Corin, I think you are referring to STACK_WIND/UNWIND when you say "stack-based" design. The STACK_WIND/UNWIND macros in effect implement a continuation-like mechanism in C. The original reason we introduced this was to make file operations asynchronous, in that we didn't have to wait for the reply to come back from a server to issue another request. Simulating our own stack over the normal C stack has given us many other advantages. To take a concrete example, if the posix-locks translator wishes to block a call, all it needs to do is save the frame for the call and return (return in the C stack). When it needs to unblock, it simply does a STACK_UNWIND on the saved frame. Similarly the stack mechanism allows a great deal of control for translators like unify and afr, where control flow branches, loops, etc. By having the stack mechanism we explicitly transfer control from one translator to another, which gives us enormous flexibility. Vikas -- Engineer - Z Research http://gluster.com/
