mirror of
https://github.com/honeymoose/OpenSearch.git
synced 2025-02-07 21:48:39 +00:00
2c38d12e23
The current implementation starts/stops watcher using an executor. This can result in our of order operations. This commit reduces those executor calls to an absolute minimum in order to be able to do state changes within the cluster state listener method, which runs in sequence. When a state change occurs that forces the watcher service to pause (like no watcher index, no master node, no local shards), the service is now in a paused state. Pausing is a super lightweight operation, which marks the ExecutionService as paused and waits for the currently executing watches to finish in the background via an executor. The same applies for stopping, the potentially long running operation is outsourced in to an executor, as waiting for executed watches is decoupled from the current state. The only other long running operation is starting, where watches need to be loaded. This is also done via an executor, but has an additional protection by checking the cluster state version it was started with. If another cluster state version was trying to load the watches, then this loading will not take effect. This PR also cleans up some unused states, like the a simple boolean in the HistoryStore/TriggeredWatchStore marking it as started or stopped, as this can now be caught in the execution service. Another advantage of this approach is the fact, that now only triggered watches are not getting executed, while watches that are run via the Execute Watch API will still be executed regardless if watcher is stopped or not. Lastly the TickerScheduleTriggerEngine thread now only starts on data nodes.