Steve Yurong Su created IOTDB-5925:
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Summary: Pipe: WAL Resource Management
Key: IOTDB-5925
URL: https://issues.apache.org/jira/browse/IOTDB-5925
Project: Apache IoTDB
Issue Type: Task
Reporter: Steve Yurong Su
This code is designed to manage PipeWAL resources by implementing safe and
efficient reference counting for these resources, as well as regularly checking
if these resources have expired or become invalid to ensure code integrity.
The `PipeWALResourceManager` class uses a `HashMap` called
`memtableIdToPipeWALResourceMap` to store `PipeWALResource` objects mapped to
their corresponding memtable IDs. It also uses an array of `ReentrantLocks`
called `memtableIdSegmentLocks` to synchronize concurrent access to the
`memtableIdToPipeWALResourceMap` hash map by dividing the map into segments
based on the number of locks.
The code schedules the `PIPE_WAL_RESOURCE_TTL_CHECKER`, a
`ScheduledExecutorService`, using `IoTDBThreadPoolFactory`, to regularly check
for expired or invalid resources, based on a minimum time to live in
milliseconds. The `pin` and `unpin` methods increment and decrement the
reference count for the memtable IDs respectively, ensuring that a memtable
cannot be removed from the `memtableIdToPipeWALResourceMap` hash map if it is
still being used by other clients.
Finally, the `close` method cancels the `ttlCheckerFuture`, closes all
remaining `PipeWALResource` objects and removes them from the
`memtableIdToPipeWALResourceMap` hash map, while the `getReferenceCount` method
returns the current reference count for a specified memtable ID.
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