mranney / node_redis源代码阅读

 

redis - a node.js redis client

 

mranney / node_redis

 

 

This is a complete Redis client for node.js. It supports all Redis commands, including MULTI, WATCH, and PUBLISH/SUBSCRIBE.

 

npm install hiredis redis 

 

 

node_redis的源代码大概可以分为三个主要部分：

• 经常被使用的util函数，分别是Queue(lib/queue.js), to_array(lib/to_array.js)

queue.js主要是构造一个Queue，发送给redis的命令是放在Queue中的，主要由两种类型的queue，一个是offline_queue；另外一个是command_queue， offline_queue是在连接还没有准备好的情况下发送的命令会存放在这里，那么当连接ready以后，会将其中的command全部发送给redis；command_queue则是没次发送给redis的命令同时也会存放在这里，当返回成功的时候再将command从其中移除出去。

 

to_array.js则是一个数组的深拷贝，下面是它的源代码：

 

function to_array(args) { var len = args.length, arr = new Array(len), i; for (i = 0; i < len; i += 1) { arr[i] = args[i]; } return arr; }; module.exports = to_array; 

 

这里我不想说to_array是如何实现的，因为它很简单，而是想提一下"module.exports  = to_array"， 通过这种方式exports以后，

我们就可以这样使用它了：

 

var to_array = require("./to_array"); function Queue() { this.tail = []; this.head = to_array(arguments); this.offset = 0; } 

 

• 用来解析redis返回的数据的parser

parser主要由两种实现，一种是javascript.js(/lib/parser/javascript.js)；另外一个是hiredis.js(/lib/parser/hiredis.js)，默认使用的javascript.js来解析返回的数据，但是hiredis.js的性能更好些。

 

JavaScript parser:

 

PING: 20000 ops 42283.30 ops/sec 0/5/1.182 SET: 20000 ops 32948.93 ops/sec 1/7/1.515 GET: 20000 ops 28694.40 ops/sec 0/9/1.740 INCR: 20000 ops 39370.08 ops/sec 0/8/1.269 LPUSH: 20000 ops 36429.87 ops/sec 0/8/1.370 LRANGE (10 elements): 20000 ops 9891.20 ops/sec 1/9/5.048 LRANGE (100 elements): 20000 ops 1384.56 ops/sec 10/91/36.072 

 

hiredis parser:

 

PING: 20000 ops 46189.38 ops/sec 1/4/1.082 SET: 20000 ops 41237.11 ops/sec 0/6/1.210 GET: 20000 ops 39682.54 ops/sec 1/7/1.257 INCR: 20000 ops 40080.16 ops/sec 0/8/1.242 LPUSH: 20000 ops 41152.26 ops/sec 0/3/1.212 LRANGE (10 elements): 20000 ops 36563.07 ops/sec 1/8/1.363 LRANGE (100 elements): 20000 ops 21834.06 ops/sec 0/9/2.287 

 

• 最后出场的当然是核心模块，管理redis命令（保存command、发送command、处理reply）

对index.js的源代码加了一些注释，可以沿着两天主要的线走，一是和redis打交道的接口，看它是如何处理事件 connect, data, end, timeout, drain, error, close的，另外则是和node-redis使用者打交道的接口，看它是如何处理redis命令的。

 

