Define the GLib logging domain in the following libraries: conf,
daemon, event_pipe, log.

Free memory before exiting.

Removed all allocation functions, xwrite(), xread(), ARRAY_SIZE().
Those have been superseded by GLib.

xclose() aims to be the signal safe version of close(). However during
cleanup, this isn't important.

Windows has no pipe(), it only has _pipe() with two additional
parameters.

There is only one location using PIPE_EVENT_SIGNAL: to synchronize
player_command() with player_command_finished().  Use the "notify"
library instead of the event_pipe here.

event_pipe_emit_fast() is aimed for use in signal handlers: it doesn't
lock the mutex, and doesn't log on error.  That makes it potentially
lossy, but for its intended use, that does not matter.

Make the event_pipe (formerly main_notify) send/receive a set of
events, with a callback for each one.

The default event PIPE_EVENT_SIGNAL does not have a callback.  It
is still there for waking up the main thread, when it is waiting for
the player thread.

Continuing the previous patch.

We are going to migrate away from the concept of notifying the main
thread.  There should be events sent to it instead.  This patch starts
a series to implement that.

These functions are not used anymore since we use the GLib main loop.

This is a rather huge patch, which unfortunately cannot be splitted.

Instead of using our custom ioops.h library, convert everything to use
the GLib main loop.

Currently, both sides of the pipe are blocking, although we do not
need blocking read().  Convert it back to blocking.  Eliminate the
select() from wait_main_task().

To wake up the main thread, don't attempt to use a GCond/GMutex
(struct notify).  This kind of mixed wakeup method has known race
conditions.

The idea behind this patch is: for wakeups which happen while the main
thread is sleeping, use only a pipe.  For wakeups which happen while
the main thread is waiting for the player thread, we can later change
to GCond.  For now, accept the overhead of using a pipe for the
latter.

In the long run, the main thread will never wait for the player
thread, but will do everything asynchronously.

When there are standardized headers, use these instead of the bloated
os_compat.h.

Typedefs shouldn't be used, use the bare struct names instead.

It'll be easier to keep track of what code runs in what
task/thread this way.

There was a known deadlocking bug in the notify library: when the
other thread set notify->pending after the according check in
notify_wait(), the latter thread was deadlocked.  Resolve this by
synchronizing all accesses to notify->pending with the notify object's
mutex.  Since notify_signal_sync() was never used, we can remove it.
As a consequence, we don't need notify_enter() and notify_leave()
anymore; eliminate them, too.

Destroy the mutex when it is not used anymore.

It is legal to call wakeup_main_task() from within the main thread,
e.g. from within a signal handler.  Remove the assertion.

Remove duplicated code.

Avoid some duplicated code in main_notify.c.

The function wait_main_task() is racy: if the function
wakeup_via_cond() sees the mutex is locked just before
wait_main_task() executes pthread_cond_wait(), the main thread blocks
forever.

Work around this issue by adding a "pending" flag just like in my
notify.c code.  A standards-compliant solution should be implemented
later.

git-svn-id: https://svn.musicpd.org/mpd/trunk@7365 09075e82-0dd4-0310-85a5-a0d7c8717e4f

pthread_cond_signal is a no-op if nothing is waiting on it

git-svn-id: https://svn.musicpd.org/mpd/trunk@7351 09075e82-0dd4-0310-85a5-a0d7c8717e4f

signal is all we need since we only have one waiter and
likely faster

git-svn-id: https://svn.musicpd.org/mpd/trunk@7349 09075e82-0dd4-0310-85a5-a0d7c8717e4f

Oops, forgot to unlock a mutex

git-svn-id: https://svn.musicpd.org/mpd/trunk@7348 09075e82-0dd4-0310-85a5-a0d7c8717e4f

The select() in the main event loop blocks now (saving us many
unnecessary wakeups).  This interacted badly with the threads
that were trying to wakeup the main task via
pthread_cond_signal() since the main task was not blocked
on a condition variable, but on select().

So now if we detect a need to wakeup the player, we write
to a pipe which select() is watching instead of blindly
calling pthread_cond_signal().

git-svn-id: https://svn.musicpd.org/mpd/trunk@7347 09075e82-0dd4-0310-85a5-a0d7c8717e4f