Some improvements

doc/remote_tuto.rst

@@ -110,10 +110,17 @@ And ``pyactor\examples\Remote\s4_clientb.py``:
 .. literalinclude:: ../examples/Remote/s4_clientb.py
     :linenos:
 
-Here we have a registry where Servers can be bind. The registry module starts an
-actor which is the registry itself. The first client, binds a server to the
-registry and waits for queries. The second one, uses the registry to find the
-first one and send work to its server.
+In this example we have a registry where Servers can be bind. The registry
+module starts an actor which is the registry itself to which servers can be
+bind and clients look for servers. The first client, binds a server to the
+registry and waits for queries to that server. The second one, uses the registry
+to find the first one and spawn a server instance on it to afterwards send work
+to it.
+
+In order to execute the second client repeatedly without having to restart
+all the processes, before spawning the server remotely, it checks if the first
+client has already the server by using the method ``has_actor`` on the
+remote_host.
 
 
 

doc/tutorial.rst

@@ -398,7 +398,17 @@ blocked with another job (an I/O call or a synchronous call to another actor).
 To make one method execute parallel, you need to specify it in the class attribute
 _parallel, which is a list. The method must also be in one of the lists _tell or
 _ask. The methods with this tag will be executed in new threads so their execution
-do not interfere with other queries.
+do not interfere with other queries. That is, the actor can attend other queries
+while executing the parallel method.
+
+As you could think, executing methods of the same actor at the same time can compromise
+the integrity of data. PyActor ensures that only one thread is executing on an
+actor at the same time, allowing other threads to execute when the one executing
+is blocked with some call. This prevents two threads from accessing the same data
+at a time, but is up to the programmer to prevent the data to change during the
+execution of a method if that is not intended, as a method could modify a property
+of the actor while a parallel, that operates with that data, is blocked, leading
+to an inconsistency.
 
 In this example we have three classes: File, Web and Workload. File represents a
 server that serve the download of files. Simulates the work with a sleep.

examples/Remote/s4_client.py

@@ -7,9 +7,9 @@
 
 if __name__ == "__main__":
     set_context()
-    host = create_host('http://127.0.0.1:1679')
+    host = create_host('http://127.0.0.1:6001')
 
-    registry = host.lookup_url('http://127.0.0.1:1277/regis', 'Registry',
+    registry = host.lookup_url('http://127.0.0.1:6000/regis', 'Registry',
                                's4_registry')
 
     registry.bind('host1', host)

examples/Remote/s4_clientb.py

@@ -24,18 +24,21 @@ def wait_a_lot(self):
 
 if __name__ == "__main__":
     set_context()
-    host = create_host('http://127.0.0.1:1777')
+    host = create_host('http://127.0.0.1:6002')
 
-    registry = host.lookup_url('http://127.0.0.1:1277/regis', 'Registry',
+    registry = host.lookup_url('http://127.0.0.1:6000/regis', 'Registry',
                                's4_registry')
     remote_host = registry.lookup('host1')
-
-    server = remote_host.spawn('server', 's4_clientb/Server')
-    z = server.add(6, 7)
-    print z
-    server.substract(6, 5)
-    t = server.add(8, 7)
-    print t
+    if remote_host is not None:
+        if not remote_host.has_actor('server'):
+            server = remote_host.spawn('server', 's4_clientb/Server')
+        else:
+            server = remote_host.lookup('server')
+        z = server.add(6, 7)
+        print z
+        server.substract(6, 5)
+        t = server.add(8, 7)
+        print t
 
     try:
         registry.unbind('None')

examples/Remote/s4_registry.py

@@ -27,18 +27,21 @@ def unbind(self, name):
             raise NotFound()
 
     def lookup(self, name):
-        return self.actors[name]
+        if name in self.actors:
+            return self.actors[name]
+        else:
+            return None
 
     def get_all(self):
         return self.actors.values()
 
 
 if __name__ == "__main__":
     set_context()
-    host = create_host('http://127.0.0.1:1277/')
+    host = create_host('http://127.0.0.1:6000/')
 
     registry = host.spawn('regis', Registry)
 
-    print 'host listening at port 1277'
+    print 'host listening at port 6000'
 
     serve_forever()

pyactor/context.py

@@ -124,7 +124,8 @@ class Host(object):
     :param str. url: URL that identifies the host and where to find it.
     '''
     _tell = ['attach_interval', 'detach_interval', 'hello', 'stop_actor']
-    _ask = ['spawn', 'lookup', 'lookup_url', 'say_hello', 'interval', 'later']
+    _ask = ['spawn', 'lookup', 'lookup_url', 'say_hello', 'interval', 'later',
+            'has_actor']
     _ref = ['spawn', 'lookup', 'lookup_url', 'interval', 'later']
 
     def __init__(self, url):
@@ -233,6 +234,16 @@ def spawn(self, aid, klass, param=None):
             self.launch_actor(url, new_actor)
             return Proxy(new_actor)
 
