Hi, glad to see that you are working on this. Howard Hinnant-3 wrote:
Three years ago I wrote N2406 "Mutex, Lock, Condition Variable Rationale" (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2406.html) for the C++ committee in an attempt to explain the combined proposed std::mutex/std::unique_lock package and how it fit together with the tr2-targeted shared_mutex/shared_lock package. This paper also proposed an upgrade_mutex and upgrade_lock.
Since that time, the std-proposed stuff has been accepted with some name changes, and a reworking of the timed-locking interface. Additionally Anthony Williams has implemented much of the shared-locking functionality in boost (and done a very nice job with it).
That being said, I disagree with some fairly major design changes between N2406 and what is now in the boost library. Four of the major changes are:
1. upgrade_mutex has been dropped. 2. Some, but not all of the functionality in upgrade_mutex has been moved into shared_mutex. 3. Some of the upgrade_mutex functionality is missing completely. The missing functionality is summarized in the "Ownership Modes" charts in the form of red arrows. 4. boost allows implicit conversions between the lock types. N2406 made these conversions explicit. Rationale: changing the ownership mode of a mutex is something that should be well documented in the code.
Some weeks ago I proposed to Anthony and Ion to unify the synchronization parts of Boost.Thread and Boost.Interprocess and try to follow C++0x as close as possible, using Boost.Move, Boost.System and Boost.Chrono (if accepted). I had a positive answer from Ion. Ion was interested in preserving backward compatibility and in maintaining his Interprocess library header only, so I tried to make Boost.System and Boost.Chrono configurable either as a header only library or a dynamic library. Unfortunately Boost.Move has not been accepted yet neither. We need to see how backward compatibility can be preserved as there are a lot of differences between both interfaces. I guess you know already that Boost.Interprocess interface is quite close to N2406 and also to your design.
I have an updated implementation of <shared_mutex> (under the boost license) here:
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Thanks for sharing all these material with us. Best, Vicente -- View this message in context: http://boost.2283326.n4.nabble.com/thread-On-shared-mutex-tp3062751p3062860.... Sent from the Boost - Dev mailing list archive at Nabble.com.