/*global Buffer require exports console setTimeout */ var net = require("net"), util = require("./lib/util").util, Queue = require("./lib/queue").Queue, to_array = require("./lib/to_array"), events = require("events"), parsers = [], default_port = 6379, default_host = "127.0.0.1"; // can set this to true to enable for all connections exports.debug_mode = false; // hiredis might not be installed try { require("./lib/parser/hiredis"); parsers.push(require("./lib/parser/hiredis")); } catch (err) { if (exports.debug_mode) { console.log("hiredis parser not installed."); } } parsers.push(require("./lib/parser/javascript")); function RedisClient(stream, options) { // stream是用net.CreateConnection创建的连接返回的net.Socket this.stream = stream; this.options = options || {}; this.connected = false; this.ready = false; this.connections = 0; this.attempts = 1; this.command_queue = new Queue(); // holds sent commands to de-pipeline them this.offline_queue = new Queue(); // holds commands issued but not able to be sent this.commands_sent = 0; this.retry_delay = 250; // inital reconnection delay this.current_retry_delay = this.retry_delay; this.retry_backoff = 1.7; // each retry waits current delay * retry_backoff this.subscriptions = false; this.monitoring = false; this.closing = false; this.server_info = {}; this.auth_pass = null; // parser模块的初始化工作 var parser_module, self = this; if (self.options.parser) { if (! parsers.some(function (parser) { if (parser.name === self.options.parser) { parser_module = parser; if (exports.debug_mode) { console.log("Using parser module: " + parser_module.name); } return true; } })) { throw new Error("Couldn't find named parser " + self.options.parser + " on this system"); } } else { if (exports.debug_mode) { console.log("Using default parser module: " + parsers[0].name); } parser_module = parsers[0]; } parser_module.debug_mode = exports.debug_mode; this.reply_parser = new parser_module.Parser({ // reply_parser是一个关键的部分，负责解析接收到的数据 return_buffers: self.options.return_buffers || false }); // parser会丢出三种事件，1）redis返回的reply 2) redis返回的error 3)parser解析出现的error // "reply error" is an error sent back by Redis this.reply_parser.on("reply error", function (reply) { self.return_error(new Error(reply)); }); this.reply_parser.on("reply", function (reply) { self.return_reply(reply); }); // "error" is bad. Somehow the parser got confused. It'll try to reset and continue. this.reply_parser.on("error", function (err) { self.emit("error", new Error("Redis reply parser error: " + err.stack)); }); // 和网络连接相关的一些事件函数（net.Socket event: connect, data, end, timeout, drain, error, close） this.stream.on("connect", function () { self.on_connect(); }); this.stream.on("data", function (buffer_from_socket) { self.on_data(buffer_from_socket); }); this.stream.on("error", function (msg) { if (this.closing) { return; } var message = "Redis connection to " + self.host + ":" + self.port + " failed - " + msg.message; if (exports.debug_mode) { console.warn(message); } self.offline_queue.forEach(function (args) { if (typeof args[2] === "function") { args[2](message); } }); self.offline_queue = new Queue(); self.command_queue.forEach(function (args) { if (typeof args[2] === "function") { args[2](message); } }); self.command_queue = new Queue(); self.connected = false; self.ready = false; self.emit("error", new Error(message)); // "error" events get turned into exceptions if they aren't listened for. If the user handled this error // then we should try to reconnect. self.connection_gone("error"); }); this.stream.on("close", function () { self.connection_gone("close"); }); this.stream.on("end", function () { self.connection_gone("end"); }); this.stream.on("drain", function () { self.emit("drain"); }); events.EventEmitter.call(this); // 在EventEmitter函数中的this会被传进去的this代替，也就是借用EventEmitter去初始化RedisClient } util.inherits(RedisClient, events.EventEmitter); exports.RedisClient = RedisClient; RedisClient.prototype.on_connect = function () { if (exports.debug_mode) { console.log("Stream connected " + this.host + ":" + this.port + " fd " + this.stream.fd); } var self = this; this.connected = true; // 连接成功 this.ready = false; this.attempts = 0; this.connections += 1; // 连接数+1 this.command_queue = new Queue(); // 为连接创建发送command的队列 this.emitted_end = false; this.retry_timer = null; this.current_retry_delay = this.retry_time; this.stream.setNoDelay(); // 告诉网络层，立即发送数据 this.stream.setTimeout(0); // 即使连接idle很长时间也无需发送timeout事件 if (this.auth_pass) { if (exports.debug_mode) { console.log("Sending auth to " + this.host + ":" + this.port + " fd " + this.stream.fd); } self.send_anyway = true; self.send_command("auth", this.auth_pass, function (err, res) { if (err) { return self.emit("error", "Auth error: " + err); } if (res.toString() !