This fixes a freeze bug in the NFS input/storage plugins: when libnfs
auto-reconnets after a failure, it installs the new socket on the same
file descriptor number. MPD's attempt to unregister the old socket by
calling SocketMonitor::Steal() from NfsConnection::ScheduleSocket()
fails because the new/old socket number is not registered in epoll, so
epoll_ctl() returns ENOENT. The problem is that it left
`scheduled_flags`, and so subsequent Schedule() calls will use
`EPOLL_CTL_MOD`, which will fail again and again. Instead, we need to
use `EPOLL_CTL_ADD` to register the new socket.
Closes https://github.com/MusicPlayerDaemon/MPD/issues/806
Closes https://github.com/MusicPlayerDaemon/MPD/issues/756
The ALSA "null" driver opens /dev/null and returns the file handle
from snd_pcm_poll_descriptors(), but /dev/null cannot be used with
epoll, the epoll_ctl() system call returns -EPERM. This means that
the ALSA output hangs, eventually freezing the whole MPD process.
This commit adds a workaround to the MultiSocketMonitor class which is
used by the ALSA output plugin.
Closes https://github.com/MusicPlayerDaemon/MPD/issues/695
Expect OnSocketReady() to cancel events. If it returns false, the
SocketMonitor may be destructed already. This fixes a use-after-free
bug in the "httpd" output plugin.
This replaces the old `dead` flag which was unreliable; it was `false`
if the EventThread was not yet started, which could cause deadlocks in
BlockingCall().
Since we switched from autotools to Meson in commit
94592c1406, we don't need to include
`config.h` early to properly enable large file support. Meson passes
the required macros on the compiler command line instead of defining
them in `config.h`.
This means we can include `config.h` at any time, whenever we want to
check its macros, and there are no ordering constraints.
MPD's default is 100ms, which is too long for the real-time I/O
thread. The OutputThread has 100us, but the real-time I/O thread
might have tighter deadlines.
This change has currently no effect (I believe), because nobody uses
timers on the RTIO thread.
So long, autotools! This is my last MPD related project to migrate
away from it. It has its strengths, but also very obvious weaknesses
and weirdnesses. Today, many of its quirks are not needed anymore,
and are cumbersome and slow. Now welcome our new Meson overlords!
The normal I/O event thread can have a large latency, e.g. when
libgnutls loads all TLS CA certificates for a https connect. This
makes it unreliable for the ALSA I/O notifications, and causes ring
buffer xruns. To avoid interfering with high latency events such as
CURL's, we move the ALSA I/O events to a separate I/O thread which
also obtains real-time scheduling (if possible).
Closes#221
