Optimize codes.String() method using a switch instead of a slice of indexes (#1712)

benchmark/primitives/code_string_test.go

@@ -0,0 +1,135 @@
+/*
+ *
+ * Copyright 2017 gRPC 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 primitives_test
+
+import (
+	"strconv"
+	"testing"
+
+	"google.golang.org/grpc/codes"
+)
+
+type codeBench uint32
+
+const (
+	OK codeBench = iota
+	Canceled
+	Unknown
+	InvalidArgument
+	DeadlineExceeded
+	NotFound
+	AlreadyExists
+	PermissionDenied
+	ResourceExhausted
+	FailedPrecondition
+	Aborted
+	OutOfRange
+	Unimplemented
+	Internal
+	Unavailable
+	DataLoss
+	Unauthenticated
+)
+
+// The following String() function was generated by stringer.
+const _Code_name = "OKCanceledUnknownInvalidArgumentDeadlineExceededNotFoundAlreadyExistsPermissionDeniedResourceExhaustedFailedPreconditionAbortedOutOfRangeUnimplementedInternalUnavailableDataLossUnauthenticated"
+
+var _Code_index = [...]uint8{0, 2, 10, 17, 32, 48, 56, 69, 85, 102, 120, 127, 137, 150, 158, 169, 177, 192}
+
+func (i codeBench) String() string {
+	if i >= codeBench(len(_Code_index)-1) {
+		return "Code(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _Code_name[_Code_index[i]:_Code_index[i+1]]
+}
+
+var nameMap = map[codeBench]string{
+	OK:                 "OK",
+	Canceled:           "Canceled",
+	Unknown:            "Unknown",
+	InvalidArgument:    "InvalidArgument",
+	DeadlineExceeded:   "DeadlineExceeded",
+	NotFound:           "NotFound",
+	AlreadyExists:      "AlreadyExists",
+	PermissionDenied:   "PermissionDenied",
+	ResourceExhausted:  "ResourceExhausted",
+	FailedPrecondition: "FailedPrecondition",
+	Aborted:            "Aborted",
+	OutOfRange:         "OutOfRange",
+	Unimplemented:      "Unimplemented",
+	Internal:           "Internal",
+	Unavailable:        "Unavailable",
+	DataLoss:           "DataLoss",
+	Unauthenticated:    "Unauthenticated",
+}
+
+func (i codeBench) StringUsingMap() string {
+	if s, ok := nameMap[i]; ok {
+		return s
+	}
+	return "Code(" + strconv.FormatInt(int64(i), 10) + ")"
+}
+
+func BenchmarkCodeStringStringer(b *testing.B) {
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		c := codeBench(uint32(i % 17))
+		_ = c.String()
+	}
+	b.StopTimer()
+}
+
+func BenchmarkCodeStringMap(b *testing.B) {
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		c := codeBench(uint32(i % 17))
+		_ = c.StringUsingMap()
+	}
+	b.StopTimer()
+}
+
+// codes.Code.String() does a switch.
+func BenchmarkCodeStringSwitch(b *testing.B) {
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		c := codes.Code(uint32(i % 17))
+		_ = c.String()
+	}
+	b.StopTimer()
+}
+
+// Testing all codes (0<=c<=16) and also one overflow (17).
+func BenchmarkCodeStringStringerWithOverflow(b *testing.B) {
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		c := codeBench(uint32(i % 18))
+		_ = c.String()
+	}
+	b.StopTimer()
+}
+
+// Testing all codes (0<=c<=16) and also one overflow (17).
+func BenchmarkCodeStringSwitchWithOverflow(b *testing.B) {
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		c := codes.Code(uint32(i % 18))
+		_ = c.String()
+	}
+	b.StopTimer()
+}

codes/code_string.go

@@ -1,16 +1,62 @@
-// Code generated by "stringer -type=Code"; DO NOT EDIT.
+/*
+ *
+ * Copyright 2017 gRPC 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 codes
 
 import "strconv"
 
-const _Code_name = "OKCanceledUnknownInvalidArgumentDeadlineExceededNotFoundAlreadyExistsPermissionDeniedResourceExhaustedFailedPreconditionAbortedOutOfRangeUnimplementedInternalUnavailableDataLossUnauthenticated"
-
-var _Code_index = [...]uint8{0, 2, 10, 17, 32, 48, 56, 69, 85, 102, 120, 127, 137, 150, 158, 169, 177, 192}
-
-func (i Code) String() string {
-	if i >= Code(len(_Code_index)-1) {
-		return "Code(" + strconv.FormatInt(int64(i), 10) + ")"
+func (c Code) String() string {
+	switch c {
+	case OK:
+		return "OK"
+	case Canceled:
+		return "Canceled"
+	case Unknown:
+		return "Unknown"
+	case InvalidArgument:
+		return "InvalidArgument"
+	case DeadlineExceeded:
+		return "DeadlineExceeded"
+	case NotFound:
+		return "NotFound"
+	case AlreadyExists:
+		return "AlreadyExists"
+	case PermissionDenied:
+		return "PermissionDenied"
+	case ResourceExhausted:
+		return "ResourceExhausted"
+	case FailedPrecondition:
+		return "FailedPrecondition"
+	case Aborted:
+		return "Aborted"
+	case OutOfRange:
+		return "OutOfRange"
+	case Unimplemented:
+		return "Unimplemented"
+	case Internal:
+		return "Internal"
+	case Unavailable:
+		return "Unavailable"
+	case DataLoss:
+		return "DataLoss"
+	case Unauthenticated:
+		return "Unauthenticated"
+	default:
+		return "Code(" + strconv.FormatInt(int64(c), 10) + ")"
 	}
-	return _Code_name[_Code_index[i]:_Code_index[i+1]]
 }