Merge of r4619: accept moderation on EMFILE/ENFILE. In case of EMFILE/ENFILE returned from accept() we disable accept events, and (in case of no accept mutex used) arm timer to re-enable them later. With accept mutex we just drop it, and rely on normal accept mutex handling to re-enable accept events once it's acquired again. As we now handle errors in question, logging level was changed to "crit" (instead of "alert" used for unknown errors). Note: the code might call ngx_enable_accept_events() multiple times if there are many listen sockets. The ngx_enable_accept_events() function was modified to check if connection is already active (via c->read->active) and skip it then, thus making multiple calls safe.

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


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


ngx_uint_t  ngx_pagesize;
ngx_uint_t  ngx_pagesize_shift;
ngx_uint_t  ngx_cacheline_size;


void *ngx_alloc(size_t size, ngx_log_t *log)
{
    void  *p;

    p = malloc(size);
    if (p == NULL) {
        ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
                      "malloc(%uz) failed", size);
    }

    ngx_log_debug2(NGX_LOG_DEBUG_ALLOC, log, 0, "malloc: %p:%uz", p, size);

    return p;
}


void *ngx_calloc(size_t size, ngx_log_t *log)
{
    void  *p;

    p = ngx_alloc(size, log);

    if (p) {
        ngx_memzero(p, size);
    }

    return p;
}