== "OK") { return self.emit("error", "Auth failed: " + res.toString()); } if (exports.debug_mode) { console.log("Auth succeeded " + self.host + ":" + self.port + " fd " + self.stream.fd); } if (self.auth_callback) { self.auth_callback(err, res); self.auth_callback = null; } }); self.send_anyway = false; } this.emit("connect"); // 为什么还要发送connect事件呢？？？？ if (this.options.no_ready_check) { // 不需要测试是否连接成功 this.ready = true; this.send_offline_queue(); } else { this.ready_check(); // 类似ping操作 } }; RedisClient.prototype.ready_check = function () { var self = this; function send_info_cmd() { if (exports.debug_mode) { console.log("checking server ready state..."); } self.send_anyway = true; // secret flag to send_command to send something even if not "ready" self.info(function (err, res) { if (err) { return self.emit("error", "Ready check failed: " + err); } var lines = res.toString().split("/r/n"), obj = {}, retry_time; lines.forEach(function (line) { var parts = line.split(':'); if (parts[1]) { obj[parts[0]] = parts[1]; } }); obj.versions = []; obj.redis_version.split('.').forEach(function (num) { obj.versions.push(+num); }); // expose info key/vals to users self.server_info = obj; if (!obj.loading || (obj.loading && obj.loading === "0")) { if (exports.debug_mode) { console.log("Redis server ready."); } self.ready = true; self.send_offline_queue(); self.emit("ready"); } else { retry_time = obj.loading_eta_seconds * 1000; if (retry_time > 1000) { retry_time = 1000; } if (exports.debug_mode) { console.log("Redis server still loading, trying again in " + retry_time); } setTimeout(send_info_cmd, retry_time); } }); self.send_anyway = false; } send_info_cmd(); }; RedisClient.prototype.send_offline_queue = function () { var command_obj; while (this.offline_queue.length > 0) { // 发送离线命令 command_obj = this.offline_queue.shift(); if (exports.debug_mode) { console.log("Sending offline command: " + command_obj.command); } this.send_command(command_obj.command, command_obj.args, command_obj.callback); } this.offline_queue = new Queue(); // Even though items were shifted off, Queue backing store still uses memory until next add }; RedisClient.prototype.connection_gone = function (why) { var self = this; // If a retry is already in progress, just let that happen if (this.retry_timer) { return; } // Note that this may trigger another "close" or "end" event this.stream.destroy(); if (exports.debug_mode) { console.warn("Redis connection is gone from " + why + " event."); } this.connected = false; this.ready = false; this.subscriptions = false; this.monitoring = false; // since we are collapsing end and close, users don't expect to be called twice if (! this.emitted_end) { this.emit("end"); this.emitted_end = true; } this.command_queue.forEach(function (args) { if (typeof args[2] === "function") { args[2]("Server connection closed"); } }); this.command_queue = new Queue(); // If this is a requested shutdown, then don't retry if (this.closing) { this.retry_timer = null; return; } this.current_retry_delay = this.retry_delay * this.retry_backoff; if (exports.debug_mode) { console.log("Retry connection in " + this.current_retry_delay + " ms"); } this.attempts += 1; this.emit("reconnecting", { delay: this.current_retry_delay, attempt: this.attempts }); this.retry_timer = setTimeout(function () { if (exports.debug_mode) { console.log("Retrying connection..."); } self.stream.connect(self.port, self.host); self.retry_timer = null; }, this.current_retry_delay); }; RedisClient.prototype.on_data = function (data) { // 数据来了，先让parser去解析一些 if (exports.debug_mode) { console.log("net read " + this.host + ":" + this.port + " fd " + this.stream.fd + ": " + data.toString()); } try { this.reply_parser.execute(data); } catch (err) { // This is an unexpected parser problem, an exception that came from the parser code itself. // Parser should emit "error" events if it notices things are out of whack. // Callbacks that throw exceptions