treesteps: UpdateLastOpf

Add a convenience function that automatically uses the last op, to
avoid having to plumb the operation through layers of functions.

Author: RaduBerinde

internal/treesteps/tree_steps_off.go

@@ -35,8 +35,9 @@ func IsRecording(n Node) bool { return false }
 
 type Op struct{}
 
-func StartOpf(node Node, format string, args ...any) *Op { return nil }
-func (op *Op) Updatef(format string, args ...any)        {}
-func (op *Op) Finishf(format string, args ...any)        {}
+func StartOpf(node Node, format string, args ...any) *Op  { return nil }
+func (op *Op) Updatef(format string, args ...any)         {}
+func UpdateLastOpf(node Node, format string, args ...any) {}
+func (op *Op) Finishf(format string, args ...any)         {}
 
 func TreeToString(n Node) string { return "treesteps not supported in this build" }

internal/treesteps/tree_steps_on.go

@@ -227,7 +227,7 @@ func StartOpf(node Node, format string, args ...any) *Op {
 }
 
 // Updatef changes the state of the operation and emits a step. The state of the
-// // operation shows up after the details that were provided in StartOpf.
+// operation shows up after the details that were provided in StartOpf.
 func (op *Op) Updatef(format string, args ...any) {
 	if op == nil {
 		return
@@ -238,6 +238,23 @@ func (op *Op) Updatef(format string, args ...any) {
 	op.nodeState.recording.stepLockedf("%s on %s updated", firstWord(op.details), firstWord(op.nodeState.name))
 }
 
+// UpdateLastOpf calls Updatef on the most recently started operation for this
+// node.
+func UpdateLastOpf(node Node, format string, args ...any) {
+	if !mu.recordingInProgress.Load() {
+		return
+	}
+	mu.Lock()
+	defer mu.Unlock()
+	state, ok := mu.nodeMap[node]
+	if !ok || len(state.ops) == 0 {
+		return
+	}
+	op := state.ops[len(state.ops)-1]
+	op.state = fmt.Sprintf(format, args...)
+	op.nodeState.recording.stepLockedf("%s on %s updated", firstWord(op.details), firstWord(op.nodeState.name))
+}
+
 // Finishf changes the state of the operation, emits a step, and cleans up the
 // operation.The state of the operation shows up after the details that were
 // provided in StartOpf.