doodle/pkg/scripting/pubsub.go

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package scripting
import (
"git.kirsle.net/apps/doodle/pkg/log"
"github.com/dop251/goja"
)
// Message holds data being published from one script VM with information sent
// to the linked VMs.
type Message struct {
Name string
SenderID string
Args []goja.Value
}
/*
RegisterPublishHooks adds the pub/sub hooks to a JavaScript VM.
This adds the global methods `Message.Subscribe(name, func)` and
`Message.Publish(name, args)` to the JavaScript VM's scope.
*/
func RegisterPublishHooks(s *Supervisor, vm *VM) {
// Goroutine to watch the VM's inbound channel and invoke Subscribe handlers
// for any matching messages received.
go func() {
// Catch any exceptions raised by the JavaScript VM.
defer func() {
if err := recover(); err != nil {
// TODO EXCEPTIONS
log.Error("RegisterPublishHooks(%s): %s", vm.Name, err)
}
}()
// Watch the Inbound channel for PubSub messages and the stop channel for Teardown.
for {
select {
case <-vm.stop:
log.Info("JavaScript VM %s stopping PubSub goroutine", vm.Name)
return
case msg := <-vm.Inbound:
vm.muSubscribe.Lock()
if _, ok := vm.subscribe[msg.Name]; ok {
for _, callback := range vm.subscribe[msg.Name] {
log.Debug("PubSub: %s receives from %s: %s", vm.Name, msg.SenderID, msg.Name)
if function, ok := goja.AssertFunction(callback); ok {
function(goja.Undefined(), msg.Args...)
}
}
}
vm.muSubscribe.Unlock()
}
}
}()
// Register the Message.Subscribe and Message.Publish functions.
vm.vm.Set("Message", map[string]interface{}{
"Subscribe": func(name string, callback goja.Value) {
vm.muSubscribe.Lock()
defer vm.muSubscribe.Unlock()
if _, ok := goja.AssertFunction(callback); !ok {
log.Error("SUBSCRIBE(%s): callback is not a function", name)
return
}
if _, ok := vm.subscribe[name]; !ok {
vm.subscribe[name] = []goja.Value{}
}
vm.subscribe[name] = append(vm.subscribe[name], callback)
},
"Publish": func(name string, v ...goja.Value) {
for _, channel := range vm.Outbound {
channel <- Message{
Name: name,
SenderID: vm.Name,
Args: v,
}
}
},
"Broadcast": func(name string, v ...goja.Value) {
// Send the message to all actor VMs.
for _, toVM := range s.scripts {
if toVM == nil {
continue
}
if vm.Name == toVM.Name {
log.Debug("Broadcast(%s): skip to vm '%s' cuz it is the sender", name, toVM.Name)
continue
}
toVM.Inbound <- Message{
Name: name,
SenderID: vm.Name,
Args: v,
}
}
},
})
}