Fix RawBsonDocument encoding performance regression#1888
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vbabanin wants to merge 1 commit intomongodb:mainfrom
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Fix RawBsonDocument encoding performance regression#1888vbabanin wants to merge 1 commit intomongodb:mainfrom
vbabanin wants to merge 1 commit intomongodb:mainfrom
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Add instanceof check in BsonDocumentCodec and BsonArrayCodec to route RawBsonDocument values to RawBsonDocumentCodec, restoring efficient byte-copy encoding. Previous BsonType-based lookup led to sub-optimal performance as it could not distinguish RawBsonDocument from BsonDocument. JAVA-6101
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PR #1632 optimized codec lookup from class-based (
codecRegistry.get(value.getClass())) to BsonType-based (bsonTypeCodecMap.get(value.getBsonType())). This is faster, but it regressed encoding of nestedRawBsonDocumentinsideBsonDocument / BsonArraybecauseRawBsonDocumentandBsonDocumentboth reportBsonType.DOCUMENT. NestedRawBsonDocumentswere encoded viaBsonDocumentCodec, triggering full deserialize and re-serialize instead of thewriter.pipe(reader)byte-copy path.Changes:
instanceof RawBsonDocumentcheck before the BsonType lookup. This keeps the BsonType fast path for the common case while correctly routing the special case forRawBsonDocument.RawBsonNestedEncodingBenchmarkandRawBsonArrayEncodingBenchmarkto CI to prevent regressions for themongot.Why not revert the optimization?
Reverting to class-based lookup would fix correctness but lose the performance gains from PR #1632 (
BsonTypelookup is an array index vsConcurrentHashMaplookup). The instanceof check is negligible and only affects paths withRawBsonDocument.