1 /* $NetBSD: qmgr_transport.c,v 1.1.1.1 2009/06/23 10:08:52 tron Exp $ */ 2 3 /*++ 4 /* NAME 5 /* qmgr_transport 3 6 /* SUMMARY 7 /* per-transport data structures 8 /* SYNOPSIS 9 /* #include "qmgr.h" 10 /* 11 /* QMGR_TRANSPORT *qmgr_transport_create(name) 12 /* const char *name; 13 /* 14 /* QMGR_TRANSPORT *qmgr_transport_find(name) 15 /* const char *name; 16 /* 17 /* QMGR_TRANSPORT *qmgr_transport_select() 18 /* 19 /* void qmgr_transport_alloc(transport, notify) 20 /* QMGR_TRANSPORT *transport; 21 /* void (*notify)(QMGR_TRANSPORT *transport, VSTREAM *fp); 22 /* 23 /* void qmgr_transport_throttle(transport, dsn) 24 /* QMGR_TRANSPORT *transport; 25 /* DSN *dsn; 26 /* 27 /* void qmgr_transport_unthrottle(transport) 28 /* QMGR_TRANSPORT *transport; 29 /* DESCRIPTION 30 /* This module organizes the world by message transport type. 31 /* Each transport can have zero or more destination queues 32 /* associated with it. 33 /* 34 /* qmgr_transport_create() instantiates a data structure for the 35 /* named transport type. 36 /* 37 /* qmgr_transport_find() looks up an existing message transport 38 /* data structure. 39 /* 40 /* qmgr_transport_select() attempts to find a transport that 41 /* has messages pending delivery. This routine implements 42 /* round-robin search among transports. 43 /* 44 /* qmgr_transport_alloc() allocates a delivery process for the 45 /* specified transport type. Allocation is performed asynchronously. 46 /* When a process becomes available, the application callback routine 47 /* is invoked with as arguments the transport and a stream that 48 /* is connected to a delivery process. It is an error to call 49 /* qmgr_transport_alloc() while delivery process allocation for 50 /* the same transport is in progress. 51 /* 52 /* qmgr_transport_throttle blocks further allocation of delivery 53 /* processes for the named transport. Attempts to throttle a 54 /* throttled transport are ignored. 55 /* 56 /* qmgr_transport_unthrottle() undoes qmgr_transport_throttle(). 57 /* Attempts to unthrottle a non-throttled transport are ignored. 58 /* DIAGNOSTICS 59 /* Panic: consistency check failure. Fatal: out of memory. 60 /* LICENSE 61 /* .ad 62 /* .fi 63 /* The Secure Mailer license must be distributed with this software. 64 /* AUTHOR(S) 65 /* Wietse Venema 66 /* IBM T.J. Watson Research 67 /* P.O. Box 704 68 /* Yorktown Heights, NY 10598, USA 69 /* 70 /* Preemptive scheduler enhancements: 71 /* Patrik Rak 72 /* Modra 6 73 /* 155 00, Prague, Czech Republic 74 /*--*/ 75 76 /* System library. */ 77 78 #include <sys_defs.h> 79 #include <unistd.h> 80 81 #include <sys/time.h> /* FD_SETSIZE */ 82 #include <sys/types.h> /* FD_SETSIZE */ 83 #include <unistd.h> /* FD_SETSIZE */ 84 85 #ifdef USE_SYS_SELECT_H 86 #include <sys/select.h> /* FD_SETSIZE */ 87 #endif 88 89 /* Utility library. */ 90 91 #include <msg.h> 92 #include <htable.h> 93 #include <events.h> 94 #include <mymalloc.h> 95 #include <vstream.h> 96 #include <iostuff.h> 97 98 /* Global library. */ 99 100 #include <mail_proto.h> 101 #include <recipient_list.h> 102 #include <mail_conf.h> 103 #include <mail_params.h> 104 105 /* Application-specific. */ 106 107 #include "qmgr.h" 108 109 HTABLE *qmgr_transport_byname; /* transport by name */ 110 QMGR_TRANSPORT_LIST qmgr_transport_list;/* transports, round robin */ 111 112 /* 113 * A local structure to remember a delivery process allocation request. 