Avoid duplicates in the attributes table

Author: rockdaboot

pdata/pprofile/attributes.go

@@ -78,14 +78,26 @@ func PutAttribute(table AttributeTableSlice, record attributable, key string, va
 		}
 	}
 
-	if table.Len() >= math.MaxInt32 {
-		return errTooManyTableEntries
-	}
-
 	if record.AttributeIndices().Len() >= math.MaxInt32 {
 		return errors.New("too many entries in AttributeIndices")
 	}
 
+	for j := range table.Len() {
+		a := table.At(j)
+		if a.Key() == key && a.Value().Equal(value) {
+			if j > math.MaxInt32 {
+				return errTooManyTableEntries
+			}
+			// Add the index of the existing attribute to the indices.
+			record.AttributeIndices().Append(int32(j)) //nolint:gosec // overflow checked
+			return nil
+		}
+	}
+
+	if table.Len() >= math.MaxInt32 {
+		return errTooManyTableEntries
+	}
+
 	// Add the key/value pair as a new attribute to the table...
 	entry := table.AppendEmpty()
 	entry.SetKey(key)

pdata/pprofile/attributes_test.go

@@ -58,6 +58,13 @@ func testPutAttribute(t *testing.T, record attributable) {
 	assert.Equal(t, 1, table.Len())
 	assert.Equal(t, []int32{0}, record.AttributeIndices().AsRaw())
 
+	// Special case: removing and adding again should not change the table as
+	// this can lead to multiple identical attributes in the table.
+	record.AttributeIndices().FromRaw([]int32{})
+	require.NoError(t, PutAttribute(table, record, "hello", pcommon.NewValueStr("world")))
+	assert.Equal(t, 1, table.Len())
+	assert.Equal(t, []int32{0}, record.AttributeIndices().AsRaw())
+
 	// Put an attribute, same key, different value.
 	// This updates the index and adds to the table.
 	fmt.Printf("test\n")