protofsm: use new fn.GoroutineManager to manage goroutines

This fixes an isuse that can occur when we have concurrent calls to
`Stop` while the state machine is driving forward.

protofsm/state_machine.go

@@ -1,6 +1,7 @@
 package protofsm
 
 import (
+	"context"
 	"fmt"
 	"sync"
 	"time"
@@ -135,12 +136,11 @@ type StateMachine[Event any, Env Environment] struct {
 	// query the internal state machine state.
 	stateQuery chan stateQuery[Event, Env]
 
+	wg   fn.GoroutineManager
+	quit chan struct{}
+
 	startOnce sync.Once
 	stopOnce  sync.Once
-
-	// TODO(roasbeef): also use that context guard here?
-	quit chan struct{}
-	wg   sync.WaitGroup
 }
 
 // ErrorReporter is an interface that's used to report errors that occur during
@@ -194,8 +194,9 @@ func NewStateMachine[Event any, Env Environment](cfg StateMachineCfg[Event, Env]
 		cfg:            cfg,
 		events:         make(chan Event, 1),
 		stateQuery:     make(chan stateQuery[Event, Env]),
-		quit:           make(chan struct{}),
+		wg:             *fn.NewGoroutineManager(context.Background()),
 		newStateEvents: fn.NewEventDistributor[State[Event, Env]](),
+		quit:           make(chan struct{}),
 	}
 }
 
@@ -203,8 +204,9 @@ func NewStateMachine[Event any, Env Environment](cfg StateMachineCfg[Event, Env]
 // the state machine to completion.
 func (s *StateMachine[Event, Env]) Start() {
 	s.startOnce.Do(func() {
-		s.wg.Add(1)
-		go s.driveMachine()
+		_ = s.wg.Go(func(ctx context.Context) {
+			s.driveMachine()
+		})
 	})
 }
 
@@ -213,7 +215,7 @@ func (s *StateMachine[Event, Env]) Start() {
 func (s *StateMachine[Event, Env]) Stop() {
 	s.stopOnce.Do(func() {
 		close(s.quit)
-		s.wg.Wait()
+		s.wg.Stop()
 	})
 }
 
@@ -320,7 +322,7 @@ func (s *StateMachine[Event, Env]) RemoveStateSub(sub StateSubscriber[
 // executeDaemonEvent executes a daemon event, which is a special type of event
 // that can be emitted as part of the state transition function of the state
 // machine. An error is returned if the type of event is unknown.
-func (s *StateMachine[Event, Env]) executeDaemonEvent( //nolint:funlen
+func (s *StateMachine[Event, Env]) executeDaemonEvent(
 	event DaemonEvent) error {
 
 	switch daemonEvent := event.(type) {
@@ -342,14 +344,10 @@ func (s *StateMachine[Event, Env]) executeDaemonEvent( //nolint:funlen
 					err)
 			}
 
-			// If a post-send event was specified, then we'll
-			// funnel that back into the main state machine now as
-			// well.
-			daemonEvent.PostSendEvent.WhenSome(func(event Event) {
-				s.wg.Add(1)
-				go func() {
-					defer s.wg.Done()
-
+			// If a post-send event was specified, then we'll funnel
+			// that back into the main state machine now as well.
+			return fn.MapOptionZ(daemonEvent.PostSendEvent, func(event Event) error { //nolint:lll
+				return s.wg.Go(func(ctx context.Context) {
 					log.Debugf("FSM(%v): sending "+
 						"post-send event: %v",
 						s.cfg.Env.Name(),
@@ -357,10 +355,8 @@ func (s *StateMachine[Event, Env]) executeDaemonEvent( //nolint:funlen
 					)
 
 					s.SendEvent(event)
-				}()
 				})
-
-			return nil
+			})
 		}
 
 		// If this doesn't have a SendWhen predicate, then we can just
@@ -372,10 +368,7 @@ func (s *StateMachine[Event, Env]) executeDaemonEvent( //nolint:funlen
 		// Otherwise, this has a SendWhen predicate, so we'll need
 		// launch a goroutine to poll the SendWhen, then send only once
 		// the predicate is true.
-		s.wg.Add(1)
-		go func() {
-			defer s.wg.Done()
-
+		return s.wg.Go(func(ctx context.Context) {
 			predicateTicker := time.NewTicker(
 				s.cfg.CustomPollInterval.UnwrapOr(pollInterval),
 			)
@@ -408,13 +401,11 @@ func (s *StateMachine[Event, Env]) executeDaemonEvent( //nolint:funlen
 						return
 					}
 
-				case <-s.quit:
+				case <-ctx.Done():
 					return
 				}
 			}
-		}()
-
-		return nil
+		})
 
 	// If this is a broadcast transaction event, then we'll broadcast with
 	// the label attached.
@@ -445,9 +436,7 @@ func (s *StateMachine[Event, Env]) executeDaemonEvent( //nolint:funlen
 			return fmt.Errorf("unable to register spend: %w", err)
 		}
 
-		s.wg.Add(1)
-		go func() {
-			defer s.wg.Done()
+		return s.wg.Go(func(ctx context.Context) {
 			for {
 				select {
 				case spend, ok := <-spendEvent.Spend:
@@ -466,13 +455,11 @@ func (s *StateMachine[Event, Env]) executeDaemonEvent( //nolint:funlen
 
 					return
 
-				case <-s.quit:
+				case <-ctx.Done():
 					return
 				}
 			}
-		}()
-
-		return nil
+		})
 
 	// The state machine has requested a new event to be sent once a
 	// specified txid+pkScript pair has confirmed.
@@ -489,9 +476,7 @@ func (s *StateMachine[Event, Env]) executeDaemonEvent( //nolint:funlen
 			return fmt.Errorf("unable to register conf: %w", err)
 		}
 
-		s.wg.Add(1)
-		go func() {
-			defer s.wg.Done()
+		return s.wg.Go(func(ctx context.Context) {
 			for {
 				select {
 				case <-confEvent.Confirmed:
@@ -508,11 +493,11 @@ func (s *StateMachine[Event, Env]) executeDaemonEvent( //nolint:funlen
 
 					return
 
-				case <-s.quit:
+				case <-ctx.Done():
 					return
 				}
 			}
-		}()
+		})
 	}
 
 	return fmt.Errorf("unknown daemon event: %T", event)
@@ -632,8 +617,6 @@ func (s *StateMachine[Event, Env]) applyEvents(currentState State[Event, Env],
 // incoming events, and then drives the state machine forward until it reaches
 // a terminal state.
 func (s *StateMachine[Event, Env]) driveMachine() {
-	defer s.wg.Done()
-
 	log.Debugf("FSM(%v): starting state machine", s.cfg.Env.Name())
 
 	currentState := s.cfg.InitialState
@@ -676,16 +659,11 @@ func (s *StateMachine[Event, Env]) driveMachine() {
 		// An outside caller is querying our state, so we'll return the
 		// latest state.
 		case stateQuery := <-s.stateQuery:
-			if !fn.SendOrQuit(
-				stateQuery.CurrentState, currentState, s.quit,
-			) {
-
+			if !fn.SendOrQuit(stateQuery.CurrentState, currentState, s.quit) { //nolint:lll
 				return
 			}
 
-		case <-s.quit:
-			// TODO(roasbeef): logs, etc
-			//  * something in env?
+		case <-s.wg.Done():
 			return
 		}
 	}