+    def has_actor(self, aid):
+        '''
+        Checks if the given id is used in the host by some actor.
+
+        :param str. aid: identifier of the actor to check.
+        :return: True if the id is used within the host.
+        '''
+        url = '%s://%s/%s' % (self.transport, self.host_url.netloc, aid)
+        return url in self.actors.keys()
+
     def lookup(self, aid):
         '''
         Gets a new proxy that references to the actor of this host
@@ -487,7 +498,12 @@ def loads(self, param):
         proxies for actors from another host.
         '''
         if isinstance(param, ProxyRef):
-            return self.lookup_url(param.url, param.klass, param.module)
+            try:
+                return self.lookup_url(param.url, param.klass, param.module)
+            except HostError:
+                print "Can't lookup for the actor received with the call. \
+                    It does not exist or the url is unreachable.", param
+                raise HostError
         elif isinstance(param, list):
             return [self.loads(elem) for elem in param]
         elif isinstance(param, dict):

pyactor/green_thread/rpcactor.py

@@ -10,7 +10,7 @@
 
 class RPCDispatcher(Actor):
     '''
-    This is the actor that will manage the sends and recieves of remote
+    This is the actor that will manage the sends and receives of remote
     queries with other hosts. Each host has one, configured depending on
     the scheme specified when created.
     '''
@@ -29,7 +29,7 @@ def __init__(self, url, host, mode):
         self.source.start()
         self.running = True
         self.channel = Channel()
-        self.pending = {}   # Sended to another host
+        self.pending = {}   # Sent to another host
         self.executing = {}  # Waiting for the response in this server
         self.tell = ['stop']
         self.ask = []
@@ -68,7 +68,7 @@ def receive(self, msg):
                     except Exception:
                         print (('Error sending a response to %r.'
                                % (self.executing[msg[RPC_ID]])) +
-                               ' Receiver is offline?')
+                               ' Is the receiver offline?')
                         del self.executing[msg[RPC_ID]]
                 elif msg[TYPE] == FUTURE:
                     rpc_id = msg[RPC_ID]

pyactor/thread/rpcactor.py

@@ -10,7 +10,7 @@
 
 class RPCDispatcher(Actor):
     '''
-    This is the actor that will manage the sends and recieves of remote
+    This is the actor that will manage the sends and receives of remote
     queries with other hosts. Each host has one, configured depending on
     the scheme specified when created.
     '''
@@ -29,7 +29,7 @@ def __init__(self, url, host, mode):
         self.source.start()
         self.running = True
         self.channel = Channel()
-        self.pending = {}   # Sended to another host
+        self.pending = {}   # Sent to another host
         self.executing = {}  # Waiting for the response in this server
         self.tell = ['stop']
         self.ask = []
@@ -68,7 +68,7 @@ def receive(self, msg):
                     except Exception:
                         print (('Error sending a response to %r.'
                                % (self.executing[msg[RPC_ID]])) +
-                               ' Receiver is offline?')
+                               ' Is the receiver offline?')
                         del self.executing[msg[RPC_ID]]
                 elif msg[TYPE] == FUTURE:
                     rpc_id = msg[RPC_ID]

pyactor/util.py

@@ -8,6 +8,9 @@
 from threading import current_thread
 
 
+from pyactor.exceptions import HostError
+
+
 RABBITU = "guest"
 RABBITP = "guest"
 
@@ -76,8 +79,13 @@ def get_lock():
 def ref_l(f):
     def wrap_ref_l(*args):
         new_args = list(args)
-        new_args[0][PARAMS] = get_host().loads(list(args[0][PARAMS]))
-        return f(*new_args)
+        try:
+            new_args[0][PARAMS] = get_host().loads(list(args[0][PARAMS]))
+            return f(*new_args)
+        except HostError:
+            pass
+            # If there is a problem deserializing the params, the method is not
+            # executed.
     return wrap_ref_l
 
 

testing/tests_gevent.py

@@ -221,7 +221,7 @@ def test_1hostcreation(self):
         self.assertEqual(self.h.actor.tell, ['attach_interval',
                                              'detach_interval',
                                              'hello', 'stop_actor', 'stop'])
-        self.assertEqual(self.h.actor.ask, ['say_hello'])
+        self.assertEqual(self.h.actor.ask, ['say_hello', 'has_actor'])
         self.assertEqual(self.h.actor.ask_ref, ['spawn', 'interval', 'lookup',
                                                 'lookup_url', 'later'])
         with self.assertRaises(Exception):

testing/tests_thread.py

@@ -222,7 +222,7 @@ def test_1hostcreation(self):
         self.assertEqual(self.h.actor.tell, ['attach_interval',
                                              'detach_interval', 'hello',
                                              'stop_actor', 'stop'])
-        self.assertEqual(self.h.actor.ask, ['say_hello'])
+        self.assertEqual(self.h.actor.ask, ['say_hello', 'has_actor'])
         self.assertEqual(self.h.actor.ask_ref, ['spawn', 'interval', 'lookup',
                                                 'lookup_url', 'later'])
         with self.assertRaises(Exception):