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/*++
/* NAME
/* qmgr_transport 3
/* SUMMARY
/* per-transport data structures
/* SYNOPSIS
/* #include "qmgr.h"
/*
/* QMGR_TRANSPORT *qmgr_transport_create(name)
/* const char *name;
/*
/* QMGR_TRANSPORT *qmgr_transport_find(name)
/* const char *name;
/*
/* QMGR_TRANSPORT *qmgr_transport_select()
/*
/* void qmgr_transport_alloc(transport, notify)
/* QMGR_TRANSPORT *transport;
/* void (*notify)(QMGR_TRANSPORT *transport, VSTREAM *fp);
/*
/* void qmgr_transport_throttle(transport, dsn)
/* QMGR_TRANSPORT *transport;
/* DSN *dsn;
/*
/* void qmgr_transport_unthrottle(transport)
/* QMGR_TRANSPORT *transport;
/* DESCRIPTION
/* This module organizes the world by message transport type.
/* Each transport can have zero or more destination queues
/* associated with it.
/*
/* qmgr_transport_create() instantiates a data structure for the
/* named transport type.
/*
/* qmgr_transport_find() looks up an existing message transport
/* data structure.
/*
/* qmgr_transport_select() attempts to find a transport that
/* has messages pending delivery. This routine implements
/* round-robin search among transports.
/*
/* qmgr_transport_alloc() allocates a delivery process for the
/* specified transport type. Allocation is performed asynchronously.
/* When a process becomes available, the application callback routine
/* is invoked with as arguments the transport and a stream that
/* is connected to a delivery process. It is an error to call
/* qmgr_transport_alloc() while delivery process allocation for
/* the same transport is in progress.
/*
/* qmgr_transport_throttle blocks further allocation of delivery
/* processes for the named transport. Attempts to throttle a
/* throttled transport are ignored.
/*
/* qmgr_transport_unthrottle() undoes qmgr_transport_throttle().
/* Attempts to unthrottle a non-throttled transport are ignored.
/* DIAGNOSTICS
/* Panic: consistency check failure. Fatal: out of memory.
/* 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
/*
/* Wietse Venema
/* Google, Inc.
/* 111 8th Avenue
/* New York, NY 10011, USA
/*--*/
/* System library. */
#include <sys_defs.h>
#include <unistd.h>
#include <sys/time.h> /* FD_SETSIZE */
#include <sys/types.h> /* FD_SETSIZE */
#include <unistd.h> /* FD_SETSIZE */
#ifdef USE_SYS_SELECT_H
#include <sys/select.h> /* FD_SETSIZE */
#endif
/* Utility library. */
#include <msg.h>
#include <htable.h>
#include <events.h>
#include <mymalloc.h>
#include <vstream.h>
#include <iostuff.h>
/* Global library. */
#include <mail_proto.h>
#include <recipient_list.h>
#include <mail_conf.h>
#include <mail_params.h>
/* Application-specific. */
#include "qmgr.h"
HTABLE *qmgr_transport_byname; /* transport by name */
QMGR_TRANSPORT_LIST qmgr_transport_list;/* transports, round robin */
/*
* A local structure to remember a delivery process allocation request.
*/
typedef struct QMGR_TRANSPORT_ALLOC QMGR_TRANSPORT_ALLOC;
struct QMGR_TRANSPORT_ALLOC {
QMGR_TRANSPORT *transport; /* transport context */
VSTREAM *stream; /* delivery service stream */
QMGR_TRANSPORT_ALLOC_NOTIFY notify; /* application call-back routine */
};
/*
* Connections to delivery agents are managed asynchronously. Each delivery
* agent connection goes through multiple wait states:
*
* - With Linux/Solaris and old queue manager implementations only, wait for
* the server to invoke accept().
*
* - Wait for the delivery agent's announcement that it is ready to receive a
* delivery request.
*
* - Wait for the delivery request completion status.
*
* Older queue manager implementations had only one pending delivery agent
* connection per transport. With low-latency destinations, the output rates
* were reduced on Linux/Solaris systems that had the extra wait state.
*
* To maximize delivery agent output rates with low-latency destinations, the
* following changes were made to the queue manager by the end of the 2.4
* development cycle:
*
* - The Linux/Solaris accept() wait state was eliminated.
