view src/core/ngx_open_file_cache.h @ 4207:4fc91bae6f83

Better recheck of dead upstream servers. Previously nginx used to mark backend again as live as soon as fail_timeout passes (10s by default) since last failure. On the other hand, detecting dead backend takes up to 60s (proxy_connect_timeout) in typical situation "backend is down and doesn't respond to any packets". This resulted in suboptimal behaviour in the above situation (up to 23% of requests were directed to dead backend with default settings). More detailed description of the problem may be found here (in Russian): http://mailman.nginx.org/pipermail/nginx-ru/2011-August/042172.html Fix is to only allow one request after fail_timeout passes, and mark backend as "live" only if this request succeeds. Note that with new code backend will not be marked "live" unless "check" request is completed, and this may take a while in some specific workloads (e.g. streaming). This is believed to be acceptable.
author Maxim Dounin <mdounin@mdounin.ru>
date Wed, 12 Oct 2011 14:22:48 +0000
parents e7cd13b7f759
children d620f497c50f
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/*
 * Copyright (C) Igor Sysoev
 */


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


#ifndef _NGX_OPEN_FILE_CACHE_H_INCLUDED_
#define _NGX_OPEN_FILE_CACHE_H_INCLUDED_


#define NGX_OPEN_FILE_DIRECTIO_OFF  NGX_MAX_OFF_T_VALUE


typedef struct {
    ngx_fd_t                 fd;
    ngx_file_uniq_t          uniq;
    time_t                   mtime;
    off_t                    size;
    off_t                    fs_size;
    off_t                    directio;
    size_t                   read_ahead;

    ngx_err_t                err;
    char                    *failed;

    time_t                   valid;

    ngx_uint_t               min_uses;

    unsigned                 test_dir:1;
    unsigned                 test_only:1;
    unsigned                 log:1;
    unsigned                 errors:1;
    unsigned                 events:1;

    unsigned                 is_dir:1;
    unsigned                 is_file:1;
    unsigned                 is_link:1;
    unsigned                 is_exec:1;
    unsigned                 is_directio:1;
} ngx_open_file_info_t;


typedef struct ngx_cached_open_file_s  ngx_cached_open_file_t;

struct ngx_cached_open_file_s {
    ngx_rbtree_node_t        node;
    ngx_queue_t              queue;

    u_char                  *name;
    time_t                   created;
    time_t                   accessed;

    ngx_fd_t                 fd;
    ngx_file_uniq_t          uniq;
    time_t                   mtime;
    off_t                    size;
    ngx_err_t                err;

    uint32_t                 uses;

    unsigned                 count:24;
    unsigned                 close:1;
    unsigned                 use_event:1;

    unsigned                 is_dir:1;
    unsigned                 is_file:1;
    unsigned                 is_link:1;
    unsigned                 is_exec:1;
    unsigned                 is_directio:1;

    ngx_event_t             *event;
};


typedef struct {
    ngx_rbtree_t             rbtree;
    ngx_rbtree_node_t        sentinel;
    ngx_queue_t              expire_queue;

    ngx_uint_t               current;
    ngx_uint_t               max;
    time_t                   inactive;
} ngx_open_file_cache_t;


typedef struct {
    ngx_open_file_cache_t   *cache;
    ngx_cached_open_file_t  *file;
    ngx_uint_t               min_uses;
    ngx_log_t               *log;
} ngx_open_file_cache_cleanup_t;


typedef struct {

    /* ngx_connection_t stub to allow use c->fd as event ident */
    void                    *data;
    ngx_event_t             *read;
    ngx_event_t             *write;
    ngx_fd_t                 fd;

    ngx_cached_open_file_t  *file;
    ngx_open_file_cache_t   *cache;
} ngx_open_file_cache_event_t;


ngx_open_file_cache_t *ngx_open_file_cache_init(ngx_pool_t *pool,
    ngx_uint_t max, time_t inactive);
ngx_int_t ngx_open_cached_file(ngx_open_file_cache_t *cache, ngx_str_t *name,
    ngx_open_file_info_t *of, ngx_pool_t *pool);


#endif /* _NGX_OPEN_FILE_CACHE_H_INCLUDED_ */