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view src/core/ngx_open_file_cache.h @ 7281:bd6563e81cea

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Limit req: improved handling of negative times. Negative times can appear since workers only update time on an event loop iteration start. If a worker was blocked for a long time during an event loop iteration, it is possible that another worker already updated the time stored in the node. As such, time since last update of the node (ms) will be negative. Previous code used ngx_abs(ms) in the calculations. That is, negative times were effectively treated as positive ones. As a result, it was not possible to maintain high request rates, where the same node can be updated multiple times from during an event loop iteration. In particular, this affected setups with many SSL handshakes, see http://mailman.nginx.org/pipermail/nginx/2018-May/056291.html. Fix is to only update the last update time stored in the node if the new time is larger than previously stored one. If a future time is stored in the node, we preserve this time as is. To prevent breaking things on platforms without monotonic time available if system time is updated backwards, a safety limit of 60 seconds is used. If the time stored in the node is more than 60 seconds in the future, we assume that the time was changed backwards and update lr->last to the current time.
author Maxim Dounin <mdounin@mdounin.ru>
date Wed, 30 May 2018 15:40:34 +0300
parents 47ece8818978
children
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/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#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;

#if (NGX_HAVE_OPENAT)
    size_t                   disable_symlinks_from;
    unsigned                 disable_symlinks:2;
#endif

    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;

#if (NGX_HAVE_OPENAT)
    size_t                   disable_symlinks_from;
    unsigned                 disable_symlinks:2;
#endif

    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_ */