Register each actor using its unique ID tuple

This allows for registering more then one actor with the same "name"
when you have multiple actors fulfilling the same role. Eventually
we'll need support for looking up all actors registered under a given
"service name" (or whatever we decide to call it).

Also, a fix to the arbiter such that each new instance refers to a
separate `_registry` dict (found an issue with duplicate names during
testing).

Resolves #7

tractor/_actor.py

@@ -434,7 +434,7 @@ class Actor:
                 async with get_arbiter(*arbiter_addr) as arb_portal:
                     await arb_portal.run(
                         'self', 'register_actor',
-                        name=self.name, sockaddr=self.accept_addr)
+                        uid=self.uid, sockaddr=self.accept_addr)
                     registered_with_arbiter = True
 
                 task_status.started()
@@ -522,7 +522,7 @@ class Actor:
             if arbiter_addr is not None:
                 async with get_arbiter(*arbiter_addr) as arb_portal:
                     await arb_portal.run(
-                        'self', 'unregister_actor', name=self.name)
+                        'self', 'unregister_actor', uid=self.uid)
         except OSError:
             log.warn(f"Unable to unregister {self.name} from arbiter")
 
@@ -580,24 +580,30 @@ class Actor:
 
 class Arbiter(Actor):
     """A special actor who knows all the other actors and always has
-    access to the top level nursery.
+    access to a top level nursery.
 
     The arbiter is by default the first actor spawned on each host
     and is responsible for keeping track of all other actors for
     coordination purposes. If a new main process is launched and an
     arbiter is already running that arbiter will be used.
     """
-    _registry = defaultdict(list)
     is_arbiter = True
 
+    def __init__(self, *args, **kwargs):
+        self._registry = defaultdict(list)
+        super().__init__(*args, **kwargs)
+
     def find_actor(self, name):
-        return self._registry[name]
+        for uid, actor in self._registry.items():
+            if name in uid:
+                print('found it!')
+                return actor
 
-    def register_actor(self, name, sockaddr):
-        self._registry[name].append(sockaddr)
+    def register_actor(self, uid, sockaddr):
+        self._registry[uid].append(sockaddr)
 
-    def unregister_actor(self, name):
-        self._registry.pop(name, None)
+    def unregister_actor(self, uid):
+        self._registry.pop(uid, None)
 
 
 async def _start_actor(actor, main, host, port, arbiter_addr, nursery=None):