Adding interface methods to logical.Backend for parity (#2242)

logical/framework/backend.go

@@ -68,6 +68,9 @@ type Backend struct {
 	// to the backend, if required.
 	Clean CleanupFunc
 
+	// Invalidate is called when a keys is modified if required
+	Invalidate InvalidateFunc
+
 	// AuthRenew is the callback to call when a RenewRequest for an
 	// authentication comes in. By default, renewal won't be allowed.
 	// See the built-in AuthRenew helpers in lease.go for common callbacks.
@@ -92,6 +95,9 @@ type WALRollbackFunc func(*logical.Request, string, interface{}) error
 // CleanupFunc is the callback for backend unload.
 type CleanupFunc func()
 
+// InvalidateFunc is the callback for backend key invalidation.
+type InvalidateFunc func(string)
+
 func (b *Backend) HandleExistenceCheck(req *logical.Request) (checkFound bool, exists bool, err error) {
 	b.once.Do(b.init)
 
@@ -218,12 +224,20 @@ func (b *Backend) Setup(config *logical.BackendConfig) (logical.Backend, error)
 	return b, nil
 }
 
+// Cleanup is used to release resources and prepare to stop the backend
 func (b *Backend) Cleanup() {
 	if b.Clean != nil {
 		b.Clean()
 	}
 }
 
+// InvalidateKey is used to clear caches and reset internal state on key changes
+func (b *Backend) InvalidateKey(key string) {
+	if b.Invalidate != nil {
+		b.Invalidate(key)
+	}
+}
+
 // Logger can be used to get the logger. If no logger has been set,
 // the logs will be discarded.
 func (b *Backend) Logger() log.Logger {