114 */ 115 typedef struct QMGR_TRANSPORT_ALLOC QMGR_TRANSPORT_ALLOC; 116 117 struct QMGR_TRANSPORT_ALLOC { 118 QMGR_TRANSPORT *transport; /* transport context */ 119 VSTREAM *stream; /* delivery service stream */ 120 QMGR_TRANSPORT_ALLOC_NOTIFY notify; /* application call-back routine */ 121 }; 122 123 /* 124 * Connections to delivery agents are managed asynchronously. Each delivery 125 * agent connection goes through multiple wait states: 126 * 127 * - With Linux/Solaris and old queue manager implementations only, wait for 128 * the server to invoke accept(). 129 * 130 * - Wait for the delivery agent's announcement that it is ready to receive a 131 * delivery request. 132 * 133 * - Wait for the delivery request completion status. 134 * 135 * Older queue manager implementations had only one pending delivery agent 136 * connection per transport. With low-latency destinations, the output rates 137 * were reduced on Linux/Solaris systems that had the extra wait state. 138 * 139 * To maximize delivery agent output rates with low-latency destinations, the 140 * following changes were made to the queue manager by the end of the 2.4 141 * development cycle: 142 * 143 * - The Linux/Solaris accept() wait state was eliminated. 144 * 145 * - A pipeline was implemented for pending delivery agent connections. The 146 * number of pending delivery agent connections was increased from one to 147 * two: the number of before-delivery wait states, plus one extra pipeline 148 * slot to prevent the pipeline from stalling easily. Increasing the 149 * pipeline much further actually hurt performance. 150 * 151 * - To reduce queue manager disk competition with delivery agents, the queue 152 * scanning algorithm was modified to import only one message per interrupt. 153 * The incoming and deferred queue scans now happen on alternate interrupts. 154 * 155 * Simplistically reasoned, a non-zero (incoming + active) queue length is 156 * equivalent to a time shift for mail deliveries; this is undesirable when 157 * delivery agents are not fully utilized. 158 * 159 * On the other hand a non-empty active queue is what allows us to do clever 160 * things such as queue file prefetch, concurrency windows, and connection 161 * caching; the idea is that such "thinking time" is affordable only after 162 * the output channels are maxed out. 163 */ 164 #ifndef QMGR_TRANSPORT_MAX_PEND 165 #define QMGR_TRANSPORT_MAX_PEND 2 166 #endif 167 168 /* qmgr_transport_unthrottle_wrapper - in case (char *) != (struct *) */ 169 170 static void qmgr_transport_unthrottle_wrapper(int unused_event, char *context) 171 { 172 qmgr_transport_unthrottle((QMGR_TRANSPORT *) context); 173 } 174 175 /* qmgr_transport_unthrottle - open the throttle */ 176 177 void qmgr_transport_unthrottle(QMGR_TRANSPORT *transport) 178 { 179 const char *myname = "qmgr_transport_unthrottle"; 180 181 /* 182 * This routine runs after expiration of the timer set by 183 * qmgr_transport_throttle(), or whenever a delivery transport has been 184 * used without malfunction. In either case, we enable delivery again if 185 * the transport was blocked, otherwise the request is ignored. 