From ef7c19d3734f67cae011006320d105c2b0c547af Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B6nke=20Ludwig?= <sludwig@rejectedsoftware.com>
Date: Tue, 26 Sep 2017 15:18:20 +0200
Subject: [PATCH 1/3] Add test for issue #25 - periodic timers overlapping
 single-shot timers.

---
 tests/issue-25-periodic-timers.d | 68 ++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 tests/issue-25-periodic-timers.d

diff --git a/tests/issue-25-periodic-timers.d b/tests/issue-25-periodic-timers.d
new file mode 100644
index 0000000..a0156cb
--- /dev/null
+++ b/tests/issue-25-periodic-timers.d
@@ -0,0 +1,68 @@
+/++ dub.sdl:
+	name "test"
+	dependency "eventcore" path=".."
++/
+module test;
+
+import eventcore.core;
+import std.datetime : Clock, SysTime, UTC;
+import std.stdio : writefln;
+import core.time : Duration, msecs;
+
+SysTime s_startTime;
+int s_cnt = 0;
+bool s_done;
+
+void main()
+{
+	s_startTime = Clock.currTime(UTC());
+
+	bool timer1fired = false;
+
+	// first timer: one-shot 200ms
+	auto tm = eventDriver.timers.create();
+	eventDriver.timers.wait(tm, (tm) nothrow @safe {
+		scope (failure) assert(false);
+		writefln("First timer");
+
+		auto dur = Clock.currTime(UTC()) - s_startTime;
+		assert(dur > 200.msecs);
+		assert(dur < 220.msecs);
+
+		timer1fired = true;
+	});
+	eventDriver.timers.set(tm, 200.msecs, 0.msecs);
+
+	// second timer repeating 100ms, 3 times
+	auto tm2 = eventDriver.timers.create();
+	eventDriver.timers.set(tm2, 100.msecs, 100.msecs);
+	void periodicCallback(TimerID timer) nothrow @safe {
+		try {
+			writefln("Second timer");
+
+			auto dur = Clock.currTime(UTC()) - s_startTime;
+			s_cnt++;
+			assert(dur > 100.msecs * s_cnt);
+			assert(dur < 100.msecs * s_cnt + 20.msecs);
+			assert(s_cnt <= 3);
+
+			if (s_cnt == 3) {
+				s_done = true;
+				eventDriver.timers.stop(timer);
+				assert(timer1fired, "Timer 1 didn't fire within 300ms");
+			} else eventDriver.timers.wait(tm2, &periodicCallback);
+		} catch (Exception e) {
+			assert(false, e.msg);
+		}
+	}
+
+	eventDriver.timers.wait(tm2, &periodicCallback);
+
+
+	ExitReason er;
+	do er = eventDriver.core.processEvents(Duration.max);
+	while (er == ExitReason.idle);
+	assert(er == ExitReason.outOfWaiters);
+	assert(s_done);
+	s_done = false;
+}

From 60407b783b8c64928b6cce2d4cc075467ca621d9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B6nke=20Ludwig?= <sludwig@rejectedsoftware.com>
Date: Tue, 26 Sep 2017 15:42:03 +0200
Subject: [PATCH 2/3] Fix re-enqueuing of periodic timers. Fixes #25.

Periodic timers were first re-enqueued and then removed, effectively causing them to stay at their old position, cutting off the tail of the timer queue.
---
 source/eventcore/drivers/timer.d | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/source/eventcore/drivers/timer.d b/source/eventcore/drivers/timer.d
index a9bbfba..15277ea 100644
--- a/source/eventcore/drivers/timer.d
+++ b/source/eventcore/drivers/timer.d
@@ -51,14 +51,15 @@ final class LoopTimeoutTimerDriver : EventDriverTimers {
 			if (tm.repeatDuration > 0) {
 				do tm.timeout += tm.repeatDuration;
 				while (tm.timeout <= stdtime);
-				enqueueTimer(tm);
 			} else tm.pending = false;
 			m_firedTimers ~= tm;
 		}
 
-		// NOTE: this isn't yet verified to work under all circumstances
-		foreach (tm; m_firedTimers)
+		foreach (tm; m_firedTimers) {
 			m_timerQueue.remove(tm);
+			if (tm.repeatDuration > 0)
+				enqueueTimer(tm);
+		}
 
 		foreach (tm; m_firedTimers) {
 			auto cb = tm.callback;

From 8799b7b01eb163af8dfce0c6ee630e9345103b03 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B6nke=20Ludwig?= <sludwig@rejectedsoftware.com>
Date: Tue, 26 Sep 2017 15:42:23 +0200
Subject: [PATCH 3/3] Add assertion.

---
 source/eventcore/internal/dlist.d | 1 +
 1 file changed, 1 insertion(+)

diff --git a/source/eventcore/internal/dlist.d b/source/eventcore/internal/dlist.d
index 5186fc8..8358e5d 100644
--- a/source/eventcore/internal/dlist.d
+++ b/source/eventcore/internal/dlist.d
@@ -59,6 +59,7 @@ struct StackDList(T) {
 
 	void insertAfter(T* item, T* after)
 	{
+		assert(!item.prev && !item.next);
 		if (!after) insertBack(item);
 		else {
 			item.prev = after;