I am forwarding the review below: ---------- Forwarded message ---------- From: <Jean-Christophe.BENOIST@fr.thalesgroup.com> Date: Tue, Nov 4, 2008 at 8:43 AM Subject: [signals2][review] The review of the signals2 library (formerly t hread_safe_signals) begins today, Nov 1st : little REVIEW To: stjepan.rajko@gmail.com (first of all please excuse my weak english, I am not a native english speaker) I am a regular user of boost::signals, so I am very interested by signals2. I'll review from a user standpoint. * On the documentation : - I am surprised to find very little information or rationale about multi-threading in documentation. We know the library is now "thread safe" but we don't know exactly what it means. There is only one MT use case (just) detailed in "tutorial" : what happens when a thread disconnect a slot from a signal, while another thread calls it. But there are another interesting MT use cases : - what if 2 threads simultaneously calls the same signal ? How to mutex slots in this case ? Are slots automatically excluded by an hidden mutex ? - What if a thread adds a slot to a signal while another calls it ? Is the slot added after signal call ? There should be tutorials and explanations for these cases, IMO. - About rationale : why is there special signals2::mutex ? May we use boost::thread::mutex for mutex template ? What are advantages/drawbacks of choosing signals2::mutex or boost::thread::mutex ? - Use of "postconstructible" or "predestructible" classes is rather obscure, and should be tutorialized / better documented. * On interface : - Very close from original signals interface : no particular comment. * On test suite / test cases : - I cannot see any MT test case (from the documentation, in "acceptance tests" section at least). It's rather surprising. I cannot imagine there is no test case for MT (calling a signal while disconnecting slot etc..). In particular, I'd whish to see if this library is robust in a multi-core environment and run test cases in this environment (I know cases where a library is perfectly thread safe on mono-core, even hyperthreading, but fails on multi-core). At least, there should be a rationale explaining why this library should be robust in a multi-core environment (especially with a proprietary signals2::mutex). * Final statement : All in all, I think this library is very close to be accepted as a Boost library, but without MT test cases and MT documentation, I can't give a total agreement for now. I have little doubt this library is MT tested and robust, even in a multi-core environment, but I have no real clue to assert it. Feel free to ask me further details. Best regards Jean-Christophe BENOIST Software Engineer THALES Communications France