Redis键空间事件未触发

小编典典

Redis键空间事件未触发

redis

我有两个Redis客户端，在一个文件中，我有一个简单的脚本设置并删除了Redis密钥：

var redis = require("redis");

var client = redis.createClient('6379','127.0.0.1');
client.config("SET","notify-keyspace-events", "KEA");

client.set("string key 1", "string val", redis.print);
client.set("string key 2", "string val", redis.print);
client.set("placeholder","placeholder value", redis.print);
client.del("string key 1", redis.print);
client.del("string key", redis.print);

在第二个文件中，我有一个Redis客户端充当订户：

var redis = require("redis");
var subscriber = redis.createClient('6379','127.0.0.1');

const REDIS_PUB_MESSAGE = 'redis_pub_message';
const EVENT_SET = '__keyevent@0__:set';
const EVENT_DEL = '__keyevent@0__:del';
const SPACE_SPECIFIC_KEY = '__keyspace@0__:placeholder set';
const EVENT_SPECIFIC_KEY = '__keyevent@0__:placeholder set';
const SPACE_SPECIFIC_KEY_set = '__keyspace@0__:set placeholder';
const EVENT_SPECIFIC_KEY_set = '__keyevent@0__:set placeholder';

subscriber.on('message', function(channel, key) {
    switch (channel) {
        case SPACE_SPECIFIC_KEY_set:
            console.log('space specific key channel:',channel,'key:',key);
        case EVENT_SPECIFIC_KEY_set:
            console.log('event specific key channel:',channel,'key:',key);
        case EVENT_SPECIFIC_KEY:
            console.log('space specific key channel:',channel,'key:',key);
        case SPACE_SPECIFIC_KEY:
            console.log('event specific key channel:',channel,'key:',key);
    }
});

关键的“占位符”已设置，那么是否有充分的理由使我在“消息”处理程序中未获得任何输出？

阅读 424

2020-06-20

共1个答案

小编典典

您忘记了订阅用户客户端订阅特定的频道。此外，如果要监视所有事件，则需要使用基于模式的订阅。

您可能想要执行以下操作（未测试）：

subscriber.on("pmessage", function (pattern, channel, message) {
    console.log("("+  pattern +")" + " client received message on " + channel + ": " + message);
    switch (channel) {
        // blah blah blah
        // ...
    }
});
subscriber.psubscribe(''__key*__:*')

请参阅Redis文档和node_redis示例中的更多信息。

更新：

这是一个示例，说明了频道订阅和模式订阅之间的区别。为了简洁起见，省略了正确的错误处理。

var redis = require("redis");

var client = redis.createClient('6379','127.0.0.1');
var subscriber1 = redis.createClient('6379','127.0.0.1');
var subscriber2 = redis.createClient('6379','127.0.0.1');

// First subscriber listens only to events occurring for key mykey
function S1(next) {
    subscriber1.on('message', function(channel, msg) {
        console.log( "S1: received on "+channel+" event "+msg )
    });
    subscriber1.subscribe( "__keyspace@0__:mykey", function (err) {
        next();
    });
}

// Second subscriber listens to events occuring for ALL keys
function S2(next) {
    subscriber2.on('pmessage', function(pattern,channel, msg) {
        console.log( "S2: received on "+channel+" event "+msg )
    });
    subscriber2.psubscribe( "__keyspace@0__:*", function (err) {
        next();
    });
}

// Do something with keys mykey and anotherkey
function do_something() {
    client.set("mykey","example", function( err ) {
        client.set("mykey", "another example", function( err ) {
            client.del("mykey", function( err ) {
                client.set("anotherkey","example", function( err ) {
                    client.del("anotherkey");
                });
            });
        });
    });
}

// Here we go
S1( function () {
    S2( function () {
        do_something();
    });
});

该脚本的结果是：

S1: received on __keyspace@0__:mykey event set
S2: received on __keyspace@0__:mykey event set
S2: received on __keyspace@0__:mykey event set
S1: received on __keyspace@0__:mykey event set
S1: received on __keyspace@0__:mykey event del
S2: received on __keyspace@0__:mykey event del
S2: received on __keyspace@0__:anotherkey event set
S2: received on __keyspace@0__:anotherkey event del

您可以看到第一个订阅者仅接收了mykey事件，而第二个订阅者接收了所有关键字事件。

2020-06-20