add write handler hook

websocketpp/impl/connection_impl.hpp

@@ -1594,6 +1594,7 @@ void connection<config>::handle_write_frame(lib::error_code const & ec)
     bool terminate = m_current_msg->get_terminal();
 
     m_send_buffer.clear();
+    m_msg_manager->write_handler_hook(m_current_msg);
     m_current_msg.reset();
 
     if (ec) {

websocketpp/message_buffer/alloc.hpp

@@ -87,6 +87,10 @@ public:
         // nothing to do here
     }
 
+    void write_handler_hook(message_ptr msg) {
+        // nothing to do here
+    }
+
     /// Recycle a message
     /**
      * This method shouldn't be called. If it is, return false to indicate an

websocketpp/message_buffer/fixed.hpp

@@ -102,6 +102,13 @@ public:
         recycle(msg);
     }
 
+    void write_handler_hook(message_ptr msg) {
+        // TODO: we shouldn't recycle a message every time it is written. If a
+        // message is queued for writing multiple times... Needs a reference
+        // count in the message to deal with this.
+        recycle(msg);
+    }
+
     bool recycle(message_ptr msg) {
         if (msg == m_incoming_message) {
             m_incoming_message_busy = false;