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mod.ts
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mod.ts
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// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
import { MuxAsyncIterator } from "../async/mux_async_iterator.ts";
export type Disposable = { dispose: () => void };
/**
* Generates an AsyncIterable which can be awaited on for one or more signals.
* `dispose()` can be called when you are finished waiting on the events.
*
* Example:
*
* const sig = signal(Deno.Signal.SIGUSR1, Deno.Signal.SIGINT);
* setTimeout(() => {}, 5000); // Prevents exiting immediately
*
* for await (const _ of sig) {
* console.log("interrupt or usr1 signal received");
* }
*
* // At some other point in your code when finished listening:
* sig.dispose();
*
* @param signos - one or more `Deno.Signal`s to await on
*/
export function signal(
...signos: [number, ...number[]]
): AsyncIterable<void> & Disposable {
const mux = new MuxAsyncIterator<void>();
if (signos.length < 1) {
throw new Error(
"No signals are given. You need to specify at least one signal to create a signal stream.",
);
}
const streams = signos.map(Deno.signal);
streams.forEach((stream) => {
mux.add(stream);
});
// Create dispose method for the muxer of signal streams.
const dispose = (): void => {
streams.forEach((stream) => {
stream.dispose();
});
};
return Object.assign(mux, { dispose });
}
/**
* Registers a callback function to be called on triggering of a signal event.
*
* const handle = onSignal(Deno.Signal.SIGINT, () => {
* console.log('Received SIGINT');
* handle.dispose(); // de-register from receiving further events
* });
*
* @param signo One of Deno.Signal (e.g. Deno.Signal.SIGINT)
* @param callback Callback function triggered upon signal event
*/
export function onSignal(signo: number, callback: () => void): Disposable {
const sig = signal(signo);
// allows `sig` to be returned before blocking on the await
(async () => {
for await (const _ of sig) {
callback();
}
})();
return sig;
}