func (mon *SlaveMonitor) slaveDidBeginRegistration(fd int) {
// Having just started the process, we expect an IO, which we convert to a UNIX domain socket
fileName := strconv.Itoa(rand.Int())
slaveFile := os.NewFile(uintptr(fd), fileName)
slaveUsock, err := unixsocket.NewFromFile(slaveFile)
if err != nil {
slog.Error(err)
}
// We now expect the slave to use this fd they send us to send a Pid&Identifier Message
msg, err := slaveUsock.ReadMessage()
if err != nil {
slog.Error(err)
}
pid, identifier, err := messages.ParsePidMessage(msg)
// And the last step before executing its action, the slave sends us a pipe it will later use to
// send us all the features it's loaded.
featurePipeFd, err := slaveUsock.ReadFD()
if err != nil {
slog.Error(err)
}
slaveNode := mon.tree.FindSlaveByName(identifier)
if slaveNode == nil {
Error("slavemonitor.go:slaveDidBeginRegistration:Unknown identifier:" + identifier)
}
slaveNode.SlaveWasInitialized(pid, slaveUsock, featurePipeFd)
}
func StartSlaveMonitor(tree *ProcessTree, fileChanges <-chan []string, done chan bool) chan bool {
quit := make(chan bool)
go func() {
localMasterFile, remoteMasterFile, err := unixsocket.Socketpair(syscall.SOCK_DGRAM)
if err != nil {
Error("Couldn't create socketpair")
}
monitor := &SlaveMonitor{tree, remoteMasterFile}
defer monitor.cleanupChildren()
localMasterSocket, err := unixsocket.NewFromFile(localMasterFile)
if err != nil {
Error("Couldn't Open UNIXSocket")
}
// We just want this unix socket to be a channel so we can select on it...
registeringFds := make(chan int, 3)
go func() {
for {
if fd, err := localMasterSocket.ReadFD(); err != nil {
slog.Error(err)
} else {
registeringFds <- fd
}
}
}()
for _, slave := range monitor.tree.SlavesByName {
go slave.Run(monitor)
}
for {
select {
case <-quit:
done <- true
return
case fd := <-registeringFds:
go monitor.slaveDidBeginRegistration(fd)
case files := <-fileChanges:
if len(files) > 0 {
tree.RestartNodesWithFeatures(files)
}
}
}
}()
return quit
}
func bootNewCommand(slaveNode *processtree.SlaveNode, command string, err error) (*unixsocket.Usock, error) {
if err != nil {
return nil, err
}
request := &processtree.CommandRequest{Name: command, Retchan: make(chan *processtree.CommandReply)}
slaveNode.RequestCommandBoot(request)
reply := <-request.Retchan // TODO: don't really want to wait indefinitely.
// defer commandFile.Close() // TODO: can't do this here anymore.
if reply.State == processtree.SCrashed {
return nil, errors.New("Process has crashed")
}
return unixsocket.NewFromFile(reply.File)
}