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perf(web-watcher): rate-limit page-title lookups - #345
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ErikBjare merged 4 commits intoOct 11, 2026
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Every content-change event from a browser walked the event's subtree for a WebView title (up to 2000 binder calls on the service's main thread), including for Firefox where the lookup can never match. Skip Firefox and look the title up at most every 500ms while it is unknown and every 5s once found.
A rate-limited lookup could miss the title for good: if the event that carried it was skipped and the page then went quiet, the session ended with an empty title. When an event is skipped, schedule one lookup for when the gate next allows it, on a fresh tree from rootInActiveWindow while the same browser is still in front. The timing moves into TitleLookupGate with an injected clock so its boundaries are unit-tested.
…changes A single global pending flag blocked the follow-up for a newly opened browser while one for the previous browser was waiting, and the old one then exited because the session had moved on. Track which browser the pending follow-up is for and replace it on a switch.
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…check A pending 5s recheck for the same browser blocked scheduling the 500ms retry a newly opened page needs, so its title could be lost if the user left the page before the recheck ran. Track when the pending follow-up runs and replace it when the new one is due sooner.
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Part of #333.
WebWatchersubscribes totypeWindowContentChanged, which a browser emits up to every 100 ms (notificationTimeout) while a page is loading or animating. For every such event it ranfindWebView, a bounded walk of the event's subtree of up toMAX_TRAVERSAL_NODES(2000)getChildbinder calls, on the accessibility service's main thread. For Firefox the walk can never match (documented onfindWebView), so it was pure cost.Change
BrowserSessionTrackerexposeshasTitle(title seen since the URL last changed).Testing
./gradlew :mobile:testStandardDebugUnitTestpasses.