 108 * GUC variable is not constant, but we use "const" here to denote that 109 * it can't be changed through this reference.) 110 */ 111 typedef struct LockMethodData 112 { 113 int numLockModes; 114 const LOCKMASK *conflictTab; 115 const char *const *lockModeNames; 116 const bool *trace_flag; 117 } LockMethodData; 118 119 typedef const LockMethodData *LockMethod; 120 121 /* 122 * Lock methods are identified by LOCKMETHODID. (Despite the declaration as 123 * uint16, we are constrained to 256 lockmethods by the layout of LOCKTAG.) 124 */ 125 typedef uint16 LOCKMETHODID; 126 127 /* These identify the known lock methods */ 128 #define DEFAULT_LOCKMETHOD 1 129 #define USER_LOCKMETHOD 2 130 131 /* 132 * LOCKTAG is the key information needed to look up a LOCK item in the 133 * lock hashtable. A LOCKTAG value uniquely identifies a lockable object. 134 * 135 * The LockTagType enum defines the different kinds of objects we can lock. 136 * We can handle up to 256 different LockTagTypes. 137 */ 138 typedef enum LockTagType 139 { 140 LOCKTAG_RELATION, /* whole relation */ 141 /* ID info for a relation is DB OID + REL OID; DB OID = 0 if shared */ 142 LOCKTAG_RELATION_EXTEND, /* the right to extend a relation */ 143 /* same ID info as RELATION */ 144 LOCKTAG_PAGE, /* one page of a relation */ 145 /* ID info for a page is RELATION info + BlockNumber */ 146 LOCKTAG_TUPLE, /* one physical tuple */ 147 /* ID info for a tuple is PAGE info + OffsetNumber */ 148 LOCKTAG_TRANSACTION, /* transaction (for waiting for xact done) */ 149 /* ID info for a transaction is its TransactionId */ 150 LOCKTAG_VIRTUALTRANSACTION, /* virtual transaction (ditto) */ 151 /* ID info for a virtual transaction is its VirtualTransactionId */ 152 LOCKTAG_SPECULATIVE_TOKEN, /* speculative insertion Xid and token */ 153 /* ID info for a transaction is its TransactionId */ 154 LOCKTAG_OBJECT, /* non-relation database object */ 155 /* ID info for an object is DB OID + CLASS OID + OBJECT OID + SUBID */ 156 157 /* 158 * Note: object ID has same representation as in pg_depend and 159 * pg_description, but notice that we are constraining SUBID to 16 bits. 160 * Also, we use DB OID = 0 for shared objects such as tablespaces. 161 */ 162 LOCKTAG_USERLOCK, /* reserved for old contrib/userlock code */ 163 LOCKTAG_ADVISORY, /* advisory user locks */ 164 LOCKTAG_DATABASE_FROZEN_IDS /* pg_database.datfrozenxid */ 165 /* ID info for frozen IDs is DB OID */ 166 } LockTagType; 167 168 #define LOCKTAG_LAST_TYPE LOCKTAG_DATABASE_FROZEN_IDS 169 170 extern const char *const LockTagTypeNames[]; 171 172 /* 173 * The LOCKTAG struct is defined with malice aforethought to fit into 16 174 * bytes with no padding. Note that this would need adjustment if we were 175 * to widen Oid, BlockNumber, or TransactionId to more than 32 bits. 176 * 177 * We include lockmethodid in the locktag so that a single hash table in 178 * shared memory can store locks of different lockmethods. 179 */ 180 typedef struct LOCKTAG 181 { 182 uint32 locktag_field1; /* a 32-bit ID field */ 183 uint32 locktag_field2; /* a 32-bit ID field */ 184 uint32 locktag_field3; /* a 32-bit ID field */ 185 uint16 locktag_field4; /* a 16-bit ID field */ 186 uint8 locktag_type; /* see enum LockTagType */ 187 uint8 locktag_lockmethodid; /* lockmethod indicator */ 188 } LOCKTAG; 189 190 /* 191 * These macros define how we map logical IDs of lockable objects into 192 * the physical fields of LOCKTAG. Use these to set up LOCKTAG values, 193 * rather than accessing the fields directly. Note multiple eval of target! 