186 */ 187 if ((transport->flags & QMGR_TRANSPORT_STAT_DEAD) != 0) { 188 if (msg_verbose) 189 msg_info("%s: transport %s", myname, transport->name); 190 transport->flags &= ~QMGR_TRANSPORT_STAT_DEAD; 191 if (transport->dsn == 0) 192 msg_panic("%s: transport %s: null reason", 193 myname, transport->name); 194 dsn_free(transport->dsn); 195 transport->dsn = 0; 196 event_cancel_timer(qmgr_transport_unthrottle_wrapper, 197 (char *) transport); 198 } 199 } 200 201 /* qmgr_transport_throttle - disable delivery process allocation */ 202 203 void qmgr_transport_throttle(QMGR_TRANSPORT *transport, DSN *dsn) 204 { 205 const char *myname = "qmgr_transport_throttle"; 206 207 /* 208 * We are unable to connect to a deliver process for this type of message 209 * transport. Instead of hosing the system by retrying in a tight loop, 210 * back off and disable this transport type for a while. 211 */ 212 if ((transport->flags & QMGR_TRANSPORT_STAT_DEAD) == 0) { 213 if (msg_verbose) 214 msg_info("%s: transport %s: status: %s reason: %s", 215 myname, transport->name, dsn->status, dsn->reason); 216 transport->flags |= QMGR_TRANSPORT_STAT_DEAD; 217 if (transport->dsn) 218 msg_panic("%s: transport %s: spurious reason: %s", 219 myname, transport->name, transport->dsn->reason); 220 transport->dsn = DSN_COPY(dsn); 221 event_request_timer(qmgr_transport_unthrottle_wrapper, 222 (char *) transport, var_transport_retry_time); 223 } 224 } 225 226 /* qmgr_transport_abort - transport connect watchdog */ 227 228 static void qmgr_transport_abort(int unused_event, char *context) 229 { 230 QMGR_TRANSPORT_ALLOC *alloc = (QMGR_TRANSPORT_ALLOC *) context; 231 232 msg_fatal("timeout connecting to transport: %s", alloc->transport->name); 233 } 234 235 /* qmgr_transport_event - delivery process availability notice */ 236 237 static void qmgr_transport_event(int unused_event, char *context) 238 { 239 QMGR_TRANSPORT_ALLOC *alloc = (QMGR_TRANSPORT_ALLOC *) context; 240 241 /* 242 * This routine notifies the application when the request given to 243 * qmgr_transport_alloc() completes. 244 */ 245 if (msg_verbose) 246 msg_info("transport_event: %s", alloc->transport->name); 247 248 /* 249 * Connection request completed. Stop the watchdog timer. 250 */ 251 event_cancel_timer(qmgr_transport_abort, context); 252 253 /* 254 * Disable further read events that end up calling this function, and 255 * free up this pending connection pipeline slot. 256 */ 257 if (alloc->stream) { 258 event_disable_readwrite(vstream_fileno(alloc->stream)); 259 non_blocking(vstream_fileno(alloc->stream), BLOCKING); 260 } 261 alloc->transport->pending -= 1; 262 263 /* 264 * Notify the requestor. 265 */ 266 alloc->notify(alloc->transport, alloc->stream); 267 myfree((char *) alloc); 268 } 269 270 /* qmgr_transport_select - select transport for allocation */ 271 272 QMGR_TRANSPORT *qmgr_transport_select(void) 273 { 274 QMGR_TRANSPORT *xport; 275 QMGR_QUEUE *queue; 276 int need; 277 278 /* 279 * If we find a suitable transport, rotate the list of transports to 280 * effectuate round-robin selection. See similar selection code in 281 * qmgr_peer_select(). 282 * 283 * This function is called repeatedly until all transports have maxed out 284 * the number of pending delivery agent connections, until all delivery 285 * agent concurrency windows are maxed out, or until we run out of "todo" 286 * queue entries. 