static QMGR_JOB *qmgr_job_create(QMGR_MESSAGE *message, QMGR_TRANSPORT *transport)
{
QMGR_JOB *job;
job = (QMGR_JOB *) mymalloc(sizeof(QMGR_JOB));
job->message = message;
QMGR_LIST_APPEND(message->job_list, job, message_peers);
htable_enter(transport->job_byname, message->queue_id, (void *) job);
job->transport = transport;
QMGR_LIST_INIT(job->transport_peers);
QMGR_LIST_INIT(job->time_peers);
job->stack_parent = 0;
QMGR_LIST_INIT(job->stack_children);
QMGR_LIST_INIT(job->stack_siblings);
job->stack_level = -1;
job->blocker_tag = 0;
job->peer_byname = htable_create(0);
QMGR_LIST_INIT(job->peer_list);
job->slots_used = 0;
job->slots_available = 0;
job->selected_entries = 0;
job->read_entries = 0;
job->rcpt_count = 0;
job->rcpt_limit = 0;
return (job);
}
QMGR_QUEUE *qmgr_queue_create(QMGR_TRANSPORT *transport, const char *name,
const char *nexthop)
{
QMGR_QUEUE *queue;
/*
* If possible, choose an initial concurrency of > 1 so that one bad
* message or one bad network won't slow us down unnecessarily.
*/
queue = (QMGR_QUEUE *) mymalloc(sizeof(QMGR_QUEUE));
qmgr_queue_count++;
queue->dflags = 0;
queue->last_done = 0;
queue->name = mystrdup(name);
queue->nexthop = mystrdup(nexthop);
queue->todo_refcount = 0;
queue->busy_refcount = 0;
queue->transport = transport;
queue->window = transport->init_dest_concurrency;
queue->success = queue->failure = queue->fail_cohorts = 0;
QMGR_LIST_INIT(queue->todo);
QMGR_LIST_INIT(queue->busy);
queue->dsn = 0;
queue->clog_time_to_warn = 0;
queue->blocker_tag = 0;
QMGR_LIST_APPEND(transport->queue_list, queue, peers);
htable_enter(transport->queue_byname, name, (char *) queue);
return (queue);
}
QMGR_TRANSPORT *qmgr_transport_create(const char *name)
{
QMGR_TRANSPORT *transport;
if (htable_find(qmgr_transport_byname, name) != 0)
msg_panic("qmgr_transport_create: transport exists: %s", name);
transport = (QMGR_TRANSPORT *) mymalloc(sizeof(QMGR_TRANSPORT));
transport->flags = 0;
transport->pending = 0;
transport->name = mystrdup(name);
/*
* Use global configuration settings or transport-specific settings.
*/
transport->dest_concurrency_limit =
get_mail_conf_int2(name, _DEST_CON_LIMIT,
var_dest_con_limit, 0, 0);
transport->recipient_limit =
get_mail_conf_int2(name, _DEST_RCPT_LIMIT,
var_dest_rcpt_limit, 0, 0);
transport->init_dest_concurrency =
get_mail_conf_int2(name, _INIT_DEST_CON,
var_init_dest_concurrency, 1, 0);
transport->xport_rate_delay = get_mail_conf_time2(name, _XPORT_RATE_DELAY,
var_xport_rate_delay,
's', 0, 0);
transport->rate_delay = get_mail_conf_time2(name, _DEST_RATE_DELAY,
var_dest_rate_delay,
's', 0, 0);
if (transport->rate_delay > 0)
transport->dest_concurrency_limit = 1;
if (transport->dest_concurrency_limit != 0
&& transport->dest_concurrency_limit < transport->init_dest_concurrency)
transport->init_dest_concurrency = transport->dest_concurrency_limit;
transport->queue_byname = htable_create(0);
QMGR_LIST_INIT(transport->queue_list);
transport->dsn = 0;
qmgr_feedback_init(&transport->pos_feedback, name, _CONC_POS_FDBACK,
VAR_CONC_POS_FDBACK, var_conc_pos_feedback);
qmgr_feedback_init(&transport->neg_feedback, name, _CONC_NEG_FDBACK,
VAR_CONC_NEG_FDBACK, var_conc_neg_feedback);
transport->fail_cohort_limit =
get_mail_conf_int2(name, _CONC_COHORT_LIM,
var_conc_cohort_limit, 0, 0);
if (qmgr_transport_byname == 0)
qmgr_transport_byname = htable_create(10);
htable_enter(qmgr_transport_byname, name, (void *) transport);
QMGR_LIST_APPEND(qmgr_transport_list, transport);
if (msg_verbose)
msg_info("qmgr_transport_create: %s concurrency %d recipients %d",
transport->name, transport->dest_concurrency_limit,
transport->recipient_limit);
return (transport);
}
static void qmgr_job_parent_gone(QMGR_JOB *job, QMGR_JOB *parent)
{
QMGR_JOB *child;
while ((child = job->stack_children.next) != 0) {
QMGR_LIST_UNLINK(job->stack_children, QMGR_JOB *, child, stack_siblings);
if (parent != 0)
QMGR_LIST_APPEND(parent->stack_children, child, stack_siblings);
child->stack_parent = parent;
}
}
QMGR_PEER *qmgr_peer_create(QMGR_JOB *job, QMGR_QUEUE *queue)
{
QMGR_PEER *peer;
peer = (QMGR_PEER *) mymalloc(sizeof(QMGR_PEER));
peer->queue = queue;
peer->job = job;
QMGR_LIST_APPEND(job->peer_list, peer, peers);
htable_enter(job->peer_byname, queue->name, (char *) peer);
peer->refcount = 0;
QMGR_LIST_INIT(peer->entry_list);
return (peer);
}
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;
}
}
}
static QMGR_JOB *qmgr_job_preempt(QMGR_JOB *current)
{
const char *myname = "qmgr_job_preempt";
QMGR_TRANSPORT *transport = current->transport;
QMGR_JOB *job, *prev;
int expected_slots;
int rcpt_slots;
/*
* Suppress preempting completely if the current job is not big enough to
* accumulate even the minimal number of slots required.
