merge upstream

1 files changed, 87 insertions, 0 deletions

diff --git a/ethutil/reactor.go b/ethutil/reactor.go
new file mode 100644
index 000000000..7cf145245
--- /dev/null
+++ b/ethutil/reactor.go
@@ -0,0 +1,87 @@
+package ethutil
+
+import (
+	"sync"
+)
+
+type ReactorEvent struct {
+	mut   sync.Mutex
+	event string
+	chans []chan React
+}
+
+// Post the specified reactor resource on the channels
+// currently subscribed
+func (e *ReactorEvent) Post(react React) {
+	e.mut.Lock()
+	defer e.mut.Unlock()
+
+	for _, ch := range e.chans {
+		go func(ch chan React) {
+			ch <- react
+		}(ch)
+	}
+}
+
+// Add a subscriber to this event
+func (e *ReactorEvent) Add(ch chan React) {
+	e.mut.Lock()
+	defer e.mut.Unlock()
+
+	e.chans = append(e.chans, ch)
+}
+
+// Remove a subscriber
+func (e *ReactorEvent) Remove(ch chan React) {
+	e.mut.Lock()
+	defer e.mut.Unlock()
+
+	for i, c := range e.chans {
+		if c == ch {
+			e.chans = append(e.chans[:i], e.chans[i+1:]...)
+		}
+	}
+}
+
+// Basic reactor resource
+type React struct {
+	Resource interface{}
+	Event    string
+}
+
+// The reactor basic engine. Acts as bridge
+// between the events and the subscribers/posters
+type ReactorEngine struct {
+	patterns map[string]*ReactorEvent
+}
+
+func NewReactorEngine() *ReactorEngine {
+	return &ReactorEngine{patterns: make(map[string]*ReactorEvent)}
+}
+
+// Subscribe a channel to the specified event
+func (reactor *ReactorEngine) Subscribe(event string, ch chan React) {
+	ev := reactor.patterns[event]
+	// Create a new event if one isn't available
+	if ev == nil {
+		ev = &ReactorEvent{event: event}
+		reactor.patterns[event] = ev
+	}
+
+	// Add the channel to reactor event handler
+	ev.Add(ch)
+}
+
+func (reactor *ReactorEngine) Unsubscribe(event string, ch chan React) {
+	ev := reactor.patterns[event]
+	if ev != nil {
+		ev.Remove(ch)
+	}
+}
+
+func (reactor *ReactorEngine) Post(event string, resource interface{}) {
+	ev := reactor.patterns[event]
+	if ev != nil {
+		ev.Post(React{Resource: resource, Event: event})
+	}
+}