sdk: consolidate attribute normalization in attrnorm

internal/shared/attrdedup/dedup.go.tmpl → internal/shared/attrnorm/dedup.go.tmpl

@@ -2,10 +2,10 @@
 // SPDX-License-Identifier: Apache-2.0
 
 // DO NOT MODIFY. Generated by gotmpl.
-// source: internal/shared/attrdedup/dedup.go.tmpl
+// source: internal/shared/attrnorm/dedup.go.tmpl
 
-// Package attrdedup deduplicates attribute map values.
-package attrdedup
+// Package attrnorm normalizes attribute values.
+package attrnorm
 
 import (
 	"reflect"

internal/shared/attrdedup/dedup_test.go.tmpl → internal/shared/attrnorm/dedup_test.go.tmpl

@@ -2,9 +2,9 @@
 // SPDX-License-Identifier: Apache-2.0
 
 // DO NOT MODIFY. Generated by gotmpl.
-// source: internal/shared/attrdedup/dedup_test.go.tmpl
+// source: internal/shared/attrnorm/dedup_test.go.tmpl
 
-package attrdedup
+package attrnorm
 
 import (
 	"testing"

internal/shared/attrnorm/truncate.go.tmpl

@@ -0,0 +1,232 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+// DO NOT MODIFY. Generated by gotmpl.
+// source: internal/shared/attrnorm/truncate.go.tmpl
+
+package attrnorm
+
+import (
+	"slices"
+	"strings"
+	"unicode/utf8"
+
+	"go.opentelemetry.io/otel/attribute"
+)
+
+// Truncate returns a truncated version of attr. Only string, string slice,
+// byte slice, slice, and map attribute values are truncated. String values are
+// truncated to at most a length of limit. Each string slice value is truncated
+// in this fashion (the slice length itself is unaffected), and byte slice
+// values are truncated to at most limit bytes. For slice and map attribute
+// values, the limit is applied recursively to contained values.
+//
+// No truncation is performed for a negative limit.
+func Truncate(limit int, attr attribute.KeyValue) attribute.KeyValue {
+	if limit < 0 {
+		return attr
+	}
+	switch attr.Value.Type() {
+	case attribute.STRING:
+		v := attr.Value.AsString()
+		return attr.Key.String(truncate(limit, v))
+	case attribute.STRINGSLICE:
+		v := attr.Value.AsStringSlice()
+		for i := range v {
+			v[i] = truncate(limit, v[i])
+		}
+		return attr.Key.StringSlice(v)
+	case attribute.BYTESLICE:
+		v := attr.Value.AsString()
+		if len(v) > limit {
+			return attr.Key.ByteSlice([]byte(v[:limit]))
+		}
+		return attr
+	case attribute.SLICE:
+		v := attr.Value.AsSlice()
+		if !slices.ContainsFunc(v, func(e attribute.Value) bool { return needsTruncation(limit, e) }) {
+			return attr
+		}
+		newV := make([]attribute.Value, len(v))
+		for i, elem := range v {
+			newV[i] = TruncateValue(limit, elem)
+		}
+		return attr.Key.Slice(newV...)
+	case attribute.MAP:
+		v := attr.Value.AsMap()
+		if !slices.ContainsFunc(v, func(kv attribute.KeyValue) bool { return needsTruncation(limit, kv.Value) }) {
+			return attr
+		}
+		newV := make([]attribute.KeyValue, len(v))
+		for i, elem := range v {
+			elem.Value = TruncateValue(limit, elem.Value)
+			newV[i] = elem
+		}
+		return attr.Key.Map(newV...)
+	}
+	return attr
+}
+
+// TruncateValue returns a truncated version of v. Only string, string
+// slice, byte slice, and (recursively) slice and map values are modified.
+//
+// No truncation is performed for a negative limit.
+func TruncateValue(limit int, v attribute.Value) attribute.Value {
+	if limit < 0 {
+		return v
+	}
+
+	switch v.Type() {
+	case attribute.STRING:
+		return attribute.StringValue(truncate(limit, v.AsString()))
+	case attribute.STRINGSLICE:
+		ss := v.AsStringSlice()
+		for i := range ss {
+			ss[i] = truncate(limit, ss[i])
+		}
+		return attribute.StringSliceValue(ss)
+	case attribute.BYTESLICE:
+		// len(v.AsString()) is identical to len(v.AsByteSlice()) but
+		// avoids allocating the full slice before truncation.
+		s := v.AsString()
+		if limit >= 0 && len(s) > limit {
+			return attribute.ByteSliceValue([]byte(s[:limit]))
