From 9d1867c7ebf729d4ad59efef249876a4e0c39dff Mon Sep 17 00:00:00 2001
From: Fastigium <fastigiummusic@gmail.com>
Date: Tue, 16 Feb 2016 13:34:13 +0100
Subject: [PATCH] Make Mixer::removePlayHandle check m_newPlayHandles, too

This fixes a problem where a PresetPreviewPlayHandle would be put in
m_newPlayHandles to be added, then "removed" before it was actually added,
leaving it dangling.
---
 src/core/Mixer.cpp | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/core/Mixer.cpp b/src/core/Mixer.cpp
index 92124a660..012144a2c 100644
--- a/src/core/Mixer.cpp
+++ b/src/core/Mixer.cpp
@@ -642,12 +642,32 @@ void Mixer::removePlayHandle( PlayHandle * _ph )
 	{
 		lockPlayHandleRemoval();
 		_ph->audioPort()->removePlayHandle( _ph );
+		bool removedFromList = false;
+		// Check m_newPlayHandles first because doing it the other way around
+		// creates a race condition
+		m_playHandleMutex.lock();
 		PlayHandleList::Iterator it =
-				qFind( m_playHandles.begin(),
-						m_playHandles.end(), _ph );
+				qFind( m_newPlayHandles.begin(),
+						m_newPlayHandles.end(), _ph );
+		if( it != m_newPlayHandles.end() )
+		{
+			m_newPlayHandles.erase( it );
+			removedFromList = true;
+		}
+		m_playHandleMutex.unlock();
+		// Now check m_playHandles
+		it = qFind( m_playHandles.begin(),
+					m_playHandles.end(), _ph );
 		if( it != m_playHandles.end() )
 		{
 			m_playHandles.erase( it );
+			removedFromList = true;
+		}
+		// Only deleting PlayHandles that were actually found in the list
+		// "fixes crash when previewing a preset under high load"
+		// (See tobydox's 2008 commit 4583e48)
+		if ( removedFromList )
+		{
 			if( _ph->type() == PlayHandle::TypeNotePlayHandle )
 			{
 				NotePlayHandleManager::release( (NotePlayHandle*) _ph );