*
* - A pipeline was implemented for pending delivery agent connections. The
* number of pending delivery agent connections was increased from one to
* two: the number of before-delivery wait states, plus one extra pipeline
* slot to prevent the pipeline from stalling easily. Increasing the
* pipeline much further actually hurt performance.
*
* - To reduce queue manager disk competition with delivery agents, the queue
* scanning algorithm was modified to import only one message per interrupt.
* The incoming and deferred queue scans now happen on alternate interrupts.
*
* Simplistically reasoned, a non-zero (incoming + active) queue length is
* equivalent to a time shift for mail deliveries; this is undesirable when
* delivery agents are not fully utilized.
*
* On the other hand a non-empty active queue is what allows us to do clever
* things such as queue file prefetch, concurrency windows, and connection
* caching; the idea is that such "thinking time" is affordable only after
* the output channels are maxed out.
*/
#ifndef QMGR_TRANSPORT_MAX_PEND
#define QMGR_TRANSPORT_MAX_PEND 2
#endif
/*
* Important note on the _transport_rate_delay implementation: after
* qmgr_transport_alloc() sets the QMGR_TRANSPORT_STAT_RATE_LOCK flag, all
* code paths must directly or indirectly invoke qmgr_transport_unthrottle()
* or qmgr_transport_throttle(). Otherwise, transports with non-zero
* _transport_rate_delay will become stuck.
*/
/* qmgr_transport_unthrottle_wrapper - in case (char *) != (struct *) */
static void qmgr_transport_unthrottle_wrapper(int unused_event, void *context)
{
qmgr_transport_unthrottle((QMGR_TRANSPORT *) context);
}
/* qmgr_transport_unthrottle - open the throttle */
void qmgr_transport_unthrottle(QMGR_TRANSPORT *transport)
{
const char *myname = "qmgr_transport_unthrottle";
/*
* This routine runs after expiration of the timer set by
* qmgr_transport_throttle(), or whenever a delivery transport has been
* used without malfunction. In either case, we enable delivery again if
* the transport was throttled. We always reset the transport rate lock.
*/
if ((transport->flags & QMGR_TRANSPORT_STAT_DEAD) != 0) {
if (msg_verbose)
msg_info("%s: transport %s", myname, transport->name);
transport->flags &= ~QMGR_TRANSPORT_STAT_DEAD;
if (transport->dsn == 0)
msg_panic("%s: transport %s: null reason",
myname, transport->name);
dsn_free(transport->dsn);
transport->dsn = 0;
event_cancel_timer(qmgr_transport_unthrottle_wrapper,
(void *) transport);
}
if (transport->flags & QMGR_TRANSPORT_STAT_RATE_LOCK)
transport->flags &= ~QMGR_TRANSPORT_STAT_RATE_LOCK;
}
/* qmgr_transport_throttle - disable delivery process allocation */
void qmgr_transport_throttle(QMGR_TRANSPORT *transport, DSN *dsn)
{
const char *myname = "qmgr_transport_throttle";
/*
* We are unable to connect to a deliver process for this type of message
* transport. Instead of hosing the system by retrying in a tight loop,
* back off and disable this transport type for a while.
*/
if ((transport->flags & QMGR_TRANSPORT_STAT_DEAD) == 0) {
if (msg_verbose)
msg_info("%s: transport %s: status: %s reason: %s",
myname, transport->name, dsn->status, dsn->reason);
transport->flags |= QMGR_TRANSPORT_STAT_DEAD;
if (transport->dsn)
msg_panic("%s: transport %s: spurious reason: %s",
myname, transport->name, transport->dsn->reason);
transport->dsn = DSN_COPY(dsn);
event_request_timer(qmgr_transport_unthrottle_wrapper,
(void *) transport, var_transport_retry_time);
}
}
/* qmgr_transport_abort - transport connect watchdog */
static void qmgr_transport_abort(int unused_event, void *context)
{
QMGR_TRANSPORT_ALLOC *alloc = (QMGR_TRANSPORT_ALLOC *) context;
msg_fatal("timeout connecting to transport: %s", alloc->transport->name);
}
/* qmgr_transport_rate_event - delivery process availability notice */
static void qmgr_transport_rate_event(int unused_event, void *context)
{
QMGR_TRANSPORT_ALLOC *alloc = (QMGR_TRANSPORT_ALLOC *) context;
alloc->notify(alloc->transport, alloc->stream);
myfree((void *) alloc);
}
/* qmgr_transport_event - delivery process availability notice */
static void qmgr_transport_event(int unused_event, void *context)
{
QMGR_TRANSPORT_ALLOC *alloc = (QMGR_TRANSPORT_ALLOC *) context;
/*
* This routine notifies the application when the request given to
* qmgr_transport_alloc() completes.
