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Bug 1676618 - [devtools] Do not create legacy listeners twice for same target r=ochameau,nchevobbe

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Differential Revision: https://phabricator.services.mozilla.com/D102307
This commit is contained in:
Julian Descottes 2021-01-20 14:55:49 +00:00
parent 8beeb972c0
commit cb6de899a4
1 changed files with 33 additions and 1 deletions
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34
devtools/shared/resources/resource-watcher.js
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@ -40,6 +40,12 @@ class ResourceWatcher {
this._cache = [];
this._listenerCount = new Map();
// WeakMap used to avoid starting a legacy listener twice for the same
// target + resource-type pair. Legacy listener creation can be subject to
// race conditions.
// Maps a target front to an array of resource types.
this._existingLegacyListeners = new WeakMap();
this._notifyWatchers = this._notifyWatchers.bind(this);
this._throttledNotifyWatchers = throttle(this._notifyWatchers, 100);
}
@ -331,7 +337,10 @@ class ResourceWatcher {
* See _onTargetAvailable for arguments, they are the same.
*/
_onTargetDestroyed({ targetFront }) {
//TODO: Is there a point in doing anything?
// Clear the map of legacy listeners for this target.
this._existingLegacyListeners.set(targetFront, []);
//TODO: Is there a point in doing anything else?
//
// We could remove the available/destroyed event, but as the target is destroyed
// its listeners will be destroyed anyway.
@ -716,6 +725,20 @@ class ResourceWatcher {
if (!(resourceType in LegacyListeners)) {
throw new Error(`Missing legacy listener for ${resourceType}`);
}
const legacyListeners =
this._existingLegacyListeners.get(targetFront) || [];
if (legacyListeners.includes(resourceType)) {
console.error(
`Already started legacy listener for ${resourceType} on ${targetFront.actorID}`
);
return Promise.resolve();
}
this._existingLegacyListeners.set(
targetFront,
legacyListeners.concat(resourceType)
);
return LegacyListeners[resourceType]({
targetList: this.targetList,
targetFront,
@ -793,6 +816,15 @@ class ResourceWatcher {
// We are aware of one case where that might be useful.
// When a panel is disabled via the options panel, after it has been opened.
// Would that justify doing this? Is there another usecase?
// XXX: This is most likely only needed to avoid growing the Map infinitely.
// Unless in the "disabled panel" use case mentioned in the comment above,
// we should not see the same target actorID again.
const listeners = this._existingLegacyListeners.get(targetFront);
if (listeners && listeners.includes(resourceType)) {
const remainingListeners = listeners.filter(l => l !== resourceType);
this._existingLegacyListeners.set(targetFront, remainingListeners);
}
}
}