Introduce TimerCallback2.

This allows getting notified also if the timer has been stopped, so that it is guaranteed to be called, except if cancelWait is called.

Necessary for fixing vibe-d/vibe-core#86

source/eventcore/driver.d

@@ -564,7 +564,12 @@ interface EventDriverTimers {
 	void stop(TimerID timer);
 	bool isPending(TimerID timer);
 	bool isPeriodic(TimerID timer);
-	void wait(TimerID timer, TimerCallback callback);
+	final void wait(TimerID timer, TimerCallback callback) {
+		wait(timer, (tm, fired) {
+			if (fired) callback(tm);
+		});
+	}
+	void wait(TimerID timer, TimerCallback2 callback);
 	void cancelWait(TimerID timer);
 
 	/** Increments the reference count of the given resource.
@@ -668,6 +673,7 @@ alias FileIOCallback = void delegate(FileFD, IOStatus, size_t);
 alias EventCallback = void delegate(EventID);
 alias SignalCallback = void delegate(SignalListenID, SignalStatus, int);
 alias TimerCallback = void delegate(TimerID);
+alias TimerCallback2 = void delegate(TimerID, bool fired);
 alias FileChangesCallback = void delegate(WatcherID, in ref FileChange change);
 @system alias DataInitializer = void function(void*) @nogc;
 

source/eventcore/drivers/timer.d

@@ -79,7 +79,7 @@ final class LoopTimeoutTimerDriver : EventDriverTimers {
 		foreach (tm; processed_timers) {
 			auto cb = tm.callback;
 			tm.callback = null;
-			if (cb) cb(tm.id);
+			if (cb) cb(tm.id, true);
 		}
 
 		return processed_timers.length > 0;
@@ -91,8 +91,8 @@ final class LoopTimeoutTimerDriver : EventDriverTimers {
 		TimerSlot* tm;
 		try tm = ms_allocator.make!TimerSlot;
 		catch (Exception e) return TimerID.invalid;
-		GC.addRange(tm, TimerSlot.sizeof, typeid(TimerSlot));
 		assert(tm !is null);
+		GC.addRange(tm, TimerSlot.sizeof, typeid(TimerSlot));
 		tm.id = id;
 		tm.refCount = 1;
 		tm.timeout = long.max;
@@ -113,8 +113,13 @@ final class LoopTimeoutTimerDriver : EventDriverTimers {
 
 	final override void stop(TimerID timer)
 	@trusted {
+		import std.algorithm.mutation : swap;
+
 		auto tm = m_timers[timer];
 		if (!tm.pending) return;
+		TimerCallback2 cb;
+		swap(cb, tm.callback);
+		if (cb) cb(timer, false);
 		tm.pending = false;
 		m_timerQueue.remove(tm);
 	}
@@ -129,11 +134,12 @@ final class LoopTimeoutTimerDriver : EventDriverTimers {
 		return m_timers[descriptor].repeatDuration > 0;
 	}
 
-	final override void wait(TimerID timer, TimerCallback callback)
+	final override void wait(TimerID timer, TimerCallback2 callback)
 	{
-		assert(!m_timers[timer].callback, "Calling wait() no a timer that is already waiting.");
+		assert(!m_timers[timer].callback, "Calling wait() on a timer that is already waiting.");
 		m_timers[timer].callback = callback;
 	}
+	alias wait = EventDriverTimers.wait;
 
 	final override void cancelWait(TimerID timer)
 	{
@@ -214,7 +220,7 @@ struct TimerSlot {
 	bool pending;
 	long timeout; // stdtime
 	long repeatDuration;
-	TimerCallback callback; // TODO: use a list with small-value optimization
+	TimerCallback2 callback; // TODO: use a list with small-value optimization
 
 	DataInitializer userDataDestructor;
 	ubyte[16*size_t.sizeof] userData;

tests/0-timer.d

@@ -57,6 +57,21 @@ void main()
 
 	eventDriver.timers.set(tm, 1200.msecs, 0.msecs);
 
+	// test if stop() produces a callback with fire==false
+	bool got_event = false;
+	auto tm2 = eventDriver.timers.create();
+	eventDriver.timers.wait(tm2, (t, fired) { assert(!fired); got_event = true; });
+	eventDriver.timers.set(tm2, 100.msecs, 0.msecs);
+	eventDriver.timers.stop(tm2);
+	assert(got_event);
+
+
+	// test that cancelWait() does not produce a callback
+	eventDriver.timers.wait(tm2, (t, fired) { assert(false); });
+	eventDriver.timers.set(tm2, 100.msecs, 0.msecs);
+	eventDriver.timers.cancelWait(tm2);
+	eventDriver.timers.stop(tm2);
+
 	ExitReason er;
 	do er = eventDriver.core.processEvents(Duration.max);
 	while (er == ExitReason.idle);