830172 - Change WMFByteStream to use an nsThreadPool for async I/O operations

Status: RESOLVED FIXED

(Core :: Audio/Video, defect)

Description

[Chris Pearce [:cpearce (Not reading bugmail)]]

WMFByteStream's async read implementation simply creates one WMF work queue per WMFByteStream. If we open too many WMFByteStreams at once (like test_too_many_elements does), the creation of work queues fails, and we fail to playback media. We can just use an nsThreadPool to perform the MediaResource I/O operations instead.

We use the byte stream's work queue to call the WMF "I/O complete" callbacks, we'll need to move these calls to a shared work queue.

Comment 1

[Valerio]

Is this related to Bug 823646 ?

Comment 2

[Paul Adenot (:padenot)]

Nope.

Comment 3

[Chris Pearce [:cpearce (Not reading bugmail)]]

Attachment: Patch v1: Use nsIThreadPool instead of MFWorkQueues.

* Use shared nsIThreadPool instead of MFWorkQueues for processing WMFByteStream async read requests.
* We use an nsIThreadPoolListener to ensure MSCOM is initialized and uninitialized on the work pool threads.
* Manage thread pool lifetime on the main thread.
* Fail reads if the byte stream has been shutdown.
* test_too_many_elements passes with MP3 and MP4 files.

Comment 4

[Chris Pearce [:cpearce (Not reading bugmail)]]

(In reply to Chris Pearce (:cpearce) from comment #3)
> * test_too_many_elements passes with MP3 and MP4 files.

(It didn't before).

Comment 5

[Paul Adenot (:padenot)]

Comment on attachment 708825 [details] [diff] [review]
Patch v1: Use nsIThreadPool instead of MFWorkQueues.

Review of attachment 708825 [details] [diff] [review]:
-----------------------------------------------------------------

::: content/media/wmf/WMFByteStream.cpp
@@ +128,5 @@
> +  if (!sThreadPool) {
> +    nsresult rv;
> +    nsCOMPtr<nsIThreadPool> pool = do_CreateInstance(NS_THREADPOOL_CONTRACTID, &rv);
> +    NS_ENSURE_SUCCESS(rv, rv);
> +  

nit: trailing space.

Comment 6

[Chris Pearce [:cpearce (Not reading bugmail)]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/8d404fcb334b

Comment 7

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/8d404fcb334b