194 */ 195 #define SET_LOCKTAG_RELATION(locktag,dboid,reloid) \ 196 ((locktag).locktag_field1 = (dboid), \ 197 (locktag).locktag_field2 = (reloid), \ 198 (locktag).locktag_field3 = 0, \ 199 (locktag).locktag_field4 = 0, \ 200 (locktag).locktag_type = LOCKTAG_RELATION, \ 201 (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD) 202 203 #define SET_LOCKTAG_RELATION_EXTEND(locktag,dboid,reloid) \ 204 ((locktag).locktag_field1 = (dboid), \ 205 (locktag).locktag_field2 = (reloid), \ 206 (locktag).locktag_field3 = 0, \ 207 (locktag).locktag_field4 = 0, \ 208 (locktag).locktag_type = LOCKTAG_RELATION_EXTEND, \ 209 (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD) 210 211 #define SET_LOCKTAG_DATABASE_FROZEN_IDS(locktag,dboid) \ 212 ((locktag).locktag_field1 = (dboid), \ 213 (locktag).locktag_field2 = 0, \ 214 (locktag).locktag_field3 = 0, \ 215 (locktag).locktag_field4 = 0, \ 216 (locktag).locktag_type = LOCKTAG_DATABASE_FROZEN_IDS, \ 217 (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD) 218 219 #define SET_LOCKTAG_PAGE(locktag,dboid,reloid,blocknum) \ 220 ((locktag).locktag_field1 = (dboid), \ 221 (locktag).locktag_field2 = (reloid), \ 222 (locktag).locktag_field3 = (blocknum), \ 223 (locktag).locktag_field4 = 0, \ 224 (locktag).locktag_type = LOCKTAG_PAGE, \ 225 (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD) 226 227 #define SET_LOCKTAG_TUPLE(locktag,dboid,reloid,blocknum,offnum) \ 228 ((locktag).locktag_field1 = (dboid), \ 229 (locktag).locktag_field2 = (reloid), \ 230 (locktag).locktag_field3 = (blocknum), \ 231 (locktag).locktag_field4 = (offnum), \ 232 (locktag).locktag_type = LOCKTAG_TUPLE, \ 233 (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD) 234 235 #define SET_LOCKTAG_TRANSACTION(locktag,xid) \ 236 ((locktag).locktag_field1 = (xid), \ 237 (locktag).locktag_field2 = 0, \ 238 (locktag).locktag_field3 = 0, \ 239 (locktag).locktag_field4 = 0, \ 240 (locktag).locktag_type = LOCKTAG_TRANSACTION, \ 241 (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD) 242 243 #define SET_LOCKTAG_VIRTUALTRANSACTION(locktag,vxid) \ 244 ((locktag).locktag_field1 = (vxid).backendId, \ 245 (locktag).locktag_field2 = (vxid).localTransactionId, \ 246 (locktag).locktag_field3 = 0, \ 247 (locktag).locktag_field4 = 0, \ 248 (locktag).locktag_type = LOCKTAG_VIRTUALTRANSACTION, \ 249 (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD) 250 251 #define SET_LOCKTAG_SPECULATIVE_INSERTION(locktag,xid,token) \ 252 ((locktag).locktag_field1 = (xid), \ 253 (locktag).locktag_field2 = (token), \ 254 (locktag).locktag_field3 = 0, \ 255 (locktag).locktag_field4 = 0, \ 256 (locktag).locktag_type = LOCKTAG_SPECULATIVE_TOKEN, \ 257 (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD) 258 259 #define SET_LOCKTAG_OBJECT(locktag,dboid,classoid,objoid,objsubid) \ 260 ((locktag).locktag_field1 = (dboid), \ 261 (locktag).locktag_field2 = (classoid), \ 262 (locktag).locktag_field3 = (objoid), \ 263 (locktag).locktag_field4 = (objsubid), \ 264 (locktag).locktag_type = LOCKTAG_OBJECT, \ 265 (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD) 266 267 #define SET_LOCKTAG_ADVISORY(locktag,id1,id2,id3,id4) \ 268 ((locktag).locktag_field1 = (id1), \ 269 (locktag).locktag_field2 = (id2), \ 270 (locktag).locktag_field3 = (id3), \ 271 (locktag).locktag_field4 = (id4), \ 272 (locktag).locktag_type = LOCKTAG_ADVISORY, \ 273 (locktag).locktag_lockmethodid = USER_LOCKMETHOD) 274 275 276 /* 277 * Per-locked-object lock information: 278 * 279 * tag -- uniquely identifies the object being locked 280 * grantMask -- bitmask for all lock types currently granted on this object. 