在下面一行中使用它之前等待从函数中获得响应？

Question

我正在使用旧版本的 Node (8.x) 做一些事情，并且我编写了一个函数来计算 redis 中一堆哈希的值。

问题是，代码总是使用默认值 0，因为该函数似乎是在它在它下面的行中使用之后才运行的。我可以在日志中看到函数返回的值不是 0。

如何确保函数在继续运行之前运行并在它下面的 redis 命令中使用？

谢谢，如果这是菜鸟问题，对不起：

您可以在下面看到我正在定义 blockEffort = 0。然后我调用下面的函数来获取实际值。但在“redisCommands.push(['sadd', coin + ':blocksExplorer', [dateNow, shareData.height, shareData.blockHash, shareData.worker, blockEffort].join(':')] );"它仍然是零。

if (isValidBlock) {
            var blockEffort = parseFloat(0);
            this.getCurrentRoundShares(function (roundShares) {
                    logger.debug("calling GetCurrentRoundShares");
                    blockEffort = [roundShares / shareData.blockDiff];
                    logger.debug(`{"message": "Calculating Block Effort", "totalRoundShares": "${roundShares}", "blockEffort": "${blockEffort}"}`);
                });
            redisCommands.push(['rename', coin + ':shares:roundCurrent', coin + ':shares:round' + shareData.height]);
            redisCommands.push(['rename', coin + ':shares:timesCurrent', coin + ':shares:times' + shareData.height]);
            redisCommands.push(['sadd', coin + ':blocksPending', [shareData.blockHash, shareData.txHash, shareData.height].join(':')]);
            redisCommands.push(['sadd', coin + ':blocksExplorer', [dateNow, shareData.height, shareData.blockHash, shareData.worker, blockEffort].join(':')]);
            redisCommands.push(['zadd', coin + ':lastBlock', dateNow / 1000 | 0, [shareData.blockHash, shareData.txHash, shareData.worker, shareData.height, dateNow].join(':')]);
            redisCommands.push(['zadd', coin + ':lastBlockTime', dateNow / 1000 | 0, [dateNow].join(':')]);
            redisCommands.push(['hincrby', coin + ':stats', 'validBlocks', 1]);
            redisCommands.push(['hincrby', coin + ':blocksFound', shareData.worker, 1]);
}



this.getCurrentRoundShares = function(cback) {
        
        connection.hgetall('ravencoin:shares:roundCurrent', function(error,result) {
            if (error) {
                logger.error(`{"message": "Error getCurrentRoundShares", "data": "${error}"}`);
                cback(error);
                return;
            } else {
                logger.debug(`{"message": "Calculating all shares in current round"}`);
                logger.debug(result.toString());

                var _shareTotal = parseFloat(0);
                for (var worker in result) {
                    logger.debug(`{"message": "Shares for each Worker", "worker": "${worker}", "shares": "${parseFloat(result[worker])}"} }`);
                    _shareTotal += parseFloat(result[worker]);
                }
                logger.debug("Total Shares: " + _shareTotal );
                cback(_shareTotal);
            }
        });         
        },
        function(err) {
              if (err) {
                logger.error(`{"message": "Error getCurrentRoundShares", "data": "${err}"}`);
                cback(0);
                return;
            }
    };

完整文件在这里：https://github.com/devdevdevdev1/rvnpool/blob/main/shareProcessor.js

Answer 1

您可以让this.getCurrentRoundShares 函数返回Promise。

this.getCurrentRoundShares = function(cback) {
    return new Promise((resolve, reject) => {
        // do your stuf..
        
        let processHasFinishedSuccessfully = true;
        // if your stuff failed
        if (processHasFinishedSuccessfully){
           resolve();
        }
        else {
           reject(Error('Failed'));
        }
    };

然后，在您的 this.handleShare 函数中，您等待响应

this.handleShare = async function(isValidShare, isValidBlock, shareData) {
    // your stuff ...

            await this.getCurrentRoundShares(function (roundShares) {
                    logger.debug("calling GetCurrentRoundShares");
                    blockEffort = parseFloat([roundShares / shareData.blockDiff]);
                    logger.debug(`{"message": "Calculating Block Effort", "totalRoundShares": "${roundShares}", "blockEffort": "${blockEffort}"}`);
                });

    // your stuff...
    };

这应该确保代码执行不会继续进行，直到您收到来自 getCurrentRoundShares () 函数的响应。

Answer 2

如果你正在使用这个redis module，那么它已经内置了 Promise 支持，你可以直接使用它。你不显示调用代码，但是如果你调用函数async，你可以这样做：

async function someFunction() {

    // ... other code here

    if (isValidBlock) {
        try {
            var blockEffort = parseFloat(0);
            let roundShares = await this.getCurrentRoundShares();
            logger.debug("calling GetCurrentRoundShares");
            blockEffort = [roundShares / shareData.blockDiff];
            logger.debug(`{"message": "Calculating Block Effort", "totalRoundShares": "${roundShares}", "blockEffort": "${blockEffort}"}`);
            redisCommands.push(['rename', coin + ':shares:roundCurrent', coin + ':shares:round' + shareData.height]);
            redisCommands.push(['rename', coin + ':shares:timesCurrent', coin + ':shares:times' + shareData.height]);
            redisCommands.push(['sadd', coin + ':blocksPending', [shareData.blockHash, shareData.txHash, shareData.height].join(':')]);
            redisCommands.push(['sadd', coin + ':blocksExplorer', [dateNow, shareData.height, shareData.blockHash, shareData.worker, blockEffort].join(':')]);
            redisCommands.push(['zadd', coin + ':lastBlock', dateNow / 1000 | 0, [shareData.blockHash, shareData.txHash, shareData.worker, shareData.height, dateNow].join(':')]);
            redisCommands.push(['zadd', coin + ':lastBlockTime', dateNow / 1000 | 0, [dateNow].join(':')]);
            redisCommands.push(['hincrby', coin + ':stats', 'validBlocks', 1]);
            redisCommands.push(['hincrby', coin + ':blocksFound', shareData.worker, 1]);
        } catch(e) {
            logger.debug(e);
            // handle error in this.getCurrentRoundShares() here
        }
    }
}

this.getCurrentRoundShares = async function() {
    let result = await connection.hGetAll('ravencoin:shares:roundCurrent');
    logger.debug(`{"message": "Calculating all shares in current round"}`);
    logger.debug(result.toString());

    let _shareTotal = parseFloat(0);
    for (var worker in result) {
        logger.debug(
            `{"message": "Shares for each Worker", "worker": "${worker}", "shares": "${parseFloat(result[worker])}"} }`
            );
        _shareTotal += parseFloat(result[worker]);
    }
    logger.debug("Total Shares: " + _shareTotal);
    return _shareTotal;
};