pc_rpc: multiple target support

artiq/management/pc_rpc.py

@@ -30,7 +30,7 @@ class RemoteError(Exception):
 
 class IncompatibleServer(Exception):
     """Raised by the client when attempting to connect to a server that does
-    not have the expected type.
+    not have the expected target.
 
     """
     pass
@@ -62,22 +62,38 @@ class Client:
         hostname or a IPv4 or IPv6 address (see
         ``socket.create_connection`` in the Python standard library).
     :param port: TCP port to use.
-    :param expected_id_type: Server type to expect. ``IncompatibleServer`` is
+    :param target_name: Target name to select. ``IncompatibleServer`` is
-        raised when the types do not match. Use ``None`` to accept any server
+        raised if the target does not exist.
-        type.
+        Use ``None`` to skip selecting a target. The list of targets can then
+        be retrieved using ``get_rpc_id`` and then one can be selected later
+        using ``select_rpc_target``.
 
     """
-    def __init__(self, host, port, expected_id_type):
+    def __init__(self, host, port, target_name):
-        self.socket = socket.create_connection((host, port))
+        self._socket = socket.create_connection((host, port))
-        self.socket.sendall(_init_string)
+        self._socket.sendall(_init_string)
-        self._identify(expected_id_type)
+
+        server_identification = self._recv()
+        self._target_names = server_identification["targets"]
+        self._id_parameters = server_identification["parameters"]
+        if target_name is not None:
+            self.select_rpc_target(target_name)
+
+    def select_rpc_target(self, target_name):
+        """Selects a RPC target by name. This function should be called
+        exactly once if the object was created with ``target_name=None``.
+
+        """
+        if target_name not in self._target_names:
+            raise IncompatibleServer
+        self._socket.sendall((target_name + "\n").encode())
 
     def get_rpc_id(self):
-        """Returns a dictionary containing the identification information of
+        """Returns a tuple (target_names, id_parameters) containing the
-        the server.
+        identification information of the server.
 
         """
-        return self._server_identification
+        return (self._target_names, self._id_parameters)
 
     def close_rpc(self):
         """Closes the connection to the RPC server.
@@ -85,15 +101,16 @@ class Client:
         No further method calls should be done after this method is called.
 
         """
-        self.socket.close()
+        self._socket.close()
 
-    def _send_recv(self, obj):
+    def _send(self, obj):
         line = pyon.encode(obj) + "\n"
-        self.socket.sendall(line.encode())
+        self._socket.sendall(line.encode())
 
-        buf = self.socket.recv(4096).decode()
+    def _recv(self):
+        buf = self._socket.recv(4096).decode()
         while "\n" not in buf:
-            more = self.socket.recv(4096)
+            more = self._socket.recv(4096)
             if not more:
                 break
             buf += more.decode()
@@ -101,20 +118,15 @@ class Client:
 
         return obj
 
-    def _identify(self, expected_id_type):
-        obj = {"action": "identify"}
-        self._server_identification = self._send_recv(obj)
-        if (expected_id_type is not None
-                and self._server_identification["type"] != expected_id_type):
-            raise IncompatibleServer
-
     def _do_rpc(self, name, args, kwargs):
         obj = {"action": "call", "name": name, "args": args, "kwargs": kwargs}
-        obj = self._send_recv(obj)
+        self._send(obj)
-        if obj["result"] == "ok":
+
+        obj = self._recv()
+        if obj["status"] == "ok":
             return obj["ret"]
-        elif obj["result"] == "error":
+        elif obj["status"] == "failed":
-            raise RemoteError(obj["message"] + "\n" + obj["traceback"])
+            raise RemoteError(obj["message"])
         else:
             raise ValueError
 
@@ -134,18 +146,16 @@ class Server(AsyncioServer):
     simple cases: it allows new connections to be be accepted even when the
     previous client failed to properly shut down its connection.
 
-    :param target: Object providing the RPC methods to be exposed to the
+    :param targets: A dictionary of objects providing the RPC methods to be
-        client.
+        exposed to the client. Keys are names identifying each object.
-    :param id_type: A string identifying the server type. Clients use it to
+        Clients select one of these objects using its name upon connection.
-        verify that they are connected to the proper server.
     :param id_parameters: An optional human-readable string giving more
         information about the parameters of the server.
 
