Module signal 

Signals (unix) and console control events (Windows), as streams. Signals: a stream of the deliveries of one signal (unix) or console control event (Windows), and ctrl_c.

Each signal has a count of its deliveries, which the process’s handler raises. A listener remembers the count it last saw: a poll that finds the count moved is one item, however many deliveries that was. A listener that waits registers its waker, then looks at the count once more; whoever dispatches looks at the count after the delivery raised it, then wakes the listeners of each signal whose count moved, so no delivery is missed (the register-then-look pattern of the sync module).

On unix a signal handler may do little: it raises the count and writes to one wake descriptor of the process, never closed, which every shard with a listener reads through a pump task of its own and then dispatches (see unix). On Windows the console control handler runs on a thread of its own and dispatches itself.

Modules

unix

Unix signals as streams: signal listens to one SignalKind.

Functions

ctrl_c

Completes once the process gets a Ctrl-C: SIGINT on unix, the console’s CTRL_C_EVENT on Windows. Listening starts with the first poll; on unix the default action of SIGINT (ending the process) is replaced for good from then on.