GeneratedJNIWrappers.h was updated in bug 1192079 to use inherited
constructors, which is a gcc 4.8 feature. Many people are still using an
older version of NDK which only comes with gcc 4.7.
First we need to set the Gecko thread JNIEnv* in nsAndroidStartup, but
after that we can initialize and deinitialize the rest of JNI, including
AndroidBridge, in GeckoAppShell. This makes nsAppShell control the
AndroidBridge lifetime. Over time, parts of the AndroidBridge
functionality will be migrated to nsAppShell.
Merge all the init code into AndroidBridge constructor and
AndroidBridge::ConstructBridge; merge all the deinit code into
AndroidBridge destructor and AndroidBridge::DeconstructBridge.
In particular, the SetMainThread call is obsolete and removed.
The creation of the surrogate native window in the child NPAPI process was
failing when then sandbox was at low integrity, because the parent is from the
chrome process, so at medium integrity.
Instead of making an IPC call to get the parent, we now create the window upfront
and send it in an IPC message to be parented in the chrome process.
This is done with asynchronous messaging.
This is motivated by three separate but related problems:
1. Our concept of recursion depth is broken for things that run from AfterProcessNextEvent observers (e.g. Promises). We decrement the recursionDepth counter before firing observers, so a Promise callback running at the lowest event loop depth has a recursion depth of 0 (whereas a regular nsIRunnable would be 1). This is a problem because it's impossible to distinguish a Promise running after a sync XHR's onreadystatechange handler from a top-level event (since the former runs with depth 2 - 1 = 1, and the latter runs with just 1).
2. The nsIThreadObserver mechanism that is used by a lot of code to run "after" the current event is a poor fit for anything that runs script. First, the order the observers fire in is the order they were added, not anything fixed by spec. Additionally, running script can cause the event loop to spin, which is a big source of pain here (bholley has some nasty bug caused by this).
3. We run Promises from different points in the code for workers and main thread. The latter runs from XPConnect's nsIThreadObserver callbacks, while the former runs from a hardcoded call to run Promises in the worker event loop. What workers do is particularly problematic because it means we can't get the right recursion depth no matter what we do to nsThread.
The solve this, this patch does the following:
1. Consolidate some handling of microtasks and all handling of stable state from appshell and WorkerPrivate into CycleCollectedJSRuntime.
2. Make the recursionDepth counter only available to CycleCollectedJSRuntime (and its consumers) and remove it from the nsIThreadInternal and nsIThreadObserver APIs.
3. Adjust the recursionDepth counter so that microtasks run with the recursionDepth of the task they are associated with.
4. Introduce the concept of metastable state to replace appshell's RunBeforeNextEvent. Metastable state is reached after every microtask or task is completed. This provides the semantics that bent and I want for IndexedDB, where transactions autocommit at the end of a microtask and do not "spill" from one microtask into a subsequent microtask. This differs from appshell's RunBeforeNextEvent in two ways:
a) It fires between microtasks, which was the motivation for starting this.
b) It no longer ensures that we're at the same event loop depth in the native event queue. bent decided we don't care about this.
5. Reorder stable state to happen after microtasks such as Promises, per HTML. Right now we call the regular thread observers, including appshell, before the main thread observer (XPConnect), so stable state tasks happen before microtasks.
Wes Kocher
Boris Chiou
Ryan VanderMeulen
Randall Barker
JerryShih
Christoph Kerschbaumer
Aryeh Gregor
Masayuki Nakano
Jim Chen
Matt Woodrow
Jared Wein
Xidorn Quan
Gabor Krizsanits
Jacek Caban
Mason Chang
Mike Conley
Bob Owen
Terrence Cole
Nick Robson
Kyle Huey
Makoto Kato
Sotaro Ikeda
Andrew Comminos
Lee Salzman
Petr Jasicek