Mercurial > hg > nginx
view src/http/modules/ngx_http_sub_filter_module.c @ 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 | 08d7165b6be1 |
children | d620f497c50f |
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/* * Copyright (C) Igor Sysoev */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> typedef struct { ngx_str_t match; ngx_http_complex_value_t value; ngx_hash_t types; ngx_flag_t once; ngx_array_t *types_keys; } ngx_http_sub_loc_conf_t; typedef enum { sub_start_state = 0, sub_match_state, } ngx_http_sub_state_e; typedef struct { ngx_str_t match; ngx_str_t saved; ngx_str_t looked; ngx_uint_t once; /* unsigned once:1 */ ngx_buf_t *buf; u_char *pos; u_char *copy_start; u_char *copy_end; ngx_chain_t *in; ngx_chain_t *out; ngx_chain_t **last_out; ngx_chain_t *busy; ngx_chain_t *free; ngx_str_t sub; ngx_uint_t state; } ngx_http_sub_ctx_t; static ngx_int_t ngx_http_sub_output(ngx_http_request_t *r, ngx_http_sub_ctx_t *ctx); static ngx_int_t ngx_http_sub_parse(ngx_http_request_t *r, ngx_http_sub_ctx_t *ctx); static char * ngx_http_sub_filter(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static void *ngx_http_sub_create_conf(ngx_conf_t *cf); static char *ngx_http_sub_merge_conf(ngx_conf_t *cf, void *parent, void *child); static ngx_int_t ngx_http_sub_filter_init(ngx_conf_t *cf); static ngx_command_t ngx_http_sub_filter_commands[] = { { ngx_string("sub_filter"), NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE2, ngx_http_sub_filter, NGX_HTTP_LOC_CONF_OFFSET, 0, NULL }, { ngx_string("sub_filter_types"), NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_1MORE, ngx_http_types_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_sub_loc_conf_t, types_keys), &ngx_http_html_default_types[0] }, { ngx_string("sub_filter_once"), NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG, ngx_conf_set_flag_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_sub_loc_conf_t, once), NULL }, ngx_null_command }; static ngx_http_module_t ngx_http_sub_filter_module_ctx = { NULL, /* preconfiguration */ ngx_http_sub_filter_init, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ ngx_http_sub_create_conf, /* create location configuration */ ngx_http_sub_merge_conf /* merge location configuration */ }; ngx_module_t ngx_http_sub_filter_module = { NGX_MODULE_V1, &ngx_http_sub_filter_module_ctx, /* module context */ ngx_http_sub_filter_commands, /* module directives */ NGX_HTTP_MODULE, /* module type */ NULL, /* init master */ NULL, /* init module */ NULL, /* init process */ NULL, /* init thread */ NULL, /* exit thread */ NULL, /* exit process */ NULL, /* exit master */ NGX_MODULE_V1_PADDING }; static ngx_http_output_header_filter_pt ngx_http_next_header_filter; static ngx_http_output_body_filter_pt ngx_http_next_body_filter; static ngx_int_t ngx_http_sub_header_filter(ngx_http_request_t *r) { ngx_http_sub_ctx_t *ctx; ngx_http_sub_loc_conf_t *slcf; slcf = ngx_http_get_module_loc_conf(r, ngx_http_sub_filter_module); if (slcf->match.len == 0 || r->headers_out.content_length_n == 0 || ngx_http_test_content_type(r, &slcf->types) == NULL) { return ngx_http_next_header_filter(r); } ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_sub_ctx_t)); if (ctx == NULL) { return NGX_ERROR; } ctx->saved.data = ngx_pnalloc(r->pool, slcf->match.len); if (ctx->saved.data == NULL) { return NGX_ERROR; } ctx->looked.data = ngx_pnalloc(r->pool, slcf->match.len); if (ctx->looked.data == NULL) { return NGX_ERROR; } ngx_http_set_ctx(r, ctx, ngx_http_sub_filter_module); ctx->match = slcf->match; ctx->last_out = &ctx->out; r->filter_need_in_memory = 1; if (r == r->main) { ngx_http_clear_content_length(r); ngx_http_clear_last_modified(r); } return ngx_http_next_header_filter(r); } static ngx_int_t ngx_http_sub_body_filter(ngx_http_request_t *r, ngx_chain_t *in) { ngx_int_t rc; ngx_buf_t *b; ngx_chain_t *cl; ngx_http_sub_ctx_t *ctx; ngx_http_sub_loc_conf_t *slcf; ctx = ngx_http_get_module_ctx(r, ngx_http_sub_filter_module); if (ctx == NULL) { return ngx_http_next_body_filter(r, in); } if ((in == NULL && ctx->buf == NULL && ctx->in == NULL && ctx->busy == NULL)) { return ngx_http_next_body_filter(r, in); } if (ctx->once && (ctx->buf == NULL || ctx->in == NULL)) { if (ctx->busy) { if (ngx_http_sub_output(r, ctx) == NGX_ERROR) { return NGX_ERROR; } } return ngx_http_next_body_filter(r, in); } /* add the incoming chain to the chain ctx->in */ if (in) { if (ngx_chain_add_copy(r->pool, &ctx->in, in) != NGX_OK) { return NGX_ERROR; } } ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http sub filter \"%V\"", &r->uri); while (ctx->in || ctx->buf) { if (ctx->buf == NULL) { ctx->buf = ctx->in->buf; ctx->in = ctx->in->next; ctx->pos = ctx->buf->pos; } if (ctx->state == sub_start_state) { ctx->copy_start = ctx->pos; ctx->copy_end = ctx->pos; } b = NULL; while (ctx->pos < ctx->buf->last) { ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "saved: \"%V\" state: %d", &ctx->saved, ctx->state); rc = ngx_http_sub_parse(r, ctx); ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "parse: %d, looked: \"%V\" %p-%p", rc, &ctx->looked, ctx->copy_start, ctx->copy_end); if (rc == NGX_ERROR) { return rc; } if (ctx->copy_start != ctx->copy_end) { ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "saved: \"%V\"", &ctx->saved); if (ctx->saved.len) { if (ctx->free) { cl = ctx->free; ctx->free = ctx->free->next; b = cl->buf; ngx_memzero(b, sizeof(ngx_buf_t)); } else { b = ngx_calloc_buf(r->pool); if (b == NULL) { return NGX_ERROR; } cl = ngx_alloc_chain_link(r->pool); if (cl == NULL) { return NGX_ERROR; } cl->buf = b; } b->pos = ngx_pnalloc(r->pool, ctx->saved.len); if (b->pos == NULL) { return NGX_ERROR; } ngx_memcpy(b->pos, ctx->saved.data, ctx->saved.len); b->last = b->pos + ctx->saved.len; b->memory = 1; *ctx->last_out = cl; ctx->last_out = &cl->next; ctx->saved.len = 0; } if (ctx->free) { cl = ctx->free; ctx->free = ctx->free->next; b = cl->buf; } else { b = ngx_alloc_buf(r->pool); if (b == NULL) { return NGX_ERROR; } cl = ngx_alloc_chain_link(r->pool); if (cl == NULL) { return NGX_ERROR; } cl->buf = b; } ngx_memcpy(b, ctx->buf, sizeof(ngx_buf_t)); b->pos = ctx->copy_start; b->last = ctx->copy_end; b->shadow = NULL; b->last_buf = 0; b->recycled = 0; if (b->in_file) { b->file_last = b->file_pos + (b->last - ctx->buf->pos); b->file_pos += b->pos - ctx->buf->pos; } cl->next = NULL; *ctx->last_out = cl; ctx->last_out = &cl->next; } if (ctx->state == sub_start_state) { ctx->copy_start = ctx->pos; ctx->copy_end = ctx->pos; } else { ctx->copy_start = NULL; ctx->copy_end = NULL; } if (rc == NGX_AGAIN) { continue; } /* rc == NGX_OK */ b = ngx_calloc_buf(r->pool); if (b == NULL) { return NGX_ERROR; } cl = ngx_alloc_chain_link(r->pool); if (cl == NULL) { return NGX_ERROR; } slcf = ngx_http_get_module_loc_conf(r, ngx_http_sub_filter_module); if (ctx->sub.data == NULL) { if (ngx_http_complex_value(r, &slcf->value, &ctx->sub) != NGX_OK) { return NGX_ERROR; } } if (ctx->sub.len) { b->memory = 1; b->pos = ctx->sub.data; b->last = ctx->sub.data + ctx->sub.len; } else { b->sync = 1; } cl->buf = b; cl->next = NULL; *ctx->last_out = cl; ctx->last_out = &cl->next; ctx->once = slcf->once; continue; } if (ctx->buf->last_buf || ngx_buf_in_memory(ctx->buf)) { if (b == NULL) { if (ctx->free) { cl = ctx->free; ctx->free = ctx->free->next; b = cl->buf; ngx_memzero(b, sizeof(ngx_buf_t)); } else { b = ngx_calloc_buf(r->pool); if (b == NULL) { return NGX_ERROR; } cl = ngx_alloc_chain_link(r->pool); if (cl == NULL) { return NGX_ERROR; } cl->buf = b; } b->sync = 1; cl->next = NULL; *ctx->last_out = cl; ctx->last_out = &cl->next; } b->last_buf = ctx->buf->last_buf; b->shadow = ctx->buf; b->recycled = ctx->buf->recycled; } ctx->buf = NULL; ctx->saved.len = ctx->looked.len; ngx_memcpy(ctx->saved.data, ctx->looked.data, ctx->looked.len); } if (ctx->out == NULL && ctx->busy == NULL) { return NGX_OK; } return ngx_http_sub_output(r, ctx); } static ngx_int_t ngx_http_sub_output(ngx_http_request_t *r, ngx_http_sub_ctx_t *ctx) { ngx_int_t rc; ngx_buf_t *b; ngx_chain_t *cl; #if 1 b = NULL; for (cl = ctx->out; cl; cl = cl->next) { ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "sub out: %p %p", cl->buf, cl->buf->pos); if (cl->buf == b) { ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0, "the same buf was used in sub"); ngx_debug_point(); return NGX_ERROR; } b = cl->buf; } #endif rc = ngx_http_next_body_filter(r, ctx->out); if (ctx->busy == NULL) { ctx->busy = ctx->out; } else { for (cl = ctx->busy; cl->next; cl = cl->next) { /* void */ } cl->next = ctx->out; } ctx->out = NULL; ctx->last_out = &ctx->out; while (ctx->busy) { cl = ctx->busy; b = cl->buf; if (ngx_buf_size(b) != 0) { break; } if (b->shadow) { b->shadow->pos = b->shadow->last; } ctx->busy = cl->next; if (ngx_buf_in_memory(b) || b->in_file) { /* add data bufs only to the free buf chain */ cl->next = ctx->free; ctx->free = cl; } } if (ctx->in || ctx->buf) { r->buffered |= NGX_HTTP_SUB_BUFFERED; } else { r->buffered &= ~NGX_HTTP_SUB_BUFFERED; } return rc; } static ngx_int_t ngx_http_sub_parse(ngx_http_request_t *r, ngx_http_sub_ctx_t *ctx) { u_char *p, *last, *copy_end, ch, match; size_t looked; ngx_http_sub_state_e state; if (ctx->once) { ctx->copy_start = ctx->pos; ctx->copy_end = ctx->buf->last; ctx->pos = ctx->buf->last; ctx->looked.len = 0; ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "once"); return NGX_AGAIN; } state = ctx->state; looked = ctx->looked.len; last = ctx->buf->last; copy_end = ctx->copy_end; for (p = ctx->pos; p < last; p++) { ch = *p; ch = ngx_tolower(ch); if (state == sub_start_state) { /* the tight loop */ match = ctx->match.data[0]; for ( ;; ) { if (ch == match) { copy_end = p; ctx->looked.data[0] = *p; looked = 1; state = sub_match_state; goto match_started; } if (++p == last) { break; } ch = *p; ch = ngx_tolower(ch); } ctx->state = state; ctx->pos = p; ctx->looked.len = looked; ctx->copy_end = p; if (ctx->copy_start == NULL) { ctx->copy_start = ctx->buf->pos; } return NGX_AGAIN; match_started: continue; } /* state == sub_match_state */ if (ch == ctx->match.data[looked]) { ctx->looked.data[looked] = *p; looked++; if (looked == ctx->match.len) { if ((size_t) (p - ctx->pos) < looked) { ctx->saved.len = 0; } ctx->state = sub_start_state; ctx->pos = p + 1; ctx->looked.len = 0; ctx->copy_end = copy_end; if (ctx->copy_start == NULL && copy_end) { ctx->copy_start = ctx->buf->pos; } return NGX_OK; } } else if (ch == ctx->match.data[0]) { copy_end = p; ctx->looked.data[0] = *p; looked = 1; } else { copy_end = p; looked = 0; state = sub_start_state; } } ctx->state = state; ctx->pos = p; ctx->looked.len = looked; ctx->copy_end = (state == sub_start_state) ? p : copy_end; if (ctx->copy_start == NULL && ctx->copy_end) { ctx->copy_start = ctx->buf->pos; } return NGX_AGAIN; } static char * ngx_http_sub_filter(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_http_sub_loc_conf_t *slcf = conf; ngx_str_t *value; ngx_http_compile_complex_value_t ccv; if (slcf->match.len) { return "is duplicate"; } value = cf->args->elts; ngx_strlow(value[1].data, value[1].data, value[1].len); slcf->match = value[1]; ngx_memzero(&ccv, sizeof(ngx_http_compile_complex_value_t)); ccv.cf = cf; ccv.value = &value[2]; ccv.complex_value = &slcf->value; if (ngx_http_compile_complex_value(&ccv) != NGX_OK) { return NGX_CONF_ERROR; } return NGX_CONF_OK; } static void * ngx_http_sub_create_conf(ngx_conf_t *cf) { ngx_http_sub_loc_conf_t *slcf; slcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_sub_loc_conf_t)); if (slcf == NULL) { return NULL; } /* * set by ngx_pcalloc(): * * conf->match = { 0, NULL }; * conf->sub = { 0, NULL }; * conf->sub_lengths = NULL; * conf->sub_values = NULL; * conf->types = { NULL }; * conf->types_keys = NULL; */ slcf->once = NGX_CONF_UNSET; return slcf; } static char * ngx_http_sub_merge_conf(ngx_conf_t *cf, void *parent, void *child) { ngx_http_sub_loc_conf_t *prev = parent; ngx_http_sub_loc_conf_t *conf = child; ngx_conf_merge_value(conf->once, prev->once, 1); ngx_conf_merge_str_value(conf->match, prev->match, ""); if (conf->value.value.len == 0) { conf->value = prev->value; } if (ngx_http_merge_types(cf, &conf->types_keys, &conf->types, &prev->types_keys, &prev->types, ngx_http_html_default_types) != NGX_OK) { return NGX_CONF_ERROR; } return NGX_CONF_OK; } static ngx_int_t ngx_http_sub_filter_init(ngx_conf_t *cf) { ngx_http_next_header_filter = ngx_http_top_header_filter; ngx_http_top_header_filter = ngx_http_sub_header_filter; ngx_http_next_body_filter = ngx_http_top_body_filter; ngx_http_top_body_filter = ngx_http_sub_body_filter; return NGX_OK; }