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view src/http/modules/ngx_http_ssi_filter_module.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 d620f497c50f
children 49e7db44b57c
line wrap: on
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/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_HTTP_SSI_FILTER_H_INCLUDED_
#define _NGX_HTTP_SSI_FILTER_H_INCLUDED_


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


#define NGX_HTTP_SSI_MAX_PARAMS       16

#define NGX_HTTP_SSI_COMMAND_LEN      32
#define NGX_HTTP_SSI_PARAM_LEN        32
#define NGX_HTTP_SSI_PARAMS_N         4


#define NGX_HTTP_SSI_COND_IF          1
#define NGX_HTTP_SSI_COND_ELSE        2


#define NGX_HTTP_SSI_NO_ENCODING      0
#define NGX_HTTP_SSI_URL_ENCODING     1
#define NGX_HTTP_SSI_ENTITY_ENCODING  2


typedef struct {
    ngx_hash_t                hash;
    ngx_hash_keys_arrays_t    commands;
} ngx_http_ssi_main_conf_t;


typedef struct {
    ngx_buf_t                *buf;

    u_char                   *pos;
    u_char                   *copy_start;
    u_char                   *copy_end;

    ngx_uint_t                key;
    ngx_str_t                 command;
    ngx_array_t               params;
    ngx_table_elt_t          *param;
    ngx_table_elt_t           params_array[NGX_HTTP_SSI_PARAMS_N];

    ngx_chain_t              *in;
    ngx_chain_t              *out;
    ngx_chain_t             **last_out;
    ngx_chain_t              *busy;
    ngx_chain_t              *free;

    ngx_uint_t                state;
    ngx_uint_t                saved_state;
    size_t                    saved;
    size_t                    looked;

    size_t                    value_len;

    ngx_list_t               *variables;
    ngx_array_t              *blocks;

#if (NGX_PCRE)
    ngx_uint_t                ncaptures;
    int                      *captures;
    u_char                   *captures_data;
#endif

    unsigned                  conditional:2;
    unsigned                  encoding:2;
    unsigned                  block:1;
    unsigned                  output:1;
    unsigned                  output_chosen:1;

    ngx_http_request_t       *wait;
    void                     *value_buf;
    ngx_str_t                 timefmt;
    ngx_str_t                 errmsg;
} ngx_http_ssi_ctx_t;


typedef ngx_int_t (*ngx_http_ssi_command_pt) (ngx_http_request_t *r,
    ngx_http_ssi_ctx_t *ctx, ngx_str_t **);


typedef struct {
    ngx_str_t                 name;
    ngx_uint_t                index;

    unsigned                  mandatory:1;
    unsigned                  multiple:1;
} ngx_http_ssi_param_t;


typedef struct {
    ngx_str_t                 name;
    ngx_http_ssi_command_pt   handler;
    ngx_http_ssi_param_t     *params;

    unsigned                  conditional:2;
    unsigned                  block:1;
    unsigned                  flush:1;
} ngx_http_ssi_command_t;


extern ngx_module_t  ngx_http_ssi_filter_module;


#endif /* _NGX_HTTP_SSI_FILTER_H_INCLUDED_ */