Question

给出以下javascript代码（或等效的代码）：

var buf = [];
setInterval(function () {
  buf.push("token");
  // If buf has something pushed here we are screwed
  if (buf.length == 1) {
    sendCriticalLog();
  }
});

setInterval(function () {
  buf.push("other token");
});

有没有办法确保第一个区间的功能与buf有关？

我能提出的唯一方法是：

function atomic(lock, cb){
  var finish = function () {
    lock.callbacks = lock.callbacks.slice(1);
    if (lock.callbacks.length) {
      lock.callbacks[0].call();
    }
  };

  cb = cb.bind(null, finish);
  if ((lock.callbacks = (lock.callbacks || []).concat([cb])).length == 1) {
    // Nothing is running
    lock.callbacks[0]();
  };
}

var buf = [];
setInterval(function () {
  atomic(buf, function () {
    buf.push("token");
    // If buf has something pushed here we are screwed
    if (buf.length == 1) {
      sendCriticalLog();
    }
  });
});

setInterval(function () {
  atomic(buf, function () {
    buf.push("other token");
  });
});

但这是假设((lock.callbacks = (lock.callbacks || []).concat([cb])).length == 1)将保证以原子方式处理。例如，如果concat是用普通javascript编写的，那么这可能不起作用......

Answer 1

JavaScript不是多线程的，所以你的回调实际上已经是＆＃34; atomic＆＃34;。 buf只能在调用回调之间改变。

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