281 * waitMask -- bitmask for all lock types currently awaited on this object. 282 * procLocks -- list of PROCLOCK objects for this lock. 283 * waitProcs -- queue of processes waiting for this lock. 284 * requested -- count of each lock type currently requested on the lock 285 * (includes requests already granted!!). 286 * nRequested -- total requested locks of all types. 287 * granted -- count of each lock type currently granted on the lock. 288 * nGranted -- total granted locks of all types. 289 * 290 * Note: these counts count 1 for each backend. Internally to a backend, 291 * there may be multiple grabs on a particular lock, but this is not reflected 292 * into shared memory. 293 */ 294 typedef struct LOCK 295 { 296 /* hash key */ 297 LOCKTAG tag; /* unique identifier of lockable object */ 298 299 /* data */ 300 LOCKMASK grantMask; /* bitmask for lock types already granted */ 301 LOCKMASK waitMask; /* bitmask for lock types awaited */ 302 SHM_QUEUE procLocks; /* list of PROCLOCK objects assoc. with lock */ 303 PROC_QUEUE waitProcs; /* list of PGPROC objects waiting on lock */ 304 int requested[MAX_LOCKMODES]; /* counts of requested locks */ 305 int nRequested; /* total of requested[] array */ 306 int granted[MAX_LOCKMODES]; /* counts of granted locks */ 307 int nGranted; /* total of granted[] array */ 308 } LOCK; 309 310 #define LOCK_LOCKMETHOD(lock) ((LOCKMETHODID) (lock).tag.locktag_lockmethodid) 311 312 313 /* 314 * We may have several different backends holding or awaiting locks 315 * on the same lockable object. We need to store some per-holder/waiter 316 * information for each such holder (or would-be holder). This is kept in 317 * a PROCLOCK struct. 318 * 319 * PROCLOCKTAG is the key information needed to look up a PROCLOCK item in the 320 * proclock hashtable. A PROCLOCKTAG value uniquely identifies the combination 321 * of a lockable object and a holder/waiter for that object. (We can use 322 * pointers here because the PROCLOCKTAG need only be unique for the lifespan 323 * of the PROCLOCK, and it will never outlive the lock or the proc.) 324 * 325 * Internally to a backend, it is possible for the same lock to be held 326 * for different purposes: the backend tracks transaction locks separately 327 * from session locks. However, this is not reflected in the shared-memory 328 * state: we only track which backend(s) hold the lock. This is OK since a 329 * backend can never block itself. 330 * 331 * The holdMask field shows the already-granted locks represented by this 332 * proclock. Note that there will be a proclock object, possibly with 333 * zero holdMask, for any lock that the process is currently waiting on. 334 * Otherwise, proclock objects whose holdMasks are zero are recycled 335 * as soon as convenient. 336 * 337 * releaseMask is workspace for LockReleaseAll(): it shows the locks due 338 * to be released during the current call. This must only be examined or 339 * set by the backend owning the PROCLOCK. 340 * 341 * Each PROCLOCK object is linked into lists for both the associated LOCK 342 * object and the owning PGPROC object. Note that the PROCLOCK is entered 343 * into these lists as soon as it is created, even if no lock has yet been 344 * granted. A PGPROC that is waiting for a lock to be granted will also be 345 * linked into the lock's waitProcs queue. 