bool await(const process::Future<T>& future, const Duration& duration)
{
if (!process::Clock::paused()) {
return future.await(duration);
}
// If the clock is paused, no new timers will expire.
// Future::await(duration) may hang forever because it depends on
// a timer to expire after 'duration'. We instead ensure all
// expired timers are flushed and check if the future is satisfied.
Stopwatch stopwatch;
stopwatch.start();
// Settle to make sure all expired timers are executed (not
// necessarily finished, see below).
process::Clock::settle();
while (future.isPending() && stopwatch.elapsed() < duration) {
// Synchronous operations and asynchronous process::Process
// operations should finish when the above 'settle()' returns.
// Other types of async operations such as io::write() may not.
// Therefore we wait the specified duration for it to complete.
// Note that nothing prevents the operations to schedule more
// timeouts for some time in the future. These timeouts will
// never be executed due to the paused process::Clock. In this
// case we return after the stopwatch (system clock) runs out.
os::sleep(Milliseconds(10));
}
return !future.isPending();
}
Option<Error> _check_failed(const process::Future<T>& f)
{
if (f.isPending()) {
return Some("is PENDING");
} else if (f.isReady()) {
return Some("is READY");
} else if (f.isDiscarded()) {
return Some("is DISCARDED");
} else {
CHECK(f.isFailed());
return None();
}
}
Option<Error> _check_discarded(const process::Future<T>& f)
{
if (f.isPending()) {
return Error("is PENDING");
} else if (f.isReady()) {
return Error("is READY");
} else if (f.isFailed()) {
return Error("is FAILED: " + f.failure());
} else {
CHECK(f.isDiscarded());
return None();
}
}