+		}
+	case attribute.SLICE:
+		sl := v.AsSlice()
+		if !slices.ContainsFunc(sl, func(e attribute.Value) bool { return needsTruncation(limit, e) }) {
+			return v
+		}
+		newSl := make([]attribute.Value, len(sl))
+		for i, elem := range sl {
+			newSl[i] = TruncateValue(limit, elem)
+		}
+		return attribute.SliceValue(newSl...)
+	case attribute.MAP:
+		m := v.AsMap()
+		if !slices.ContainsFunc(m, func(kv attribute.KeyValue) bool { return needsTruncation(limit, kv.Value) }) {
+			return v
+		}
+		newM := make([]attribute.KeyValue, len(m))
+		for i, elem := range m {
+			elem.Value = TruncateValue(limit, elem.Value)
+			newM[i] = elem
+		}
+		return attribute.MapValue(newM...)
+	}
+	return v
+}
+
+// stringNeedsTruncation reports whether s would be modified by truncate for the
+// given limit.
+func stringNeedsTruncation(limit int, s string) bool {
+	if limit < 0 || len(s) <= limit {
+		return false
+	}
+	return utf8.RuneCountInString(s) > limit || !utf8.ValidString(s)
+}
+
+// needsTruncation reports whether v would be modified by TruncateValue for the
+// given limit.
+func needsTruncation(limit int, v attribute.Value) bool {
+	switch v.Type() {
+	case attribute.STRING:
+		return stringNeedsTruncation(limit, v.AsString())
+	case attribute.BYTESLICE:
+		// len(v.AsString()) is identical to len(v.AsByteSlice()) but
+		// avoids memory allocation.
+		if limit >= 0 && len(v.AsString()) > limit {
+			return true
+		}
+	case attribute.STRINGSLICE:
+		for _, s := range v.AsStringSlice() {
+			if stringNeedsTruncation(limit, s) {
+				return true
+			}
+		}
+	case attribute.SLICE:
+		return slices.ContainsFunc(v.AsSlice(), func(e attribute.Value) bool { return needsTruncation(limit, e) })
+	case attribute.MAP:
+		return slices.ContainsFunc(
+			v.AsMap(),
+			func(kv attribute.KeyValue) bool { return needsTruncation(limit, kv.Value) },
+		)
+	}
+	return false
+}
+
+// truncate returns a truncated version of s such that it contains less than
+// the limit number of characters. Truncation is applied by returning the limit
+// number of valid characters contained in s.
+//
+// If limit is negative, it returns the original string.
+//
+// UTF-8 is supported. When truncating, all invalid characters are dropped
+// before applying truncation.
+//
+// If s already contains less than the limit number of bytes, it is returned
+// unchanged. No invalid characters are removed.
+func truncate(limit int, s string) string {
+	// This prioritize performance in the following order based on the most
+	// common expected use-cases.
+	//
+	//  - Short values less than the default limit (128).
+	//  - Strings with valid encodings that exceed the limit.
+	//  - No limit.
+	//  - Strings with invalid encodings that exceed the limit.
+	if limit < 0 || len(s) <= limit {
+		return s
+	}
+
+	// Optimistically, assume all valid UTF-8.
+	var b strings.Builder
+	count := 0
+	for i, c := range s {
+		if c != utf8.RuneError {
+			count++
+			if count > limit {
+				return s[:i]
+			}
+			continue
+		}
+
+		_, size := utf8.DecodeRuneInString(s[i:])
+		if size == 1 {
+			// Invalid encoding.
+			b.Grow(len(s) - 1)
+			_, _ = b.WriteString(s[:i])
+			s = s[i:]
+			break
+		}
+	}
+
+	// Fast-path, no invalid input.
+	if b.Cap() == 0 {
+		return s
+	}
+
+	// Truncate while validating UTF-8.
+	for i := 0; i < len(s) && count < limit; {
+		c := s[i]
+		if c < utf8.RuneSelf {
+			// Optimization for single byte runes (common case).
+			_ = b.WriteByte(c)
+			i++
+			count++
+			continue
+		}
+
+		_, size := utf8.DecodeRuneInString(s[i:])
+		if size == 1 {
+			// We checked for all 1-byte runes above, this is a RuneError.
+			i++
+			continue
+		}
+
+		_, _ = b.WriteString(s[i : i+size])
+		i += size
+		count++
+	}
+
+	return b.String()
+}