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denoland-deno/runtime/js/40_signals.js
Bartek Iwańczuk f3c0f0565b
feat(core): Add ability to "ref" and "unref" pending ops (#12889)
This commit adds an ability to "ref" or "unref" pending ops.

Up to this point Deno had a notion of "async ops" and "unref async ops";
the former keep event loop alive, while the latter do not block event loop
from finishing. It was not possible to change between op types after
dispatching, one had to decide which type to use before dispatch.

Instead of storing ops in two separate "FuturesUnordered" collections,
now ops are stored in a single collection, with supplemental "HashSet"
storing ids of promises that were "unrefed".

Two APIs were added to "Deno.core":

"Deno.core.refOp(promiseId)" which allows to mark promise id
to be "refed" and keep event loop alive (the default behavior)
"Deno.core.unrefOp(promiseId)" which allows to mark promise
id as "unrefed" which won't block event loop from exiting
2021-11-25 19:49:09 +01:00

85 lines
2.1 KiB
JavaScript

// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
"use strict";
((window) => {
const core = window.Deno.core;
const {
Set,
SymbolFor,
TypeError,
} = window.__bootstrap.primordials;
function bindSignal(signo) {
return core.opSync("op_signal_bind", signo);
}
function pollSignal(rid) {
const promise = core.opAsync("op_signal_poll", rid);
core.unrefOp(promise[SymbolFor("Deno.core.internalPromiseId")]);
return promise;
}
function unbindSignal(rid) {
core.opSync("op_signal_unbind", rid);
}
// Stores signal listeners and resource data. This has type of
// `Record<string, { rid: number | undefined, listeners: Set<() => void> }`
const signalData = {};
/** Gets the signal handlers and resource data of the given signal */
function getSignalData(signo) {
return signalData[signo] ??
(signalData[signo] = { rid: undefined, listeners: new Set() });
}
function checkSignalListenerType(listener) {
if (typeof listener !== "function") {
throw new TypeError(
`Signal listener must be a function. "${typeof listener}" is given.`,
);
}
}
function addSignalListener(signo, listener) {
checkSignalListenerType(listener);
const sigData = getSignalData(signo);
sigData.listeners.add(listener);
if (!sigData.rid) {
// If signal resource doesn't exist, create it.
// The program starts listening to the signal
sigData.rid = bindSignal(signo);
loop(sigData);
}
}
function removeSignalListener(signo, listener) {
checkSignalListenerType(listener);
const sigData = getSignalData(signo);
sigData.listeners.delete(listener);
if (sigData.listeners.size === 0 && sigData.rid) {
unbindSignal(sigData.rid);
sigData.rid = undefined;
}
}
async function loop(sigData) {
while (sigData.rid) {
if (await pollSignal(sigData.rid)) {
return;
}
for (const listener of sigData.listeners) {
listener();
}
}
}
window.__bootstrap.signals = {
addSignalListener,
removeSignalListener,
};
})(this);