Mercurial > hg > nginx
view src/core/ngx_array.h @ 6080:4296627f385a stable-1.6
Core: fixed a race resulting in extra sem_post()'s.
The mtx->wait counter was not decremented if we were able to obtain the lock
right after incrementing it. This resulted in unneeded sem_post() calls,
eventually leading to EOVERFLOW errors being logged, "sem_post() failed
while wake shmtx (75: Value too large for defined data type)".
To close the race, mtx->wait is now decremented if we obtain the lock right
after incrementing it in ngx_shmtx_lock(). The result can become -1 if a
concurrent ngx_shmtx_unlock() decrements mtx->wait before the added code does.
However, that only leads to one extra iteration in the next call of
ngx_shmtx_lock().
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Wed, 04 Feb 2015 16:22:43 +0300 |
parents | 65b895cd0dfa |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #ifndef _NGX_ARRAY_H_INCLUDED_ #define _NGX_ARRAY_H_INCLUDED_ #include <ngx_config.h> #include <ngx_core.h> typedef struct { void *elts; ngx_uint_t nelts; size_t size; ngx_uint_t nalloc; ngx_pool_t *pool; } ngx_array_t; ngx_array_t *ngx_array_create(ngx_pool_t *p, ngx_uint_t n, size_t size); void ngx_array_destroy(ngx_array_t *a); void *ngx_array_push(ngx_array_t *a); void *ngx_array_push_n(ngx_array_t *a, ngx_uint_t n); static ngx_inline ngx_int_t ngx_array_init(ngx_array_t *array, ngx_pool_t *pool, ngx_uint_t n, size_t size) { /* * set "array->nelts" before "array->elts", otherwise MSVC thinks * that "array->nelts" may be used without having been initialized */ array->nelts = 0; array->size = size; array->nalloc = n; array->pool = pool; array->elts = ngx_palloc(pool, n * size); if (array->elts == NULL) { return NGX_ERROR; } return NGX_OK; } #endif /* _NGX_ARRAY_H_INCLUDED_ */