command: trigger still applying cancellations from a channel

command/hook_ui.go

@@ -33,8 +33,12 @@ type UiHook struct {
 
 // uiResourceState tracks the state of a single resource
 type uiResourceState struct {
+	Name       string
+	ResourceId string
 	Op         uiResourceOp
 	Start      time.Time
+
+	DoneCh chan struct{} // To be used for cancellation
 }
 
 // uiResourceOp is an enum for operations on a resource
@@ -63,13 +67,6 @@ func (h *UiHook) PreApply(
 		op = uiResourceCreate
 	}
 
-	h.l.Lock()
-	h.resources[id] = uiResourceState{
-		Op:    op,
-		Start: time.Now().Round(time.Second),
-	}
-	h.l.Unlock()
-
 	var operation string
 	switch op {
 	case uiResourceModify:
@@ -131,8 +128,9 @@ func (h *UiHook) PreApply(
 		attrString = "\n  " + attrString
 	}
 
-	var stateIdSuffix string
+	var stateId, stateIdSuffix string
 	if s != nil && s.ID != "" {
+		stateId = s.ID
 		stateIdSuffix = fmt.Sprintf(" (ID: %s)", truncateId(s.ID, maxIdLen))
 	}
 
@@ -143,22 +141,32 @@ func (h *UiHook) PreApply(
 		stateIdSuffix,
 		attrString)))
 
-	// Set a timer to show an operation is still happening
+	uiState := uiResourceState{
-	time.AfterFunc(periodicUiTimer, func() { h.stillApplying(id, s) })
+		Name:       id,
+		ResourceId: stateId,
+		Op:         op,
+		Start:      time.Now().Round(time.Second),
+		DoneCh:     make(chan struct{}),
+	}
+
+	h.l.Lock()
+	h.resources[id] = uiState
+	h.l.Unlock()
+
+	// Start goroutine that shows progress
+	go h.stillApplying(uiState)
 
 	return terraform.HookActionContinue, nil
 }
 
-func (h *UiHook) stillApplying(id string, s *terraform.InstanceState) {
+func (h *UiHook) stillApplying(state uiResourceState) {
-	// Grab the operation. We defer the lock here to avoid the "still..."
+	for {
-	// message showing up after a completion message.
+		select {
-	h.l.Lock()
+		case <-state.DoneCh:
-	defer h.l.Unlock()
-	state, ok := h.resources[id]
-
-	// If the resource is out of the map it means we're done with it
-	if !ok {
 			return
+
+		case <-time.After(periodicUiTimer):
+			// Timer up, show status
 		}
 
 		var msg string
@@ -173,21 +181,19 @@ func (h *UiHook) stillApplying(id string, s *terraform.InstanceState) {
 			return
 		}
 
-	var stateIdSuffix string
+		idSuffix := ""
-	if s != nil && s.ID != "" {
+		if v := state.ResourceId; v != "" {
-		stateIdSuffix = fmt.Sprintf("ID: %s, ", truncateId(s.ID, maxIdLen))
+			idSuffix = fmt.Sprintf("ID: %s, ", truncateId(v, maxIdLen))
 		}
 
 		h.ui.Output(h.Colorize.Color(fmt.Sprintf(
 			"[reset][bold]%s: %s (%s%s elapsed)[reset]",
-		id,
+			state.Name,
 			msg,
-		stateIdSuffix,
+			idSuffix,
 			time.Now().Round(time.Second).Sub(state.Start),
 		)))
-
+	}
-	// Reschedule
-	time.AfterFunc(periodicUiTimer, func() { h.stillApplying(id, s) })
 }
 
 func (h *UiHook) PostApply(
@@ -200,6 +206,10 @@ func (h *UiHook) PostApply(
 
 	h.l.Lock()
 	state := h.resources[id]
+	if state.DoneCh != nil {
+		close(state.DoneCh)
+	}
+
 	delete(h.resources, id)
 	h.l.Unlock()