Reducing RAM consumption by deleting unused caches

When the user deletes a buffer, we can delete the clang caches for that file.
Fixes #184.

autoload/youcompleteme.vim

@@ -61,6 +61,7 @@ function! youcompleteme#Enable()
     " that happens *after" BufRead/BufEnter has already triggered for the
     " initial file.
     autocmd BufRead,BufEnter * call s:OnBufferVisit()
+    autocmd BufDelete * call s:OnBufferDelete( expand( '<afile>:p' ) )
     autocmd CursorHold,CursorHoldI * call s:OnCursorHold()
     autocmd InsertLeave * call s:OnInsertLeave()
     autocmd InsertEnter * call s:OnInsertEnter()
@@ -183,6 +184,15 @@ function! s:OnBufferVisit()
 endfunction
 
 
+function! s:OnBufferDelete( deleted_buffer_file )
+  if !s:AllowedToCompleteInCurrentFile() || empty( a:deleted_buffer_file )
+    return
+  endif
+
+  py ycm_state.OnBufferDelete( vim.eval( 'a:deleted_buffer_file' ) )
+endfunction
+
+
 function! s:OnCursorHold()
   if !s:AllowedToCompleteInCurrentFile()
     return

cpp/ycm/ClangCompleter/ClangCompleter.cpp

@@ -262,6 +262,16 @@ ClangCompleter::CandidatesForQueryAndLocationInFileAsync(
 }
 
 
+void ClangCompleter::DeleteCachesForFile( const std::string &filename ) {
+  // If the clang thread is currently parsing the file when the user deletes the
+  // buffer and thus we try to delete the caches, Vim's GUI thread would block
+  // until the clang thread releases the mutex. Move this operation to the clang
+  // thread.
+  lock_guard< mutex > lock( filename_to_translation_unit_mutex_ );
+  filename_to_translation_unit_.erase( filename );
+}
+
+
 bool ClangCompleter::ShouldSkipClangResultCache( const std::string &query,
                                                  int line,
                                                  int column ) {

cpp/ycm/ClangCompleter/ClangCompleter.h

@@ -93,6 +93,8 @@ public:
     const std::vector< UnsavedFile > &unsaved_files,
     const std::vector< std::string > &flags );
 
+  void DeleteCachesForFile( const std::string &filename );
+
 private:
 
   // This is basically a union. Only one of the two tasks is set to something

cpp/ycm/ClangCompleter/TranslationUnit.cpp

@@ -81,6 +81,8 @@ TranslationUnit::~TranslationUnit() {
 }
 
 void TranslationUnit::Destroy() {
+  unique_lock< mutex > lock( clang_access_mutex_ );
+
   if ( clang_translation_unit_ ) {
     clang_disposeTranslationUnit( clang_translation_unit_ );
     clang_translation_unit_ = NULL;

cpp/ycm/ycm_core.cpp

@@ -115,6 +115,7 @@ BOOST_PYTHON_MODULE(ycm_core)
   class_< ClangCompleter, boost::noncopyable >( "ClangCompleter" )
     .def( "EnableThreading", &ClangCompleter::EnableThreading )
     .def( "DiagnosticsForFile", &ClangCompleter::DiagnosticsForFile )
+    .def( "DeleteCachesForFile", &ClangCompleter::DeleteCachesForFile )
     .def( "UpdatingTranslationUnit", &ClangCompleter::UpdatingTranslationUnit )
     .def( "UpdateTranslationUnitAsync",
           &ClangCompleter::UpdateTranslationUnitAsync )

python/completers/completer.py

@@ -235,6 +235,10 @@ class Completer( object ):
     pass
 
 
+  def OnBufferDelete( self, deleted_buffer_file ):
+    pass
+
+
   def OnCursorHold( self ):
     pass
 

python/completers/cpp/clang_completer.py

@@ -147,6 +147,10 @@ class ClangCompleter( Completer ):
       flags )
 
 
+  def OnBufferDelete( self, deleted_buffer_file ):
+    self.completer.DeleteCachesForFile( deleted_buffer_file )
+
+
   def DiagnosticsForCurrentFileReady( self ):
     if not self.parse_future:
       return False

python/ycm.py

@@ -139,6 +139,13 @@ class YouCompleteMe( object ):
       self.GetFiletypeCompleter().OnFileReadyToParse()
 
 
+  def OnBufferDelete( self, deleted_buffer_file ):
+    self.identcomp.OnBufferDelete( deleted_buffer_file )
+
+    if self.FiletypeCompletionUsable():
+      self.GetFiletypeCompleter().OnBufferDelete( deleted_buffer_file )
+
+
   def OnInsertLeave( self ):
     self.identcomp.OnInsertLeave()