*
* Also, don't look for better job candidate if there are no available slots
* yet (the count can get negative due to the slot loans below).
*/
if (current->slots_available <= 0
|| MAX_ENTRIES(current) < transport->min_slots * transport->slot_cost)
return (current);
/*
* Find best candidate for preempting the current job.
*
* Note that the function also takes care that the candidate fits within the
* number of delivery slots which the current job is still able to
* accumulate.
*/
if ((job = qmgr_job_candidate(current)) == 0)
return (current);
/*
* Sanity checks.
*/
if (job == current)
msg_panic("%s: attempt to preempt itself", myname);
if (job->stack_children.next != 0)
msg_panic("%s: already on the job stack (%d)", myname, job->stack_level);
if (job->stack_level < 0)
msg_panic("%s: not on the job list (%d)", myname, job->stack_level);
/*
* Check if there is enough available delivery slots accumulated to
* preempt the current job.
*
* The slot loaning scheme improves the average message response time. Note
* that the loan only allows the preemption happen earlier, though. It
* doesn't affect how many slots have to be "paid" - in either case the
* full number of slots required has to be accumulated later before the
* current job can be preempted again.
*/
expected_slots = MAX_ENTRIES(job) - job->selected_entries;
if (current->slots_available / transport->slot_cost + transport->slot_loan
< expected_slots * transport->slot_loan_factor / 100.0)
return (current);
/*
* Preempt the current job.
*
* This involves placing the selected candidate in front of the current job
* on the job list and updating the stack parent/child/sibling pointers
* appropriately. But first we need to make sure that the candidate is
* taken from its previous job stack which it might be top of.
*/
if (job->stack_level > 0)
qmgr_job_pop(job);
QMGR_LIST_UNLINK(transport->job_list, QMGR_JOB *, job, transport_peers);
prev = current->transport_peers.prev;
QMGR_LIST_LINK(transport->job_list, prev, job, current, transport_peers);
job->stack_parent = current;
QMGR_LIST_APPEND(current->stack_children, job, stack_siblings);
job->stack_level = current->stack_level + 1;
/*
* Update the current job pointer and explicitly reset the candidate
* cache.
*/
transport->job_current = job;
RESET_CANDIDATE_CACHE(transport);
/*
* Since the single job can be preempted by several jobs at the same
* time, we have to adjust the available slot count now to prevent using
* the same slots multiple times. To do that we subtract the number of
* slots the preempting job will supposedly use. This number will be
* corrected later when that job is popped from the stack to reflect the
* number of slots really used.
*
* As long as we don't need to keep track of how many slots were really
* used, we can (ab)use the slots_used counter for counting the
* difference between the real and expected amounts instead of the
* absolute amount.
*/
current->slots_available -= expected_slots * transport->slot_cost;
job->slots_used = -expected_slots;
/*
* Add part of extra recipient slots reserved for preempting jobs to the
* new current job if necessary.
*
* Note that transport->rcpt_unused is within <-rcpt_per_stack,0> in such
* case.
*/
if (job->message->rcpt_offset != 0) {
rcpt_slots = (transport->rcpt_per_stack + transport->rcpt_unused + 1) / 2;
job->rcpt_limit += rcpt_slots;
job->message->rcpt_limit += rcpt_slots;
transport->rcpt_unused -= rcpt_slots;
}
if (msg_verbose)
msg_info("%s: %s by %s, level %d", myname, current->message->queue_id,
job->message->queue_id, job->stack_level);
return (job);
}