346 */ 347 typedef struct PROCLOCKTAG 348 { 349 /* NB: we assume this struct contains no padding! */ 350 LOCK *myLock; /* link to per-lockable-object information */ 351 PGPROC *myProc; /* link to PGPROC of owning backend */ 352 } PROCLOCKTAG; 353 354 typedef struct PROCLOCK 355 { 356 /* tag */ 357 PROCLOCKTAG tag; /* unique identifier of proclock object */ 358 359 /* data */ 360 PGPROC *groupLeader; /* proc's lock group leader, or proc itself */ 361 LOCKMASK holdMask; /* bitmask for lock types currently held */ 362 LOCKMASK releaseMask; /* bitmask for lock types to be released */ 363 SHM_QUEUE lockLink; /* list link in LOCK's list of proclocks */ 364 SHM_QUEUE procLink; /* list link in PGPROC's list of proclocks */ 365 } PROCLOCK; 366 367 #define PROCLOCK_LOCKMETHOD(proclock) \ 368 LOCK_LOCKMETHOD(*((proclock).tag.myLock)) 369 370 /* 371 * Each backend also maintains a local hash table with information about each 372 * lock it is currently interested in. In particular the local table counts 373 * the number of times that lock has been acquired. This allows multiple 374 * requests for the same lock to be executed without additional accesses to 375 * shared memory. We also track the number of lock acquisitions per 376 * ResourceOwner, so that we can release just those locks belonging to a 377 * particular ResourceOwner. 378 * 379 * When holding a lock taken "normally", the lock and proclock fields always 380 * point to the associated objects in shared memory. However, if we acquired 381 * the lock via the fast-path mechanism, the lock and proclock fields are set 382 * to NULL, since there probably aren't any such objects in shared memory. 383 * (If the lock later gets promoted to normal representation, we may eventually 384 * update our locallock's lock/proclock fields after finding the shared 385 * objects.) 386 * 387 * Caution: a locallock object can be left over from a failed lock acquisition 388 * attempt. In this case its lock/proclock fields are untrustworthy, since 389 * the shared lock object is neither held nor awaited, and hence is available 390 * to be reclaimed. If nLocks > 0 then these pointers must either be valid or 391 * NULL, but when nLocks == 0 they should be considered garbage. 392 */ 393 typedef struct LOCALLOCKTAG 394 { 395 LOCKTAG lock; /* identifies the lockable object */ 396 LOCKMODE mode; /* lock mode for this table entry */ 397 } LOCALLOCKTAG; 398 399 typedef struct LOCALLOCKOWNER 400 { 401 /* 402 * Note: if owner is NULL then the lock is held on behalf of the session; 403 * otherwise it is held on behalf of my current transaction. 404 * 405 * Must use a forward struct reference to avoid circularity. 406 */ 407 struct ResourceOwnerData *owner; 408 int64 nLocks; /* # of times held by this owner */ 409 } LOCALLOCKOWNER; 410 411 typedef struct LOCALLOCK 412 { 413 /* tag */ 414 LOCALLOCKTAG tag; /* unique identifier of locallock entry */ 415 416 /* data */ 417 LOCK *lock; /* associated LOCK object, if any */ 418 PROCLOCK *proclock; /* associated PROCLOCK object, if any */ 419 uint32 hashcode; /* copy of LOCKTAG's hash value */ 420 int64 nLocks; /* total number of times lock is held */ 421 int numLockOwners; /* # of relevant ResourceOwners */ 422 int maxLockOwners; /* allocated size of array */ 423 bool holdsStrongLockCount; /* bumped FastPathStrongRelationLocks */ 424 bool lockCleared; /* we read all sinval msgs for lock */ 425 LOCALLOCKOWNER *lockOwners; /* dynamically resizable array */ 426 } LOCALLOCK; 427 428 #define LOCALLOCK_LOCKMETHOD(llock) ((llock).tag.lock.locktag_lockmethodid) 429 430 431 /* 432 * These structures hold information passed from lmgr internals to the lock 433 * listing user-level functions (in lockfuncs.c). 