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Robert Pająk
bec9f66b45
Fixes #7955 Per the OTel spec, attribute value limits must be applied recursively to array elements. Previously truncateAttr only handled STRING and STRINGSLICE. Add a SLICE case to truncateAttr and two unexported helpers: - truncateValue: recursively truncates STRING, STRINGSLICE, and SLICE - needsTruncation: pre-scan guard that avoids allocating a new slice when no element would be modified (mirrors sdk/log's pattern) ``` goarch: amd64 pkg: go.opentelemetry.io/otel/sdk/trace cpu: 13th Gen Intel(R) Core(TM) i7-13800H BenchmarkSpanLimits/None-20 205869 6757 ns/op 11296 B/op 38 allocs/op BenchmarkSpanLimits/AttributeValueLengthLimit-20 189799 5271 ns/op 11712 B/op 45 allocs/op BenchmarkSpanLimits/AttributeCountLimit-20 135494 9970 ns/op 10592 B/op 38 allocs/op BenchmarkSpanLimits/EventCountLimit-20 121084 9672 ns/op 10224 B/op 35 allocs/op BenchmarkSpanLimits/LinkCountLimit-20 110524 9419 ns/op 9824 B/op 35 allocs/op BenchmarkSpanLimits/AttributePerEventCountLimit-20 123159 9308 ns/op 11296 B/op 38 allocs/op BenchmarkSpanLimits/AttributePerLinkCountLimit-20 146022 9337 ns/op 11296 B/op 38 allocs/op ``` The new `attribute.SLICE` item makes `BenchmarkSpanLimits/AttributeValueLengthLimit` ~12% slower with 5 extra allocs in that path compared to `main`. This is fine as 3 strings and 2 arrays need to be allocated because of the limits+truncation. ``` SpanLimits/AttributeValueLengthLimit 5.030µs ± 2% 5.651µs ± 2% +12.34% (p=0.000 n=10) SpanLimits/AttributeValueLengthLimit 10.53KiB ± 0% 11.44KiB ± 0% +8.61% (p=0.000 n=10) SpanLimits/AttributeValueLengthLimit 40.00 allocs 45.00 allocs +12.50% (p=0.000 n=10) ```