Avoid unnecessary synchronization in QueryCache#queryContains - #2298
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1wairesd wants to merge 2 commits into
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Avoid unnecessary synchronization in QueryCache#queryContains#22981wairesd wants to merge 2 commits into
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Use a lock-free ConcurrentHashMap.get() before falling back to compute() to avoid bucket-level locking when the result is already cached. On the hot path (repeated queries to the same block position within a tick), this eliminates contention on the CHM segment lock entirely, reducing overhead to a single volatile read.
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It looks like the lock ensures that access to the inner map is synchronized, which seems to be required. |
Replace EnumMap with ConcurrentHashMap in QueryOption.createCache() so that concurrent reads and computeIfAbsent calls on the inner map are thread-safe. This allows QueryCache.queryContains() to use a lock-free get() fast-path before falling back to compute(), avoiding unnecessary bucket-level locking on repeated queries to the same location. Use QueryOption.values().length as initial capacity since the map will never hold more entries than there are QueryOption enum constants.
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Fixed the thread-safety concern by replacing EnumMap with ConcurrentHashMap for the inner option map in all three QueryOption.createCache() implementations. The computeIfAbsent calls on the inner map are now safe, and the lock-free get() fast-path in QueryCache.queryContains() is correct. |
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Use a lock-free ConcurrentHashMap.get() before falling back to compute() to avoid bucket-level locking when the result is already cached. On the hot path (repeated queries to the same block position within a tick), this eliminates contention on the CHM segment lock entirely, reducing overhead to a single volatile read.