55 lines
1 KiB
JavaScript
55 lines
1 KiB
JavaScript
|
const { setTimeout } = require('timers');
|
||
|
|
|
||
|
|
// A cache that expires.
|
||
|
|
module.exports = class Cache extends Map {
|
||
|
|
constructor(timeout = 1000) {
|
||
|
|
super();
|
||
|
|
this.timeout = timeout;
|
||
|
|
}
|
||
|
|
set(key, value) {
|
||
|
|
if (this.has(key)) {
|
||
|
|
clearTimeout(super.get(key).tid);
|
||
|
|
}
|
||
|
|
super.set(key, {
|
||
|
|
tid: setTimeout(this.delete.bind(this, key), this.timeout).unref(),
|
||
|
|
value,
|
||
|
|
});
|
||
|
|
}
|
||
|
|
get(key) {
|
||
|
|
let entry = super.get(key);
|
||
|
|
if (entry) {
|
||
|
|
return entry.value;
|
||
|
|
}
|
||
|
|
return null;
|
||
|
|
}
|
||
|
|
getOrSet(key, fn) {
|
||
|
|
if (this.has(key)) {
|
||
|
|
return this.get(key);
|
||
|
|
} else {
|
||
|
|
let value = fn();
|
||
|
|
this.set(key, value);
|
||
|
|
(async() => {
|
||
|
|
try {
|
||
|
|
await value;
|
||
|
|
} catch (err) {
|
||
|
|
this.delete(key);
|
||
|
|
}
|
||
|
|
})();
|
||
|
|
return value;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
delete(key) {
|
||
|
|
let entry = super.get(key);
|
||
|
|
if (entry) {
|
||
|
|
clearTimeout(entry.tid);
|
||
|
|
super.delete(key);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
clear() {
|
||
|
|
for (let entry of this.values()) {
|
||
|
|
clearTimeout(entry.tid);
|
||
|
|
}
|
||
|
|
super.clear();
|
||
|
|
}
|
||
|
|
};
|