承诺：重复操作直到成功？ [英] Promises: Repeat operation until it succeeds?

问题描述

我想重复执行一个操作，每次操作之间的超时时间增加，直到成功或经过一定的时间。如何用Q中的promises构建它？

I want to perform an operation repeatedly, with an increasing timeout between each operation, until it succeeds or a certain amount of time elapses. How do I structure this with promises in Q?

推荐答案

我认为这里的所有答案都非常复杂。 Kos有正确的想法，但您可以通过编写更多惯用的承诺代码来缩短代码：

All the answers here are really complicated in my opinion. Kos has the right idea but you can shorten the code by writing more idiomatic promise code:

function retry(operation, delay) {
    return operation().catch(function(reason) {
        return Q.delay(delay).then(retry.bind(null, operation, delay * 2));
    });
}

并附有评论：

function retry(operation, delay) {
    return operation(). // run the operation
        catch(function(reason) { // if it fails
            return Q.delay(delay). // delay 
               // retry with more time
               then(retry.bind(null, operation, delay * 2)); 
        });
}

如果你想在一段时间后计时（让我们说10秒钟） ，你可以简单地做：

If you want to time it out after a certain time (let's say 10 seconds , you can simply do:

var promise = retry(operation, 1000).timeout(10000);

该功能内置于Q中，无需重新发明它：）

That functionality is built right into Q, no need to reinvent it :)

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