Merge pull request #54 from woutdenolf/fix_double_registration_bug

fix double registration bug and add documentation

dahu/app/register.py

@@ -16,59 +16,93 @@ def get_uri(proxy):
 
 
 def register(
-    server="DahuDS", instance="dahu", domain="id00", family="dahu", member="1"
+    server_instance="dahu",
+    domain="id00",
+    family="dahu",
+    member="1",
+    device_class="DahuDS",
 ):
-    """Register TANGO device of class DahuDSClass"""
+    """Register a TANGO device of particular device class"""
     dev_name = "/".join([domain, family, member])
+    db = PyTango.Database()
     try:
         proxy = PyTango.DeviceProxy(dev_name)
-        logger.info("'%s' already registered", get_uri(proxy))
     except PyTango.DevFailed:
-        db = PyTango.Database()
         dev_info = PyTango.DbDevInfo()
         dev_info.name = dev_name
-        dev_info._class = "DahuDSClass"
-        server = "/".join([server, instance])
-        dev_info.server = server
+        dev_info._class = device_class
+        dev_info.server = "/".join([device_class, server_instance])
         db.add_device(dev_info)
         proxy = PyTango.DeviceProxy(dev_name)
-        logger.info("'%s' registered", get_uri(proxy))
+        logger.info("Registered a new TANGO device '%s'", get_uri(proxy))
+    else:
+        dev_info = db.get_device_info(dev_name)
+        server_instance2 = dev_info.ds_full_name.split("/")[-1]
+        if server_instance == server_instance2:
+            logger.info("TANGO device '%s' is already registered", get_uri(proxy))
+        else:
+            logger.info(
+                "TANGO device '%s' is already registered with another server '%s'",
+                get_uri(proxy),
+                server_instance2,
+            )
+            server_instance = server_instance2
     logger.info(
-        "To start the server:\n\n   TANGO_HOST=%s:%s dahu-server %s\n",
+        "To start the TANGO device server:\n\n   TANGO_HOST=%s:%s dahu-server %s\n",
         proxy.get_db_host(),
         proxy.get_db_port(),
-        instance,
+        server_instance,
+    )
+    logger.info(
+        "To get a proxy to the device:\n\n   proxy = DeviceProxy('%s')\n",
+        get_uri(proxy),
     )
-    logger.info("To get a proxy to the device:\n\n   DeviceProxy('%s')\n", get_uri(proxy))
 
 
 def main(argv=None):
     if argv is None:
         argv = sys.argv
 
-    parser = argparse.ArgumentParser(description="Register a Dahu Tango device")
+    description = """Register a Dahu TANGO device
+
+    The full device name "<domain>/<family>/<member>" ("id00/dahu/1" by default)
+    needs to be unique in the scope of one TANGO database.
+
+    TANGO devices are instantiated in TANGO device servers ("dahu" by default).
+
+    Each TANGO device server corresponds to one system process.
+    """
+
+    parser = argparse.ArgumentParser(
+        description=description, formatter_class=argparse.RawTextHelpFormatter
+    )
     parser.add_argument(
-        "--instance",
+        "--server",
         type=str,
         default="dahu",
-        help="Server instance name (session name by default)",
+        help="Server instance name (Default: 'dahu')",
     )
     parser.add_argument(
         "--domain",
         type=str,
         default="id00",
-        help="Device domain name",
+        help="Device domain name (Default: 'id00')",
     )
     parser.add_argument(
         "--family",
         type=str,
         default="dahu",
-        help="Device family name",
+        help="Device family name (Default: 'dahu')",
+    )
+    parser.add_argument(
+        "--member",
+        type=str,
+        default="1",
+        help="Device name (Default: '1')",
     )
-    parser.add_argument("--member", type=str, default="1", help="Device name")
     args = parser.parse_args(argv[1:])
     register(
-        instance=args.instance,
+        server_instance=args.server,
         domain=args.domain,
         family=args.family,
         member=args.member,