Mercurial > hg > nginx-quic
view src/http/ngx_http_write_filter_module.c @ 6750:cb330cd39030 stable-1.10
HTTP/2: implemented preread buffer for request body (closes #959).
Previously, the stream's window was kept zero in order to prevent a client
from sending the request body before it was requested (see 887cca40ba6a for
details). Until such initial window was acknowledged all requests with
data were rejected (see 0aa07850922f for details).
That approach revealed a number of problems:
1. Some clients (notably MS IE/Edge, Safari, iOS applications) show an error
or even crash if a stream is rejected;
2. This requires at least one RTT for every request with body before the
client receives window update and able to send data.
To overcome these problems the new directive "http2_body_preread_size" is
introduced. It sets the initial window and configures a special per stream
preread buffer that is used to save all incoming data before the body is
requested and processed.
If the directive's value is lower than the default initial window (65535),
as previously, all streams with data will be rejected until the new window
is acknowledged. Otherwise, no special processing is used and all requests
with data are welcome right from the connection start.
The default value is chosen to be 64k, which is bigger than the default
initial window. Setting it to zero is fully complaint to the previous
behavior.
author | Valentin Bartenev <vbart@nginx.com> |
---|---|
date | Tue, 24 May 2016 17:37:52 +0300 |
parents | f01ab2dbcfdc |
children | a7ff19afbb14 |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> static ngx_int_t ngx_http_write_filter_init(ngx_conf_t *cf); static ngx_http_module_t ngx_http_write_filter_module_ctx = { NULL, /* preconfiguration */ ngx_http_write_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_write_filter_module = { NGX_MODULE_V1, &ngx_http_write_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 }; ngx_int_t ngx_http_write_filter(ngx_http_request_t *r, ngx_chain_t *in) { off_t size, sent, nsent, limit; ngx_uint_t last, flush, sync; ngx_msec_t delay; ngx_chain_t *cl, *ln, **ll, *chain; ngx_connection_t *c; ngx_http_core_loc_conf_t *clcf; c = r->connection; if (c->error) { return NGX_ERROR; } size = 0; flush = 0; sync = 0; last = 0; ll = &r->out; /* find the size, the flush point and the last link of the saved chain */ for (cl = r->out; cl; cl = cl->next) { ll = &cl->next; ngx_log_debug7(NGX_LOG_DEBUG_EVENT, c->log, 0, "write old buf t:%d f:%d %p, pos %p, size: %z " "file: %O, size: %O", cl->buf->temporary, cl->buf->in_file, cl->buf->start, cl->buf->pos, cl->buf->last - cl->buf->pos, cl->buf->file_pos, cl->buf->file_last - cl->buf->file_pos); #if 1 if (ngx_buf_size(cl->buf) == 0 && !ngx_buf_special(cl->buf)) { ngx_log_error(NGX_LOG_ALERT, c->log, 0, "zero size buf in writer " "t:%d r:%d f:%d %p %p-%p %p %O-%O", cl->buf->temporary, cl->buf->recycled, cl->buf->in_file, cl->buf->start, cl->buf->pos, cl->buf->last, cl->buf->file, cl->buf->file_pos, cl->buf->file_last); ngx_debug_point(); return NGX_ERROR; } #endif size += ngx_buf_size(cl->buf); if (cl->buf->flush || cl->buf->recycled) { flush = 1; } if (cl->buf->sync) { sync = 1; } if (cl->buf->last_buf) { last = 1; } } /* add the new chain to the existent one */ for (ln = in; ln; ln = ln->next) { cl = ngx_alloc_chain_link(r->pool); if (cl == NULL) { return NGX_ERROR; } cl->buf = ln->buf; *ll = cl; ll = &cl->next; ngx_log_debug7(NGX_LOG_DEBUG_EVENT, c->log, 