*/
if (msg_verbose)
msg_info("transport_event: %s", alloc->transport->name);
/*
* Connection request completed. Stop the watchdog timer.
*/
event_cancel_timer(qmgr_transport_abort, context);
/*
* Disable further read events that end up calling this function, and
* free up this pending connection pipeline slot.
*/
if (alloc->stream) {
event_disable_readwrite(vstream_fileno(alloc->stream));
non_blocking(vstream_fileno(alloc->stream), BLOCKING);
}
alloc->transport->pending -= 1;
/*
* Notify the requestor.
*/
if (alloc->transport->xport_rate_delay > 0) {
if ((alloc->transport->flags & QMGR_TRANSPORT_STAT_RATE_LOCK) == 0)
msg_panic("transport_event: missing rate lock for transport %s",
alloc->transport->name);
event_request_timer(qmgr_transport_rate_event, (void *) alloc,
alloc->transport->xport_rate_delay);
} else {
alloc->notify(alloc->transport, alloc->stream);
myfree((void *) alloc);
}
}
/* qmgr_transport_select - select transport for allocation */
QMGR_TRANSPORT *qmgr_transport_select(void)
{
QMGR_TRANSPORT *xport;
QMGR_QUEUE *queue;
int need;
/*
* If we find a suitable transport, rotate the list of transports to
* effectuate round-robin selection. See similar selection code in
* qmgr_peer_select().
*
* This function is called repeatedly until all transports have maxed out
* the number of pending delivery agent connections, until all delivery
* agent concurrency windows are maxed out, or until we run out of "todo"
* queue entries.
*/
#define MIN5af51743e4eef(x, y) ((x) < (y) ? (x) : (y))
for (xport = qmgr_transport_list.next; xport; xport = xport->peers.next) {
if ((xport->flags & QMGR_TRANSPORT_STAT_DEAD) != 0
|| (xport->flags & QMGR_TRANSPORT_STAT_RATE_LOCK) != 0
|| xport->pending >= QMGR_TRANSPORT_MAX_PEND)
continue;
need = xport->pending + 1;
for (queue = xport->queue_list.next; queue; queue = queue->peers.next) {
if (QMGR_QUEUE_READY(queue) == 0)
continue;
if ((need -= MIN5af51743e4eef(queue->window - queue->busy_refcount,
queue->todo_refcount)) <= 0) {
QMGR_LIST_ROTATE(qmgr_transport_list, xport, peers);
if (msg_verbose)
msg_info("qmgr_transport_select: %s", xport->name);
return (xport);
}
}
}
return (0);
}
/* qmgr_transport_alloc - allocate delivery process */
void qmgr_transport_alloc(QMGR_TRANSPORT *transport, QMGR_TRANSPORT_ALLOC_NOTIFY notify)
{
QMGR_TRANSPORT_ALLOC *alloc;
/*
* Sanity checks.
*/
if (transport->flags & QMGR_TRANSPORT_STAT_DEAD)
msg_panic("qmgr_transport: dead transport: %s", transport->name);
if (transport->flags & QMGR_TRANSPORT_STAT_RATE_LOCK)
msg_panic("qmgr_transport: rate-locked transport: %s", transport->name);
if (transport->pending >= QMGR_TRANSPORT_MAX_PEND)
msg_panic("qmgr_transport: excess allocation: %s", transport->name);
/*
* When this message delivery transport is rate-limited, do not select it
* again before the end of a message delivery transaction.
