1527736 - ProfilerIOInterposeObserver cannot be re-enabled when restarting the profiler

Status: NEW

(Core :: Gecko Profiler, defect, P2)

Description

[Greg Tatum [:gregtatum]]

The function ProfilerIOInterposeObserver::Observe does not run when re-enabled.

Steps to reproduce:

• Start the profiler with the "mainthreadio" feature turned on.
• Do some DiskIO
• Capture profile.
• The profiler has DiskIO markers.
• Fully stop the profiler with Services.profiler.StopProfiler()
• Start the profiler with the "mainthreadio" feature turned on.
• Do some DiskIO
• Capture profile.

Expected behavior:

• There are DiskIO markers

Actual behavior:

• There are no disk IO markers, and the ProfilerIOInterposeObserver::Observe function is never run.

I was doing some debugging and found that the interposer was being re-created correctly, and the Observe function was being added to the ObserverLists. I believe the poisoned file io functions were still valid, but I suspect for some reason the ObserverList wasn't being updated to use the new one.