server: Add verification of whether lock was called within out outside of apply

server/storage/backend/verify.go

@@ -0,0 +1,56 @@
+// Copyright 2022 The etcd 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 backend
+
+import (
+	"os"
+	"runtime/debug"
+	"strings"
+
+	"go.uber.org/zap"
+)
+
+const (
+	ENV_VERIFY           = "ETCD_VERIFY"
+	ENV_VERIFY_ALL_VALUE = "all"
+	ENV_VERIFY_LOCK      = "lock"
+)
+
+func ValidateCalledInsideApply(lg *zap.Logger) {
+	if !verifyLockEnabled() {
+		return
+	}
+	if !insideApply() {
+		lg.Panic("Called outside of APPLY!", zap.Stack("stacktrace"))
+	}
+}
+
+func ValidateCalledOutSideApply(lg *zap.Logger) {
+	if !verifyLockEnabled() {
+		return
+	}
+	if insideApply() {
+		lg.Panic("Called inside of APPLY!", zap.Stack("stacktrace"))
+	}
+}
+
+func verifyLockEnabled() bool {
+	return os.Getenv(ENV_VERIFY) == ENV_VERIFY_ALL_VALUE || os.Getenv(ENV_VERIFY) == ENV_VERIFY_LOCK
+}
+
+func insideApply() bool {
+	stackTraceStr := string(debug.Stack())
+	return strings.Contains(stackTraceStr, ".applyEntries")
+}