1062666 - Debugging aid for MSE data handling

Status: RESOLVED FIXED

(Core :: Audio/Video, defect)

Description

[Matthew Gregan [:kinetik]]

When debugging particular classes of bugs, it'd be useful to dump each chunk of data appended to a SourceBuffer to disk for later inspection/reconstruction.  This would consist of a directory tree for each MediaSource, then each SourceBuffer, then each TrackBuffer and each decoder.  A log of which chunks were appended to what in which order (for, e.g. later replay) would also be useful along with the raw data.

Comment 1

[Matthew Gregan [:kinetik]]

Attachment: wip

Comment 2

[Matthew Gregan [:kinetik]]

Attached patch is already useful for debugging.  Given $mse is a pointer to a MediaSource object, invoking:

    p (('mozilla::dom::MediaSource'*)$mse)->Dump("/path/to/use/mse-debug")

The dump code assumes /path/to/use exists, and will create "mse-debug" and a tree below it containing each ResourceItem for each MediaDecoderReader for each TrackBuffer.

Comment 3

[Matthew Gregan [:kinetik]]

Attachment: Add a debug-only dump method to MediaSource for debugging issues with appended data.

Cleaned up slightly.  This is already useful enough to land, so I'll request review after a try push.

Comment 4

[Matthew Gregan [:kinetik]]

https://tbpl.mozilla.org/?tree=Try&rev=46e44e3f7bd9

Comment 5

[Matthew Gregan [:kinetik]]

(In reply to Matthew Gregan [:kinetik] from comment #4)
> https://tbpl.mozilla.org/?tree=Try&rev=46e44e3f7bd9

Killed, darn unified builds.

Comment 6

[Matthew Gregan [:kinetik]]

https://tbpl.mozilla.org/?tree=Try&rev=793d85ac7a72

Comment 7

[Matthew Gregan [:kinetik]]

Attachment: Add a debug-only dump method to MediaSource for debugging issues with appended data

Comment 8

[cajbir (:cajbir)]

Comment on attachment 8486844 [details] [diff] [review]
Add a debug-only dump method to MediaSource for debugging issues with appended data

Review of attachment 8486844 [details] [diff] [review]:
-----------------------------------------------------------------

::: content/media/mediasource/MediaSource.cpp
@@ +516,5 @@
> +void
> +MediaSource::Dump(const char* aPath)
> +{
> +  char buf[255];
> +  sprintf(buf, "%s/mediasource-%p", aPath, this);

Use PR_snprintf (or similar function that handles the size of 'buf') in places throughout where sprintf is used.

::: content/media/mediasource/MediaSource.h
@@ +98,5 @@
>    // initialization.
>    void QueueInitializationEvent();
>  
> +#if defined(DEBUG)
> +  void Dump(const char* aPath);

Add a comment explaining what this function is for and what it does to the given path. How to call it from gdb as you describe in comment 2 would also be useful.

Comment 9

[Matthew Gregan [:kinetik]]

https://tbpl.mozilla.org/?tree=Try&rev=44617df48387

Comment 10

[Matthew Gregan [:kinetik]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/b3f02eb02208

Comment 11

[Matthew Gregan [:kinetik]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/b36d31ca6e14

Comment 12

[Matthew Gregan [:kinetik]]

Backed out, my try push was opt only, which isn't that useful for stuff hidden behind DEBUG.

Comment 13

[Matthew Gregan [:kinetik]]

https://tbpl.mozilla.org/?tree=Try&rev=c076134d2899

Comment 14

[Matthew Gregan [:kinetik]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/0a3666402f8b

Comment 15

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/0a3666402f8b