*/
if (transport->xport_rate_delay > 0)
transport->flags |= QMGR_TRANSPORT_STAT_RATE_LOCK;
/*
* Connect to the well-known port for this delivery service, and wake up
* when a process announces its availability. Allow only a limited number
* of delivery process allocation attempts for this transport. In case of
* problems, back off. Do not hose the system when it is in trouble
* already.
*
* Use non-blocking connect(), so that Linux won't block the queue manager
* until the delivery agent calls accept().
*
* When the connection to delivery agent cannot be completed, notify the
* event handler so that it can throttle the transport and defer the todo
* queues, just like it does when communication fails *after* connection
* completion.
*
* Before Postfix 2.4, the event handler was not invoked after connect()
* error, and mail was not deferred. Because of this, mail would be stuck
* in the active queue after triggering a "connection refused" condition.
*/
alloc = (QMGR_TRANSPORT_ALLOC *) mymalloc(sizeof(*alloc));
alloc->transport = transport;
alloc->notify = notify;
transport->pending += 1;
if ((alloc->stream = mail_connect(MAIL_CLASS_PRIVATE, transport->name,
NON_BLOCKING)) == 0) {
msg_warn("connect to transport %s/%s: %m",
MAIL_CLASS_PRIVATE, transport->name);
event_request_timer(qmgr_transport_event, (void *) alloc, 0);
return;
}
#if (EVENTS_STYLE != EVENTS_STYLE_SELECT) && defined(CA_VSTREAM_CTL_DUPFD)
#ifndef THRESHOLD_FD_WORKAROUND
#define THRESHOLD_FD_WORKAROUND 128
#endif
vstream_control(alloc->stream,
CA_VSTREAM_CTL_DUPFD(THRESHOLD_FD_WORKAROUND),
CA_VSTREAM_CTL_END);
#endif
event_enable_read(vstream_fileno(alloc->stream), qmgr_transport_event,
(void *) alloc);
/*
* Guard against broken systems.
*/
event_request_timer(qmgr_transport_abort, (void *) alloc,
var_daemon_timeout);
}
/* qmgr_transport_create - create transport instance */
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->slot_cost = get_mail_conf_int2(name, _DELIVERY_SLOT_COST,
var_delivery_slot_cost, 0, 0);
transport->slot_loan = get_mail_conf_int2(name, _DELIVERY_SLOT_LOAN,
var_delivery_slot_loan, 0, 0);
transport->slot_loan_factor =
100 - get_mail_conf_int2(name, _DELIVERY_SLOT_DISCOUNT,
var_delivery_slot_discount, 0, 100);
transport->min_slots = get_mail_conf_int2(name, _MIN_DELIVERY_SLOTS,
var_min_delivery_slots, 0, 0);
transport->rcpt_unused = get_mail_conf_int2(name, _XPORT_RCPT_LIMIT,
var_xport_rcpt_limit, 0, 0);
transport->rcpt_per_stack = get_mail_conf_int2(name, _STACK_RCPT_LIMIT,
var_stack_rcpt_limit, 0, 0);
transport->refill_limit = get_mail_conf_int2(name, _XPORT_REFILL_LIMIT,
var_xport_refill_limit, 1, 0);
transport->refill_delay = get_mail_conf_time2(name, _XPORT_REFILL_DELAY,
var_xport_refill_delay, 's', 1, 0);
transport->queue_byname = htable_create(0);
QMGR_LIST_INIT(transport->queue_list);
transport->job_byname = htable_create(0);
QMGR_LIST_INIT(transport->job_list);
QMGR_LIST_INIT(transport->job_bytime);
transport->job_current = 0;
transport->job_next_unread = 0;
transport->candidate_cache = 0;
transport->candidate_cache_current = 0;
transport->candidate_cache_time = (time_t) 0;
transport->blocker_tag = 1;
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_PREPEND(qmgr_transport_list, transport, peers);
if (msg_verbose)
msg_info("qmgr_transport_create: %s concurrency %d recipients %d",
transport->name, transport->dest_concurrency_limit,
transport->recipient_limit);
return (transport);
}
/* qmgr_transport_find - find transport instance */
QMGR_TRANSPORT *qmgr_transport_find(const char *name)
{
return ((QMGR_TRANSPORT *) htable_find(qmgr_transport_byname, name));
}