987415 - GeckoAppShell.gPendingEvents is not thread safe

Status: RESOLVED FIXED

(Firefox for Android Graveyard :: General, defect)

Description

[Richard Newman [:rnewman]]

Accessed from multiple threads, no synchronization, not a thread-safe data structure. This is an early-runtime race condition waiting to happen.

Comment 1

[Richard Newman [:rnewman]]

Attachment: Part 0: GeckoAppShell cleanup. v1

gThe mMisuse sOf prefixes makes me crylaugh.

Comment 2

[Richard Newman [:rnewman]]

Attachment: Part 1: GeckoAppShell thread-safety. v1

Switched to using concurrent data structures for these two members.

Comment 3

[Brian Nicholson (:bnicholson)]

Comment on attachment 8396043 [details] [diff] [review]
Part 1: GeckoAppShell thread-safety. v1

Review of attachment 8396043 [details] [diff] [review]:
-----------------------------------------------------------------

::: mobile/android/base/GeckoAppShell.java
@@ +374,5 @@
> +        }
> +
> +        boolean offered = PENDING_EVENTS.offer(e);
> +        if (!offered) {
> +            Log.e(LOGTAG, "Unable to queue event for Gecko: " + e);

We have no idea what event got skipped here, so it might be better to use add() and fail fast -- though hopefully we'll never hit this to begin with.

Comment 4

[Richard Newman [:rnewman]]

Using `add`, documentation added to note exceptions.

   https://hg.mozilla.org/integration/fx-team/rev/54e12e510264
   https://hg.mozilla.org/integration/fx-team/rev/b4fce211dbde

We might consider uplifting Part 1.

Comment 5

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/54e12e510264
https://hg.mozilla.org/mozilla-central/rev/b4fce211dbde

Comment 6

[Richard Newman [:rnewman]]

Comment on attachment 8396043 [details] [diff] [review]
Part 1: GeckoAppShell thread-safety. v1

[Approval Request Comment]
Bug caused by (feature/regressing bug #): 
  Long-ago coding errors.

User impact if declined: 
  Potential for arbitrary crashes or corruption due to thread-unsafe operations, particularly early in startup.

Testing completed (on m-c, etc.): 
  Baking happily on Nightly for a while.

Risk to taking this patch (and alternatives if risky): 
  Low: switching implementations for two simple data structures.

String or IDL/UUID changes made by this patch:
  None.

Comment 7

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/6e508a3526e6
https://hg.mozilla.org/releases/mozilla-aurora/rev/ec30bfc1c545