Looks good to me.
--alex
On 20.01.2017 16:35, Anton Litvinov wrote:
Hello Sergey,
Thank you for review of this fix. Yes, I agree that 4 fields of
"DirectAudioDevice.DirectClip" class which you specified
("loopStartFrame", "loopEndFrame", "newFramePosition",
"clipBytePosition") are also not thread-safe and should be marked with
"volatile" modifier, though they are not directly related to this bug.
The second version of the fix, which addresses your remark, was created.
In the second version of the fix "volatile" modifier was added to the
next 8 fields of "DirectClip" class, all of which are accessed both from
"DirectClip.run()" method and other methods of this class: "audioData",
"frameSize", "m_lengthInFrames", "loopCount", "clipBytePosition",
"newFramePosition", "loopStartFrame", "loopEndFrame". Could you please
review the second version of the fix.
Webrev: http://cr.openjdk.java.net/~alitvinov/8168751/jdk9/webrev.01
Thank you,
Anton
On 1/19/2017 12:34 AM, Sergey Bylokhov wrote:
Hi, Anton.
Probably some other fields in the DirectClip should be marked as
volatile? For example loopStartFrame/loopEndFrame/ are used in the
run() but assigned in the setLoopPoints
() w/o any synchronization?(the same setFramePosition
+newFramePosition/clipBytePosition)
Hello,
Could you please review the following fix for the bug.
Bug: https://bugs.openjdk.java.net/browse/JDK-8168751
Webrev: http://cr.openjdk.java.net/~alitvinov/8168751/jdk9/webrev.00
The bug consists in the fact that after many repetitive sequential
calls to the methods "loop()", "stop()" on the same instance of
"java.applet.AudioClip" at some moment two threads with the name
"Direct Clip", which play this "AudioClip" instance, are created and
start existing in parallel, what makes the being played clip sound as
corrupted.
"Direct Clip" thread is represented by the instance variable
"com.sun.media.sound.DirectAudioDevice.DirectClip.thread", is created
in the method
"com.sun.media.sound.DirectAudioDevice.DirectClip.open()" and is
stopped by assigning "null" value to "DirectClip.thread" instance
variable in the method
"com.sun.media.sound.DirectAudioDevice.DirectClip.implClose()".
THE DEFINED ROOT CAUSES OF THE BUG:
1. The fact that "DirectClip.thread" instance variable is not
thread-safe. There is a possibility that null value assigned to it in
one thread through the former mentioned "DirectClip.implClose()"
method does not become visible for the running "Direct Clip" thread
in the method "DirectClip.run()".
2. In the method "DirectClip.run()" not taking into account the fact
that a new "Direct Clip" thread could have already been started and
assigned to "DirectClip.thread" instance variable after the call to
"DirectClip.implClose()", by the moment when "DirectClip.thread"
value is checked for null in "DirectClip.run()" method, or by the
moment when the previous "Direct Clip" thread is awakened and
continues execution after the following code block in
"DirectClip.run()" from the file
"jdk/src/java.desktop/share/classes/com/sun/media/sound/DirectAudioDevice.java".
1354 try {
1355 lock.wait();
1356 } catch(InterruptedException ie) {}
THE SOLUTION:
The solution is based on correction of the listed above 2 root causes
of the bug.
Thank you,
Anton
