Mercurial > hg > nginx-quic
view src/http/modules/ngx_http_chunked_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 | 4b0b0e77dc3d |
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_chain_t *free; ngx_chain_t *busy; } ngx_http_chunked_filter_ctx_t; static ngx_int_t ngx_http_chunked_filter_init(ngx_conf_t *cf); static ngx_http_module_t ngx_http_chunked_filter_module_ctx = { NULL, /* preconfiguration */ ngx_http_chunked_filter_init, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ NULL, /* create location configuration */ NULL /* merge location configuration */ }; ngx_module_t ngx_http_chunked_filter_module = { NGX_MODULE_V1, &ngx_http_chunked_filter_module_ctx, /* module context */ NULL, /* 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_chunked_header_filter(ngx_http_request_t *r) { ngx_http_core_loc_conf_t *clcf; ngx_http_chunked_filter_ctx_t *ctx; if (r->headers_out.status == NGX_HTTP_NOT_MODIFIED || r->headers_out.status == NGX_HTTP_NO_CONTENT || r != r->main || (r->method & NGX_HTTP_HEAD)) { return ngx_http_next_header_filter(r); } if (r->headers_out.content_length_n == -1) { if (r->http_version < NGX_HTTP_VERSION_11) { r->keepalive = 0; } else { clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module); if (clcf->chunked_transfer_encoding) { r->chunked = 1; ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_chunked_filter_ctx_t)); if (ctx == NULL) { return NGX_ERROR; } ngx_http_set_ctx(r, ctx, ngx_http_chunked_filter_module); } else { r->keepalive = 0; } } } return ngx_http_next_header_filter(r); } static ngx_int_t ngx_http_chunked_body_filter(ngx_http_request_t *r, ngx_chain_t *in) { u_char *chunk; off_t size; ngx_int_t rc; ngx_buf_t *b; ngx_chain_t *out, *cl, *tl, **ll; ngx_http_chunked_filter_ctx_t *ctx; if (in == NULL || !r->chunked || r->header_only) { return ngx_http_next_body_filter(r, in); } ctx = ngx_http_get_module_ctx(r, ngx_http_chunked_filter_module); out = NULL; ll = &out; size = 0; cl = in; for ( ;; ) { ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http chunk: %d", ngx_buf_size(cl->buf)); size += ngx_buf_size(cl->buf); if (cl->buf->flush || cl->buf->sync || ngx_buf_in_memory(cl->buf) || cl->buf->in_file) { tl = ngx_alloc_chain_link(r->pool); if (tl == NULL) { return NGX_ERROR; } tl->buf = cl->buf; *ll = tl; ll = &tl->next; } if (cl->next == NULL) { break; } cl = cl->next; } if (size) { tl = ngx_chain_get_free_buf(r->pool, &ctx->free); if (tl == NULL) { return NGX_ERROR; } b = tl->buf; chunk = b->start; if (chunk == NULL) { /* the "0000000000000000" is 64-bit hexadecimal string */ chunk = ngx_palloc(r->pool, sizeof("0000000000000000" CRLF) - 1); if (chunk == NULL) { return NGX_ERROR; } b->start = chunk; b->end = chunk + sizeof("0000000000000000" CRLF) - 1; } b->tag = (ngx_buf_tag_t) &ngx_http_chunked_filter_module; b->memory = 0; b->temporary = 1; b->pos = chunk; b->last = ngx_sprintf(chunk, "%xO" CRLF, size); tl->next = out; out = tl; } if (cl->buf->last_buf) { tl = ngx_chain_get_free_buf(r->pool, &ctx->free); if (tl == NULL) { return NGX_ERROR; } b = tl->buf; b->tag = (ngx_buf_tag_t) &ngx_http_chunked_filter_module; b->temporary = 0; b->memory = 1; b->last_buf = 1; b->pos = (u_char *) CRLF "0" CRLF CRLF; b->last = b->pos + 7; cl->buf->last_buf = 0; *ll = tl; if (size == 0) { b->pos += 2; } } else if (size > 0) { tl = ngx_chain_get_free_buf(r->pool, &ctx->free); if (tl == NULL) { return NGX_ERROR; } b = tl->buf; b->tag = (ngx_buf_tag_t) &ngx_http_chunked_filter_module; b->temporary = 0; b->memory = 1; b->pos = (u_char *) CRLF; b->last = b->pos + 2; *ll = tl; } else { *ll = NULL; } rc = ngx_http_next_body_filter(r, out); ngx_chain_update_chains(r->pool, &ctx->free, &ctx->busy, &out, (ngx_buf_tag_t) &ngx_http_chunked_filter_module); return rc; } static ngx_int_t ngx_http_chunked_filter_init(ngx_conf_t *cf) { ngx_http_next_header_filter = ngx_http_top_header_filter; ngx_http_top_header_filter = ngx_http_chunked_header_filter; ngx_http_next_body_filter = ngx_http_top_body_filter; ngx_http_top_body_filter = ngx_http_chunked_body_filter; return NGX_OK; }