[pdata] Change outcome of misuse of oneof collection accessors. (#5034)

Change misuse outcome of `pdata.AttributeMap.MapVal()` and `pdata.AttributeValueSlice.SliceVal()`
  function calls. In case of type mismatch, they now return an invalid zero-initialized instance
  instead of returning a valid detached collection.

CHANGELOG.md

@@ -8,6 +8,9 @@
 - Remove pdata `InternalRep` deprecated funcs (#5018)
 - Remove service/defaultcomponents deprecated package (#5019)
 - Remove deprecated UseOpenTelemetryForInternalMetrics (#5026)
+- Change outcome of `pdata.Value.MapVal()` and `pdata.Value.SliceVal()` functions misuse. In case of
+  type mismatch, they now return an invalid zero-initialized instance instead of a detached
+  collection (#5034)
 
 ### 🚩 Deprecations 🚩
 

model/internal/pdata/common.go

@@ -233,27 +233,27 @@ func (v Value) BoolVal() bool {
 }
 
 // MapVal returns the map value associated with this Value.
-// If the Type() is not ValueTypeMap then returns an empty map. Note that modifying
-// such empty map has no effect on this Value.
+// If the Type() is not ValueTypeMap then returns an invalid map. Note that using
+// such map can cause panic.
 //
 // Calling this function on zero-initialized Value will cause a panic.
 func (v Value) MapVal() Map {
 	kvlist := v.orig.GetKvlistValue()
 	if kvlist == nil {
-		return NewMap()
+		return Map{}
 	}
 	return newMap(&kvlist.Values)
 }
 
 // SliceVal returns the slice value associated with this Value.
-// If the Type() is not ValueTypeArray then returns an empty slice. Note that modifying
-// such empty slice has no effect on this Value.
+// If the Type() is not ValueTypeArray then returns an invalid slice. Note that using
+// such slice can cause panic.
 //
 // Calling this function on zero-initialized Value will cause a panic.
 func (v Value) SliceVal() Slice {
 	arr := v.orig.GetArrayValue()
 	if arr == nil {
-		return NewSlice()
+		return Slice{}
 	}
 	return newSlice(&arr.Values)
 }

model/internal/pdata/common_test.go

@@ -154,7 +154,7 @@ func TestAttributeValueMap(t *testing.T) {
 	// Test nil KvlistValue case for MapVal() func.
 	orig := &otlpcommon.AnyValue{Value: &otlpcommon.AnyValue_KvlistValue{KvlistValue: nil}}
 	m1 = Value{orig: orig}
-	assert.EqualValues(t, NewMap(), m1.MapVal())
+	assert.EqualValues(t, Map{}, m1.MapVal())
 }
 
 func TestNilOrigSetAttributeValue(t *testing.T) {
@@ -1010,7 +1010,7 @@ func TestAttributeValueArray(t *testing.T) {
 
 	// Test nil values case for SliceVal() func.
 	a1 = Value{orig: &otlpcommon.AnyValue{Value: &otlpcommon.AnyValue_ArrayValue{ArrayValue: nil}}}
-	assert.EqualValues(t, NewSlice(), a1.SliceVal())
+	assert.EqualValues(t, Slice{}, a1.SliceVal())
 }
 
 func TestAttributeSliceWithNilValues(t *testing.T) {
@@ -1305,3 +1305,21 @@ func constructTestAttributeSubarray() Value {
 	value.SliceVal().AppendEmpty().SetStringVal("strTwo")
 	return value
 }
+
+func BenchmarkAttributeValueMapAccessor(b *testing.B) {
+	val := simpleValueMap()
+
+	b.ResetTimer()
+	for n := 0; n < b.N; n++ {
+		val.MapVal()
+	}
+}
+
+func BenchmarkAttributeValueArrayAccessor(b *testing.B) {
+	val := simpleValueArray()
+
+	b.ResetTimer()
+	for n := 0; n < b.N; n++ {
+		val.SliceVal()
+	}
+}