916773 - Initialize mLatency in SharedBuffer's constructor

Status: RESOLVED FIXED

(Core :: Web Audio, defect)

Comment 1

[Paul Adenot (:padenot)]

Attachment: patch

Comment 2

[Paul Adenot (:padenot)]

Attachment: Initialize mLatency in SharedBuffer's constructor.

Comment 3

[(no longer active)]

Comment on attachment 805285 [details] [diff] [review]
Initialize mLatency in SharedBuffer's constructor.

Review of attachment 805285 [details] [diff] [review]:
-----------------------------------------------------------------

Oops!

Comment 4

[Paul Adenot (:padenot)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/3d2aac8dc618

Comment 5

[Paul Adenot (:padenot)]

Comment on attachment 805285 [details] [diff] [review]
Initialize mLatency in SharedBuffer's constructor.

[Approval Request Comment]
Bug caused by (feature/regressing bug #): bug 899135
User impact if declined: Unpredictable initial latency, when using WebAudio, suspected test timeout on b2g. This is important to have a solid WebAudio implementation.
Testing completed (on m-c, etc.): This is a trivial programming error (uninitialized variable).
Risk to taking this patch (and alternatives if risky): none.
String or IDL/UUID changes made by this patch: none.

Comment 6

[(no longer active)]

Do we have any evidence that this is responsible for the test timeouts in b2g?

Comment 7

[Ed Morley [:emorley]]

The push this bug was in + followups have been backed out for crashes of form:
https://tbpl.mozilla.org/php/getParsedLog.php?id=27977619&tree=Mozilla-Inbound
https://tbpl.mozilla.org/php/getParsedLog.php?id=27976043&tree=Mozilla-Inbound

https://hg.mozilla.org/integration/mozilla-inbound/rev/58dbd84ae828
https://hg.mozilla.org/integration/mozilla-inbound/rev/9524b1df278e
https://hg.mozilla.org/integration/mozilla-inbound/rev/fb89f2090779
https://hg.mozilla.org/integration/mozilla-inbound/rev/fe576415129e
https://hg.mozilla.org/integration/mozilla-inbound/rev/5e5d5e42f6c2
https://hg.mozilla.org/integration/mozilla-inbound/rev/b221626331b4
https://hg.mozilla.org/integration/mozilla-inbound/rev/2aa38a1a2b06
https://hg.mozilla.org/integration/mozilla-inbound/rev/3d2aac8dc618
https://hg.mozilla.org/integration/mozilla-inbound/rev/ade49a801461
https://hg.mozilla.org/integration/mozilla-inbound/rev/4323508b3412

Comment 8

[Karl Tomlinson (:karlt)]

(In reply to :Ehsan Akhgari (needinfo? me!) from comment #6)
> Do we have any evidence that this is responsible for the test timeouts in
> b2g?

Nothing experimental.  Just looking at the code, imagining what would happen with a large latency, and 908306 comment 11 observing that onaudioprocess is not called when a test times out.

There seem to have been some tests timing out even though they don't use ScriptProcessor, so this may not be the only issue on b2g.

Comment 9

[Karl Tomlinson (:karlt)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/425870d13b13

Comment 10

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/425870d13b13

Comment 11

[Alex Keybl [:akeybl]]

Comment on attachment 805285 [details] [diff] [review]
Initialize mLatency in SharedBuffer's constructor.

Doesn't meet the bar of needing uplift to Desktop/Mobile Firefox 25, good for Aurora and B2G 1.2 though

Comment 12

[(no longer active)]

Comment on attachment 805285 [details] [diff] [review]
Initialize mLatency in SharedBuffer's constructor.

(In reply to comment #11)
> Comment on attachment 805285 [details] [diff] [review]
>   --> https://bugzilla.mozilla.org/attachment.cgi?id=805285
> Initialize mLatency in SharedBuffer's constructor.
> 
> Doesn't meet the bar of needing uplift to Desktop/Mobile Firefox 25, good for
> Aurora and B2G 1.2 though

This patch is almost as low-risk as a patch can possibly be, and it fixes a bug where we just read from garbage memory.  Can you please reconsider?  Thanks!

Comment 13

[Alex Keybl [:akeybl]]

Comment on attachment 805285 [details] [diff] [review]
Initialize mLatency in SharedBuffer's constructor.

Low risk early in the beta, not hugely against it.

Comment 14

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/367b18c23eb2
https://hg.mozilla.org/releases/mozilla-beta/rev/b09d09f59611