99 lines
2.4 KiB
JSON
99 lines
2.4 KiB
JSON
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{
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"date": "2026-07-22",
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"status": "accepted",
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"scope": "CachedBlobBackend range reads",
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"contract": {
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"range_semantics": "[start, end)",
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"production_change": "Replace end - start + 1 with end.saturating_sub(start) on cold and hot cached reads."
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},
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"baseline_correctness_probe": {
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"ranges": [
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"[0, 1)",
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"[1, 3)",
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"[3, 3)",
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"[2, EOF)"
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],
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"expected_lengths": [
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1,
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2,
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0,
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4
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],
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"local_backend_lengths": [
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1,
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2,
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0,
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4
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],
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"historical_cached_backend_lengths": [
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2,
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3,
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1,
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4
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],
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"cold_fill": {
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"remote_gets": 1,
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"remote_bytes": 6,
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"elapsed_us": 408.5
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},
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"hot_read_loop": {
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"iterations": 500,
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"local_bytes": 1000,
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"historical_cached_bytes": 1500,
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"local_average_us": 32.16,
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"historical_cached_average_us": 30.839
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},
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"outcome": "failed: the cached backend returned one extra byte whenever end was present"
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},
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"candidate_correctness": {
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"cached_backend_lengths": [
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1,
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2,
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0,
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4
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],
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"cold_fill_remote_gets": 1,
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"cold_fill_remote_bytes": 6,
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"hot_read_loop_bytes": 1000,
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"focused_test": "cargo test --lib cached_blob_backend::tests::range_end_is_exclusive_on_cold_and_hot_cache_reads",
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"focused_test_result": "1 passed; 0 failed"
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},
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"standalone_ab": {
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"source": "tools/perf-audit/cached_range_ab.rs",
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"command": "cargo run --release --manifest-path tools/perf-audit/Cargo.toml --bin cached_range_ab",
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"environment": {
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"os": "macos",
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"arch": "aarch64"
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},
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"range": {
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"start": 1,
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"end_exclusive": 3
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},
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"warmups_per_variant": 1000,
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"iterations_per_variant": 10000,
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"historical_inclusive": {
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"bytes": 30000,
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"bytes_per_read": 3,
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"p50_us": 8.459,
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"p95_us": 28.292,
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"checksum": 2970000
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},
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"corrected_exclusive": {
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"bytes": 20000,
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"bytes_per_read": 2,
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"p50_us": 8.459,
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"p95_us": 26.917,
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"checksum": 1970000
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},
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"delta_percent": {
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"bytes": -33.333,
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"p50_latency": 0.0,
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"p95_latency": -4.86
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}
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},
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"decision": {
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"status": "accepted",
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"reason": "The candidate restores the exclusive-end contract, removes exactly one surplus byte per bounded cached range, adds no remote request or round trip, and is latency-neutral at p50 while improving this sample's p95."
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}
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}
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