434 */ 435 436 typedef struct LockInstanceData 437 { 438 LOCKTAG locktag; /* tag for locked object */ 439 LOCKMASK holdMask; /* locks held by this PGPROC */ 440 LOCKMODE waitLockMode; /* lock awaited by this PGPROC, if any */ 441 BackendId backend; /* backend ID of this PGPROC */ 442 LocalTransactionId lxid; /* local transaction ID of this PGPROC */ 443 int pid; /* pid of this PGPROC */ 444 int leaderPid; /* pid of group leader; = pid if no group */ 445 bool fastpath; /* taken via fastpath? */ 446 } LockInstanceData; 447 448 typedef struct LockData 449 { 450 int nelements; /* The length of the array */ 451 LockInstanceData *locks; /* Array of per-PROCLOCK information */ 452 } LockData; 453 454 typedef struct BlockedProcData 455 { 456 int pid; /* pid of a blocked PGPROC */ 457 /* Per-PROCLOCK information about PROCLOCKs of the lock the pid awaits */ 458 /* (these fields refer to indexes in BlockedProcsData.locks[]) */ 459 int first_lock; /* index of first relevant LockInstanceData */ 460 int num_locks; /* number of relevant LockInstanceDatas */ 461 /* PIDs of PGPROCs that are ahead of "pid" in the lock's wait queue */ 462 /* (these fields refer to indexes in BlockedProcsData.waiter_pids[]) */ 463 int first_waiter; /* index of first preceding waiter */ 464 int num_waiters; /* number of preceding waiters */ 465 } BlockedProcData; 466 467 typedef struct BlockedProcsData 468 { 469 BlockedProcData *procs; /* Array of per-blocked-proc information */ 470 LockInstanceData *locks; /* Array of per-PROCLOCK information */ 471 int *waiter_pids; /* Array of PIDs of other blocked PGPROCs */ 472 int nprocs; /* # of valid entries in procs[] array */ 473 int maxprocs; /* Allocated length of procs[] array */ 474 int nlocks; /* # of valid entries in locks[] array */ 475 int maxlocks; /* Allocated length of locks[] array */ 476 int npids; /* # of valid entries in waiter_pids[] array */ 477 int maxpids; /* Allocated length of waiter_pids[] array */ 478 } BlockedProcsData; 479 480 481 /* Result codes for LockAcquire() */ 482 typedef enum 483 { 484 LOCKACQUIRE_NOT_AVAIL, /* lock not available, and dontWait=true */ 485 LOCKACQUIRE_OK, /* lock successfully acquired */ 486 LOCKACQUIRE_ALREADY_HELD, /* incremented count for lock already held */ 487 LOCKACQUIRE_ALREADY_CLEAR /* incremented count for lock already clear */ 488 } LockAcquireResult; 489 490 /* Deadlock states identified by DeadLockCheck() */ 491 typedef enum 492 { 493 DS_NOT_YET_CHECKED, /* no deadlock check has run yet */ 494 DS_NO_DEADLOCK, /* no deadlock detected */ 495 DS_SOFT_DEADLOCK, /* deadlock avoided by queue rearrangement */ 496 DS_HARD_DEADLOCK, /* deadlock, no way out but ERROR */ 497 DS_BLOCKED_BY_AUTOVACUUM /* no deadlock; queue blocked by autovacuum 498 * worker */ 499 } DeadLockState; 500 501 /* 502 * The lockmgr's shared hash tables are partitioned to reduce contention. 503 * To determine which partition a given locktag belongs to, compute the tag's 504 * hash code with LockTagHashCode(), then apply one of these macros. 505 * NB: NUM_LOCK_PARTITIONS must be a power of 2! 506 */ 507 #define LockHashPartition(hashcode) \ 508 ((hashcode) % NUM_LOCK_PARTITIONS) 509 #define LockHashPartitionLock(hashcode) \ 510 (&MainLWLockArray[LOCK_MANAGER_LWLOCK_OFFSET + \ 511 LockHashPartition(hashcode)].lock) 512 #define LockHashPartitionLockByIndex(i) \ 513 (&MainLWLockArray[LOCK_MANAGER_LWLOCK_OFFSET + (i)].lock) 514 515 /* 516 * The deadlock detector needs to be able to access lockGroupLeader and 517 * related fields in the PGPROC, so we arrange for those fields to be protected 518 * by one of the lock hash partition locks. Since the deadlock detector 519 * acquires all such locks anyway, this makes it safe for it to access these 520 * fields without doing anything extra. To avoid contention as much as 521 * possible, we map different PGPROCs to different partition locks. The lock 522 * used for a given lock group is determined by the group leader's pgprocno. 