287 */ 288 #define MIN5af51743e4eef(x, y) ((x) < (y) ? (x) : (y)) 289 290 for (xport = qmgr_transport_list.next; xport; xport = xport->peers.next) { 291 if ((xport->flags & QMGR_TRANSPORT_STAT_DEAD) != 0 292 || xport->pending >= QMGR_TRANSPORT_MAX_PEND) 293 continue; 294 need = xport->pending + 1; 295 for (queue = xport->queue_list.next; queue; queue = queue->peers.next) { 296 if (QMGR_QUEUE_READY(queue) == 0) 297 continue; 298 if ((need -= MIN5af51743e4eef(queue->window - queue->busy_refcount, 299 queue->todo_refcount)) <= 0) { 300 QMGR_LIST_ROTATE(qmgr_transport_list, xport, peers); 301 if (msg_verbose) 302 msg_info("qmgr_transport_select: %s", xport->name); 303 return (xport); 304 } 305 } 306 } 307 return (0); 308 } 309 310 /* qmgr_transport_alloc - allocate delivery process */ 311 312 void qmgr_transport_alloc(QMGR_TRANSPORT *transport, QMGR_TRANSPORT_ALLOC_NOTIFY notify) 313 { 314 QMGR_TRANSPORT_ALLOC *alloc; 315 316 /* 317 * Sanity checks. 318 */ 319 if (transport->flags & QMGR_TRANSPORT_STAT_DEAD) 320 msg_panic("qmgr_transport: dead transport: %s", transport->name); 321 if (transport->pending >= QMGR_TRANSPORT_MAX_PEND) 322 msg_panic("qmgr_transport: excess allocation: %s", transport->name); 323 324 /* 325 * Connect to the well-known port for this delivery service, and wake up 326 * when a process announces its availability. Allow only a limited number 327 * of delivery process allocation attempts for this transport. In case of 328 * problems, back off. Do not hose the system when it is in trouble 329 * already. 330 * 331 * Use non-blocking connect(), so that Linux won't block the queue manager 332 * until the delivery agent calls accept(). 333 * 334 * When the connection to delivery agent cannot be completed, notify the 335 * event handler so that it can throttle the transport and defer the todo 336 * queues, just like it does when communication fails *after* connection 337 * completion. 338 * 339 * Before Postfix 2.4, the event handler was not invoked after connect() 340 * error, and mail was not deferred. Because of this, mail would be stuck 341 * in the active queue after triggering a "connection refused" condition. 342 */ 343 alloc = (QMGR_TRANSPORT_ALLOC *) mymalloc(sizeof(*alloc)); 344 alloc->transport = transport; 345 alloc->notify = notify; 346 transport->pending += 1; 347 if ((alloc->stream = mail_connect(MAIL_CLASS_PRIVATE, transport->name, 348 NON_BLOCKING)) == 0) { 349 msg_warn("connect to transport %s/%s: %m", 350 MAIL_CLASS_PRIVATE, transport->name); 351 event_request_timer(qmgr_transport_event, (char *) alloc, 0); 352 return; 353 } 354 #if (EVENTS_STYLE != EVENTS_STYLE_SELECT) && defined(VSTREAM_CTL_DUPFD) 355 #ifndef THRESHOLD_FD_WORKAROUND 356 #define THRESHOLD_FD_WORKAROUND 128 357 #endif 358 vstream_control(alloc->stream, 359 VSTREAM_CTL_DUPFD, THRESHOLD_FD_WORKAROUND, 360 VSTREAM_CTL_END); 361 #endif 362 event_enable_read(vstream_fileno(alloc->stream), qmgr_transport_event, 363 (char *) alloc); 364 365 /* 366 * Guard against broken systems. 367 */ 368 event_request_timer(qmgr_transport_abort, (char *) alloc, 369 var_daemon_timeout); 370 } 371 372 /* qmgr_transport_create - create transport instance */ 373 374 QMGR_TRANSPORT *qmgr_transport_create(const char *name) 375 { 376 QMGR_TRANSPORT *transport; 377 378 if (htable_find(qmgr_transport_byname, name) != 0) 379 msg_panic("qmgr_transport_create: transport exists: %s", name); 380 transport = (QMGR_TRANSPORT *) mymalloc(sizeof(QMGR_TRANSPORT)); 381 transport->flags = 0; 382 transport->pending = 0; 383 transport->name = mystrdup(name); 384 385 /* 386 * Use global configuration settings or transport-specific settings. 