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如何构建一个具有重试机制的 Steem 区块链见证人投票检查器

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当使用像 Steem 这样的去中心化平台时,重要的是要预期偶尔的故障——网络问题、API 限制或暂时的停机。这就是为什么你构建的任何集成、机器人或工具都应该能够优雅地失败并智能地恢复。

在这篇文章中,我将带你了解一个简单而强大的 Steem 区块链见证人(也就是STEEM上的矿工)投票检查工具:

第一版:检查是否由某个见证人投票

这是一个实用的 Node.js 函数,用于检查一个 Steem 用户是否投票支持了某个特定的 见证人——无论是直接投票还是通过代理。

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function is_voted_by(witness, id) {
    return new Promise((resolve, reject) => {
        steem.api.getAccounts([id], function(err, response) {
            if (err) reject(err);
            if (typeof response == "undefined") reject("undefined");
            const data = response[0];
            resolve((data.proxy === witness) || data.witness_votes.includes(witness)); 
        });          
    });
}
function is_voted_by(witness, id) {
    return new Promise((resolve, reject) => {
        steem.api.getAccounts([id], function(err, response) {
            if (err) reject(err);
            if (typeof response == "undefined") reject("undefined");
            const data = response[0];
            resolve((data.proxy === witness) || data.witness_votes.includes(witness)); 
        });          
    });
}

它获取给定 id 的账户数据,然后检查该用户是否设置了匹配目标见证人的投票代理,或者该见证人是否在他们的直接投票列表中。

启用重试的 Steem 见证人投票检查器

这是更新版的函数,包含简单的重试机制(最多重试 3 次,每次重试间隔 1 秒)。以下的代码加入了重试功能:

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function is_voted_by(witness, id, retries = 3) {
    return new Promise((resolve, reject) => {
        const attempt = (remaining) => {
            steem.api.getAccounts([id], function(err, response) {
                if (err || typeof response === "undefined") {
                    if (remaining > 0) {
                        setTimeout(() => attempt(remaining - 1), 1000); // 重试 1 秒后
                    } else {
                        reject(err || "undefined response");
                    }
                    return;
                }
                const data = response[0];
                resolve((data.proxy === witness) || data.witness_votes.includes(witness)); 
            });
        };
        attempt(retries);
    });
}
function is_voted_by(witness, id, retries = 3) {
    return new Promise((resolve, reject) => {
        const attempt = (remaining) => {
            steem.api.getAccounts([id], function(err, response) {
                if (err || typeof response === "undefined") {
                    if (remaining > 0) {
                        setTimeout(() => attempt(remaining - 1), 1000); // 重试 1 秒后
                    } else {
                        reject(err || "undefined response");
                    }
                    return;
                }
                const data = response[0];
                resolve((data.proxy === witness) || data.witness_votes.includes(witness)); 
            });
        };
        attempt(retries);
    });
}

此版本在 Steem API 调用失败或返回 undefined 时最多进行 3 次重试,帮助处理不稳定的网络状况或临时的 API 问题。功能保持不变:检查直接的见证人投票或代理委托/Proxy。

重试的指数退避机制

使用指数退避机制/Exponential backoff来避免过度请求 API,并记录每次尝试以便于调试和更好的可视化。

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module.exports.is_voted_by = function(witness, id, retries = 3, delay = 1000) {
    return new Promise((resolve, reject) => {
        const attempt = (remaining, currentDelay) => {
            console.log(`Checking vote for "${id}" against witness "${witness}"... (${retries - remaining + 1}/${retries})`);
 
            steem.api.getAccounts([id], function(err, response) {
                if (err || typeof response === "undefined") {
                    console.warn(`Attempt failed: ${err || 'undefined response'}`);
                    
                    if (remaining > 0) {
                        console.log(`Retrying in ${currentDelay}ms...`);
                        setTimeout(() => attempt(remaining - 1, currentDelay * 2), currentDelay); // 指数退避
                    } else {
                        reject(err || "undefined response after retries");
                    }
                    return;
                }
 
                const data = response[0];
                const voted = (data.proxy === witness) || data.witness_votes.includes(witness);
                console.log(`Vote check result: ${voted}`);
                resolve(voted);
            });
        };
 
        attempt(retries, delay);
    });
};
module.exports.is_voted_by = function(witness, id, retries = 3, delay = 1000) {
    return new Promise((resolve, reject) => {
        const attempt = (remaining, currentDelay) => {
            console.log(`Checking vote for "${id}" against witness "${witness}"... (${retries - remaining + 1}/${retries})`);

            steem.api.getAccounts([id], function(err, response) {
                if (err || typeof response === "undefined") {
                    console.warn(`Attempt failed: ${err || 'undefined response'}`);
                    
                    if (remaining > 0) {
                        console.log(`Retrying in ${currentDelay}ms...`);
                        setTimeout(() => attempt(remaining - 1, currentDelay * 2), currentDelay); // 指数退避
                    } else {
                        reject(err || "undefined response after retries");
                    }
                    return;
                }

                const data = response[0];
                const voted = (data.proxy === witness) || data.witness_votes.includes(witness);
                console.log(`Vote check result: ${voted}`);
                resolve(voted);
            });
        };

        attempt(retries, delay);
    });
};

该函数:

如果 API 调用失败或返回 undefined,它将:

为什么要使用指数退避?

指数退避是网络编程中的经典策略——如果服务暂时不可用,快速连续请求只会让问题更加严重。通过在重试之间增加延迟,可以让系统有时间恢复,并且对 API 更加友好。

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is_voted_by('witness-name', 'username')
    .then(voted => {
        if (voted) {
            console.log("User supports the witness!");
        } else {
            console.log("User has not voted for the witness.");
        }
    })
    .catch(err => {
        console.error("Error checking vote:", err);
    });
is_voted_by('witness-name', 'username')
    .then(voted => {
        if (voted) {
            console.log("User supports the witness!");
        } else {
            console.log("User has not voted for the witness.");
        }
    })
    .catch(err => {
        console.error("Error checking vote:", err);
    });

最后的思考

在构建与区块链交互的工具时,弹性至关重要。适当的重试逻辑能大大提高你的应用程序的稳定性和用户友好性——即使在底层基础设施出现问题时也能保持正常运行。

Steem/Steemit区块链

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