Flags in global queue is for concurrent, because change a 64 bits pointer may not be atomic. so don't remove them.

Pointer on a 64bit OS on a 64bit CPU is atomicity, so I will remove flags array, thank you for the pr :)

http://stackoverflow.com/questions/3123326/atomicity-in-32-64-bit

I remember why we use a flags array separately. The reason is not 64it atomic.

Because when we push a mq to global queue, we should push the pointer first, and then set the flag. only then the pop can ensure the pointer is the new version.

See http://blog.codingnow.com/2012/10/bug_and_lockfree_queue.html

Hi, sorry for the late reply. It's good to know the 64-bit pointer operations are atomic. I was not very aware of this issue before you mentioned it, and I think it's a very interesting topic to consider in the code.

Although the stackoverflow page has mentioned that pointer operations are atomic, one thing I'm still not very sure is whether the values in the queue will be treated as "integers" or "pointers", as the operations here are all assignments and comparisons, but not dereferencing.

I "restored" the branch so that you could take a look at the code. Maybe it is still of a little use.

Btw, in the blog, you mentioned an issue about the "context handle". You have addressed the issue long ago. But since the context object and its corresponding "message_queue" are always related 1-to-1, maybe they could be bundled together, so that they are created and destroyed always at the same time. That is, put the message_queue structure, instead of its pointer, inside the skynet_context structure, and use the "." operator and the "offsetof" macro to reference each other.

Since the current code works just fine, maybe this is an unneccesary modification, but I think it could make the code more robust. Just my two cents.