0, "write new buf t:%d f:%d %p, pos %p, size: %z " "file: %O, size: %O", cl->buf->temporary, cl->buf->in_file, cl->buf->start, cl->buf->pos, cl->buf->last - cl->buf->pos, cl->buf->file_pos, cl->buf->file_last - cl->buf->file_pos); #if 1 if (ngx_buf_size(cl->buf) == 0 && !ngx_buf_special(cl->buf)) { ngx_log_error(NGX_LOG_ALERT, c->log, 0, "zero size buf in writer " "t:%d r:%d f:%d %p %p-%p %p %O-%O", cl->buf->temporary, cl->buf->recycled, cl->buf->in_file, cl->buf->start, cl->buf->pos, cl->buf->last, cl->buf->file, cl->buf->file_pos, cl->buf->file_last); ngx_debug_point(); return NGX_ERROR; } #endif size += ngx_buf_size(cl->buf); if (cl->buf->flush || cl->buf->recycled) { flush = 1; } if (cl->buf->sync) { sync = 1; } if (cl->buf->last_buf) { last = 1; } } *ll = NULL; ngx_log_debug3(NGX_LOG_DEBUG_HTTP, c->log, 0, "http write filter: l:%ui f:%ui s:%O", last, flush, size); clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module); /* * avoid the output if there are no last buf, no flush point, * there are the incoming bufs and the size of all bufs * is smaller than "postpone_output" directive */ if (!last && !flush && in && size < (off_t) clcf->postpone_output) { return NGX_OK; } if (c->write->delayed) { c->buffered |= NGX_HTTP_WRITE_BUFFERED; return NGX_AGAIN; } if (size == 0 && !(c->buffered & NGX_LOWLEVEL_BUFFERED) && !(last && c->need_last_buf)) { if (last || flush || sync) { for (cl = r->out; cl; /* void */) { ln = cl; cl = cl->next; ngx_free_chain(r->pool, ln); } r->out = NULL; c->buffered &= ~NGX_HTTP_WRITE_BUFFERED; return NGX_OK; } ngx_log_error(NGX_LOG_ALERT, c->log, 0, "the http output chain is empty"); ngx_debug_point(); return NGX_ERROR; } if (r->limit_rate) { if (r->limit_rate_after == 0) { r->limit_rate_after = clcf->limit_rate_after; } limit = (off_t) r->limit_rate * (ngx_time() - r->start_sec + 1) - (c->sent - r->limit_rate_after); if (limit <= 0) { c->write->delayed = 1; delay = (ngx_msec_t) (- limit * 1000 / r->limit_rate + 1); ngx_add_timer(c->write, delay); c->buffered |= NGX_HTTP_WRITE_BUFFERED; return NGX_AGAIN; } if (clcf->sendfile_max_chunk && (off_t) clcf->sendfile_max_chunk < limit) { limit = clcf->sendfile_max_chunk; } } else { limit = clcf->sendfile_max_chunk; } sent = c->sent; ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0, "http write filter limit %O", limit); chain = c->send_chain(c, r->out, limit); ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0, "http write filter %p", chain); if (chain == NGX_CHAIN_ERROR) { c->error = 1; return NGX_ERROR; } if (r->limit_rate) { nsent = c->sent; if (r->limit_rate_after) { sent -= r->limit_rate_after; if (sent < 0) { sent = 0; } nsent -= r->limit_rate_after; if (nsent < 0) { nsent = 0; } } delay = (ngx_msec_t) ((nsent - sent) * 1000 / r->limit_rate); if (delay > 0) { limit = 0; c->write->delayed = 1; ngx_add_timer(c->write, delay); } } if (limit && c->write->ready && c->sent - sent >= limit - (off_t) (2 * ngx_pagesize)) { c->write->delayed = 1; ngx_add_timer(c->write, 1); } for (cl = r->out; cl && cl != chain; /* void */) { ln = cl; cl = cl->next; ngx_free_chain(r->pool, ln); } r->out = chain; if (chain) { c->buffered |= NGX_HTTP_WRITE_BUFFERED; return NGX_AGAIN; } c->buffered &= ~NGX_HTTP_WRITE_BUFFERED; if ((c->buffered & NGX_LOWLEVEL_BUFFERED) && r->postponed == NULL) { return NGX_AGAIN; } return NGX_OK; } static ngx_int_t ngx_http_write_filter_init(ngx_conf_t *cf) { ngx_http_top_body_filter = ngx_http_write_filter; return NGX_OK; }