Restart the io_service in preparation for a subsequent run() invocation.

void restart();

This function must be called prior to any second or later set of invocations of the run(), run_one(), poll() or poll_one() functions when a previous invocation of these functions returned due to the io_service being stopped or running out of work. After a call to restart(), the io_service object's stopped() function will return false.

This function must not be called while there are any unfinished calls to the run(), run_one(), poll() or poll_one() functions.