Phil Endecott <spam_from_boost_dev <at> chezphil.org> writes:
I notice that Anthony Williams used the term "lockable concept" in the Boost.Threads release notes that he posted here recently. Anthony, would it be possible to say e.g. "mutex concept" in your context so that we can keep the term "lockable" available for something like this? (Or maybe they are actually the same thing. Hmmm.)
I've used the concept "lockable" to describe something which can be locked. I felt this was a better term than "mutex", since some of the things that can be locked are not mutexes. For example unique_lock<some_mutex> also models "Lockable", so you can have a unique_lock<unique_lock<some_mutex> >. Hopefully the new boost.thread docs will give you a better idea. I would not describe a pair of data+mutex as "lockable" unless you could indeed lock it and unlock it (with lock()/unlock() member functions). However, even if you could, the term "lockable" wouldn't (in my view) describe what the combined data structure was. Would "protected" better describe the intent? I know it's a keyword, but surely the idea is to protect the data from concurrent access.
Something else to consider is the interaction with atomic operations and lock-free data structures. It would be great if Locked<int> and Atomic<int>, or Locked<list<int>> and lockfree_list<int>, had very similar interfaces.
The C++0x atomic<> template will work with any type that is "trivially copy assignable and bitwise equality comparable", and it is intended that operations are protected with a mutex where they cannot be done with atomic ops. The is_lock_free() member distinguishes the two cases. I would expect this to cover many uses, though obviously you can't write atomic<list<int>>, since list<> is definitely not bitwise equality-comparable. How about synchronized<> to pinch a term from Java? Anthony -- Anthony Williams Just Software Solutions Ltd - http://www.justsoftwaresolutions.co.uk Registered in England, Company Number 5478976. Registered Office: 15 Carrallack Mews, St Just, Cornwall, TR19 7UL