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Improved EPOLLRDHUP handling.

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When it's known that the kernel supports EPOLLRDHUP, there is no need in
additional recv() call to get EOF or error when the flag is absent in the
event generated by the kernel.  A special runtime test is done at startup
to detect if EPOLLRDHUP is actually supported by the kernel because
epoll_ctl() silently ignores unknown flags.

With this knowledge it's now possible to drop the "ready" flag for partial
read.  Previously, the "ready" flag was kept until the recv() returned EOF
or error.  In particular, this change allows the lingering close heuristics
(which relies on the "ready" flag state) to actually work on Linux, and not
wait for more data in most cases.

The "available" flag is now used in the read event with the semantics similar
to the corresponding counter in kqueue.
This commit is contained in:
Valentin Bartenev
2016-05-13 17:19:23 +03:00
parent cbf6ca98bc
commit 12f4367189
6 changed files with 153 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
src/os/unix/ngx_readv_chain.c
View File

@@ -51,6 +51,20 @@ ngx_readv_chain(ngx_connection_t *c, ngx_chain_t *chain, off_t limit)
}
}
#endif
#if (NGX_HAVE_EPOLLRDHUP)
if (ngx_event_flags & NGX_USE_EPOLL_EVENT) {
ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0,
"readv: eof:%d, avail:%d",
rev->pending_eof, rev->available);
if (!rev->available && !rev->pending_eof) {
return NGX_AGAIN;
}
}
#endif
prev = NULL;
@@ -149,6 +163,24 @@ ngx_readv_chain(ngx_connection_t *c, ngx_chain_t *chain, off_t limit)
return n;
}
#endif
#if (NGX_HAVE_EPOLLRDHUP)
if ((ngx_event_flags & NGX_USE_EPOLL_EVENT)
&& ngx_use_epoll_rdhup)
{
if (n < size) {
if (!rev->pending_eof) {
rev->ready = 0;
}
rev->available = 0;
}
return n;
}
#endif
if (n < size && !(ngx_event_flags & NGX_USE_GREEDY_EVENT)) {

33
src/os/unix/ngx_recv.c
View File

@@ -48,6 +48,21 @@ ngx_unix_recv(ngx_connection_t *c, u_char *buf, size_t size)
}
}
#endif
#if (NGX_HAVE_EPOLLRDHUP)
if (ngx_event_flags & NGX_USE_EPOLL_EVENT) {
ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0,
"recv: eof:%d, avail:%d",
rev->pending_eof, rev->available);
if (!rev->available && !rev->pending_eof) {
rev->ready = 0;
return NGX_AGAIN;
}
}
#endif
do {
@@ -99,6 +114,24 @@ ngx_unix_recv(ngx_connection_t *c, u_char *buf, size_t size)
return n;
}
#endif
#if (NGX_HAVE_EPOLLRDHUP)
if ((ngx_event_flags & NGX_USE_EPOLL_EVENT)
&& ngx_use_epoll_rdhup)
{
if ((size_t) n < size) {
if (!rev->pending_eof) {
rev->ready = 0;
}
rev->available = 0;
}
return n;
}
#endif
if ((size_t) n < size