Stop doing O(n^2) work to find event's home (eventShouldLiveIn)
#3227
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In certain rooms (e.g. with many state changes hidden via user preferences), the events array presented to `eventShouldLiveIn` may contain 100s of events. As part of its various checks, `eventShouldLiveIn` would get an event's associated ID (reply / relation / redaction parent). It would then use `events.find` to search the entire (possibly large) `events` array to look for the parent. (This by itself seems sub-optimal and should probably change to use a map.) For many events in a room, there is no associated ID. Unfortunately, `eventShouldLiveIn` did not check whether the associated ID actually exists before running off to search all of `events`, resulting in O(n^2) work. This changes `eventShouldLiveIn` to first check that there is an associated ID before proceeding with its (slow) search. For some rooms, this change drastically improves performance from ~100% CPU usage to nearly idle. Signed-off-by: J. Ryan Stinnett <jryans@gmail.com>
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LGTM otherwise
Co-authored-by: Michael Telatynski <7t3chguy@gmail.com>
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* Allow via_servers property in findPredecessor (update to MSC3946) ([\matrix-org#3240](matrix-org#3240)). Contributed by @andybalaam. * Fire `closed` event when IndexedDB closes unexpectedly ([\matrix-org#3218](matrix-org#3218)). * Implement MSC3952: intentional mentions ([\matrix-org#3092](matrix-org#3092)). Fixes element-hq/element-web#24376. * Send one time key count and unused fallback keys for rust-crypto ([\matrix-org#3215](matrix-org#3215)). Fixes element-hq/element-web#24795. Contributed by @florianduros. * Improve `processBeaconEvents` hotpath ([\matrix-org#3200](matrix-org#3200)). * Implement MSC3966: a push rule condition to check if an array contains a value ([\matrix-org#3180](matrix-org#3180)). * indexddb-local-backend - return the current sync to database promise … ([\matrix-org#3222](matrix-org#3222)). Contributed by @texuf. * Revert "Add the call object to Call events" ([\matrix-org#3236](matrix-org#3236)). * Handle group call redaction ([\matrix-org#3231](matrix-org#3231)). Fixes vector-im/voip-internal#128. * Stop doing O(n^2) work to find event's home (`eventShouldLiveIn`) ([\matrix-org#3227](matrix-org#3227)). Contributed by @jryans. * Fix bug where video would not unmute if it started muted ([\matrix-org#3213](matrix-org#3213)). Fixes element-hq/element-call#925. * Fixes to event encryption in the Rust Crypto implementation ([\matrix-org#3202](matrix-org#3202)).
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In certain rooms (e.g. with many state changes hidden via user preferences), the events array presented to
eventShouldLiveInmay contain 100s of events. As part of its various checks,eventShouldLiveInwould get an event's associated ID (reply / relation / redaction parent). It would then useevents.findto search the entire (possibly large)eventsarray to look for the parent. (This by itself seems sub-optimal and should probably change to use a map.)For many events in a room, there is no associated ID. Unfortunately,
eventShouldLiveIndid not check whether the associated ID actually exists before running off to search all ofevents, resulting in O(n^2) work.This changes
eventShouldLiveInto first check that there is an associated ID before proceeding with its (slow) search. For some rooms, this change drastically improves performance from ~100% CPU usage to nearly idle.Profile before
Profile after
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🐛 Bug Fixes
eventShouldLiveIn) (#3227). Contributed by @jryans.