在Javascript中缓存和预取即将到期的承诺 [英] Caching and pre-fetching expiring promises in Javascript

问题描述

Promise是我在Javascript中管理异步代码的首选方式。
Memoize（npm上的memoizee）是一个用于轻松缓存的Javascript库。预取函数的结果。

Promises are my preferred way of managing my asynchronous code in Javascript. Memoize (memoizee on npm) is a Javascript library for easily caching & pre-fetching results of functions.

理想情况下，我希望结合两者的优点，并且能够使Promise过期并预先获取新的Promise结果（当触摸缓存并接近到期时）。 Memoize可以做到这一点，但它并没有考虑到Promise。

Ideally I want to combine the best of both, and have the ability to "expire" a Promise and pre-fetch a new Promise result (when the cache is touched and near to expiring). Memoize can do this, but it wasn't built with Promises in mind.

（我知道Promises有一个内置的永远缓存，因为它们的性质，但永远对于我的应用来说太长了

(I understand that Promises have a built-in "forever-cache" as is their nature, but forever is too long for my application)

到目前为止我做这个的最佳尝试如下（node.js示例使用< a href =https://github.com/petkaantonov/bluebird> bluebird ， memoize 和下划线）：

My best attempt to do this so far is as follows (node.js example using bluebird, memoize and underscore):

var memoize = require('memoizee')
  , Promise = require('bluebird')
  , _ = require('underscore')
  ;

// returns a memoized Promise-generating function
function memoizePromiser(funcReturningPromise, options) {
    var opts = _.defaults(options || {}, {async: true});

    return Promise.promisify(memoize(function(){
        var args = _.initial(arguments);
        var cb = _.last(arguments);
        funcReturningPromise.apply(this, args).nodeify(cb);
    }, opts));
};

这个函数允许我记忆一个异步函数（带有类似节点的回调）返回一个promise，同时还提供了Memoize库提供的所有缓存到期（+更多）功能。

This function will allow me to memoize an async function (with node-like callbacks) returning a promise, whilst also providing all the cache-expiry (+ more) functionality offered by the Memoize library.

然而，这种方法看起来很混乱，而且过度设计。我想我自己 - 这肯定是一个普遍的问题，而其他人已经提出了一个更优雅的解决方案吗？

However, this approach seems messy and over-engineered to me. I think to myself - surely this is a common enough problem hat someone else has made a more elegant solution?

这是我尝试做的最好的方法？还有另一个像memoize这样专门为promises设计的库吗？是否有一个我错过的更简单的解决方案？

Is this the best approach for what I'm trying to do? Is there another library like memoize which is designed specifically for promises? Is there a simpler solution that I've missed?

任何指导都将受到赞赏。

Any guidance would be appreciated.

推荐答案

这个函数允许我记忆一个异步函数（带有类似节点的回调）返回一个promise。然而，这种方法看起来很混乱并且过度设计了。

This function will allow me to memoize an async function (with node-like callbacks) returning a promise. However, this approach seems messy and over-engineered to me.

是的 - 你已经有一个函数返回一个promise，没有回到nodebacks的原因。

Yes - you already have a function returning a promise, there is no reason to go back to nodebacks.

我错过了一个更简单的解决方案吗？

Is there a simpler solution that I've missed?

返回promise的函数只是一个返回某个值的函数 - 一个可以通过 memoize缓存的值功能。只需

A function that returns a promise is just a function that returns some value - a value that can be cached by the memoize function. Simply do

memoize(funcReturningPromise, options)

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