view src/event/ngx_event_busy_lock.c @ 5036:6e374742043e stable-1.2

Merge of r4944: removed GLOB_NOSORT glob option. This will result in alphabetical sorting of included files if the "include" directive with wildcards is used. Note that the behaviour is now different from that on Windows, where alphabetical sorting is not guaranteed for FindFirsFile()/FindNextFile() (used to be alphabetical on NTFS, but not on FAT). Approved by Igor Sysoev, prodded by many.
author Maxim Dounin <mdounin@mdounin.ru>
date Sat, 09 Feb 2013 21:27:37 +0000
parents d620f497c50f
children
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>


static ngx_int_t ngx_event_busy_lock_look_cacheable(ngx_event_busy_lock_t *bl,
    ngx_event_busy_lock_ctx_t *ctx);
static void ngx_event_busy_lock_handler(ngx_event_t *ev);
static void ngx_event_busy_lock_posted_handler(ngx_event_t *ev);


/*
 * NGX_OK:     the busy lock is held
 * NGX_AGAIN:  the all busy locks are held but we will wait the specified time
 * NGX_BUSY:   ctx->timer == 0: there are many the busy locks
 *             ctx->timer != 0: there are many the waiting locks
 */

ngx_int_t
ngx_event_busy_lock(ngx_event_busy_lock_t *bl, ngx_event_busy_lock_ctx_t *ctx)
{
    ngx_int_t  rc;

    ngx_mutex_lock(bl->mutex);

    ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ctx->event->log, 0,
                   "event busy lock: b:%d mb:%d",
                   bl->busy, bl->max_busy);

    if (bl->busy < bl->max_busy) {
        bl->busy++;

        rc = NGX_OK;

    } else if (ctx->timer && bl->waiting < bl->max_waiting) {
        bl->waiting++;
        ngx_add_timer(ctx->event, ctx->timer);
        ctx->event->handler = ngx_event_busy_lock_handler;

        if (bl->events) {
            bl->last->next = ctx;

        } else {
            bl->events = ctx;
        }

        bl->last = ctx;

        rc = NGX_AGAIN;

    } else {
        rc = NGX_BUSY;
    }

    ngx_mutex_unlock(bl->mutex);

    return rc;
}


ngx_int_t
ngx_event_busy_lock_cacheable(ngx_event_busy_lock_t *bl,
    ngx_event_busy_lock_ctx_t *ctx)
{
    ngx_int_t  rc;

    ngx_mutex_lock(bl->mutex);

    rc = ngx_event_busy_lock_look_cacheable(bl, ctx);

    ngx_log_debug3(NGX_LOG_DEBUG_EVENT, ctx->event->log, 0,
                   "event busy lock: %d w:%d mw:%d",
                   rc, bl->waiting, bl->max_waiting);

    /*
     * NGX_OK:     no the same request, there is free slot and we locked it
     * NGX_BUSY:   no the same request and there is no free slot
     * NGX_AGAIN:  the same request is processing
     */

    if (rc == NGX_AGAIN) {

        if (ctx->timer && bl->waiting < bl->max_waiting) {
            bl->waiting++;
            ngx_add_timer(ctx->event, ctx->timer);
            ctx->event->handler = ngx_event_busy_lock_handler;

            if (bl->events == NULL) {
                bl->events = ctx;
            } else {
                bl->last->next = ctx;
            }
            bl->last = ctx;

        } else {
            rc = NGX_BUSY;
        }
    }

    ngx_mutex_unlock(bl->mutex);

    return rc;
}


void
ngx_event_busy_unlock(ngx_event_busy_lock_t *bl,
    ngx_event_busy_lock_ctx_t *ctx)
{
    ngx_event_t                *ev;
    ngx_event_busy_lock_ctx_t  *wakeup;

    ngx_mutex_lock(bl->mutex);

    if (bl->events) {
        wakeup = bl->events;
        bl->events = bl->events->next;

    } else {
        wakeup = NULL;
        bl->busy--;
    }

    /*
     * MP: all ctx's and their queue must be in shared memory,
     *     each ctx has pid to wake up
     */

    if (wakeup == NULL) {
        ngx_mutex_unlock(bl->mutex);
        return;
    }

    if (ctx->md5) {
        for (wakeup = bl->events; wakeup; wakeup = wakeup->next) {
            if (wakeup->md5 == NULL || wakeup->slot != ctx->slot) {
                continue;
            }

            wakeup->handler = ngx_event_busy_lock_posted_handler;
            wakeup->cache_updated = 1;

            ev = wakeup->event;

            ngx_post_event(ev, &ngx_posted_events);
        }

        ngx_mutex_unlock(bl->mutex);

    } else {
        bl->waiting--;

        ngx_mutex_unlock(bl->mutex);

        wakeup->handler = ngx_event_busy_lock_posted_handler;
        wakeup->locked = 1;

        ev = wakeup->event;

        if (ev->timer_set) {
            ngx_del_timer(ev);
        }

        ngx_post_event(ev, &ngx_posted_events);
    }
}


void
ngx_event_busy_lock_cancel(ngx_event_busy_lock_t *bl,
    ngx_event_busy_lock_ctx_t *ctx)
{
    ngx_event_busy_lock_ctx_t  *c, *p;

    ngx_mutex_lock(bl->mutex);

    bl->waiting--;

    if (ctx == bl->events) {
        bl->events = ctx->next;

    } else {
        p = bl->events;
        for (c = bl->events->next; c; c = c->next) {
            if (c == ctx) {
                p->next = ctx->next;
                break;
            }
            p = c;
        }
    }

    ngx_mutex_unlock(bl->mutex);
}


static ngx_int_t
ngx_event_busy_lock_look_cacheable(ngx_event_busy_lock_t *bl,
    ngx_event_busy_lock_ctx_t *ctx)
{
    ngx_int_t    free;
    ngx_uint_t   i, bit, cacheable, mask;

    bit = 0;
    cacheable = 0;
    free = -1;

#if (NGX_SUPPRESS_WARN)
    mask = 0;
#endif

    for (i = 0; i < bl->max_busy; i++) {

        if ((bit & 7) == 0) {
            mask = bl->md5_mask[i / 8];
        }

        if (mask & 1) {
            if (ngx_memcmp(&bl->md5[i * 16], ctx->md5, 16) == 0) {
                ctx->waiting = 1;
                ctx->slot = i;
                return NGX_AGAIN;
            }
            cacheable++;

        } else if (free == -1) {
            free = i;
        }

        if (cacheable == bl->cacheable) {
            if (free == -1 && cacheable < bl->max_busy) {
                free = i + 1;
            }

            break;
        }

        mask >>= 1;
        bit++;
    }

    if (free == -1) {
        return NGX_BUSY;
    }

#if 0
    if (bl->busy == bl->max_busy) {
        return NGX_BUSY;
    }
#endif

    ngx_memcpy(&bl->md5[free * 16], ctx->md5, 16);
    bl->md5_mask[free / 8] |= 1 << (free & 7);
    ctx->slot = free;

    bl->cacheable++;
    bl->busy++;

    return NGX_OK;
}


static void
ngx_event_busy_lock_handler(ngx_event_t *ev)
{
    ev->handler = ngx_event_busy_lock_posted_handler;

    ngx_post_event(ev, &ngx_posted_events);
}


static void
ngx_event_busy_lock_posted_handler(ngx_event_t *ev)
{
    ngx_event_busy_lock_ctx_t  *ctx;

    ctx = ev->data;
    ctx->handler(ev);
}