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在 redis sentinel 客户端程序 - 第一个程序中，当我保留要创建的 redis sentinel 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 sentinel client），它的连接参数 runSample。为此，我收到以下错误..

错误详情

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$

第一个工作程序..

'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

4

1 回答 1

1

问题

在示例 1 中，您有以下行：

client.on('connect', runSample);

此行附加了一个在客户端连接时要运行的函数。一切都很好。请注意，该功能在客户端连接之前不会运行。

在示例 2 中，同一行如下所示：

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

在这一行中，该runSample方法被立即执行。这个函数调用的结果（在这种情况下undefined）然后被传递到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”。

简单的修复

解决这个问题的最简单方法是使用闭包（一个吸收其作用域的函数）。这很可能是您想要做的。

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它将立即执行，就像以前一样。不同之处在于它buildRunner 返回一个传递给client.on. 如果我们再次手动进行一些评估，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`
于 2016-03-21T20:23:29.297 回答