Most event queues don't ever get many events queued at one time, but the
MainThread Input and Normal queues may.
Differential Revision: https://phabricator.services.mozilla.com/D53912
--HG--
extra : moz-landing-system : lando
This lets us determine the time that an event has been running, and the time
that the event spent queued - which can be used to figure out 'jank' at the
time the event was queued. For PrioritizedEventQueues, only if such queuing
would delay an input event then the queuing delay is reported.
Differential Revision: https://phabricator.services.mozilla.com/D41279
--HG--
extra : moz-landing-system : lando
This lets us determine the time that an event has been running, and the time
that the event spent queued - which can be used to figure out 'jank' at the
time the event was queued. For PrioritizedEventQueues, only if such queuing
would delay an input event then the queuing delay is reported.
Differential Revision: https://phabricator.services.mozilla.com/D41279
--HG--
extra : moz-landing-system : lando
This is to get initial feedback/review.
PIdleScheduler.ipdl has the documentation about the basic architecture.
(v15)
Differential Revision: https://phabricator.services.mozilla.com/D45162
--HG--
extra : moz-landing-system : lando
This is to get initial feedback/review.
PIdleScheduler.ipdl has the documentation about the basic architecture.
(v15)
Differential Revision: https://phabricator.services.mozilla.com/D45162
--HG--
extra : moz-landing-system : lando
This is to get initial feedback/review.
PIdleScheduler.ipdl has the documentation about the basic architecture.
(v15)
Differential Revision: https://phabricator.services.mozilla.com/D45162
--HG--
extra : moz-landing-system : lando
Otherwise, we might enter JS, decide to GC, and deadlock because we were
trying to dispatch tasks to the main thread's event queue while holding
the lock for the event queue.
This patch refactors the nsThread event queue to clean it up and to make it easier to restructure. The fundamental concepts are as follows:
Each nsThread will have a pointer to a refcounted SynchronizedEventQueue. A SynchronizedEQ takes care of doing the locking and condition variable work when posting and popping events. For the actual storage of events, it delegates to an AbstractEventQueue data structure. It keeps a UniquePtr to the AbstractEventQueue that it uses for storage.
Both SynchronizedEQ and AbstractEventQueue are abstract classes. There is only one concrete implementation of SynchronizedEQ in this patch, which is called ThreadEventQueue. ThreadEventQueue uses locks and condition variables to post and pop events the same way nsThread does. It also encapsulates the functionality that DOM workers need to implement their special event loops (PushEventQueue and PopEventQueue). In later Quantum DOM work, I plan to have another SynchronizedEQ implementation for the main thread, called SchedulerEventQueue. It will have special code for the cooperatively scheduling threads in Quantum DOM.
There are two concrete implementations of AbstractEventQueue in this patch: EventQueue and PrioritizedEventQueue. EventQueue replaces the old nsEventQueue. The other AbstractEventQueue implementation is PrioritizedEventQueue, which uses multiple queues for different event priorities.
The final major piece here is ThreadEventTarget, which splits some of the code for posting events out of nsThread. Eventually, my plan is for multiple cooperatively scheduled nsThreads to be able to share a ThreadEventTarget. In this patch, though, each nsThread has its own ThreadEventTarget. The class's purpose is just to collect some related code together.
One final note: I tried to avoid virtual dispatch overhead as much as possible. Calls to SynchronizedEQ methods do use virtual dispatch, since I plan to use different implementations for different threads with Quantum DOM. But all the calls to EventQueue methods should be non-virtual. Although the methods are declared virtual, all the classes used are final and the concrete classes involved should all be known through templatization.
MozReview-Commit-ID: 9Evtr9oIJvx
Boris Zbarsky
Randell Jesup
Razvan Maries
Olli Pettay
arthur.iakab
Bogdan Tara
Randell Jesup
Sylvestre Ledru
Kris Maglione
Chris Peterson
Nathan Froyd
Andreas Farre
Bill McCloskey
Stone Shih