1119060 - PluginProcessParent's pointer to its LaunchRunnable must remain non-null until the runnable has executed

Status: RESOLVED FIXED

(Core Graveyard :: Plug-ins, defect)

Description

[(No longer employed by Mozilla) Aaron Klotz]

Otherwise things behave badly if we want to do a WaitUntilConnected when the runnable is already queued up to the main thread message_loop.

Comment 1

[(No longer employed by Mozilla) Aaron Klotz]

Attachment: Fix

Comment 2

[(No longer employed by Mozilla) Aaron Klotz]

The problem is as follows:

When we are forced to wait synchronously for plugin initialization (for example a script is querying for a property), we might need to wait for the plugin container to launch.

Normally the runnable would be enqueued to the main thread and would eventually execute. Unfortunately in this scenario. That won't work in this case because the main thread must block until the plugin has launched, so in this case we execute the runnable immediately.

Without this patch, we could have a scenario where the process launch runnable would be enqueued to the main thread and PluginProcessParent::mLaunchCompleteRunnable is then set to nullptr. When the main thread tries to execute the runnable immediately, it sees a null runnable (which is incorrect), does not finish setting up the plugin process, and then tries to do stuff with the plugin.

This fix ensures that the runnable pointer is non-null until it executes either immediately or from the main thread message loop.

Comment 3

[(No longer employed by Mozilla) Aaron Klotz]

(Ignore the "Unfortunately in this scenario.")

Comment 4

[(No longer employed by Mozilla) Aaron Klotz]

https://hg.mozilla.org/integration/mozilla-inbound/rev/06402d84ac3d

Comment 5

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/06402d84ac3d