523 */ 524 #define LockHashPartitionLockByProc(leader_pgproc) \ 525 LockHashPartitionLock((leader_pgproc)->pgprocno) 526 527 /* 528 * function prototypes 529 */ 530 extern void InitLocks(void); 531 extern LockMethod GetLocksMethodTable(const LOCK *lock); 532 extern LockMethod GetLockTagsMethodTable(const LOCKTAG *locktag); 533 extern uint32 LockTagHashCode(const LOCKTAG *locktag); 534 extern bool DoLockModesConflict(LOCKMODE mode1, LOCKMODE mode2); 535 extern LockAcquireResult LockAcquire(const LOCKTAG *locktag, 536 LOCKMODE lockmode, 537 bool sessionLock, 538 bool dontWait); 539 extern LockAcquireResult LockAcquireExtended(const LOCKTAG *locktag, 540 LOCKMODE lockmode, 541 bool sessionLock, 542 bool dontWait, 543 bool reportMemoryError, 544 LOCALLOCK **locallockp); 545 extern void AbortStrongLockAcquire(void); 546 extern void MarkLockClear(LOCALLOCK *locallock); 547 extern bool LockRelease(const LOCKTAG *locktag, 548 LOCKMODE lockmode, bool sessionLock); 549 extern void LockReleaseAll(LOCKMETHODID lockmethodid, bool allLocks); 550 extern void LockReleaseSession(LOCKMETHODID lockmethodid); 551 extern void LockReleaseCurrentOwner(LOCALLOCK **locallocks, int nlocks); 552 extern void LockReassignCurrentOwner(LOCALLOCK **locallocks, int nlocks); 553 extern bool LockHasWaiters(const LOCKTAG *locktag, 554 LOCKMODE lockmode, bool sessionLock); 555 extern VirtualTransactionId *GetLockConflicts(const LOCKTAG *locktag, 556 LOCKMODE lockmode); 557 extern void AtPrepare_Locks(void); 558 extern void PostPrepare_Locks(TransactionId xid); 559 extern int LockCheckConflicts(LockMethod lockMethodTable, 560 LOCKMODE lockmode, 561 LOCK *lock, PROCLOCK *proclock); 562 extern void GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode); 563 extern void GrantAwaitedLock(void); 564 extern void RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode); 565 extern Size LockShmemSize(void); 566 extern LockData *GetLockStatusData(void); 567 extern BlockedProcsData *GetBlockerStatusData(int blocked_pid); 568 569 extern xl_standby_lock *GetRunningTransactionLocks(int *nlocks); 570 extern const char *GetLockmodeName(LOCKMETHODID lockmethodid, LOCKMODE mode); 571 572 extern void lock_twophase_recover(TransactionId xid, uint16 info, 573 void *recdata, uint32 len); 574 extern void lock_twophase_postcommit(TransactionId xid, uint16 info, 575 void *recdata, uint32 len); 576 extern void lock_twophase_postabort(TransactionId xid, uint16 info, 577 void *recdata, uint32 len); 578 extern void lock_twophase_standby_recover(TransactionId xid, uint16 info, 579 void *recdata, uint32 len); 580 581 extern DeadLockState DeadLockCheck(PGPROC *proc); 582 extern PGPROC *GetBlockingAutoVacuumPgproc(void); 583 extern void DeadLockReport(void) pg_attribute_noreturn(); 584 extern void RememberSimpleDeadLock(PGPROC *proc1, 585 LOCKMODE lockmode, 586 LOCK *lock, 587 PGPROC *proc2); 588 extern void InitDeadLockChecking(void); 589 590 extern int LockWaiterCount(const LOCKTAG *locktag); 591 592 #ifdef LOCK_DEBUG 593 extern void DumpLocks(PGPROC *proc); 594 extern void DumpAllLocks(void); 595 #endif 596 597 /* Lock a VXID (used to wait for a transaction to finish) */ 598 extern void VirtualXactLockTableInsert(VirtualTransactionId vxid); 599 extern void VirtualXactLockTableCleanup(void); 600 extern bool VirtualXactLock(VirtualTransactionId vxid, bool wait); 601 602 #endif /* LOCK_H */ 603