1663896 - Simultaneous calls to watchResources lead to missing resources from targets

Status: RESOLVED FIXED

(DevTools :: Framework, task, P3)

Description

[Julian Descottes [:jdescottes]]

If you perform two calls to resourceWatcher.watchResources "simultaneously", the second call will not be able to retrieve existing resources coming from targets.

This comes from the implementation of _watchAllTargets:

  async _watchAllTargets() {
    if (this._isWatchingTargets) {
      return;
    }
    this._isWatchingTargets = true;
    await this.targetList.watchTargets(
      this.targetList.ALL_TYPES,
      this._onTargetAvailable,
      this._onTargetDestroyed
    );
  }

https://searchfox.org/mozilla-central/rev/b2716c233e9b4398fc5923cbe150e7f83c7c6c5b/devtools/shared/resources/resource-watcher.js#173-183

Based on this, the first call to watchResources will flip _isWatchingTargets to true, and the second call will bypass it. It means the second call will jump straight to the "startListening" step, before the "resource-available-form" listeners have been added on the existing targets.

Comment 1

[Julian Descottes [:jdescottes]]

Attachment: Bug 1663896 - Always wait for _watchAllTargets to resolve in DevTools ResourceWatcher

Comment 2

[Julian Descottes [:jdescottes]]

Attachment: Bug 1663896 - Remove async for TargetList::unwatchTargets and update call sites

Depends on D89583

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/b0b56040bb4e
Always wait for _watchAllTargets to resolve in DevTools ResourceWatcher r=ochameau
https://hg.mozilla.org/integration/autoland/rev/1ed7fee9c145
Remove async for TargetList::unwatchTargets and update call sites r=ochameau

Comment 4

[Alexandru Michis [:malexandru]]

https://hg.mozilla.org/mozilla-central/rev/b0b56040bb4e
https://hg.mozilla.org/mozilla-central/rev/1ed7fee9c145