Tracing: Implement Undo step for trace enable transaction.

Implement the undo step for trace enable transaction. This
step removes the trace configuration from the store if
written.

closes #1368

Signed-off-by: Sridhar Seshasayee <sseshasa@redhat.com>

plugins/tracemgmt/init.go

@@ -34,5 +34,6 @@ func (p *Plugin) RestRoutes() route.Routes {
 func (p *Plugin) RegisterStepFuncs() {
 	transaction.RegisterStepFunc(txnTracingValidateConfig, "trace-mgmt.ValidateTraceConfig")
 	transaction.RegisterStepFunc(txnTracingStoreConfig, "trace-mgmt.StoreTraceConfig")
+	transaction.RegisterStepFunc(txnTracingDeleteStoreConfig, "trace-mgmt.UndoStoreTraceConfig")
 	transaction.RegisterStepFunc(txnTracingApplyNewConfig, "trace-mgmt.NotifyTraceConfigChange")
 }

plugins/tracemgmt/rest.go

@@ -60,10 +60,10 @@ func tracingEnableHandler(w http.ResponseWriter, r *http.Request) {
 			Nodes:  []uuid.UUID{gdctx.MyUUID},
 		},
 		{
-			DoFunc: "trace-mgmt.StoreTraceConfig",
-			//UndoFunc: "trace-mgmt.UndoStoreTraceConfig",
-			Nodes: []uuid.UUID{gdctx.MyUUID},
-			Sync:  true,
+			DoFunc:   "trace-mgmt.StoreTraceConfig",
+			UndoFunc: "trace-mgmt.UndoStoreTraceConfig",
+			Nodes:    []uuid.UUID{gdctx.MyUUID},
+			Sync:     true,
 		},
 		{
 			DoFunc: "trace-mgmt.NotifyTraceConfigChange",

plugins/tracemgmt/transactions.go

@@ -69,6 +69,12 @@ func txnTracingStoreConfig(c transaction.TxnCtx) error {
 	return nil
 }
 
+// Transaction step that reverts the trace config
+func txnTracingDeleteStoreConfig(c transaction.TxnCtx) error {
+	err := traceutils.DeleteTraceConfig()
+	return err
+}
+
 // Tranasaction step that reads trace config info from the store and updates
 // the in-memory trace config.
 func txnTracingApplyNewConfig(c transaction.TxnCtx) error {