     """
-    def __init__(self, target, id_type, id_parameters=None):
+    def __init__(self, targets, id_parameters=None):
         AsyncioServer.__init__(self)
-        self.target = target
+        self.targets = targets
-        self.id_type = id_type
         self.id_parameters = id_parameters
 
     @asyncio.coroutine
@@ -154,34 +164,41 @@ class Server(AsyncioServer):
             line = yield from reader.readline()
             if line != _init_string:
                 return
+
+            obj = {
+                "targets": sorted(self.targets.keys()),
+                "parameters": self.id_parameters
+            }
+            line = pyon.encode(obj) + "\n"
+            writer.write(line.encode())
+            line = yield from reader.readline()
+            if not line:
+                return
+            target_name = line.decode()[:-1]
+            try:
+                target = self.targets[target_name]
+            except KeyError:
+                return
+
             while True:
                 line = yield from reader.readline()
                 if not line:
                     break
                 obj = pyon.decode(line.decode())
-                action = obj["action"]
-                if action == "call":
                 try:
-                        method = getattr(self.target, obj["name"])
+                    method = getattr(target, obj["name"])
                     ret = method(*obj["args"], **obj["kwargs"])
-                        obj = {"result": "ok", "ret": ret}
+                    obj = {"status": "ok", "ret": ret}
-                    except Exception as e:
+                except Exception:
-                        obj = {"result": "error",
+                    obj = {"status": "failed",
-                               "message": type(e).__name__ + ": " + str(e),
+                           "message": traceback.format_exc()}
-                               "traceback": traceback.format_exc()}
-                    line = pyon.encode(obj) + "\n"
-                    writer.write(line.encode())
-                elif action == "identify":
-                    obj = {"type": self.id_type}
-                    if self.id_parameters is not None:
-                        obj["parameters"] = self.id_parameters
                 line = pyon.encode(obj) + "\n"
                 writer.write(line.encode())
         finally:
             writer.close()
 
 
-def simple_server_loop(target, id_type, host, port, id_parameters=None):
+def simple_server_loop(targets, host, port, id_parameters=None):
     """Runs a server until an exception is raised (e.g. the user hits Ctrl-C).
 
     See ``Server`` for a description of the parameters.
@@ -189,7 +206,7 @@ def simple_server_loop(target, id_type, host, port, id_parameters=None):
     """
     loop = asyncio.get_event_loop()
     try:
-        server = Server(target, id_type, id_parameters)
+        server = Server(targets, id_parameters)
         loop.run_until_complete(server.start(host, port))
         try:
             loop.run_forever()

artiq/test/pc_rpc.py

@@ -66,7 +66,7 @@ def run_server():
     loop = asyncio.get_event_loop()
     try:
         echo = Echo()
-        server = pc_rpc.Server(echo, "test")
+        server = pc_rpc.Server({"test": echo})
         loop.run_until_complete(server.start(test_address, test_port))
         try:
             loop.run_until_complete(echo.wait_quit())

doc/manual/drivers_reference.rst

@@ -30,12 +30,14 @@ Default TCP port list
 
 When writing a new driver, choose a free TCP port and add it to this list.
 
-+-----------+--------------+
++--------------------------+--------------+
 | Component                | Default port |
-+===========+==============+
++==========================+==============+
-| Master    | 8888         |
+| Master (notifications)   | 8887         |
-+-----------+--------------+
++--------------------------+--------------+
+| Master (control)         | 8888         |
++--------------------------+--------------+
 | PDQ2                     | 8889         |
-+-----------+--------------+
++--------------------------+--------------+
 | LDA                      | 8890         |
-+-----------+--------------+
++--------------------------+--------------+

doc/manual/writing_a_driver.rst

@@ -23,7 +23,7 @@ To turn it into a server, we use :class:`artiq.management.pc_rpc`. Import the fu
 and add a ``main`` function that is run when the program is executed: ::
 
     def main():
-        simple_server_loop(Hello(), "hello", "::1", 7777)
+        simple_server_loop({"hello": Hello()}, "::1", 7777)
 
     if __name__ == "__main__":
         main()
@@ -49,10 +49,10 @@ and verify that you can connect to the TCP port: ::
 
 :tip: Use the key combination Ctrl-AltGr-9 to get the ``telnet>`` prompt, and enter ``close`` to quit Telnet. Quit the controller with Ctrl-C.
 
-Also verify that you can get the type of the server (the "hello" string passed to ``simple_server_loop``) using the ``artiq_ctlid.py`` program from the ARTIQ front-end tools: ::
+Also verify that a target (service) named "hello" (as passed in the first argument to ``simple_server_loop``) exists using the ``artiq_ctlid.py`` program from the ARTIQ front-end tools: ::
 
     $ artiq_ctlid.py ::1 7777
-    Type:       hello
+    Target(s):   hello
 
 The client
 ----------

frontend/artiq_client.py

@@ -144,7 +144,7 @@ def main():
         _run_subscriber(args.server, args.port, subscriber)
     else:
         port = 8888 if args.port is None else args.port
-        remote = Client(args.server, port, "schedule_control")
+        remote = Client(args.server, port, "master_schedule")
         try:
             globals()["_action_" + args.action](remote, args)
         finally:

frontend/artiq_ctlid.py

@@ -19,12 +19,12 @@ def main():
     args = _get_args()
     remote = Client(args.server, args.port, None)
     try:
-        ident = remote.get_rpc_id()
+        target_names, id_parameters = remote.get_rpc_id()
     finally:
         remote.close_rpc()
-    print("Type:       " + ident["type"])
+    print("Target(s):   " + ", ".join(target_names))
-    if "parameters" in ident:
+    if id_parameters is not None:
-        print("Parameters: " + ident["parameters"])
+        print("Parameters:  " + id_parameters)
 
 if __name__ == "__main__":
     main()

frontend/artiq_gui.py

@@ -16,11 +16,11 @@ def _get_args():
         "-s", "--server", default="::1",
         help="hostname or IP of the master to connect to")
     parser.add_argument(
-        "--port-schedule-control", default=8888, type=int,
+        "--port-notify", default=8887, type=int,
-        help="TCP port to connect to for schedule control")
+        help="TCP port to connect to for notifications")
     parser.add_argument(
-        "--port-schedule-notify", default=8887, type=int,
+        "--port-control", default=8888, type=int,
-        help="TCP port to connect to for schedule notifications")
+        help="TCP port to connect to for control")
     return parser.parse_args()
 
 
@@ -39,7 +39,7 @@ def main():
         parameters_win.show_all()
 
         loop.run_until_complete(scheduler_win.sub_connect(
-            args.server, args.port_schedule_notify))
+            args.server, args.port_notify))
         try:
             loop.run_forever()
         finally:

frontend/artiq_master.py

@@ -16,11 +16,11 @@ def _get_args():
         "--bind", default="::1",
         help="hostname or IP address to bind to")
     parser.add_argument(
-        "--port-schedule-control", default=8888, type=int,
+        "--port-notify", default=8887, type=int,
-        help="TCP port to listen to for schedule control")
+        help="TCP port to listen to for notifications")
     parser.add_argument(
-        "--port-schedule-notify", default=8887, type=int,
+        "--port-control", default=8888, type=int,
-        help="TCP port to listen to for schedule notifications")
+        help="TCP port to listen to for control")
     return parser.parse_args()
 
 
@@ -38,18 +38,20 @@ def main():
     loop.run_until_complete(scheduler.start())
     atexit.register(lambda: loop.run_until_complete(scheduler.stop()))
 
-    schedule_control = Server(scheduler, "schedule_control")
+    server_control = Server({
-    loop.run_until_complete(schedule_control.start(
+        "master_schedule": scheduler
-        args.bind, args.port_schedule_control))
+    })
-    atexit.register(lambda: loop.run_until_complete(schedule_control.stop()))
+    loop.run_until_complete(server_control.start(
+        args.bind, args.port_control))
+    atexit.register(lambda: loop.run_until_complete(server_control.stop()))
 
-    schedule_notify = Publisher({
+    server_notify = Publisher({
         "queue": scheduler.queue,
         "periodic": scheduler.periodic
     })
-    loop.run_until_complete(schedule_notify.start(
+    loop.run_until_complete(server_notify.start(
-        args.bind, args.port_schedule_notify))
+        args.bind, args.port_notify))
-    atexit.register(lambda: loop.run_until_complete(schedule_notify.stop()))
+    atexit.register(lambda: loop.run_until_complete(server_notify.stop()))
 
     loop.run_forever()
 

frontend/lda_controller.py

@@ -23,7 +23,7 @@ def main():
     else:
         lda = Lda(args.serial, args.device)
 
-    simple_server_loop(lda, "lda",
+    simple_server_loop({"lda": lda},
                        args.bind, args.port)
 
 if __name__ == "__main__":

frontend/pdq2_controller.py

@@ -32,7 +32,7 @@ def main():
 
     dev = Pdq2(serial=args.serial)
     try:
-        simple_server_loop(dev, "pdq2", args.bind, args.port,
+        simple_server_loop({"pdq2": dev}, args.bind, args.port,
                            id_parameters="serial=" + str(args.serial))
     finally:
         dev.close()