PoC: Add experimental support for bound sum instruments

attribute/set.go

@@ -211,6 +211,47 @@ func NewSet(kvs ...KeyValue) Set {
 	return s
 }
 
+// NewDistinctWithFilter returns a Distinct identifier for the filtered attribute set,
+// and the sorted and de-duplicated slice of attributes. It modifies the input slice
+// in-place to sort and de-duplicate the attributes.
+//
+// The returned Distinct represents the equivalence class of the attribute set after
+// the filter is applied. The returned slice contains all unique attributes, including
+// those that did not pass the filter.
+func NewDistinctWithFilter(kvs []KeyValue, filter Filter) (Distinct, []KeyValue) {
+	if len(kvs) == 0 {
+		return Distinct{hash: emptyHash}, kvs
+	}
+
+	// Stable sort so the following de-duplication can implement
+	// last-value-wins semantics.
+	slices.SortStableFunc(kvs, func(a, b KeyValue) int {
+		return cmp.Compare(a.Key, b.Key)
+	})
+
+	position := len(kvs) - 1
+	offset := position - 1
+
+	// De-duplicate with last-value-wins semantics.
+	for ; offset >= 0; offset-- {
+		if kvs[offset].Key == kvs[position].Key {
+			continue
+		}
+		position--
+		kvs[offset], kvs[position] = kvs[position], kvs[offset]
+	}
+	kvs = kvs[position:]
+
+	h := xxhash.New()
+	for _, kv := range kvs {
+		if filter == nil || filter(kv) {
+			h = hashKV(h, kv)
+		}
+	}
+
+	return Distinct{hash: h.Sum64()}, kvs
+}
+
 // NewSetWithSortable returns a new Set. See the documentation for
 // NewSetWithSortableFiltered for more details.
 //

attribute/set_test.go

@@ -254,6 +254,42 @@ func TestFiltering(t *testing.T) {
 	}
 }
 
+func TestNewDistinctWithFilter(t *testing.T) {
+	kvs := []attribute.KeyValue{
+		attribute.String("B", "1"),
+		attribute.String("A", "1"),
+		attribute.String("C", "1"),
+		attribute.String("B", "2"), // Duplicate key, should win over B=1
+		attribute.String("D", "1"),
+	}
+	// Filter to keep A, B, and D. Drop C.
+	filter := func(kv attribute.KeyValue) bool {
+		return kv.Key != "C"
+	}
+
+	// Create a copy since NewDistinctWithFilter modifies in-place.
+	input := make([]attribute.KeyValue, len(kvs))
+	copy(input, kvs)
+
+	distinct, compacted := attribute.NewDistinctWithFilter(input, filter)
+
+	// Verify the returned slice is correctly sorted and de-duplicated.
+	// Note: the filter applies to the hash computation, NOT the physical slice returned.
+	require.Len(t, compacted, 4)
+	assert.Equal(t, "A", string(compacted[0].Key))
+	assert.Equal(t, "B", string(compacted[1].Key))
+	assert.Equal(t, "2", compacted[1].Value.AsString()) // Last value wins
+	assert.Equal(t, "C", string(compacted[2].Key))
+	assert.Equal(t, "D", string(compacted[3].Key))
+
+	// Verify the computed Distinct matches the baseline from NewSetWithFiltered.
+	input2 := make([]attribute.KeyValue, len(kvs))
+	copy(input2, kvs)
+	expectedSet, _ := attribute.NewSetWithFiltered(input2, filter)
+
+	assert.Equal(t, expectedSet.Equivalent(), distinct)
+}
+
 func TestUniqueness(t *testing.T) {
 	short := []attribute.KeyValue{
 		attribute.String("A", "0"),

internal/tools/go.mod

@@ -153,7 +153,7 @@ require (
 	github.com/maratori/testpackage v1.1.2 // indirect
 	github.com/matoous/godox v1.1.0 // indirect
 	github.com/mattn/go-colorable v0.1.14 // indirect
-	github.com/mattn/go-isatty v0.0.21 // indirect
+	github.com/mattn/go-isatty v0.0.22 // indirect
 	github.com/mattn/go-runewidth v0.0.23 // indirect
 	github.com/mgechev/revive v1.15.0 // indirect
 	github.com/mitchellh/go-homedir v1.1.0 // indirect

internal/tools/go.sum

@@ -340,8 +340,8 @@ github.com/matryer/is v1.4.0 h1:sosSmIWwkYITGrxZ25ULNDeKiMNzFSr4V/eqBQP0PeE=
 github.com/matryer/is v1.4.0/go.mod h1:8I/i5uYgLzgsgEloJE1U6xx5HkBQpAZvepWuujKwMRU=
 github.com/mattn/go-colorable v0.1.14 h1:9A9LHSqF/7dyVVX6g0U9cwm9pG3kP9gSzcuIPHPsaIE=
 github.com/mattn/go-colorable v0.1.14/go.mod h1:6LmQG8QLFO4G5z1gPvYEzlUgJ2wF+stgPZH1UqBm1s8=
-github.com/mattn/go-isatty v0.0.21 h1:xYae+lCNBP7QuW4PUnNG61ffM4hVIfm+zUzDuSzYLGs=
-github.com/mattn/go-isatty v0.0.21/go.mod h1:ZXfXG4SQHsB/w3ZeOYbR0PrPwLy+n6xiMrJlRFqopa4=
+github.com/mattn/go-isatty v0.0.22 h1:j8l17JJ9i6VGPUFUYoTUKPSgKe/83EYU2zBC7YNKMw4=
+github.com/mattn/go-isatty v0.0.22/go.mod h1:ZXfXG4SQHsB/w3ZeOYbR0PrPwLy+n6xiMrJlRFqopa4=
 github.com/mattn/go-runewidth v0.0.23 h1:7ykA0T0jkPpzSvMS5i9uoNn2Xy3R383f9HDx3RybWcw=
 github.com/mattn/go-runewidth v0.0.23/go.mod h1:XBkDxAl56ILZc9knddidhrOlY5R/pDhgLpndooCuJAs=
 github.com/mgechev/revive v1.15.0 h1:vJ0HzSBzfNyPbHKolgiFjHxLek9KUijhqh42yGoqZ8Q=

metric/x/bound.go

@@ -0,0 +1,27 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package x // import "go.opentelemetry.io/otel/metric/x"
+
+import (
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric"
+)
+
+// Float64Binder is an interface that can be implemented by instruments that support
+// binding attributes ahead of time.
+type Float64Binder interface {
+	// Bind returns a metric.Float64Counter for the given attributes.
+	// The returned counter is bound to the attributes and should be optimized
+	// for performance by avoiding map lookups on every Add call.
+	Bind(attrs ...attribute.KeyValue) metric.Float64Counter
+}
+
+// Int64Binder is an interface that can be implemented by instruments that support
+// binding attributes ahead of time.
+type Int64Binder interface {
+	// Bind returns a metric.Int64Counter for the given attributes.
+	// The returned counter is bound to the attributes and should be optimized
+	// for performance by avoiding map lookups on every Add call.
+	Bind(attrs ...attribute.KeyValue) metric.Int64Counter
+}