387 */ 388 transport->dest_concurrency_limit = 389 get_mail_conf_int2(name, _DEST_CON_LIMIT, 390 var_dest_con_limit, 0, 0); 391 transport->recipient_limit = 392 get_mail_conf_int2(name, _DEST_RCPT_LIMIT, 393 var_dest_rcpt_limit, 0, 0); 394 transport->init_dest_concurrency = 395 get_mail_conf_int2(name, _INIT_DEST_CON, 396 var_init_dest_concurrency, 1, 0); 397 transport->rate_delay = get_mail_conf_time2(name, _DEST_RATE_DELAY, 398 var_dest_rate_delay, 399 's', 0, 0); 400 401 if (transport->rate_delay > 0) 402 transport->dest_concurrency_limit = 1; 403 if (transport->dest_concurrency_limit != 0 404 && transport->dest_concurrency_limit < transport->init_dest_concurrency) 405 transport->init_dest_concurrency = transport->dest_concurrency_limit; 406 407 transport->slot_cost = get_mail_conf_int2(name, _DELIVERY_SLOT_COST, 408 var_delivery_slot_cost, 0, 0); 409 transport->slot_loan = get_mail_conf_int2(name, _DELIVERY_SLOT_LOAN, 410 var_delivery_slot_loan, 0, 0); 411 transport->slot_loan_factor = 412 100 - get_mail_conf_int2(name, _DELIVERY_SLOT_DISCOUNT, 413 var_delivery_slot_discount, 0, 100); 414 transport->min_slots = get_mail_conf_int2(name, _MIN_DELIVERY_SLOTS, 415 var_min_delivery_slots, 0, 0); 416 transport->rcpt_unused = get_mail_conf_int2(name, _XPORT_RCPT_LIMIT, 417 var_xport_rcpt_limit, 0, 0); 418 transport->rcpt_per_stack = get_mail_conf_int2(name, _STACK_RCPT_LIMIT, 419 var_stack_rcpt_limit, 0, 0); 420 transport->refill_limit = get_mail_conf_int2(name, _XPORT_REFILL_LIMIT, 421 var_xport_refill_limit, 1, 0); 422 transport->refill_delay = get_mail_conf_time2(name, _XPORT_REFILL_DELAY, 423 var_xport_refill_delay, 's', 1, 0); 424 425 transport->queue_byname = htable_create(0); 426 QMGR_LIST_INIT(transport->queue_list); 427 transport->job_byname = htable_create(0); 428 QMGR_LIST_INIT(transport->job_list); 429 QMGR_LIST_INIT(transport->job_bytime); 430 transport->job_current = 0; 431 transport->job_next_unread = 0; 432 transport->candidate_cache = 0; 433 transport->candidate_cache_current = 0; 434 transport->candidate_cache_time = (time_t) 0; 435 transport->blocker_tag = 1; 436 transport->dsn = 0; 437 qmgr_feedback_init(&transport->pos_feedback, name, _CONC_POS_FDBACK, 438 VAR_CONC_POS_FDBACK, var_conc_pos_feedback); 439 qmgr_feedback_init(&transport->neg_feedback, name, _CONC_NEG_FDBACK, 440 VAR_CONC_NEG_FDBACK, var_conc_neg_feedback); 441 transport->fail_cohort_limit = 442 get_mail_conf_int2(name, _CONC_COHORT_LIM, 443 var_conc_cohort_limit, 0, 0); 444 if (qmgr_transport_byname == 0) 445 qmgr_transport_byname = htable_create(10); 446 htable_enter(qmgr_transport_byname, name, (char *) transport); 447 QMGR_LIST_PREPEND(qmgr_transport_list, transport, peers); 448 if (msg_verbose) 449 msg_info("qmgr_transport_create: %s concurrency %d recipients %d", 450 transport->name, transport->dest_concurrency_limit, 451 transport->recipient_limit); 452 return (transport); 453 } 454 455 /* qmgr_transport_find - find transport instance */ 456 457 QMGR_TRANSPORT *qmgr_transport_find(const char *name) 458 { 459 return ((QMGR_TRANSPORT *) htable_find(qmgr_transport_byname, name)); 460 } 461