Mercurial > hg > nginx
diff src/event/ngx_event_busy_lock.c @ 276:a2d1ccc96111
nginx-0.0.2-2004-03-03-00:14:37 import
author | Igor Sysoev <igor@sysoev.ru> |
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date | Tue, 02 Mar 2004 21:14:37 +0000 |
parents | |
children | e91499541410 |
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new file mode 100644 --- /dev/null +++ b/src/event/ngx_event_busy_lock.c @@ -0,0 +1,345 @@ + +#include <ngx_config.h> +#include <ngx_core.h> +#include <ngx_event.h> + +/* + * TODO: eliminate mutex and use atomic_xchg(): + * ev->next = ev; ngx_atomic_xchg(ngx_posted_events, ev->next); + * in ngx_event_busy_unlock() and ngx_event_busy_lock_handler() + */ + + +static int ngx_event_busy_lock_look_cachable(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_BUSY: there are many the busy locks or many the waiting locks + * NGX_AGAIN: the all busy locks are held but we will wait the specified time + * NGX_ERROR: there was error while the mutex locking + */ + +ngx_int_t ngx_event_busy_lock(ngx_event_busy_lock_t *bl, + ngx_event_busy_lock_ctx_t *ctx) +{ + ngx_int_t rc; + +#if (NGX_THREADS) + if (ngx_mutex_lock(bl->mutex) == NGX_ERROR) { + return NGX_ERROR; + } +#endif + + 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->event_handler = ngx_event_busy_lock_handler; + + if (bl->events == NULL) { + bl->events = ctx; + } else { + bl->last->next = ctx; + } + bl->last = ctx; + + rc = NGX_AGAIN; + + } else { + rc = NGX_BUSY; + } + +#if (NGX_THREADS) + ngx_mutex_unlock(bl->mutex); +#endif + + return rc; +} + + +ngx_int_t ngx_event_busy_lock_cachable(ngx_event_busy_lock_t *bl, + ngx_event_busy_lock_ctx_t *ctx) +{ + ngx_int_t rc; + +#if (NGX_THREADS) + if (ngx_mutex_lock(bl->mutex) == NGX_ERROR) { + return NGX_ERROR; + } +#endif + + rc = ngx_event_busy_lock_look_cachable(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->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; + } + } + +#if (NGX_THREADS) + ngx_mutex_unlock(bl->mutex); +#endif + + return rc; +} + + +ngx_int_t 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; + +#if (NGX_THREADS) + if (ngx_mutex_lock(bl->mutex) == NGX_ERROR) { + return NGX_ERROR; + } +#endif + + if (bl->events) { + wakeup = bl->events; + bl->events = bl->events->next; + + } else { + wakeup = NULL; + bl->busy--; + } + + /* + * MP: + * nocachable (bl->md5 == NULL): ngx_shared_mutex_unlock(mutex, !wakeup) + * cachable (bl->md5): ??? + */ + + if (wakeup == NULL) { +#if (NGX_THREADS) + ngx_mutex_unlock(bl->mutex); +#endif + return NGX_OK; + } + + if (ctx->md5) { + for (wakeup = bl->events; wakeup; wakeup = wakeup->next) { + if (wakeup->md5 == NULL) { + continue; + } + + if (ngx_memcmp(ctx->md5, wakeup->md5, 16) != 0) { + continue; + } + + wakeup->handler = ngx_event_busy_lock_posted_handler; + wakeup->cache_updated = 1; + + ev = wakeup->event; + +#if (NGX_THREADS) + if (ngx_mutex_lock(ngx_posted_events_mutex) == NGX_ERROR) { + return NGX_ERROR; + } +#endif + + ev->next = (ngx_event_t *) ngx_posted_events; + ngx_posted_events = ev; + +#if (NGX_THREADS) + ngx_mutex_unlock(ngx_posted_events_mutex); +#endif + } + +#if (NGX_THREADS) + ngx_mutex_unlock(bl->mutex); +#endif + + } else { + bl->waiting--; + +#if (NGX_THREADS) + ngx_mutex_unlock(bl->mutex); +#endif + + wakeup->handler = ngx_event_busy_lock_posted_handler; + wakeup->locked = 1; + + ev = wakeup->event; + + if (ev->timer_set) { + ngx_del_timer(ev); + } + +#if (NGX_THREADS) + if (ngx_mutex_lock(ngx_posted_events_mutex) == NGX_ERROR) { + return NGX_ERROR; + } +#endif + + ev->next = (ngx_event_t *) ngx_posted_events; + ngx_posted_events = ev; + +#if (NGX_THREADS) + ngx_mutex_unlock(ngx_posted_events_mutex); +#endif + } + + return NGX_OK; +} + + +ngx_int_t 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; + +#if (NGX_THREADS) + if (ngx_mutex_lock(bl->mutex) == NGX_ERROR) { + return NGX_ERROR; + } +#endif + + 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; + } + } + +#if (NGX_THREADS) + ngx_mutex_unlock(bl->mutex); +#endif + + return NGX_OK; +} + + +static int ngx_event_busy_lock_look_cachable(ngx_event_busy_lock_t *bl, + ngx_event_busy_lock_ctx_t *ctx) +{ + ngx_int_t free; + ngx_uint_t i, bit, cachable, mask; + + bit = 0; + cachable = 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) { + return NGX_AGAIN; + } + cachable++; + + } else if (free == -1) { + free = i; + } + + if (cachable == bl->cachable) { + if (free == -1 && cachable < 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->cachable++; + bl->busy++; + + return NGX_OK; +} + + +static void ngx_event_busy_lock_handler(ngx_event_t *ev) +{ + ev->event_handler = ngx_event_busy_lock_posted_handler; + +#if (NGX_THREADS) + if (ngx_mutex_lock(ngx_posted_events_mutex) == NGX_ERROR) { + return; + } +#endif + + ev->next = (ngx_event_t *) ngx_posted_events; + ngx_posted_events = ev; + +#if (NGX_THREADS) + ngx_mutex_unlock(ngx_posted_events_mutex); +#endif +} + + +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); +}