Strict 0.5s time budget for completion requests

Vim still loves to block the main GUI thread on occasion when asking for
completions... to counteract this stupidity, we enforce a hard budget of 0.5s
for all completion requests. If the server doesn't respond by then (it should,
unless something really bad happened), we give up.

python/ycm/client/base_request.py

@@ -48,19 +48,25 @@ class BaseRequest( object ):
 
 
   # This is the blocking version of the method. See below for async.
+  # |timeout| is num seconds to tolerate no response from server before giving
+  # up; see Requests docs for details (we just pass the param along).
   @staticmethod
-  def PostDataToHandler( data, handler ):
+  def PostDataToHandler( data, handler, timeout = None ):
     return JsonFromFuture( BaseRequest.PostDataToHandlerAsync( data,
-                                                               handler ) )
+                                                               handler,
+                                                               timeout ) )
 
 
   # This returns a future! Use JsonFromFuture to get the value.
+  # |timeout| is num seconds to tolerate no response from server before giving
+  # up; see Requests docs for details (we just pass the param along).
   @staticmethod
-  def PostDataToHandlerAsync( data, handler ):
+  def PostDataToHandlerAsync( data, handler, timeout = None ):
-    def PostData( data, handler ):
+    def PostData( data, handler, timeout ):
       return BaseRequest.session.post( _BuildUri( handler ),
-                                      data = json.dumps( data ),
+                                       data = json.dumps( data ),
-                                      headers = HEADERS )
+                                       headers = HEADERS,
+                                       timeout = timeout )
 
     @retries( 3, delay = 0.5 )
     def DelayedPostData( data, handler ):
@@ -71,7 +77,7 @@ class BaseRequest( object ):
     if not _CheckServerIsHealthyWithCache():
       return EXECUTOR.submit( DelayedPostData, data, handler )
 
-    return PostData( data, handler )
+    return PostData( data, handler, timeout )
 
 
   session = FuturesSession( executor = EXECUTOR )

python/ycm/client/completion_request.py

@@ -20,8 +20,9 @@
 from ycm import base
 from ycm import vimsupport
 from ycm.client.base_request import ( BaseRequest, BuildRequestData,
-                                     JsonFromFuture )
+                                      JsonFromFuture )
 
+TIMEOUT_SECONDS = 0.5
 
 class CompletionRequest( BaseRequest ):
   def __init__( self, force_semantic = False ):
@@ -42,7 +43,8 @@ class CompletionRequest( BaseRequest ):
   def Start( self, query ):
     self.request_data[ 'query' ] = query
     self._response_future = self.PostDataToHandlerAsync( self.request_data,
-                                                         'completions' )
+                                                         'completions',
+                                                         TIMEOUT_SECONDS )
 
 
   def Done( self ):