Send the disconnect response before closing the client socket. (#531)

(see #530)

We were sending the "disconnect" response only after closing the socket, meaning the response was never actually sent. This PR fixes that by ensuring the response is sent as late as possible, whether or not it is a "single session" situation.

ptvsd/session.py

@@ -47,12 +47,16 @@ class DebugSession(Startable, Closeable):
         self._notify_disconnecting = notify_disconnecting
 
         self._sock = sock
+        self._pre_socket_close = None
         if ownsock:
             # Close the socket *after* calling sys.exit() (via notify_closing).
             def handle_closing(before):
                 if before:
                     return
+                debug('closing session socket')
                 proc = self._msgprocessor
+                if self._pre_socket_close is not None:
+                    self._pre_socket_close()
                 if proc is not None:
                     try:
                         proc.wait_while_connected(10)  # seconds
@@ -134,8 +138,9 @@ class DebugSession(Startable, Closeable):
 
     # internal methods for VSCodeMessageProcessor
 
-    def _handle_vsc_disconnect(self):
+    def _handle_vsc_disconnect(self, pre_socket_close=None):
         debug('disconnecting')
+        self._pre_socket_close = pre_socket_close  # TODO: Fail if already set?
         self._notify_disconnecting(self)
 
     def _handle_vsc_close(self):

ptvsd/wrapper.py

@@ -811,6 +811,7 @@ class VSCodeMessageProcessorBase(ipcjson.SocketIO, ipcjson.IpcChannel):
         self._notify_closing = notify_closing
 
         self.server_thread = None
+        self._closing = False
         self._closed = False
         self.readylock = threading.Lock()
         self.readylock.acquire()  # Unlock at the end of start().
@@ -824,6 +825,10 @@ class VSCodeMessageProcessorBase(ipcjson.SocketIO, ipcjson.IpcChannel):
         with self._connlock:
             return _util.is_locked(self._connected)
 
+    @property
+    def closed(self):
+        return self._closed or self._closing
+
     @property
     def listening(self):
         # TODO: must be disconnected?
@@ -882,9 +887,9 @@ class VSCodeMessageProcessorBase(ipcjson.SocketIO, ipcjson.IpcChannel):
 
     def close(self):
         """Stop the message processor and release its resources."""
-        if self._closed:
+        if self.closed:
             return
-        self._closed = True
+        self._closing = True
         debug('raw closing')
 
         self._notify_closing()
@@ -895,6 +900,7 @@ class VSCodeMessageProcessorBase(ipcjson.SocketIO, ipcjson.IpcChannel):
         with self._connlock:
             _util.lock_release(self._listening)
             _util.lock_release(self._connected)
+        self._closed = True
 
     # VSC protocol handlers
 
@@ -1080,8 +1086,20 @@ class VSCLifecycleMsgProcessor(VSCodeMessageProcessorBase):
         # TODO: docstring
         if self._debuggerstopped:  # A "terminated" event must have been sent.
             self._wait_until_exiting(self.EXITWAIT)
-        self._notify_disconnecting()
-        self.send_response(request)
+
+        status = {'sent': False}
+
+        def disconnect_response():
+            if status['sent']:
+                return
+            self.send_response(request)
+            status['sent'] = True
+
+        self._notify_disconnecting(
+            pre_socket_close=disconnect_response,
+        )
+        disconnect_response()
+
         self._set_disconnected()
 
         if self.start_reason == 'attach':
@@ -1089,7 +1107,7 @@ class VSCLifecycleMsgProcessor(VSCodeMessageProcessorBase):
                 self._handle_detach()
         # TODO: We should be able drop the "launch" branch.
         elif self.start_reason == 'launch':
-            if not self._closed:
+            if not self.closed:
                 # Closing the socket causes pydevd to resume all threads,
                 # so just terminate the process altogether.
                 sys.exit(0)

tests/system_tests/test_main.py

@@ -512,6 +512,7 @@ class LifecycleTests(TestsBase, unittest.TestCase):
         done2, waitscript2 = lockfile2.wait_in_script(timeout=5)
         filename = self.write_script('spam.py', waitscript1 + waitscript2)
         addr = Address('localhost', 8888)
+        #DebugAdapter.VERBOSE = True
         with DebugAdapter.start_for_attach(addr, filename) as adapter:
             with DebugClient() as editor:
                 # Attach initially.