de6db4038c
Note that this is the code in containerd that uses runc (as almost a library). Please see the other commit for the update to runc binary itself. Signed-off-by: Davanum Srinivas <davanum@gmail.com>
126 lines
2.6 KiB
Go
126 lines
2.6 KiB
Go
package dbus
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import (
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"sync"
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)
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// NewSequentialSignalHandler returns an instance of a new
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// signal handler that guarantees sequential processing of signals. It is a
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// guarantee of this signal handler that signals will be written to
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// channels in the order they are received on the DBus connection.
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func NewSequentialSignalHandler() SignalHandler {
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return &sequentialSignalHandler{}
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}
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type sequentialSignalHandler struct {
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mu sync.RWMutex
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closed bool
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signals []*sequentialSignalChannelData
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}
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func (sh *sequentialSignalHandler) DeliverSignal(intf, name string, signal *Signal) {
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sh.mu.RLock()
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defer sh.mu.RUnlock()
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if sh.closed {
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return
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}
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for _, scd := range sh.signals {
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scd.deliver(signal)
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}
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}
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func (sh *sequentialSignalHandler) Terminate() {
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sh.mu.Lock()
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defer sh.mu.Unlock()
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if sh.closed {
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return
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}
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for _, scd := range sh.signals {
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scd.close()
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close(scd.ch)
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}
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sh.closed = true
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sh.signals = nil
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}
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func (sh *sequentialSignalHandler) AddSignal(ch chan<- *Signal) {
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sh.mu.Lock()
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defer sh.mu.Unlock()
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if sh.closed {
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return
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}
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sh.signals = append(sh.signals, newSequentialSignalChannelData(ch))
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}
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func (sh *sequentialSignalHandler) RemoveSignal(ch chan<- *Signal) {
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sh.mu.Lock()
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defer sh.mu.Unlock()
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if sh.closed {
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return
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}
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for i := len(sh.signals) - 1; i >= 0; i-- {
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if ch == sh.signals[i].ch {
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sh.signals[i].close()
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copy(sh.signals[i:], sh.signals[i+1:])
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sh.signals[len(sh.signals)-1] = nil
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sh.signals = sh.signals[:len(sh.signals)-1]
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}
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}
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}
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type sequentialSignalChannelData struct {
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ch chan<- *Signal
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in chan *Signal
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done chan struct{}
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}
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func newSequentialSignalChannelData(ch chan<- *Signal) *sequentialSignalChannelData {
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scd := &sequentialSignalChannelData{
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ch: ch,
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in: make(chan *Signal),
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done: make(chan struct{}),
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}
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go scd.bufferSignals()
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return scd
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}
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func (scd *sequentialSignalChannelData) bufferSignals() {
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defer close(scd.done)
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// Ensure that signals are delivered to scd.ch in the same
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// order they are received from scd.in.
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var queue []*Signal
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for {
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if len(queue) == 0 {
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signal, ok := <- scd.in
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if !ok {
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return
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}
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queue = append(queue, signal)
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}
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select {
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case scd.ch <- queue[0]:
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copy(queue, queue[1:])
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queue[len(queue)-1] = nil
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queue = queue[:len(queue)-1]
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case signal, ok := <-scd.in:
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if !ok {
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return
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}
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queue = append(queue, signal)
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}
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}
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}
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func (scd *sequentialSignalChannelData) deliver(signal *Signal) {
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scd.in <- signal
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}
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func (scd *sequentialSignalChannelData) close() {
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close(scd.in)
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// Ensure that bufferSignals() has exited and won't attempt
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// any future sends on scd.ch
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<-scd.done
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}
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