* Optimize s3api encodePath to eliminate O(n^2) allocations
encodePath built its result via string concatenation in a loop, which is
O(n^2) in allocations. For non-ASCII (e.g. Chinese) runes it additionally
called make + hex.EncodeToString + strings.ToUpper per byte (~10 allocations
per character). Under high QPS with long non-ASCII object keys this produced
a very high allocation rate, frequent GC and long GC pauses, causing S3
request latency spikes.
Replace with a preallocated strings.Builder, a manual hex lookup table, and a
zero-allocation fast path. EncodePath now delegates to encodePath to remove
the duplicated implementation. Output is byte-for-byte identical, verified by
TestEncodePath and TestEncodePathEqual.
Benchmark (long Chinese path): 261 -> 1 allocs/op, 35810 -> 480 B/op, 7.5x faster.
Load test (50M calls): 212x fewer allocations, 76x fewer GC cycles.
* s3api: drop regexp from encodePath fast path
The unreserved-character scan already decides whether any byte needs
encoding, so reservedObjectNames.MatchString was a redundant second pass
that also ran the RE2 engine on every authenticated request. Rely on the
scan alone; output is unchanged. The ASCII fast path drops from ~188ns to
~11ns per call.
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Co-authored-by: LiuDoge <liudoge@LiuDogedeMacBook-Air.local>
Co-authored-by: Chris Lu <chris.lu@gmail.com>
