record by name which ports are chosen at random

Author: rolweber

jupyter_client/connect.py

@@ -333,6 +333,9 @@ def _ip_changed(self, name, old, new):
     control_port = Integer(0, config=True,
             help="set the control (ROUTER) port [default: random]")
 
+    # names of the ports with random assignment
+    _random_port_names = None
+
     @property
     def ports(self):
         return [ getattr(self, name) for name in port_names ]
@@ -417,6 +420,22 @@ def cleanup_ipc_files(self):
             except (IOError, OSError):
                 pass
 
+    def _record_random_port_names(self):
+        """Records which of the ports are randomly assigned.
+
+        Records on first invocation. Does nothing on later invocations."""
+
+        if self.transport != 'tcp':
+            return
+        if self._random_port_names is not None:
+            return
+
+        self._random_port_names = []
+        for name in port_names:
+            if getattr(self, name) <= 0:
+                self._random_port_names.append(name)
+
+
     def write_connection_file(self):
         """Write connection info to JSON dict in self.connection_file."""
         if self._connection_file_written and os.path.exists(self.connection_file):
@@ -431,6 +450,7 @@ def write_connection_file(self):
             kernel_name=self.kernel_name
         )
         # write_connection_file also sets default ports:
+        self._record_random_port_names()
         for name in port_names:
             setattr(self, name, cfg[name])
 
@@ -467,6 +487,7 @@ def load_connection_info(self, info):
         self.transport = info.get('transport', self.transport)
         self.ip = info.get('ip', self._ip_default())
 
+        self._record_random_port_names()
         for name in port_names:
             if getattr(self, name) == 0 and name in info:
                 # not overridden by config or cl_args

jupyter_client/tests/test_connect.py

@@ -21,6 +21,10 @@ def initialize(self, argv=[]):
         JupyterApp.initialize(self, argv=argv)
         self.init_connection_file()
 
+class DummyConfigurable(connect.ConnectionFileMixin):
+    def initialize(self):
+        pass
+
 sample_info = dict(ip='1.2.3.4', transport='ipc',
         shell_port=1, hb_port=2, iopub_port=3, stdin_port=4, control_port=5,
         key=b'abc123', signature_scheme='hmac-md5', kernel_name='python'
@@ -31,6 +35,7 @@ def initialize(self, argv=[]):
         key=b'abc123', signature_scheme='hmac-md5', kernel_name='test'
     )
 
+
 def test_write_connection_file():
     with TemporaryDirectory() as d:
         cf = os.path.join(d, 'kernel.json')
@@ -172,3 +177,11 @@ def test_find_connection_file_abspath():
             f.write('{}')
         assert connect.find_connection_file(abs_cf, path=jupyter_runtime_dir()) == abs_cf
 
+
+def test_mixin_record_random_ports():
+    with TemporaryDirectory() as d:
+        dc = DummyConfigurable(data_dir=d, kernel_name='via-tcp', transport='tcp')
+        dc.write_connection_file()
+        assert dc._connection_file_written
+        assert os.path.exists(dc.connection_file)
+        assert dc._random_port_names == connect.port_names