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.
client.focus() now directly uses the DOMServiceWorkerFocusClient event. The
platform popup checking is not available on service workers. Instead each
worker maintains a counter of if it is allowed to interact with windows. This
counter is currently only incremented by the notificationclick event and
dropped after the event has been dispatched.
Since acquiring a client is an async operation most service workers will
perform in notificationclick, an additional extension is granted after the event
during which the service worker may focus a client. This extension is only granted
if the script invokes NotificationEvent.waitUntil() at which point the timer begins.
The extension is terminated when the Promise passed to waitUntil() is fulfilled, or
the timer expires, whichever comes first.
This works because KeepAliveHandler only holds nsMainThreadPtrHolder<> which is
itself thread safe. It has assertions that the PromiseNativeHandler overrides
are only called on the worker and these assertions are satisfied.
client.focus() now directly uses the DOMServiceWorkerFocusClient event. The
platform popup checking is not available on service workers. Instead each
worker maintains a counter of if it is allowed to interact with windows. This
counter is currently only incremented by the notificationclick event and
dropped after the event has been dispatched.
Since acquiring a client is an async operation most service workers will
perform in notificationclick, an additional extension is granted after the event
during which the service worker may focus a client. This extension is only granted
if the script invokes NotificationEvent.waitUntil() at which point the timer begins.
The extension is terminated when the Promise passed to waitUntil() is fulfilled, or
the timer expires, whichever comes first.
Rather than store a non-thread-safe refcounted nsIStructuredCloneContainer, store the base64 representation.
Caches a jsval the first time an attempt to access data is made from content script.
Currently we don't check the dom.push.enabled pref in some cases for
some of these interfaces. This patch unifies how all of these
interfaces are exposed to Window, Worker, and ServiceWorker.
Currently we don't check the dom.push.enabled pref in some cases for
some of these interfaces. This patch unifies how all of these
interfaces are exposed to Window, Worker, and ServiceWorker.
The bit in MIRGenerator.h fixes a straight-up bug in the code, masked until now by unified builds (and unmasked because this patch adds a .cpp file, perturbing the unified build boundaries).
Refactor creation and show dispatch so Notification constructor and showNotification can use it.
Move persistence to ShowInternal.
NotificationStorage calls callback async even when fetching from cache, simply to have similar semantics.
Calls to Notification::Get() are performed async since persistence is now async after being moved to ShowInternal().
Both are in accordance with the spec where the "append to list of notifications" operation is performed in the "show steps" which are performed in parallel from API invocations.
The bulk of this commit was generated by running:
run-clang-tidy.py \
-checks='-*,llvm-namespace-comment' \
-header-filter=^/.../mozilla-central/.* \
-fix
