914392 - Remove AudioNodeEngine::NodeMutex() usage

Status: RESOLVED FIXED

(Core :: Web Audio, defect, P3)

Description

[Karl Tomlinson (:karlt)]

Most clients of the NodeMutex() and AudioNode* Node() methods on AudioNodeEngine are calling from the main thread and so should be using NodeMainThread().

ProduceAudioBlock() in AnalyserNodeEngine and ScriptProcessorNodeEngine use NodeMutex() and Node() to check whether the node is alive before dispatching the event.  This check is not necessary, because the event needs to handle the case of the Node getting destroyed before the event runs anyway.

Comment 1

[Karl Tomlinson (:karlt)]

Attachment: use NodeMainThread() to avoid NodeMutex() use on main thread

Comment 2

[Karl Tomlinson (:karlt)]

Attachment: move mSharedBuffers ownership to engine

so that it is always available.

Comment 3

[Karl Tomlinson (:karlt)]

Attachment: don't check engine's Node existence in ProcessBlock

If DestroyMediaStream() has cleared the node on the engine, then it will call
MediaStream::Destroy().  I doubt the additional code and cost of repeatedly
checking this is worth the savings in no-op events dispatched to main thread
between MediaStream::Destroy() on the main thread and destruction on the graph
thread.

Also ScriptProcessorNode should not be potentially ignoring its output buffer
immediately when the ScriptProcessor loses its last reference.  At least the
block currently being processed should output the output buffer.
(Deterministically playing the remainder of the output buffer would be best.)

Comment 4

[Karl Tomlinson (:karlt)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=8a49c1c13473

Comment 5

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/ad3370352602
https://hg.mozilla.org/integration/mozilla-inbound/rev/d3818f780309
https://hg.mozilla.org/integration/mozilla-inbound/rev/c7ddd289198c

Comment 6

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/ad3370352602
https://hg.mozilla.org/mozilla-central/rev/d3818f780309
https://hg.mozilla.org/mozilla-central/rev/c7ddd289198c