1 files changed, 125 insertions, 0 deletions
diff --git a/vendor/github.com/godbus/dbus/v5/sequential_handler.go b/vendor/github.com/godbus/dbus/v5/sequential_handler.go
new file mode 100644
index 000000000..ef2fcdba1
--- /dev/null
+++ b/vendor/github.com/godbus/dbus/v5/sequential_handler.go
@@ -0,0 +1,125 @@
+package dbus
+
+import (
+	"sync"
+)
+
+// NewSequentialSignalHandler returns an instance of a new
+// signal handler that guarantees sequential processing of signals. It is a
+// guarantee of this signal handler that signals will be written to
+// channels in the order they are received on the DBus connection.
+func NewSequentialSignalHandler() SignalHandler {
+	return &sequentialSignalHandler{}
+}
+
+type sequentialSignalHandler struct {
+	mu      sync.RWMutex
+	closed  bool
+	signals []*sequentialSignalChannelData
+}
+
+func (sh *sequentialSignalHandler) DeliverSignal(intf, name string, signal *Signal) {
+	sh.mu.RLock()
+	defer sh.mu.RUnlock()
+	if sh.closed {
+		return
+	}
+	for _, scd := range sh.signals {
+		scd.deliver(signal)
+	}
+}
+
+func (sh *sequentialSignalHandler) Terminate() {
+	sh.mu.Lock()
+	defer sh.mu.Unlock()
+	if sh.closed {
+		return
+	}
+
+	for _, scd := range sh.signals {
+		scd.close()
+		close(scd.ch)
+	}
+	sh.closed = true
+	sh.signals = nil
+}
+
+func (sh *sequentialSignalHandler) AddSignal(ch chan<- *Signal) {
+	sh.mu.Lock()
+	defer sh.mu.Unlock()
+	if sh.closed {
+		return
+	}
+	sh.signals = append(sh.signals, newSequentialSignalChannelData(ch))
+}
+
+func (sh *sequentialSignalHandler) RemoveSignal(ch chan<- *Signal) {
+	sh.mu.Lock()
+	defer sh.mu.Unlock()
+	if sh.closed {
+		return
+	}
+	for i := len(sh.signals) - 1; i >= 0; i-- {
+		if ch == sh.signals[i].ch {
+			sh.signals[i].close()
+			copy(sh.signals[i:], sh.signals[i+1:])
+			sh.signals[len(sh.signals)-1] = nil
+			sh.signals = sh.signals[:len(sh.signals)-1]
+		}
+	}
+}
+
+type sequentialSignalChannelData struct {
+	ch   chan<- *Signal
+	in   chan *Signal
+	done chan struct{}
+}
+
+func newSequentialSignalChannelData(ch chan<- *Signal) *sequentialSignalChannelData {
+	scd := &sequentialSignalChannelData{
+		ch:   ch,
+		in:   make(chan *Signal),
+		done: make(chan struct{}),
+	}
+	go scd.bufferSignals()
+	return scd
+}
+
+func (scd *sequentialSignalChannelData) bufferSignals() {
+	defer close(scd.done)
+
+	// Ensure that signals are delivered to scd.ch in the same
+	// order they are received from scd.in.
+	var queue []*Signal
+	for {
+		if len(queue) == 0 {
+			signal, ok := <- scd.in
+			if !ok {
+				return
+			}
+			queue = append(queue, signal)
+		}
+		select {
+		case scd.ch <- queue[0]:
+			copy(queue, queue[1:])
+			queue[len(queue)-1] = nil
+			queue = queue[:len(queue)-1]
+		case signal, ok := <-scd.in:
+			if !ok {
+				return
+			}
+			queue = append(queue, signal)
+		}
+	}
+}
+
+func (scd *sequentialSignalChannelData) deliver(signal *Signal) {
+	scd.in <- signal
+}
+
+func (scd *sequentialSignalChannelData) close() {
+	close(scd.in)
+	// Ensure that bufferSignals() has exited and won't attempt
+	// any future sends on scd.ch
+	<-scd.done
+}