126 lines
2.6 KiB
Go
126 lines
2.6 KiB
Go
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
|
|
}
|