GetQueuedCompletionStatus() document on MSDN says the
following signature:
http://msdn.microsoft.com/en-us/library/windows/desktop/aa364986.aspx
BOOL WINAPI GetQueuedCompletionStatus(
_In_ HANDLE CompletionPort,
_Out_ LPDWORD lpNumberOfBytes,
_Out_ PULONG_PTR lpCompletionKey,
_Out_ LPOVERLAPPED *lpOverlapped,
_In_ DWORD dwMilliseconds
);
In the latest specification, the type of the third argument
(lpCompletionKey) is PULONG_PTR not LPDWORD.
In theory, this can provide a bit better distribution of latencies.
Also it simplifies the code, since ngx_queue_t is now used instead
of custom implementation.
This fixes --with-file-aio support on systems that lack eventfd()
syscall, notably aarch64 Linux.
The syscall(SYS_eventfd) may still be necessary on systems that
have eventfd() syscall in the kernel but lack it in glibc, e.g.
as seen in the current CentOS 5 release.
Several warnings silenced, notably (ngx_socket_t) -1 is now checked
on socket operations instead of -1, as ngx_socket_t is unsigned on win32
and gcc complains on comparison.
With this patch, it's now possible to compile nginx using mingw gcc,
with options we normally compile on win32.
We generate both read and write events if an error event was returned by
port_getn() without POLLIN/POLLOUT, but we should not try to handle inactive
events, they may even have no handler.
Stale write event may happen if read and write events was reported both,
and processing of the read event closed descriptor.
In practice this might result in "sendfilev() failed (134: ..." or
"writev() failed (134: ..." errors when switching to next upstream server.
See report here:
http://mailman.nginx.org/pipermail/nginx/2013-April/038421.html
A POLLERR signalled by poll() without POLLIN/POLLOUT, as seen on
Linux, would generate both read and write events, but there's no
write event handler for resolver events. A fix is to only call
event handler of an active event.
Stale write event may happen if epoll_wait() reported both read and write
events, and processing of the read event closed descriptor.
Patch by Yichun Zhang (agentzh).
The default value is 32 AIO simultaneous requests per worker. Previously
they were hardcoded to 1024, and it was too large, since Linux allocated
them early on io_setup(), but not on request itself. So with default value
of /proc/sys/fs/aio-max-nr equal to 65536 only 64 worker processes could
be run simultaneously. 32 AIO requests are enough for modern disks even if
server runs only 1 worker.
syscall(2) uses usual libc convention, it returns -1 on error and
sets errno. Obsolete _syscall(2) returns negative value of error.
Thanks to Hagai Avrahami.
