Initial

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

vendor/github.com/docker/go-events/channel.go

@@ -0,0 +1,61 @@
+package events
+
+import (
+	"fmt"
+	"sync"
+)
+
+// Channel provides a sink that can be listened on. The writer and channel
+// listener must operate in separate goroutines.
+//
+// Consumers should listen on Channel.C until Closed is closed.
+type Channel struct {
+	C chan Event
+
+	closed chan struct{}
+	once   sync.Once
+}
+
+// NewChannel returns a channel. If buffer is zero, the channel is
+// unbuffered.
+func NewChannel(buffer int) *Channel {
+	return &Channel{
+		C:      make(chan Event, buffer),
+		closed: make(chan struct{}),
+	}
+}
+
+// Done returns a channel that will always proceed once the sink is closed.
+func (ch *Channel) Done() chan struct{} {
+	return ch.closed
+}
+
+// Write the event to the channel. Must be called in a separate goroutine from
+// the listener.
+func (ch *Channel) Write(event Event) error {
+	select {
+	case ch.C <- event:
+		return nil
+	case <-ch.closed:
+		return ErrSinkClosed
+	}
+}
+
+// Close the channel sink.
+func (ch *Channel) Close() error {
+	ch.once.Do(func() {
+		close(ch.closed)
+	})
+
+	return nil
+}
+
+func (ch *Channel) String() string {
+	// Serialize a copy of the Channel that doesn't contain the sync.Once,
+	// to avoid a data race.
+	ch2 := map[string]interface{}{
+		"C":      ch.C,
+		"closed": ch.closed,
+	}
+	return fmt.Sprint(ch2)
+}