Fix file descriptors (sockets) leak due to not closed urlopen requests

Author: alxn1

autoload/youcompleteme.vim

@@ -773,6 +773,7 @@ function! s:AbortAutohoverRequest() abort
       let request = requests[ request_id ]
       if request.origin == 'autohover'
         call remove( s:pollers.command.requests, request_id )
+        py3 ycm_state.CancelCommandRequest( int( vim.eval( "request_id" ) ) )
         call request.callback( '' )
       endif
     endfor
@@ -1551,7 +1552,7 @@ function! s:PollCommands( timer_id ) abort
 
     " This request is done
     call remove( s:pollers.command.requests, request_id )
-    py3 ycm_state.FlushCommandRequest( vim.eval( "request_id" ) )
+    py3 ycm_state.FlushCommandRequest( int( vim.eval( "request_id" ) ) )
     call request[ 'callback' ]( result )
   endfor
 

python/ycm/client/base_request.py

@@ -145,6 +145,21 @@ def PostDataToHandlerAsync( data, handler, timeout = _READ_TIMEOUT_SEC ):
     return BaseRequest._TalkToHandlerAsync( data, handler, 'POST', timeout )
 
 
+  # This method allows to cancel an async request and close the
+  # underlying request socket without waiting for a response;
+  # the method uses internal limbo thread pool where
+  # request objects are unwrapped from futures and immediately closed.
+  @staticmethod
+  def ConsumeResponseInLimboAsync( future ):
+    def _Consume( future ):
+      try:
+        future.result().close()
+      except HTTPError as response:
+          response.close()
+
+    BaseRequest.LimboExecutor().submit( _Consume, future )
+
+
   # This returns a future! Use HandleFuture to get the value.
   # |method| is either 'POST' or 'GET'.
   # |timeout| is num seconds to tolerate no response from server before giving
@@ -213,6 +228,16 @@ def Executor( cls ):
       return cls.executor
 
 
+  @classmethod
+  def LimboExecutor( cls ):
+    try:
+      return cls.limbo_executor
+    except AttributeError:
+      from ycm.unsafe_thread_pool_executor import UnsafeThreadPoolExecutor
+      cls.limbo_executor = UnsafeThreadPoolExecutor( max_workers = 1 )
+      return cls.limbo_executor
+
+
   server_location = ''
   hmac_secret = ''
 

python/ycm/client/command_request.py

@@ -78,6 +78,12 @@ def Response( self ):
     return self._response
 
 
+  def Detach( self ):
+    if self._response is None and self._response_future is not None:
+      self.ConsumeResponseInLimboAsync( self._response_future )
+      self._response_future = None
+
+
   def RunPostCommandActionsIfNeeded( self,
                                      modifiers,
                                      buffer_command = DEFAULT_BUFFER_COMMAND ):

python/ycm/client/event_notification.py

@@ -55,8 +55,15 @@ def Response( self ):
     return self._cached_response if self._cached_response else []
 
 
+  def Detach( self ):
+     if self._cached_response is None and self._response_future is not None:
+        self.ConsumeResponseInLimboAsync( self._response_future )
+        self._response_future = None
+
+
 def SendEventNotificationAsync( event_name,
                                 buffer_number = None,
                                 extra_data = None ):
   event = EventNotification( event_name, buffer_number, extra_data )
   event.Start()
+  event.Detach()

python/ycm/youcompleteme.py

@@ -509,6 +509,15 @@ def GetCommandRequest( self, request_id ):
     return self._command_requests.get( request_id )
 
 
+  def CancelCommandRequest( self, request_id ):
+    request = self._command_requests.pop( request_id, None )
+    if request is not None:
+      # As a request can't be canceled, we simply detach it now,
+      # it will be consumed in the background and
+      # immediately closed without response parsing.
+      request.Detach()
+
+
   def FlushCommandRequest( self, request_id ):
     self._command_requests.pop( request_id, None )