如何在 JavaScript 中实现锁 [英] How to implement a lock in JavaScript

问题描述

如何在 JavaScript 中实现与 C# 中的 lock 等效的东西?

How could something equivalent to lock in C# be implemented in JavaScript?

所以，为了解释我的想法，一个简单的用例是:

So, to explain what I'm thinking a simple use case is:

用户点击按钮B.B 引发一个 onclick 事件.如果B 处于event-state，则事件在传播之前等待B 处于ready-state.如果B处于ready-state，B被锁定并设置为event-state，则事件传播.当事件传播完成后，B 设置为 ready-state.

User clicks button B. B raises an onclick event. If B is in event-state the event waits for B to be in ready-state before propagating. If B is in ready-state, B is locked and is set to event-state, then the event propagates. When the event's propagation is complete, B is set to ready-state.

我可以看到如何完成与此类似的事情，只需从按钮中添加和删除 ready-state 类即可.但是，问题在于用户可以比设置变量更快地连续单击按钮两次，因此在某些情况下，这种锁定尝试会失败.

I could see how something close to this could be done, simply by adding and removing the class ready-state from the button. However, the problem is that a user can click a button twice in a row faster than the variable can be set, so this attempt at a lock will fail in some circumstances.

有谁知道如何在 JavaScript 中实现一个不会失败的锁?

Does anyone know how to implement a lock that will not fail in JavaScript?

推荐答案

Lock 在 JS 中是一个有问题的想法，它旨在实现无线程并且不需要并发保护.您希望结合对延迟执行的调用.我遵循的模式是使用回调.像这样:

Lock is a questionable idea in JS which is intended to be threadless and not needing concurrency protection. You're looking to combine calls on deferred execution. The pattern I follow for this is the use of callbacks. Something like this:

var functionLock = false;
var functionCallbacks = [];
var lockingFunction = function (callback) {
    if (functionLock) {
        functionCallbacks.push(callback);
    } else {
        $.longRunning(function(response) {
             while(functionCallbacks.length){
                 var thisCallback = functionCallbacks.pop();
                 thisCallback(response);
             }
        });
    }
}

您也可以使用 DOM 事件侦听器或发布订阅解决方案来实现这一点.

You can also implement this using DOM event listeners or a pubsub solution.

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