No longer use a list for registering self references in the abstract tcp

server

Updated assert message

Use a local variable that won't destruct at the end of the if-branch

Updated comment

contrib/epee/include/net/abstract_tcp_server2.h

@@ -155,7 +155,8 @@ namespace net_utils
     //this should be the last one, because it could be wait on destructor, while other activities possible on other threads
     t_protocol_handler m_protocol_handler;
     //typename t_protocol_handler::config_type m_dummy_config;
-    std::list<boost::shared_ptr<connection<t_protocol_handler> > > m_self_refs; // add_ref/release support
+    size_t m_reference_count = 0; // reference count managed through add_ref/release support
+    boost::shared_ptr<connection<t_protocol_handler> > m_self_ref; // the reference to hold
     critical_section m_self_refs_lock;
     critical_section m_chunking_lock; // held while we add small chunks of the big do_send() to small do_send_chunk()
     critical_section m_shutdown_lock; // held while shutting down

contrib/epee/include/net/abstract_tcp_server2.inl

@@ -230,7 +230,8 @@ PRAGMA_WARNING_DISABLE_VS(4355)
     //_dbg3("[sock " << socket_.native_handle() << "] add_ref 2, m_peer_number=" << mI->m_peer_number);
     if(m_was_shutdown)
       return false;
-    m_self_refs.push_back(self);
+    ++m_reference_count;
+    m_self_ref = std::move(self);
     return true;
     CATCH_ENTRY_L0("connection<t_protocol_handler>::add_ref()", false);
   }
@@ -242,10 +243,12 @@ PRAGMA_WARNING_DISABLE_VS(4355)
     boost::shared_ptr<connection<t_protocol_handler> >  back_connection_copy;
     LOG_TRACE_CC(context, "[sock " << socket_.native_handle() << "] release");
     CRITICAL_REGION_BEGIN(m_self_refs_lock);
-    CHECK_AND_ASSERT_MES(m_self_refs.size(), false, "[sock " << socket_.native_handle() << "] m_self_refs empty at connection<t_protocol_handler>::release() call");
-    //erasing from container without additional copy can cause start deleting object, including m_self_refs
-    back_connection_copy = m_self_refs.back();
-    m_self_refs.pop_back();
+    CHECK_AND_ASSERT_MES(m_reference_count, false, "[sock " << socket_.native_handle() << "] m_reference_count already at 0 at connection<t_protocol_handler>::release() call");
+    // is this the last reference?
+    if (--m_reference_count == 0) {
+        // move the held reference to a local variable, keeping the object alive until the function terminates
+        std::swap(back_connection_copy, m_self_ref);
+    }
     CRITICAL_REGION_END();
     return true;
     CATCH_ENTRY_L0("connection<t_protocol_handler>::release()", false);