view src/event/ngx_event_timer.c @ 4729:4ff2131dbce5 stable-1.2

Merge of r4691: changed default alignment to 16. This fixes alignment problems observerd on ARMs, and likely also needed for MIPSes. Unless we know alignment is not required just assume we need 16, which appears to be safe default for all architectures. See here for details: http://mailman.nginx.org/pipermail/nginx/2012-June/034139.html
author Maxim Dounin <mdounin@mdounin.ru>
date Mon, 02 Jul 2012 17:08:26 +0000
parents 876e6b0814a5
children 3377f9459e99
line wrap: on
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/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>


#if (NGX_THREADS)
ngx_mutex_t  *ngx_event_timer_mutex;
#endif


ngx_thread_volatile ngx_rbtree_t  ngx_event_timer_rbtree;
static ngx_rbtree_node_t          ngx_event_timer_sentinel;

/*
 * the event timer rbtree may contain the duplicate keys, however,
 * it should not be a problem, because we use the rbtree to find
 * a minimum timer value only
 */

ngx_int_t
ngx_event_timer_init(ngx_log_t *log)
{
    ngx_rbtree_init(&ngx_event_timer_rbtree, &ngx_event_timer_sentinel,
                    ngx_rbtree_insert_timer_value);

#if (NGX_THREADS)

    if (ngx_event_timer_mutex) {
        ngx_event_timer_mutex->log = log;
        return NGX_OK;
    }

    ngx_event_timer_mutex = ngx_mutex_init(log, 0);
    if (ngx_event_timer_mutex == NULL) {
        return NGX_ERROR;
    }

#endif

    return NGX_OK;
}


ngx_msec_t
ngx_event_find_timer(void)
{
    ngx_msec_int_t      timer;
    ngx_rbtree_node_t  *node, *root, *sentinel;

    if (ngx_event_timer_rbtree.root == &ngx_event_timer_sentinel) {
        return NGX_TIMER_INFINITE;
    }

    ngx_mutex_lock(ngx_event_timer_mutex);

    root = ngx_event_timer_rbtree.root;
    sentinel = ngx_event_timer_rbtree.sentinel;

    node = ngx_rbtree_min(root, sentinel);

    ngx_mutex_unlock(ngx_event_timer_mutex);

    timer = (ngx_msec_int_t) (node->key - ngx_current_msec);

    return (ngx_msec_t) (timer > 0 ? timer : 0);
}


void
ngx_event_expire_timers(void)
{
    ngx_event_t        *ev;
    ngx_rbtree_node_t  *node, *root, *sentinel;

    sentinel = ngx_event_timer_rbtree.sentinel;

    for ( ;; ) {

        ngx_mutex_lock(ngx_event_timer_mutex);

        root = ngx_event_timer_rbtree.root;

        if (root == sentinel) {
            return;
        }

        node = ngx_rbtree_min(root, sentinel);

        /* node->key <= ngx_current_time */

        if ((ngx_msec_int_t) (node->key - ngx_current_msec) <= 0) {
            ev = (ngx_event_t *) ((char *) node - offsetof(ngx_event_t, timer));

#if (NGX_THREADS)

            if (ngx_threaded && ngx_trylock(ev->lock) == 0) {

                /*
                 * We cannot change the timer of the event that is being
                 * handled by another thread.  And we cannot easy walk
                 * the rbtree to find next expired timer so we exit the loop.
                 * However, it should be a rare case when the event that is
                 * being handled has an expired timer.
                 */

                ngx_log_debug1(NGX_LOG_DEBUG_EVENT, ev->log, 0,
                               "event %p is busy in expire timers", ev);
                break;
            }
#endif

            ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ev->log, 0,
                           "event timer del: %d: %M",
                           ngx_event_ident(ev->data), ev->timer.key);

            ngx_rbtree_delete(&ngx_event_timer_rbtree, &ev->timer);

            ngx_mutex_unlock(ngx_event_timer_mutex);

#if (NGX_DEBUG)
            ev->timer.left = NULL;
            ev->timer.right = NULL;
            ev->timer.parent = NULL;
#endif

            ev->timer_set = 0;

#if (NGX_THREADS)
            if (ngx_threaded) {
                ev->posted_timedout = 1;

                ngx_post_event(ev, &ngx_posted_events);

                ngx_unlock(ev->lock);

                continue;
            }
#endif

            ev->timedout = 1;

            ev->handler(ev);

            continue;
        }

        break;
    }

    ngx_mutex_unlock(ngx_event_timer_mutex);
}