server: make connections 'private'

cheroot/connections.py

@@ -276,8 +276,8 @@ def close(self):
         self._selector.close()
 
     @property
-    def _num_connections(self):  # noqa: D401
-        """The current number of connections.
+    def _num_connections(self):
+        """Return the current number of connections.
 
         Includes any in the readable list or registered with the selector,
         minus one for the server socket, which is always registered

cheroot/server.py

@@ -1162,10 +1162,7 @@ def send_headers(self):  # noqa: C901  # FIXME
         # Override the decision to not close the connection if the connection
         # manager doesn't have space for it.
         if not self.close_connection:
-            can_keep = (
-                self.server.ready
-                and self.server.connections.can_add_keepalive_connection
-            )
+            can_keep = self.server.can_add_keepalive_connection
             self.close_connection = not can_keep
 
         if b'connection' not in hkeys:
@@ -1784,7 +1781,8 @@ def prepare(self):  # noqa: C901  # FIXME
         self.socket.settimeout(1)
         self.socket.listen(self.request_queue_size)
 
-        self.connections = connections.ConnectionManager(self)
+        # must not be accessed once stop() has been called
+        self._connections = connections.ConnectionManager(self)
 
         # Create worker threads
         self.requests.start()
@@ -1832,6 +1830,19 @@ def _run_in_thread(self):
         finally:
             self.stop()
 
+    @property
+    def can_add_keepalive_connection(self):
+        """Flag whether it is allowed to add a new keep-alive connection."""
+        return self.ready and self._connections.can_add_keepalive_connection
+
+    def put_conn(self, conn):
+        """Put an idle connection back into the ConnectionManager."""
+        if self.ready:
+            self._connections.put(conn)
+        else:
+            # server is shutting down, just close it
+            conn.close()
+
     def error_log(self, msg='', level=20, traceback=False):
         """Write error message to log.
 
@@ -2024,15 +2035,15 @@ def resolve_real_bind_addr(socket_):
 
     def tick(self):
         """Accept a new connection and put it on the Queue."""
-        conn = self.connections.get_conn()
+        conn = self._connections.get_conn()
         if conn:
             try:
                 self.requests.put(conn)
             except queue.Full:
                 # Just drop the conn. TODO: write 503 back?
                 conn.close()
 
-        self.connections.expire()
+        self._connections.expire()
 
     @property
     def interrupt(self):
@@ -2100,7 +2111,7 @@ def stop(self):  # noqa: C901  # FIXME
                 sock.close()
             self.socket = None
 
-        self.connections.close()
+        self._connections.close()
         self.requests.stop(self.shutdown_timeout)
 
 

cheroot/workers/threadpool.py

@@ -120,7 +120,7 @@ def run(self):
                     keep_conn_open = conn.communicate()
                 finally:
                     if keep_conn_open:
-                        self.server.connections.put(conn)
+                        self.server.put_conn(conn)
                     else:
                         conn.close()
                     if is_stats_enabled: