javascript - Promise 中的递归重试

Question

现在我正在学习如何使用 promise 编写 JavaScript 代码。这是我的情况，Sender 中的 deliverMessage 函数尝试与 amqp 连接。如果成功，则调用publish_ 发送消息。否则，在 3 秒后调用 reconnect_ 重新连接到 amqp。代码如下，

Sender.prototype.reconnect_ = function( err ) {
    console.error('MessageBus disconnected, attempting to reconnect' + err);
    this.createFakeChannel_();
    return setTimeout( this.deliverMessage.bind(this), 3000);
};
Sender.prototype.deliverMessage = function() {
    when(amqp.connect( this.addr_ ))
        .with( this )
        .then( this.createChannel_ )
        .then( this.createExchange_ )
        .then( this.handleUnrouteableMessages_ )
        .then( this.handleDisconnections_ )
        .catch( this.reconnect_ )
        .done( this.publish_ ); //? publish_ is invoked in all case?
};

实际上，无论连接成功还是失败，publish_ 都会被调用。谁能帮我如何用 promise 实现它？

Answer 1

我会那样做...

Sender.prototype.reconnect_ = function( err, attempt ) {
    attempt = attempt || 0;
    attempt++;
    if(attempt>3){  // change it to whatever value you prefer
        throw err;
    }
    console.error('MessageBus disconnected, attempting to reconnect' + err);
    this.createFakeChannel_();
    return setTimeout( this.deliverMessage.bind(this, attempt ), 3000);
};
Sender.prototype.deliverMessage = function(attempt) {
    when(amqp.connect( this.addr_ ))
        .with( this )
        .then( this.createChannel_ )
        .then( this.createExchange_ )
        .then( this.handleUnrouteableMessages_ )
        .then( this.handleDisconnections_ )
        .then( this.publish_, function(err){
            this.reconnect_(err, attempt);
        });
};