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+/*++
+/* NAME
+/* qmgr_entry 3
+/* SUMMARY
+/* per-site queue entries
+/* SYNOPSIS
+/* #include "qmgr.h"
+/*
+/* QMGR_ENTRY *qmgr_entry_create(peer, message)
+/* QMGR_PEER *peer;
+/* 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 peer and message,
+/* and appends the entry to the peer's list and its 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() discards its peer structure when the peer
+/* is not referenced anymore.
+/*
+/* 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 first 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. The entry is also removed from its peer list.
+/*
+/* 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. The entry is also prepended to its peer list again.
+/*
+/* 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
+/*
+/* Preemptive scheduler enhancements:
+/* Patrik Rak
+/* Modra 6
+/* 155 00, Prague, Czech Republic
+/*--*/
+
+/* 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_PEER *peer)
+{
+ const char *myname = "qmgr_entry_select";
+ QMGR_ENTRY *entry;
+ QMGR_QUEUE *queue;
+
+ if ((entry = peer->entry_list.next) != 0) {
+ queue = entry->queue;
+ QMGR_LIST_UNLINK(queue->todo, QMGR_ENTRY *, entry, queue_peers);
+ queue->todo_refcount--;
+ QMGR_LIST_APPEND(queue->busy, entry, queue_peers);
+ queue->busy_refcount++;
+ QMGR_LIST_UNLINK(peer->entry_list, QMGR_ENTRY *, entry, peer_peers);
+ peer->job->selected_entries++;
+
+ /*
+ * 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_ENTRY *entry)
+{
+ QMGR_PEER *peer = entry->peer;
+ QMGR_QUEUE *queue = entry->queue;
+
+ /*
+ * Move the entry back to the todo lists. In case of the peer list, put
+ * it back to the beginning, so the select()/unselect() does not reorder
+ * entries. We use this in qmgr_message_assign() to put recipients into
+ * existing entries when possible.
+ */
+ QMGR_LIST_UNLINK(queue->busy, QMGR_ENTRY *, entry, queue_peers);
+ queue->busy_refcount--;
+ QMGR_LIST_APPEND(queue->todo, entry, queue_peers);
+ queue->todo_refcount++;
+ QMGR_LIST_PREPEND(peer->entry_list, entry, peer_peers);
+ peer->job->selected_entries--;
+}
+
+/* qmgr_entry_move_todo - move entry between todo queues */
+
+void qmgr_entry_move_todo(QMGR_QUEUE *dst_queue, QMGR_ENTRY *entry)
+{
+ const char *myname = "qmgr_entry_move_todo";
+ QMGR_TRANSPORT *dst_transport = dst_queue->transport;
+ QMGR_MESSAGE *message = entry->message;
+ QMGR_QUEUE *src_queue = entry->queue;
+ QMGR_PEER *dst_peer, *src_peer = entry->peer;
+ QMGR_JOB *dst_job, *src_job = src_peer->job;
+ QMGR_ENTRY *new_entry;
+ int rcpt_count = entry->rcpt_list.len;
+
+ if (entry->stream != 0)
+ msg_panic("%s: queue %s entry is busy", myname, src_queue->name);
+ if (QMGR_QUEUE_THROTTLED(dst_queue))
+ msg_panic("%s: destination queue %s is throttled", myname, dst_queue->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 two entries,
+ * adjusting the job counters accordingly, then dispose of the old entry.
+ *
+ * Note that qmgr_entry_done() will also take care of adjusting the
+ * recipient limits of all the message jobs, so we do not have to do that
+ * explicitly for the new job 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.
+ */
+ dst_job = qmgr_job_obtain(message, dst_transport);
+ dst_peer = qmgr_peer_obtain(dst_job, dst_queue);
+
+ new_entry = qmgr_entry_create(dst_peer, message);
+
+ recipient_list_swap(&entry->rcpt_list, &new_entry->rcpt_list);
+
+ src_job->rcpt_count -= rcpt_count;
+ dst_job->rcpt_count += rcpt_count;
+
+ 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_PEER *peer = entry->peer;
+ QMGR_JOB *sponsor, *job = peer->job;
+ QMGR_TRANSPORT *transport = job->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_peers);
+ queue->busy_refcount--;
+ } else if (which == QMGR_QUEUE_TODO) {
+ QMGR_LIST_UNLINK(peer->entry_list, QMGR_ENTRY *, entry, peer_peers);
+ job->selected_entries++;
+ QMGR_LIST_UNLINK(queue->todo, QMGR_ENTRY *, entry, queue_peers);
+ queue->todo_refcount--;
+ } else {
+ msg_panic("%s: bad queue spec: %d", myname, which);
+ }
+
+ /*
+ * Decrease the in-core recipient counts and free the recipient list and
+ * the structure itself.
+ */
+ job->rcpt_count -= entry->rcpt_list.len;
+ message->rcpt_count -= entry->rcpt_list.len;
+ qmgr_recipient_count -= entry->rcpt_list.len;
+ recipient_list_free(&entry->rcpt_list);
+ myfree((void *) entry);
+
+ /*
+ * Make sure that the transport of any retired or finishing job that
+ * donated recipient slots to this message gets them back first. Then, if
+ * possible, pass the remaining unused recipient slots to the next job on
+ * the job list.
+ */
+ for (sponsor = message->job_list.next; sponsor; sponsor = sponsor->message_peers.next) {
+ if (sponsor->rcpt_count >= sponsor->rcpt_limit || sponsor == job)
+ continue;
+ if (sponsor->stack_level < 0 || message->rcpt_offset == 0)
+ qmgr_job_move_limits(sponsor);
+ }
+ if (message->rcpt_offset == 0) {
+ qmgr_job_move_limits(job);
+ }
+
+ /*
+ * We implement a rate-limited queue by emulating a slow delivery
+ * channel. We insert the artificial delays with qmgr_queue_suspend().
+ *
+ * When a queue is suspended, we must postpone any job scheduling decisions
+ * until the queue is resumed. Otherwise, we make those decisions now.
+ * The job scheduling decisions are made by qmgr_job_blocker_update().
+ */
+ 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);
+ }
+ if (!QMGR_QUEUE_SUSPENDED(queue)
+ && queue->blocker_tag == transport->blocker_tag)
+ qmgr_job_blocker_update(queue);
+
+ /*
+ * When there are no more entries for this peer, discard the peer
+ * structure.
+ */
+ peer->refcount--;
+ if (peer->refcount == 0)
+ qmgr_peer_free(peer);
+
+ /*
+ * Maintain back-to-back delivery status.
+ */
+ if (which == QMGR_QUEUE_BUSY)
+ queue->last_done = event_time();
+
+ /*
+ * When the in-core queue for this site is empty and when this site is
+ * not dead or suspended, 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.
+ */
+ 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.
+ */
+ message->refcount--;
+ if (message->refcount == 0)
+ qmgr_active_done(message);
+}
+
+/* qmgr_entry_create - create queue todo entry */
+
+QMGR_ENTRY *qmgr_entry_create(QMGR_PEER *peer, QMGR_MESSAGE *message)
+{
+ QMGR_ENTRY *entry;
+ QMGR_QUEUE *queue = peer->queue;
+
+ /*
+ * 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->peer = peer;
+ QMGR_LIST_APPEND(peer->entry_list, entry, peer_peers);
+ peer->refcount++;
+ entry->queue = queue;
+ QMGR_LIST_APPEND(queue->todo, entry, queue_peers);
+ queue->todo_refcount++;
+ peer->job->read_entries++;
+
+ /*
+ * 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 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);
+}
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