view src/event/ngx_event_posted.c @ 4576:876e6b0814a5

Fixed signed integer overflows in timer code (ticket #145). Integer overflow is undefined behaviour in C and this indeed caused problems on Solaris/SPARC (at least in some cases). Fix is to subtract unsigned integers instead, and then cast result to a signed one, which is implementation-defined behaviour and used to work. Strictly speaking, we should compare (unsigned) result with the maximum value of the corresponding signed integer type instead, this will be defined behaviour. This will require much more changes though, and considered to be overkill for now.
author Maxim Dounin <mdounin@mdounin.ru>
date Fri, 06 Apr 2012 23:46:09 +0000
parents d620f497c50f
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>


ngx_thread_volatile ngx_event_t  *ngx_posted_accept_events;
ngx_thread_volatile ngx_event_t  *ngx_posted_events;

#if (NGX_THREADS)
ngx_mutex_t                      *ngx_posted_events_mutex;
#endif


void
ngx_event_process_posted(ngx_cycle_t *cycle,
    ngx_thread_volatile ngx_event_t **posted)
{
    ngx_event_t  *ev;

    for ( ;; ) {

        ev = (ngx_event_t *) *posted;

        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                      "posted event %p", ev);

        if (ev == NULL) {
            return;
        }

        ngx_delete_posted_event(ev);

        ev->handler(ev);
    }
}


#if (NGX_THREADS) && !(NGX_WIN32)

void
ngx_wakeup_worker_thread(ngx_cycle_t *cycle)
{
    ngx_int_t     i;
#if 0
    ngx_uint_t    busy;
    ngx_event_t  *ev;

    busy = 1;

    if (ngx_mutex_lock(ngx_posted_events_mutex) == NGX_ERROR) {
        return;
    }

    for (ev = (ngx_event_t *) ngx_posted_events; ev; ev = ev->next) {
        if (*(ev->lock) == 0) {
            busy = 0;
            break;
        }
    }

    ngx_mutex_unlock(ngx_posted_events_mutex);

    if (busy) {
        return;
    }
#endif

    for (i = 0; i < ngx_threads_n; i++) {
        if (ngx_threads[i].state == NGX_THREAD_FREE) {
            ngx_cond_signal(ngx_threads[i].cv);
            return;
        }
    }
}


ngx_int_t
ngx_event_thread_process_posted(ngx_cycle_t *cycle)
{
    ngx_event_t  *ev;

    for ( ;; ) {

        ev = (ngx_event_t *) ngx_posted_events;

        for ( ;; ) {

            ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                          "posted event %p", ev);

            if (ev == NULL) {
                return NGX_OK;
            }

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

                ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                               "posted event %p is busy", ev);

                ev = ev->next;
                continue;
            }

            if (ev->lock != ev->own_lock) {
                if (*(ev->own_lock)) {
                    ngx_log_error(NGX_LOG_ALERT, cycle->log, 0,
                             "the own lock of the posted event %p is busy", ev);
                    ngx_unlock(ev->lock);
                    ev = ev->next;
                    continue;
                }
                *(ev->own_lock) = 1;
            }

            ngx_delete_posted_event(ev);

            ev->locked = 1;

            ev->ready |= ev->posted_ready;
            ev->timedout |= ev->posted_timedout;
            ev->pending_eof |= ev->posted_eof;
#if (NGX_HAVE_KQUEUE)
            ev->kq_errno |= ev->posted_errno;
#endif
            if (ev->posted_available) {
                ev->available = ev->posted_available;
            }

            ev->posted_ready = 0;
            ev->posted_timedout = 0;
            ev->posted_eof = 0;
#if (NGX_HAVE_KQUEUE)
            ev->posted_errno = 0;
#endif
            ev->posted_available = 0;

            ngx_mutex_unlock(ngx_posted_events_mutex);

            ev->handler(ev);

            ngx_mutex_lock(ngx_posted_events_mutex);

            if (ev->locked) {
                ngx_unlock(ev->lock);

                if (ev->lock != ev->own_lock) {
                    ngx_unlock(ev->own_lock);
                }
            }

            ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                           "posted event %p is done", ev);

            break;
        }
    }
}

#else

void
ngx_wakeup_worker_thread(ngx_cycle_t *cycle)
{
}

#endif