player/Thread: fix "single" mode race condition

If the decoder finishes decoding the current song between the two IsIdle() checks, MPD stops playback instead of starting the decoder for the next song. This is usually not visible problem, because the main thread restarts it via playlist::ResumePlayback(), but that way it, ignores "single" mode. As a workaround, this commit adds another "queued" check which re-enters the player loop and checks again whether to start the decoder. Closes https://github.com/MusicPlayerDaemon/MPD/issues/556

player/Thread: fix "single" mode race condition
923e6673 · Max Kellermann · ff3e2c05 · 923e6673 · 923e6673
Commit 923e6673 authored May 20, 2019 by Max Kellermann
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NEWS NEWS +1 -0

Thread.cxx src/player/Thread.cxx +10 -0

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--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,7 @@ ver 0.21.9 (not yet released)
 * Android
  - fix crash on ARMv7
  - request storage permission on Android 6+
+* fix spurious "single" mode bug
 ver 0.21.8 (2019/04/23)
 * input

--- a/src/player/Thread.cxx
+++ b/src/player/Thread.cxx
@@ -1058,6 +1058,16 @@ Player::Run() noexcept
 			SongBorder();
 		} else if (dc.IsIdle()) {
+			if (queued)
+				/* the decoder has just stopped,
+				   between the two IsIdle() checks,
+				   probably while UnlockCheckOutputs()
+				   left the mutex unlocked; to restart
+				   the decoder instead of stopping
+				   playback completely, let's re-enter
+				   this loop */
+				continue;
 			/* check the size of the pipe again, because
 			   the decoder thread may have added something
 			   since we last checked */