/*++ /* NAME /* qmgr_entry 3 /* SUMMARY /* per-site queue entries /* SYNOPSIS /* #include "qmgr.h" /* /* QMGR_ENTRY *qmgr_entry_create(queue, message) /* QMGR_QUEUE *queue; /* QMGR_MESSAGE *message; /* /* void qmgr_entry_done(entry, which) /* QMGR_ENTRY *entry; /* int which; /* /* QMGR_ENTRY *qmgr_entry_select(queue) /* QMGR_QUEUE *queue; /* /* void qmgr_entry_unselect(queue, entry) /* QMGR_QUEUE *queue; /* QMGR_ENTRY *entry; /* /* void qmgr_entry_move_todo(dst, entry) /* QMGR_QUEUE *dst; /* QMGR_ENTRY *entry; /* DESCRIPTION /* These routines add/delete/manipulate per-site message /* delivery requests. /* /* qmgr_entry_create() creates an entry for the named queue and /* message, and appends the entry to the queue's todo list. /* Filling in and cleaning up the recipients is the responsibility /* of the caller. /* /* qmgr_entry_done() discards a per-site queue entry. The /* \fIwhich\fR argument is either QMGR_QUEUE_BUSY for an entry /* of the site's `busy' list (i.e. queue entries that have been /* selected for actual delivery), or QMGR_QUEUE_TODO for an entry /* of the site's `todo' list (i.e. queue entries awaiting selection /* for actual delivery). /* /* qmgr_entry_done() triggers cleanup of the per-site queue when /* the site has no pending deliveries, and the site is either /* alive, or the site is dead and the number of in-core queues /* exceeds a configurable limit (see qmgr_queue_done()). /* /* qmgr_entry_done() triggers special action when the last in-core /* queue entry for a message is done with: either read more /* recipients from the queue file, delete the queue file, or move /* the queue file to the deferred queue; send bounce reports to the /* message originator (see qmgr_active_done()). /* /* qmgr_entry_select() selects the next entry from the named /* per-site queue's `todo' list for actual delivery. The entry is /* moved to the queue's `busy' list: the list of messages being /* delivered. /* /* qmgr_entry_unselect() takes the named entry off the named /* per-site queue's `busy' list and moves it to the queue's /* `todo' list. /* /* qmgr_entry_move_todo() moves the specified "todo" queue entry /* to the specified "todo" queue. /* DIAGNOSTICS /* Panic: interface violations, internal inconsistencies. /* LICENSE /* .ad /* .fi /* The Secure Mailer license must be distributed with this software. /* AUTHOR(S) /* Wietse Venema /* IBM T.J. Watson Research /* P.O. Box 704 /* Yorktown Heights, NY 10598, USA /*--*/ /* System library. */ #include <sys_defs.h> #include <stdlib.h> #include <time.h> /* Utility library. */ #include <msg.h> #include <mymalloc.h> #include <events.h> #include <vstream.h> /* Global library. */ #include <mail_params.h> #include <deliver_request.h> /* opportunistic session caching */ /* Application-specific. */ #include "qmgr.h" /* qmgr_entry_select - select queue entry for delivery */ QMGR_ENTRY *qmgr_entry_select(QMGR_QUEUE *queue) { const char *myname = "qmgr_entry_select"; QMGR_ENTRY *entry; if ((entry = queue->todo.prev) != 0) { QMGR_LIST_UNLINK(queue->todo, QMGR_ENTRY *, entry); queue->todo_refcount--; QMGR_LIST_APPEND(queue->busy, entry); queue->busy_refcount++; /* * With opportunistic session caching, the delivery agent must not * only 1) save a session upon completion, but also 2) reuse a cached * session upon the next delivery request. In order to not miss out * on 2), we have to make caching sticky or else we get silly * behavior when the in-memory queue drains. Specifically, new * connections must not be made as long as cached connections exist. * * Safety: don't enable opportunistic session caching unless the queue * manager is able to schedule concurrent or back-to-back deliveries * (we need to recognize back-to-back deliveries for transports with * concurrency 1). * * If caching has previously been enabled, but is not now, fetch any * existing entries from the cache, but don't add new ones. */ #define CONCURRENT_OR_BACK_TO_BACK_DELIVERY() \ (queue->busy_refcount > 1 || BACK_TO_BACK_DELIVERY()) #define BACK_TO_BACK_DELIVERY() \ (queue->last_done + 1 >= event_time()) /* * Turn on session caching after we get up to speed. Don't enable * session caching just because we have concurrent deliveries. This * prevents unnecessary session caching when we have a burst of mail * <= the initial