如何在 redis 中将 JS 对象传递给它自己的事件参数 - 连接事件上的哨兵

How to pass JS Object to its own event parameter in redis - sentinal on connect event

本文关键字：事件 参数 自己的 连接 哨兵 它自己 redis 中将 JS 对象      更新时间：2023-09-26

在 redis 哨兵客户端程序中 - 第一个程序，当我保留要创建的 redis 哨兵对象并且设置 KEY 工作正常时。但是当你观察第二个程序时，client.on（'connect'， runSample（client））;我正在传递客户端对象（redis 哨兵客户端），它的连接参数运行样本。为此，我收到以下错误..

错误详细信息

https://github.com/DocuSignDev/node-redis-sentinel-client/blob/master/index.js

 RedisSentinelClient.prototype.send_command  undefined
  /node_modules/redis-sentinel-client/index.js:293
  return client.send_command.apply(client, arguments);
           ^
  TypeError: Cannot read property 'send_command' of undefined
at RedisSentinelClient.send_command (/node_modules/redis-sentinel-client/index.js:293:16)
at RedisSentinelClient.(anonymous function).RedisSentinelClient.(anonymous function) (/node_modules/redis-sentinel-client/index.js:307:23)
at runSample (/msg/lb4.expire.onefile.2m.notworking.js:25:13)
at init (/msg/lb4.expire.onefile.2m.notworking.js:16:26)
at Object.<anonymous> (/msg/lb4.expire.onefile.2m.notworking.js:75:1)
at Module._compile (module.js:460:26)
at Object.Module._extensions..js (module.js:478:10)
at Module.load (module.js:355:32)
at Function.Module._load (module.js:310:12)
at Function.Module.runMain (module.js:501:10)
RajRajen:pubsub.local rajrajen$

第一个工作方案..

'use strict';
 var client = getRedisSentinelObject();
 client.on('error', function(err) {
   console.log('Error ' + err);
 });
client.on('connect', runSample);
function runSample() {
   var allStrings = '{abc:123}';

   client.get(allStrings, function(err, reply) {
      if (reply) {
        console.log('Key is ' + reply.toString());
        client.ttl(allStrings, writeTTL);
    } else {
        console.log('string key expired or not set before!');
        // Set a value
        client.set(allStrings, allStrings);
        // Expire in 3 seconds
        client.expire(allStrings, 3);
    }
    client.quit();
    });
 }
 function getRedisSentinelObject() {
   
   var redisSentinelHost = process.env.REDIS_SENTINEL_SERVICE_HOST;
   var redisSentinelPort = process.env.REDIS_SENTINEL_SERVICE_PORT;
   var options = {
      'master_debug': false
    };

    var redisSentinelMasterDebug = process.env.REDIS_SENTINEL_MASTER_DEBUG;

if (typeof redisSentinelMasterDebug !== "undefined") {
    if (redisSentinelMasterDebug === "true") {
        options.master_debug = true;
    }
}
console.log('redisSentinelHost ', redisSentinelHost, 'redisSentinelPort ', redisSentinelPort);
var RedisSentinel = require('redis-sentinel-client');
var sentinelClient = RedisSentinel.createClient(redisSentinelPort, redisSentinelHost, options);
console.log('sentinelClient ', sentinelClient);
return sentinelClient;
}
function writeTTL(err, data) {
    console.log('I live for this long yet: ', data);
}

第二个程序，不起作用

 'use strict';
  function init() {
var client = getRedisSentinelObject();

client.on('error', function(err) {
    console.log('Error ' + err);
});
client.on('connect', runSample(client));
}
function runSample(client1) {

var allStrings = '{abc:123}';

client1.get(allStrings, function(err, reply) {
    if (reply) {
        console.log('Key is ' , reply.toString());
        client1.ttl(allStrings, writeTTL);
    } else {
        console.log('string key expired or not set before!');
        // Set a value
        client1.set(allStrings, allStrings);
        // Expire in 3 seconds
        client1.expire(allStrings, 2);
    }
   // client1.quit();
});

}
 function getRedisSentinelObject() {
var redisSentinelHost = process.env.REDIS_SENTINEL_SERVICE_HOST;
var redisSentinelPort = process.env.REDIS_SENTINEL_SERVICE_PORT;
var options = {
    'master_debug': false
};

var redisSentinelMasterDebug = process.env.REDIS_SENTINEL_MASTER_DEBUG;
if (typeof redisSentinelMasterDebug !== "undefined") {
    if (redisSentinelMasterDebug === "true") {
        options.master_debug = true;
    }
}
console.log('redisSentinelHost ', redisSentinelHost, 'redisSentinelPort ', redisSentinelPort);
var RedisSentinel = require('redis-sentinel-client');
var sentinelClient = RedisSentinel.createClient(redisSentinelPort, redisSentinelHost, options);
console.log('sentinelClient ', sentinelClient);
return sentinelClient;
}
function writeTTL(err, data) {
console.log('I live for this long yet: ', data);
}
init();

谢谢

问题

在示例 1 中，您有以下行：

client.on('connect', runSample);

此行附加要在客户端连接时运行的函数。一切都很好。请注意，在客户端连接之前，该功能不会运行。

在示例 2 中，同一行如下所示：

client.on('connect', runSample(client));

在此行中，将立即执行runSample方法。然后，此函数调用的结果（在本例中为 undefined）传递给 client.on 。因此，如果我们在这里手动进行一些评估，javascript 可以归结为：

client.on('connect', undefined);

这失败了，因为你告诉 redis，"当你连接时，什么都没有"。

简单的解决方法

解决此问题的最简单方法是使用闭包（吸收其范围的函数）。这很可能是你打算做的。

client.on('connect', function () {
    runSample(client)
});

更复杂的修复

如果你想让事情变得更复杂一点，你可以做一个这样的函数：

function buildRunner (client) {
   return function runTests () {
       var allStrings = '{abc:123}';

       client.get(allStrings, function(err, reply) {
           if (reply) {
               console.log('Key is ' + reply.toString());
               client.ttl(allStrings, writeTTL);
           } else {
               console.log('string key expired or not set before!');
               // Set a value
               client.set(allStrings, allStrings);
               // Expire in 3 seconds
               client.expire(allStrings, 3);
           }
           client.quit();
       });
   }
}

并像这样使用它：

client.on('connect', buildRunner(client));

请注意，buildRunner将立即执行，就像以前一样。不同之处在于buildRunner返回一个传递给client.on的函数。如果我们再次手动进行评估，我们会得到：

client.on('connect', function runTests () { ... })
                  // ^ runTests is holding on to an internal copy of `client` because
                  //   `client` existed back when we built runTests
                  //   up in `buildRunner`
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