1839670 - Remove the requirement that runnables dispatched to workers need to be nsIDiscardableRunnable

Status: RESOLVED FIXED

(Core :: DOM: Workers, enhancement)

Description

[Andrew Sutherland [:asuth] (he/him)]

In bug 1800659 we removed our use of cancellation, but we retained the DEBUG assertions that require our runnables to be discardable. (Bug 1119956 changed our semantics/requirements.)

We can probably also remove the WorkerRunnable wrapping that remains in the method there, but that should likely be a separate bug to minimize potential regressions.

Comment 1

[Andrew Sutherland [:asuth] (he/him)]

Attachment: Bug 1839670 - Remove the requirement that runnables dispatched to workers need to be nsIDiscardableRunnable. r=#dom-workers!

In bug 1800659 we removed our use of cancellation, but we retained the
DEBUG assertions that require our runnables to be discardable. This
patch removes the DEBUG assertions.

However, note that at this time we continue to retain:

• Support in ExternalRunnableWrapper::Cancel to QI the wrapped runnable
  to nsIDiscardableRunnable and we will call its OnDiscard method if it
  QIs.
• The limited cancellation support where WorkerRunnable::Run checks
  WorkerPrivate::CancelBeforeWorkerScopeConstructed which will be
  flipped if the worker transition to Canceling without ever having
  created a global.
• The limited cancellation support where
  WorkerPrivate::ClearPreStartRunnables explicitly invokes Cancel on
  all of the WorkerRunnables in WorkerPrivate::mPreStartRunnables.
  Note that the runnables will all explicitly be WorkerRunnable
  instances in that case. Runnables can only get in that queue via
  WorkerPrivate::Dispatch or WorkerPrivate::EventTarget::Dispatch
  (where WorkerPrivate::EventTarget is explicitly only ever used by
  syncloops created by WorkerPrivate::CreateNewSyncLoop and it always
  wraps all of its runnables.)

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/e9232e3706ab
Remove the requirement that runnables dispatched to workers need to be nsIDiscardableRunnable. r=dom-worker-reviewers,smaug

Comment 3

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/e9232e3706ab