Changed tweets, added eca

eca/pubsub.py

@@ -0,0 +1,50 @@
+import collections
+import threading
+
+
+class PubSubChannel:
+    """
+    Publish/Subscribe channel used for distribution of events.
+
+    The operations on this channel are thread-safe, but subscribers
+    are executed by the publishing thread. Use a queue to decouple the
+    publishing thread from the consuming thread.
+    """
+
+    def __init__(self):
+        self.lock = threading.RLock()
+        self.subscriptions = collections.defaultdict(list)
+
+    def subscribe(self, target, event='message'):
+        """
+        Subscribe to an event.
+
+        The optional event name can be used to subscribe selectively.
+        """
+        with self.lock:
+            self.subscriptions[event].append(target)
+
+    def unsubscribe(self, target, event='message'):
+        """
+        Unsubscribe from an event.
+
+        The optional event name can be used to unsubscribe from another event.
+        """
+        with self.lock:
+            self.subscriptions[event].remove(target)
+
+    def publish(self, event='message', data=None, delay=None):
+        """
+        Publishes an event.
+
+        The event can be accompanied by optional data. A delay can be set to
+        delay the publish action by the given amount of seconds.
+        """
+        if delay is None:
+            with self.lock:
+                for target in self.subscriptions[event]:
+                    target(event, data)
+        else:
+            def task():
+                self.publish(event, data)
+            threading.Timer(delay, task).start()