You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
55 lines
1.9 KiB
JavaScript
55 lines
1.9 KiB
JavaScript
"use strict";
|
|
Object.defineProperty(exports, "__esModule", {
|
|
value: true
|
|
});
|
|
Object.defineProperty(exports, "Batcher", {
|
|
enumerable: true,
|
|
get: function() {
|
|
return Batcher;
|
|
}
|
|
});
|
|
const _detachedpromise = require("./detached-promise");
|
|
class Batcher {
|
|
constructor(cacheKeyFn, schedulerFn = (fn)=>fn()){
|
|
this.cacheKeyFn = cacheKeyFn;
|
|
this.schedulerFn = schedulerFn;
|
|
this.pending = new Map();
|
|
}
|
|
static create(options) {
|
|
return new Batcher(options == null ? void 0 : options.cacheKeyFn, options == null ? void 0 : options.schedulerFn);
|
|
}
|
|
/**
|
|
* Wraps a function in a promise that will be resolved or rejected only once
|
|
* for a given key. This will allow multiple calls to the function to be
|
|
* made, but only one will be executed at a time. The result of the first
|
|
* call will be returned to all callers.
|
|
*
|
|
* @param key the key to use for the cache
|
|
* @param fn the function to wrap
|
|
* @returns a promise that resolves to the result of the function
|
|
*/ async batch(key, fn) {
|
|
const cacheKey = this.cacheKeyFn ? await this.cacheKeyFn(key) : key;
|
|
if (cacheKey === null) {
|
|
return fn(cacheKey, Promise.resolve);
|
|
}
|
|
const pending = this.pending.get(cacheKey);
|
|
if (pending) return pending;
|
|
const { promise, resolve, reject } = new _detachedpromise.DetachedPromise();
|
|
this.pending.set(cacheKey, promise);
|
|
this.schedulerFn(async ()=>{
|
|
try {
|
|
const result = await fn(cacheKey, resolve);
|
|
// Resolving a promise multiple times is a no-op, so we can safely
|
|
// resolve all pending promises with the same result.
|
|
resolve(result);
|
|
} catch (err) {
|
|
reject(err);
|
|
} finally{
|
|
this.pending.delete(cacheKey);
|
|
}
|
|
});
|
|
return promise;
|
|
}
|
|
}
|
|
|
|
//# sourceMappingURL=batcher.js.map
|