Mercurial > hg > nginx
view src/os/win32/ngx_wsarecv.c @ 7583:efd71d49bde0
Events: available bytes calculation via ioctl(FIONREAD).
This makes it possible to avoid looping for a long time while working
with a fast enough peer when data are added to the socket buffer faster
than we are able to read and process them (ticket #1431). This is
basically what we already do on FreeBSD with kqueue, where information
about the number of bytes in the socket buffer is returned by
the kevent() call.
With other event methods rev->available is now set to -1 when the socket
is ready for reading. Later in ngx_recv() and ngx_recv_chain(), if
full buffer is received, real number of bytes in the socket buffer is
retrieved using ioctl(FIONREAD). Reading more than this number of bytes
ensures that even with edge-triggered event methods the event will be
triggered again, so it is safe to stop processing of the socket and
switch to other connections.
Using ioctl(FIONREAD) only after reading a full buffer is an optimization.
With this approach we only call ioctl(FIONREAD) when there are at least
two recv()/readv() calls.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Thu, 17 Oct 2019 16:02:19 +0300 |
parents | 3d2d3e1cf427 |
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> ssize_t ngx_wsarecv(ngx_connection_t *c, u_char *buf, size_t size) { int rc; u_long bytes, flags; WSABUF wsabuf[1]; ngx_err_t err; ngx_int_t n; ngx_event_t *rev; wsabuf[0].buf = (char *) buf; wsabuf[0].len = size; flags = 0; bytes = 0; rc = WSARecv(c->fd, wsabuf, 1, &bytes, &flags, NULL, NULL); ngx_log_debug4(NGX_LOG_DEBUG_EVENT, c->log, 0, "WSARecv: fd:%d rc:%d %ul of %z", c->fd, rc, bytes, size); 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; } n = ngx_connection_error(c, err, "WSARecv() failed"); if (n == NGX_ERROR) { rev->error = 1; } return n; } #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) { n = ngx_connection_error(c, ngx_socket_errno, ngx_socket_nread_n " failed"); if (n == NGX_ERROR) { rev->error = 1; } return n; } 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; } ssize_t ngx_overlapped_wsarecv(ngx_connection_t *c, u_char *buf, size_t size) { int rc; u_long bytes, flags; WSABUF wsabuf[1]; ngx_err_t err; ngx_int_t n; ngx_event_t *rev; LPWSAOVERLAPPED ovlp; rev = c->read; if (!rev->ready) { ngx_log_error(NGX_LOG_ALERT, c->log, 0, "second wsa post"); return NGX_AGAIN; } ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "rev->complete: %d", rev->complete); if (rev->complete) { rev->complete = 0; if (ngx_event_flags & NGX_USE_IOCP_EVENT) { if (rev->ovlp.error) { ngx_connection_error(c, rev->ovlp.error, "WSARecv() failed"); return NGX_ERROR; } ngx_log_debug3(NGX_LOG_DEBUG_EVENT, c->log, 0, "WSARecv ovlp: fd:%d %ul of %z", c->fd, rev->available, size); return rev->available; } if (WSAGetOverlappedResult(c->fd, (LPWSAOVERLAPPED) &rev->ovlp, &bytes, 0, NULL) == 0) { ngx_connection_error(c, ngx_socket_errno, "WSARecv() or WSAGetOverlappedResult() failed"); return NGX_ERROR; } ngx_log_debug3(NGX_LOG_DEBUG_EVENT, c->log, 0, "WSARecv: fd:%d %ul of %z", c->fd, bytes, size); return bytes; } ovlp = (LPWSAOVERLAPPED) &rev->ovlp; ngx_memzero(ovlp, sizeof(WSAOVERLAPPED)); wsabuf[0].buf = (char *) buf; wsabuf[0].len = size; flags = 0; bytes = 0; rc = WSARecv(c->fd, wsabuf, 1, &bytes, &flags, ovlp, NULL); rev->complete = 0; ngx_log_debug4(NGX_LOG_DEBUG_EVENT, c->log, 0, "WSARecv ovlp: fd:%d rc:%d %ul of %z", c->fd, rc, bytes, size); if (rc == -1) { err = ngx_socket_errno; if (err == WSA_IO_PENDING) { rev->active = 1; ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, err, "WSARecv() posted"); return NGX_AGAIN; } n = ngx_connection_error(c, err, "WSARecv() failed"); if (n == NGX_ERROR) { rev->error = 1; } return n; } if (ngx_event_flags & NGX_USE_IOCP_EVENT) { /* * if a socket was bound with I/O completion port * then GetQueuedCompletionStatus() would anyway return its status * despite that WSARecv() was already complete */ rev->active = 1; return NGX_AGAIN; } if (bytes == 0) { rev->eof = 1; rev->ready = 0; } else { rev->ready = 1; } rev->active = 0; return bytes; }