Switch Stream back to having an AttributeFilter field and add New*Filter functions (#4444)

* Add allow/deny attr filters

* Revert "Replace `Stream.AttributeFilter` with `AllowAttributeKeys` (#4288)"

This reverts commit 1633c74aea.

* Rename new attr filter funcs

Do not include the term "Attribute" in a creation function of the
"attribute" pkg.

* Update the AttributeFilter field documentation

* Add tests for filter creation funcs

* Add change to changelog

* Apply feedback

* Use NewDenyKeysFilter for allow-all and deny-list filters

* Remove links from field docs

These links do not render.

---------

Co-authored-by: Chester Cheung <cheung.zhy.csu@gmail.com>

attribute/filter.go

@@ -0,0 +1,60 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package attribute // import "go.opentelemetry.io/otel/attribute"
+
+// Filter supports removing certain attributes from attribute sets. When
+// the filter returns true, the attribute will be kept in the filtered
+// attribute set. When the filter returns false, the attribute is excluded
+// from the filtered attribute set, and the attribute instead appears in
+// the removed list of excluded attributes.
+type Filter func(KeyValue) bool
+
+// NewAllowKeysFilter returns a Filter that only allows attributes with one of
+// the provided keys.
+//
+// If keys is empty a deny-all filter is returned.
+func NewAllowKeysFilter(keys ...Key) Filter {
+	if len(keys) <= 0 {
+		return func(kv KeyValue) bool { return false }
+	}
+
+	allowed := make(map[Key]struct{})
+	for _, k := range keys {
+		allowed[k] = struct{}{}
+	}
+	return func(kv KeyValue) bool {
+		_, ok := allowed[kv.Key]
+		return ok
+	}
+}
+
+// NewDenyKeysFilter returns a Filter that only allows attributes
+// that do not have one of the provided keys.
+//
+// If keys is empty an allow-all filter is returned.
+func NewDenyKeysFilter(keys ...Key) Filter {
+	if len(keys) <= 0 {
+		return func(kv KeyValue) bool { return true }
+	}
+
+	forbid := make(map[Key]struct{})
+	for _, k := range keys {
+		forbid[k] = struct{}{}
+	}
+	return func(kv KeyValue) bool {
+		_, ok := forbid[kv.Key]
+		return !ok
+	}
+}

attribute/filter_test.go

@@ -0,0 +1,87 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package attribute
+
+import "testing"
+
+func TestNewAllowKeysFilter(t *testing.T) {
+	keys := []string{"zero", "one", "two"}
+	attrs := []KeyValue{Int(keys[0], 0), Int(keys[1], 1), Int(keys[2], 2)}
+
+	t.Run("Empty", func(t *testing.T) {
+		empty := NewAllowKeysFilter()
+		for _, kv := range attrs {
+			if empty(kv) {
+				t.Errorf("empty NewAllowKeysFilter filter accepted %v", kv)
+			}
+		}
+	})
+
+	t.Run("Partial", func(t *testing.T) {
+		partial := NewAllowKeysFilter(Key(keys[0]), Key(keys[1]))
+		for _, kv := range attrs[:2] {
+			if !partial(kv) {
+				t.Errorf("partial NewAllowKeysFilter filter denied %v", kv)
+			}
+		}
+		if partial(attrs[2]) {
+			t.Errorf("partial NewAllowKeysFilter filter accepted %v", attrs[2])
+		}
+	})
+
+	t.Run("Full", func(t *testing.T) {
+		full := NewAllowKeysFilter(Key(keys[0]), Key(keys[1]), Key(keys[2]))
+		for _, kv := range attrs {
+			if !full(kv) {
+				t.Errorf("full NewAllowKeysFilter filter denied %v", kv)
+			}
+		}
+	})
+}
+
+func TestNewDenyKeysFilter(t *testing.T) {
+	keys := []string{"zero", "one", "two"}
+	attrs := []KeyValue{Int(keys[0], 0), Int(keys[1], 1), Int(keys[2], 2)}
+
+	t.Run("Empty", func(t *testing.T) {
+		empty := NewDenyKeysFilter()
+		for _, kv := range attrs {
+			if !empty(kv) {
+				t.Errorf("empty NewDenyKeysFilter filter denied %v", kv)
+			}
+		}
+	})
+
+	t.Run("Partial", func(t *testing.T) {
+		partial := NewDenyKeysFilter(Key(keys[0]), Key(keys[1]))
+		for _, kv := range attrs[:2] {
+			if partial(kv) {
+				t.Errorf("partial NewDenyKeysFilter filter accepted %v", kv)
+			}
+		}
+		if !partial(attrs[2]) {
+			t.Errorf("partial NewDenyKeysFilter filter denied %v", attrs[2])
+		}
+	})
+
+	t.Run("Full", func(t *testing.T) {
+		full := NewDenyKeysFilter(Key(keys[0]), Key(keys[1]), Key(keys[2]))
+		for _, kv := range attrs {
+			if full(kv) {
+				t.Errorf("full NewDenyKeysFilter filter accepted %v", kv)
+			}
+		}
+	})
+}

attribute/set.go

@@ -39,13 +39,6 @@ type (
 		iface interface{}
 	}
 
-	// Filter supports removing certain attributes from attribute sets. When
-	// the filter returns true, the attribute will be kept in the filtered
-	// attribute set. When the filter returns false, the attribute is excluded
-	// from the filtered attribute set, and the attribute instead appears in
-	// the removed list of excluded attributes.
-	Filter func(KeyValue) bool
-
 	// Sortable implements sort.Interface, used for sorting KeyValue. This is
 	// an exported type to support a memory optimization. A pointer to one of
 	// these is needed for the call to sort.Stable(), which the caller may