Mercurial > hg > nginx-quic
view src/os/win32/ngx_wsarecv_chain.c @ 8759:56dec0d4e5b1 quic
QUIC: avoid excessive buffer allocations in stream output.
Previously, when a few bytes were send to a QUIC stream by the application, a
4K buffer was allocated for these bytes. Then a STREAM frame was created and
that entire buffer was used as data for that frame. The frame with the buffer
were in use up until the frame was acked by client. Meanwhile, when more
bytes were send to the stream, more buffers were allocated and assigned as
data to newer STREAM frames. In this scenario most buffer memory is unused.
Now the unused part of the stream output buffer is available for further
stream output while earlier parts of the buffer are waiting to be acked.
This is achieved by splitting the output buffer.
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Fri, 24 Dec 2021 18:13:51 +0300 |
parents | ecf2a9002b37 |
children | 56819a9491fe |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> #define NGX_WSABUFS 64 ssize_t ngx_wsarecv_chain(ngx_connection_t *c, ngx_chain_t *chain, off_t limit) { int rc; u_char *prev; u_long bytes, flags; size_t n, size; ngx_err_t err; ngx_array_t vec; ngx_event_t *rev; LPWSABUF wsabuf; WSABUF wsabufs[NGX_WSABUFS]; prev = NULL; wsabuf = NULL; flags = 0; size = 0; bytes = 0; vec.elts = wsabufs; vec.nelts = 0; vec.size = sizeof(WSABUF); vec.nalloc = NGX_WSABUFS; vec.pool = c->pool; /* coalesce the neighbouring bufs */ while (chain) { n = chain->buf->end - chain->buf->last; if (limit) { if (size >= (size_t) limit) { break; } if (size + n > (size_t) limit) { n = (size_t) limit - size; } } if (prev == chain->buf->last) { wsabuf->len += n; } else { if (vec.nelts == vec.nalloc) { break; } wsabuf = ngx_array_push(&vec); if (wsabuf == NULL) { return NGX_ERROR; } wsabuf->buf = (char *) chain->buf->last; wsabuf->len = n; } size += n; prev = chain->buf->end; chain = chain->next; } ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0, "WSARecv: %d:%d", vec.nelts, wsabuf->len); rc = WSARecv(c->fd, vec.elts, vec.nelts, &bytes, &flags, NULL, NULL); rev = c->read; if (rc == -1) { rev->ready = 0; err = ngx_socket_errno; if (err == WSAEWOULDBLOCK) { ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, err, "WSARecv() not ready"); return NGX_AGAIN; } rev->error = 1; ngx_connection_error(c, err, "WSARecv() failed"); return NGX_ERROR; } #if (NGX_HAVE_FIONREAD) if (rev->available >= 0 && bytes > 0) { rev->available -= bytes; /* * negative rev->available means some additional bytes * were received between kernel notification and WSARecv(), * and therefore ev->ready can be safely reset even for * edge-triggered event methods */ if (rev->available < 0) { rev->available = 0; rev->ready = 0; } ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "WSARecv: avail:%d", rev->available); } else if (bytes == size) { if (ngx_socket_nread(c->fd, &rev->available) == -1) { rev->error = 1; ngx_connection_error(c, ngx_socket_errno, ngx_socket_nread_n " failed"); return NGX_ERROR; } ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "WSARecv: avail:%d", rev->available); } #endif if (bytes < size) { rev->ready = 0; } if (bytes == 0) { rev->eof = 1; } return bytes; }