update dependencies (#296)

vendor/codeberg.org/gruf/go-nowish/timeout.go

@@ -0,0 +1,118 @@
+package nowish
+
+import (
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+// Timeout provides a reusable structure for enforcing timeouts with a cancel
+type Timeout struct {
+	noCopy noCopy //nolint noCopy because a copy will mess with atomics
+
+	tk *time.Timer    // tk is the underlying timeout-timer
+	ch syncer         // ch is the cancel synchronization channel
+	wg sync.WaitGroup // wg is the waitgroup to hold .Start() until timeout goroutine started
+	st timeoutState   // st stores the current timeout state (and protects concurrent use)
+}
+
+// NewTimeout returns a new Timeout instance
+func NewTimeout() Timeout {
+	tk := time.NewTimer(time.Minute)
+	tk.Stop() // don't keep it running
+	return Timeout{
+		tk: tk,
+		ch: make(syncer),
+	}
+}
+
+func (t *Timeout) runTimeout(hook func()) {
+	t.wg.Add(1)
+	go func() {
+		cancelled := false
+
+		// Signal started
+		t.wg.Done()
+
+		select {
+		// Timeout reached
+		case <-t.tk.C:
+			if !t.st.stop() /* a sneaky cancel! */ {
+				t.ch.recv()
+				cancelled = true
+				defer t.ch.send()
+			}
+
+		// Cancel called
+		case <-t.ch:
+			cancelled = true
+			defer t.ch.send()
+		}
+
+		// Ensure timer stopped
+		if cancelled && !t.tk.Stop() {
+			<-t.tk.C
+		}
+
+		// Defer reset state
+		defer t.st.reset()
+
+		// If timed out call hook
+		if !cancelled {
+			hook()
+		}
+	}()
+	t.wg.Wait()
+}
+
+// Start starts the timer with supplied timeout. If timeout is reached before
+// cancel then supplied timeout hook will be called. Error may be called if
+// Timeout is already running when this function is called
+func (t *Timeout) Start(d time.Duration, hook func()) {
+	if !t.st.start() {
+		panic("nowish: timeout already started")
+	}
+	t.runTimeout(hook)
+	t.tk.Reset(d)
+}
+
+// Cancel cancels the currently running timer. If a cancel is achieved, then
+// this function will return after the timeout goroutine is finished
+func (t *Timeout) Cancel() {
+	if !t.st.stop() {
+		return
+	}
+	t.ch.send()
+	t.ch.recv()
+}
+
+// timeoutState provides a thread-safe timeout state mechanism
+type timeoutState uint32
+
+// start attempts to start the state, must be already reset, returns success
+func (t *timeoutState) start() bool {
+	return atomic.CompareAndSwapUint32((*uint32)(t), 0, 1)
+}
+
+// stop attempts to stop the state, must already be started, returns success
+func (t *timeoutState) stop() bool {
+	return atomic.CompareAndSwapUint32((*uint32)(t), 1, 2)
+}
+
+// reset is fairly self explanatory
+func (t *timeoutState) reset() {
+	atomic.StoreUint32((*uint32)(t), 0)
+}
+
+// syncer provides helpful receiver methods for a synchronization channel
+type syncer (chan struct{})
+
+// send blocks on sending an empty value down channel
+func (s syncer) send() {
+	s <- struct{}{}
+}
+
+// recv blocks on receiving (and dropping) empty value from channel
+func (s syncer) recv() {
+	<-s
+}