152   // entries were cleared from it so that it can be re-used. It should

   152   // entries were cleared from it so that it can be re-used. It should

   153   // not return false if the buffer is still full (otherwise we can

   153   // not return false if the buffer is still full (otherwise we can

   154   // get into an infinite loop).

   154   // get into an infinite loop).

   155   virtual bool should_enqueue_buffer() { return true; }

   155   virtual bool should_enqueue_buffer() { return true; }

   156   void handle_zero_index();

   156   void handle_zero_index();

   158 

   157 

   159   void enqueue_known_active(void* ptr);

   158   void enqueue_known_active(void* ptr);

   160 

   159 

   161   // Return the size of the in-use region.

   160   // Return the size of the in-use region.

   162   size_t size() const {

   161   size_t size() const {