check that buffers are contiguous

zmq.send will fail on non-contiguous buffers

ensures errors due to bad arguments are raise in `Session.send`
instead of potentially delayed to the aysnc callback,
which is not handled well.

Author: minrk

jupyter_client/session.py

@@ -699,13 +699,18 @@ def send(self, stream, msg_or_type, content=None, parent=None, ident=None,
             )
             return
         buffers = [] if buffers is None else buffers
-        for buf in buffers:
-            if not isinstance(buf, memoryview):
+        for idx, buf in enumerate(buffers):
+            if isinstance(buf, memoryview):
+                view = buf
+            else:
                 try:
                     # check to see if buf supports the buffer protocol.
-                    memoryview(buf)
+                    view = memoryview(buf)
                 except TypeError:
                     raise TypeError("Buffer objects must support the buffer protocol.")
+            if not view.contiguous:
+                # zmq requires memoryviews to be contiguous
+                raise ValueError("Buffer %i (%r) is not contiguous" % (idx, buf))
 
         if self.adapt_version:
             msg = adapt(msg, self.adapt_version)

jupyter_client/tests/test_session.py

@@ -122,9 +122,14 @@ def test_send(self):
         self.assertEqual(new_msg['buffers'],[b'bar'])
 
         # buffers must support the buffer protocol
-        with self.assertRaises(TypeError) as cm:
+        with self.assertRaises(TypeError):
             self.session.send(A, msg, ident=b'foo', buffers=[1])
 
+        # buffers must be contiguous
+        buf = memoryview(os.urandom(16))
+        with self.assertRaises(ValueError):
+            self.session.send(A, msg, ident=b'foo', buffers=[buf[::2]])
+
         A.close()
         B.close()
         ctx.term()