add reset signal feature

example_test.go

@@ -30,16 +30,17 @@ func (s *Server) Resource() int {
 }
 
 func Example() {
-	s := &Server{}
-	s.testBus = syncbus.New(120 * time.Millisecond)
+	bus := syncbus.New(120 * time.Millisecond)
 
+	s := &Server{}
+	s.testBus = bus
 	s.AsyncInit()
-	if err := s.testBus.Wait("initialized"); err != nil {
+
+	if err := bus.Wait("initialized"); err != nil {
 		fmt.Println("failed:", err)
 	}
 
 	fmt.Println(s.Resource())
-
 	// Output:
 	// 42
 }

syncbus.go

@@ -6,7 +6,7 @@ to be used as a test hook shared between the production and the test code, or le
 
 It provides a wait function for processes in goroutines that should continue only when a predefined signal is
 set, or the timeout expires. If the predefined signals are already set at the time of calling wait, the
-calling goroutine continues immediately. Once a signal is set, it stays so until it's cleared.
+calling goroutine continues immediately. Once a signal is set, it stays so until it's cleared (reset).
 
 Wait can expect one or more signals represented by keys. The signals don't need to be set simultaneously in
 order to release a waiting goroutine. A wait continues once all the signals that it depends on were set.
@@ -26,12 +26,14 @@ type waitItem struct {
 
 // SyncBus can be used to synchronize goroutines through signals.
 type SyncBus struct {
-	timeout time.Duration
-	waiting []waitItem
-	signals map[string]bool
-	wait    chan waitItem
-	signal  chan []string
-	quit    chan struct{}
+	timeout  time.Duration
+	waiting  []waitItem
+	signals  map[string]bool
+	wait     chan waitItem
+	signal   chan []string
+	reset    chan []string
+	resetAll chan struct{}
+	quit     chan struct{}
 }
 
 // ErrTimeout is returned by Wait() when failed to receive all the signals in time.
@@ -40,11 +42,13 @@ var ErrTimeout = errors.New("timeout")
 // New creates and initializes a new SyncBus. It uses a shared timeout for all the Wait calls.
 func New(timeout time.Duration) *SyncBus {
 	b := &SyncBus{
-		timeout: timeout,
-		signals: make(map[string]bool),
-		wait:    make(chan waitItem),
-		signal:  make(chan []string),
-		quit:    make(chan struct{}),
+		timeout:  timeout,
+		signals:  make(map[string]bool),
+		wait:     make(chan waitItem),
+		signal:   make(chan []string),
+		reset:    make(chan []string),
+		resetAll: make(chan struct{}),
+		quit:     make(chan struct{}),
 	}
 
 	go b.run()
@@ -106,6 +110,16 @@ func (b *SyncBus) signalWaiting(now time.Time) {
 	b.waiting = keep
 }
 
+func (b *SyncBus) resetSignals(keys []string) {
+	for i := range keys {
+		delete(b.signals, keys[i])
+	}
+}
+
+func (b *SyncBus) resetAllSignals() {
+	b.signals = make(map[string]bool)
+}
+
 func (b *SyncBus) run() {
 	var to <-chan time.Time
 	for {
@@ -124,6 +138,10 @@ func (b *SyncBus) run() {
 			b.setSignal(signal)
 			b.signalWaiting(now)
 			to = b.nextTimeout(now)
+		case reset := <-b.reset:
+			b.resetSignals(reset)
+		case <-b.resetAll:
+			b.resetAllSignals()
 		case <-b.quit:
 			return
 		}
@@ -165,7 +183,30 @@ func (b *SyncBus) Signal(keys ...string) {
 	b.signal <- keys
 }
 
-// Close tears down the SyncBus.
+// ResetSignals clears the set signals defined by the provided keys.
+//
+// If the receiver *SyncBus is nil, or no key argument is passed to it,
+// it is a noop.
+func (b *SyncBus) ResetSignals(keys ...string) {
+	if b == nil || len(keys) == 0 {
+		return
+	}
+
+	b.reset <- keys
+}
+
+// ResetAllSignals clears all the set signals.
+//
+// If the receiver *SyncBus is nil, it is a noop.
+func (b *SyncBus) ResetAllSignals() {
+	if b == nil {
+		return
+	}
+
+	b.resetAll <- struct{}{}
+}
+
+// Close tears down the SyncBus. If the receiver is nil, it is a noop.
 func (b *SyncBus) Close() {
 	if b == nil {
 		return

syncbus_test.go

@@ -76,6 +76,34 @@ func TestNilSignal(t *testing.T) {
 	}
 }
 
+func TestNilReset(t *testing.T) {
+	var bus *SyncBus
+	tw := newTestWait(1)
+	go func() {
+		bus.Signal("test")
+		tw.done()
+	}()
+
+	bus.ResetSignals("test")
+	if err := tw.wait(); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestNilResetAll(t *testing.T) {
+	var bus *SyncBus
+	tw := newTestWait(1)
+	go func() {
+		bus.Signal("test")
+		tw.done()
+	}()
+
+	bus.ResetAllSignals()
+	if err := tw.wait(); err != nil {
+		t.Error(err)
+	}
+}
+
 func TestNilClose(t *testing.T) {
 	var bus *SyncBus
 	bus.Close()
@@ -101,6 +129,20 @@ func TestEmptySignal(t *testing.T) {
 	}
 }
 
+func TestEmptyRest(t *testing.T) {
+	bus := New(120 * time.Millisecond)
+	tw := newTestWait(1)
+	go func() {
+		bus.Signal()
+		tw.done()
+	}()
+
+	bus.ResetSignals()
+	if err := tw.wait(); err != nil {
+		t.Error(err)
+	}
+}
+
 func TestTimeout(t *testing.T) {
 	bus := New(12 * time.Millisecond)
 	defer bus.Close()
@@ -212,3 +254,38 @@ func TestMultiKeySignal(t *testing.T) {
 		t.Error(err)
 	}
 }
+
+func TestSignalBeforeWait(t *testing.T) {
+	bus := New(120 * time.Millisecond)
+	defer bus.Close()
+
+	bus.Signal("foo")
+	if err := bus.Wait("foo"); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestReset(t *testing.T) {
+	bus := New(12 * time.Millisecond)
+	defer bus.Close()
+
+	bus.Signal("foo")
+	bus.ResetSignals("foo")
+	if err := bus.Wait("foo"); err != ErrTimeout {
+		t.Error("failed to timeout")
+	}
+}
+
+func TestResetAll(t *testing.T) {
+	bus := New(12 * time.Millisecond)
+	defer bus.Close()
+
+	bus.Signal("foo")
+	bus.Signal("bar")
+	bus.Signal("baz")
+
+	bus.ResetAllSignals()
+	if err := bus.Wait("foo", "bar", "baz"); err != ErrTimeout {
+		t.Error("failed to timeout")
+	}
+}