concurrency limit. */ if ((queue->dflags & DEL_REQ_FLAG_CONN_STORE) == 0) { if (BACK_TO_BACK_DELIVERY()) { if (msg_verbose) msg_info("%s: allowing on-demand session caching for %s", myname, queue->name); queue->dflags |= DEL_REQ_FLAG_CONN_MASK; } } /* * Turn off session caching when concurrency drops and we're running * out of steam. This is what prevents from turning off session * caching too early, and from making new connections while old ones * are still cached. */ else { if (!CONCURRENT_OR_BACK_TO_BACK_DELIVERY()) { if (msg_verbose) msg_info("%s: disallowing on-demand session caching for %s", myname, queue->name); queue->dflags &= ~DEL_REQ_FLAG_CONN_STORE; } } } return (entry); } /* qmgr_entry_unselect - unselect queue entry for delivery */ void qmgr_entry_unselect(QMGR_QUEUE *queue, QMGR_ENTRY *entry) { QMGR_LIST_UNLINK(queue->busy, QMGR_ENTRY *, entry); queue->busy_refcount--; QMGR_LIST_APPEND(queue->todo, entry); queue->todo_refcount++; } /* qmgr_entry_move_todo - move entry between todo queues */ void qmgr_entry_move_todo(QMGR_QUEUE *dst, QMGR_ENTRY *entry) { const char *myname = "qmgr_entry_move_todo"; QMGR_MESSAGE *message = entry->message; QMGR_QUEUE *src = entry->queue; QMGR_ENTRY *new_entry; if (entry->stream != 0) msg_panic("%s: queue %s entry is busy", myname, src->name); if (QMGR_QUEUE_THROTTLED(dst)) msg_panic("%s: destination queue %s is throttled", myname, dst->name); if (QMGR_TRANSPORT_THROTTLED(dst->transport)) msg_panic("%s: destination transport %s is throttled", myname, dst->transport->name); /* * Create new entry, swap the recipients between the old and new entries, * then dispose of the old entry. This gives us any end-game actions that * are implemented by qmgr_entry_done(), so we don't have to duplicate * those actions here. * * XXX This does not enforce the per-entry recipient limit, but that is not * a problem as long as qmgr_entry_move_todo() is called only to bounce * or defer mail. */ new_entry = qmgr_entry_create(dst, message); recipient_list_swap(&entry->rcpt_list, &new_entry->rcpt_list); qmgr_entry_done(entry, QMGR_QUEUE_TODO); } /* qmgr_entry_done - dispose of queue entry */ void qmgr_entry_done(QMGR_ENTRY *entry, int which) { const char *myname = "qmgr_entry_done"; QMGR_QUEUE *queue = entry->queue; QMGR_MESSAGE *message = entry->message; QMGR_TRANSPORT *transport = queue->transport; /* * Take this entry off the in-core queue. */ if (entry->stream != 0) msg_panic("%s: file is open", myname); if (which == QMGR_QUEUE_BUSY) { QMGR_LIST_UNLINK(queue->busy, QMGR_ENTRY *, entry); queue->busy_refcount--; } else if (which == QMGR_QUEUE_TODO) { QMGR_LIST_UNLINK(queue->todo, QMGR_ENTRY *, entry); queue->todo_refcount--; } else { msg_panic("%s: bad queue spec: %d", myname, which); } /* * Free the recipient list and decrease the in-core recipient count * accordingly. */ qmgr_recipient_count -= entry->rcpt_list.len; recipient_list_free(&entry->rcpt_list); myfree((char *) entry); /* * Maintain back-to-back delivery status. */ if (which == QMGR_QUEUE_BUSY) queue->last_done = event_time(); /* * Suspend a rate-limited queue, so that mail trickles out. */ if (which == QMGR_QUEUE_BUSY && transport->rate_delay > 0) { if (queue->window > 1) msg_panic("%s: queue %s/%s: window %d > 1 on rate-limited service", myname, transport->name, queue->name, queue->window); if (QMGR_QUEUE_THROTTLED(queue)) /* XXX */ qmgr_queue_unthrottle(queue); if (QMGR_QUEUE_READY(queue)) qmgr_queue_suspend(queue, transport->rate_delay); } /* * When the in-core queue for this site is empty and when this site is * not dead, discard the in-core queue. When this site is dead, but the * number of in-core queues exceeds some threshold, get rid of this * in-core queue anyway, in order to avoid running out of memory. * * See also: qmgr_entry_move_todo(). */ if (queue->todo.next == 0 && queue->busy.next == 0) { if (QMGR_QUEUE_THROTTLED(queue) && qmgr_queue_count > 2 * var_qmgr_rcpt_limit) qmgr_queue_unthrottle(queue); if (QMGR_QUEUE_READY(queue)) qmgr_queue_done(queue); } /* * Update the in-core message reference count. When the in-core message * structure has no more references, dispose of the message. * * When the in-core recipient count falls below a threshold, and this * message has more recipients, read more recipients now. If we read