Mercurial > hg > nginx
view src/os/win32/ngx_wsarecv.c @ 8045:aa28c802409f
Resolver: make TCP write timer event cancelable.
Similar to 70e65bf8dfd7, the change is made to ensure that the ability to
cancel resolver tasks is fully controlled by the caller. As mentioned in the
referenced commit, it is safe to make this timer cancelable because resolve
tasks can have their own timeouts that are not cancelable.
The scenario where this may become a problem is a periodic background resolve
task (not tied to a specific request or a client connection), which receives a
response with short TTL, large enough to warrant fallback to a TCP query.
With each event loop wakeup, we either have a previously set write timer
instance or schedule a new one. The non-cancelable write timer can delay or
block graceful shutdown of a worker even if the ngx_resolver_ctx_t->cancelable
flag is set by the API user, and there are no other tasks or connections.
We use the resolver API in this way to maintain the list of upstream server
addresses specified with the 'resolve' parameter, and there could be third-party
modules implementing similar logic.
author | Aleksei Bavshin <a.bavshin@f5.com> |
---|---|
date | Wed, 01 Jun 2022 20:17:23 -0700 |
parents | efd71d49bde0 |
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; }