[Boost-commit] svn:boost r61243 - trunk/boost/signals2/detail

Subject: [Boost-commit] svn:boost r61243 - trunk/boost/signals2/detail
From: fmhess_at_[hidden]
Date: 2010-04-13 09:02:18

Author: fmhess
Date: 2010-04-13 09:02:17 EDT (Tue, 13 Apr 2010)
New Revision: 61243
URL: http://svn.boost.org/trac/boost/changeset/61243

Log:
Fix for uncontrolled growth of slot list under certain patterns
of connection/disconnection without invocation.  Refs #4089.

Text files modified: 
   trunk/boost/signals2/detail/signal_template.hpp |    23 ++++++++++++++---------                 
   1 files changed, 14 insertions(+), 9 deletions(-)

Modified: trunk/boost/signals2/detail/signal_template.hpp
==============================================================================
--- trunk/boost/signals2/detail/signal_template.hpp	(original)
+++ trunk/boost/signals2/detail/signal_template.hpp	2010-04-13 09:02:17 EDT (Tue, 13 Apr 2010)
@@ -229,7 +229,7 @@
             unique_lock<mutex_type> list_lock(_mutex);
             // only clean up if it is safe to do so
             if(_shared_state.unique())
-              nolock_cleanup_connections(false);
+              nolock_cleanup_connections(false, 1);
             /* Make a local copy of _shared_state while holding mutex, so we are
             thread safe against the combiner or connection list getting modified
             during invocation. */
@@ -253,7 +253,7 @@
             unique_lock<mutex_type> list_lock(_mutex);
             // only clean up if it is safe to do so
             if(_shared_state.unique())
-              nolock_cleanup_connections(false);
+              nolock_cleanup_connections(false, 1);
             /* Make a local copy of _shared_state while holding mutex, so we are
             thread safe against the combiner or connection list getting modified
             during invocation. */
@@ -413,11 +413,14 @@
 
         // clean up disconnected connections
         void nolock_cleanup_connections(bool grab_tracked,
-          const typename connection_list_type::iterator &begin, bool break_on_connected = false) const
+          const typename connection_list_type::iterator &begin, unsigned count = 0) const
         {
           BOOST_ASSERT(_shared_state.unique());
           typename connection_list_type::iterator it;
-          for(it = begin; it != _shared_state->connection_bodies().end();)
+          unsigned i;
+          for(it = begin, i = 0;
+            it != _shared_state->connection_bodies().end() && (count == 0 || i < count);
+            ++i)
           {
             bool connected;
             {
@@ -432,13 +435,12 @@
             }else
             {
               ++it;
-              if(break_on_connected) break;
             }
           }
           _garbage_collector_it = it;
         }
         // clean up a few connections in constant time
-        void nolock_cleanup_connections(bool grab_tracked) const
+        void nolock_cleanup_connections(bool grab_tracked, unsigned count) const
         {
           BOOST_ASSERT(_shared_state.unique());
           typename connection_list_type::iterator begin;
@@ -449,7 +451,7 @@
           {
             begin = _garbage_collector_it;
           }
-          nolock_cleanup_connections(grab_tracked, begin, true);
+          nolock_cleanup_connections(grab_tracked, begin, count);
         }
         /* Make a new copy of the slot list if it is currently being read somewhere else
         */
@@ -461,7 +463,10 @@
             nolock_cleanup_connections(true, _shared_state->connection_bodies().begin());
           }else
           {
-            nolock_cleanup_connections(true);
+            /* We need to try and check more than just 1 connection here to avoid corner
+            cases where certain repeated connect/disconnect patterns cause the slot
+            list to grow without limit. */
+            nolock_cleanup_connections(true, 2);
           }
         }
         // force a full cleanup of the connection list
@@ -478,7 +483,7 @@
           {
             _shared_state.reset(new invocation_state(*_shared_state, _shared_state->connection_bodies()));
           }
-          nolock_cleanup_connections(true, _shared_state->connection_bodies().begin());
+          nolock_cleanup_connections(false, _shared_state->connection_bodies().begin());
         }
         shared_ptr<invocation_state> get_readable_state() const
         {