Azure: Reduce allocations in ADLSLocation URI parsing#16788
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Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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ADLSLocation is constructed once per FileIO operation (newInputFile, newOutputFile, deleteFile, listPrefix, deletePrefix all call new ADLSLocation(path)), so its constructor is on the metadata path of every scan and commit.
The constructor split the authority with String.split("@", -1) and then extracted the storage account with host.split("\.", -1)[0]. The second split is the wasteful part: to read the account it materializes every dotted segment of the host (account.dfs.core.windows.net produces 5 strings plus the backing array) and then discards all but the first. This change parses the same fields with indexOf/substring, dropping the intermediate ArrayList, array, and unused substrings. The regex match is kept for scheme validation, so all parsing and error behavior is unchanged.
Behavior is identical for every valid abfs/abfss/wasb/wasbs URI (zero or one @, host with or without dots); only pathological multi-@ authorities, which are already invalid, would differ. The storage-account extraction now guards the no-dot case (indexOf returns -1) explicitly, which a new test pins.
Local JMH results (AverageTime, 5x1s warmup, 5x1s measurement, 1 fork, gc profiler; gc.alloc.rate.norm is deterministic):
That is roughly -40% allocation and about 1.6x faster per parse. The benchmark was run locally and is not included (the azure module has no JMH source set).
Tests: TestADLSLocation already covers the abfs/abfss/wasb/wasbs, with/without container, no-path and host-extraction cases; added testHostWithoutDot to pin the no-dot storage-account branch.