more * recipients as soon as the recipient count falls below the in-core * recipient limit, we do not give other messages a chance until this * message is delivered. That's good for mailing list deliveries, bad for * one-to-one mail. If we wait until the in-core recipient count drops * well below the in-core recipient limit, we give other mail a chance, * but we also allow list deliveries to become interleaved. In the worst * case, people near the start of a mailing list get a burst of postings * today, while people near the end of the list get that same burst of * postings a whole day later. */ #define FUDGE(x) ((x) * (var_qmgr_fudge / 100.0)) message->refcount--; if (message->rcpt_offset > 0 && qmgr_recipient_count < FUDGE(var_qmgr_rcpt_limit) - 100) qmgr_message_realloc(message); if (message->refcount == 0) qmgr_active_done(message); } /* qmgr_entry_create - create queue todo entry */ QMGR_ENTRY *qmgr_entry_create(QMGR_QUEUE *queue, QMGR_MESSAGE *message) { QMGR_ENTRY *entry; /* * Sanity check. */ if (QMGR_QUEUE_THROTTLED(queue)) msg_panic("qmgr_entry_create: dead queue: %s", queue->name); /* * Create the delivery request. */ entry = (QMGR_ENTRY *) mymalloc(sizeof(QMGR_ENTRY)); entry->stream = 0; entry->message = message; recipient_list_init(&entry->rcpt_list, RCPT_LIST_INIT_QUEUE); message->refcount++; entry->queue = queue; QMGR_LIST_APPEND(queue->todo, entry); queue->todo_refcount++; /* * Warn if a destination is falling behind while the active queue * contains a non-trivial amount of single-recipient email. When a * destination takes up more and more space in the active queue, then * other mail will not get through and delivery performance will suffer. * * XXX At this point in the code, the busy reference count is still less * than the concurrency limit (otherwise this code would not be invoked * in the first place) so we have to make make some awkward adjustments * below. * * XXX The queue length test below looks at the active queue share of an * individual destination. This catches the case where mail for one * destination is falling behind because it has to round-robin compete * with many other destinations. However, Postfix will also perform * poorly when most of the active queue is tied up by a small number of * concurrency limited destinations. The queue length test below detects * such conditions only indirectly. * * XXX This code does not detect the case that the active queue is being * starved because incoming mail is pounding the disk. */ if (var_helpful_warnings && var_qmgr_clog_warn_time > 0) { int queue_length = queue->todo_refcount + queue->busy_refcount; time_t now; QMGR_TRANSPORT *transport; double active_share; if (queue_length > var_qmgr_active_limit / 5 && (now = event_time()) >= queue->clog_time_to_warn) { active_share = queue_length / (double) qmgr_message_count; msg_warn("mail for %s is using up %d of %d active queue entries", queue->nexthop, queue_length, qmgr_message_count); if (active_share < 0.9) msg_warn("this may slow down other mail deliveries"); transport = queue->transport; if (transport->dest_concurrency_limit > 0 && transport->dest_concurrency_limit <= queue->busy_refcount + 1) msg_warn("you may need to increase the main.cf %s%s from %d", transport->name, _DEST_CON_LIMIT, transport->dest_concurrency_limit); else if (queue->window > var_qmgr_active_limit * active_share) msg_warn("you may need to increase the main.cf %s from %d", VAR_QMGR_ACT_LIMIT, var_qmgr_active_limit); else if (queue->peers.next != queue->peers.prev) msg_warn("you may need a separate master.cf transport for %s", queue->nexthop); else { msg_warn("you may need to reduce %s connect and helo timeouts", transport->name); msg_warn("so that Postfix quickly skips unavailable hosts"); msg_warn("you may need to increase the main.cf %s and %s", VAR_MIN_BACKOFF_TIME, VAR_MAX_BACKOFF_TIME); msg_warn("so that Postfix wastes less time on undeliverable mail"); msg_warn("you may need to increase the master.cf %s process limit", transport->name); } msg_warn("please avoid flushing the whole queue when you have"); msg_warn("lots of deferred mail, that is bad for performance"); msg_warn("to turn off these warnings specify: %s = 0", VAR_QMGR_CLOG_WARN_TIME); queue->clog_time_to_warn = now + var_qmgr_clog_warn_time; } } return (entry); }