Better Async support

[CodeLieutenant]

Currently there is no way to use Cassandra Driver in non-blocking event loops, while Future can be used for async non-blocking actions, Futures cannot be used in EventLoop (ReactPHP, Swoole, etc).

Cassandra CPP Driver uses LibUV, with some refactoring this could be made to work with other userland implementations of EventLoops

[CodeLieutenant]

After some digging through old Jira issues, I found something very interesting PHP-208, the way how to approach the issue of event loops (libuv, libevent, reactor->swoole). Basically all of those event loops rely on FDs (unix file descriptors) to do the efficient kernel polling.

Using unix socket as channel it the way to solve Async problem, but this needs to have least amount of overhead, the best way I found so far, is to use socketpair syscall and callback in Future.