will land in return_reply(), below. // TODO - it might be nice to have a different "error" event for different types of errors this.emit("error", err); } }; RedisClient.prototype.return_error = function (err) { var command_obj = this.command_queue.shift(); if (this.subscriptions === false && this.command_queue.length === 0) { this.emit("idle"); this.command_queue = new Queue(); } if (command_obj && typeof command_obj.callback === "function") { try { command_obj.callback(err); } catch (callback_err) { // if a callback throws an exception, re-throw it on a new stack so the parser can keep going process.nextTick(function () { throw callback_err; }); } } else { console.log("node_redis: no callback to send error: " + err.message); // this will probably not make it anywhere useful, but we might as well throw process.nextTick(function () { throw err; }); } }; RedisClient.prototype.return_reply = function (reply) { // 处理返回的数据 var command_obj = this.command_queue.shift(), obj, i, len, key, val, type, timestamp, args; if (this.subscriptions === false && this.command_queue.length === 0) { this.emit("idle"); this.command_queue = new Queue(); } if (command_obj && !command_obj.sub_command) { if (typeof command_obj.callback === "function") { // HGETALL special case replies with keyed Buffers if (reply && 'hgetall' === command_obj.command.toLowerCase()) { obj = {}; for (i = 0, len = reply.length; i < len; i += 2) { key = reply[i].toString(); val = reply[i + 1]; obj[key] = val; } reply = obj; } try { command_obj.callback(null, reply); } catch (err) { // if a callback throws an exception, re-throw it on a new stack so the parser can keep going process.nextTick(function () { throw err; }); } } else if (exports.debug_mode) { console.log("no callback for reply: " + (reply && reply.toString && reply.toString())); } } else if (this.subscriptions || command_obj.sub_command) { if (Array.isArray(reply)) { type = reply[0].toString(); if (type === "message") { this.emit("message", reply[1].toString(), reply[2]); // channel, message } else if (type === "pmessage") { this.emit("pmessage", reply[1].toString(), reply[2].toString(), reply[3]); // pattern, channel, message } else if (type === "subscribe" || type === "unsubscribe" || type === "psubscribe" || type === "punsubscribe") { if (reply[2] === 0) { this.subscriptions = false; if (this.debug_mode) { console.log("All subscriptions removed, exiting pub/sub mode"); } } this.emit(type, reply[1].toString(), reply[2]); // channel, count } else { throw new Error("subscriptions are active but got unknown reply type " + type); } } else if (! this.closing) { throw new Error("subscriptions are active but got an invalid reply: " + reply); } } else if (this.monitoring) { len = reply.indexOf(" "); timestamp = reply.slice(0, len); args = reply.slice(len + 1).match(/"[^"]+"/g).map(function (elem) { return elem.replace(/"/g, ""); }); this.emit("monitor", timestamp, args); } else { throw new Error("node_redis command queue state error. If you can reproduce this, please report it."); } }; RedisClient.prototype.send_command = function () { var command, callback, arg, args, this_args, command_obj, i, il, elem_count, stream = this.stream, buffer_args, command_str = ""; this_args = to_array(arguments); // 深拷贝一份参数过来 if (this_args.length === 0) { throw new Error("send_command: not enough arguments"); } if (typeof this_args[0] !== "string") { throw new Error("First argument of send_command must be the command name"); } command = this_args[0].toLowerCase(); // redis命令: set, get, mset, sadd等等 // 对于不同的命令传进来的参数可能由差异，这里做一个检查性工作 if (this_args[1] && Array.isArray(this_args[1])) { // redis命令所带的参数是作为第二个参数以数组的形式传进来的 args = this_args[1]; if (typeof this_args[2] === "function") { // 确定是否带callback函数 callback = this_args[2]; } } else {// redis命令所带的参数是以多个参数的方式传进来的 if (typeof this_args[this_args.length - 1] === "function") { // 确定是否带callback函数 callback = this_args[this_args.length - 1]; args = this_args.slice(1, this_args.length - 1); } else { args = this_args.slice(1, this_args.length); } } if (args.length === 2 && Array.isArray(args[1])) { // 对以数组的方式传进来的参数的处理省事了啊！ args = [args[0]].concat(args[1]); } command_obj = { // command_obj是这样的一个对象，我汗！ command: command, args: args, callback: callback, sub_command: false }; if (!this.ready && !this.send_anyway) { // 连接还没有准备好，暂时丢到offline_queue中去吧，等连接ready以后会将它们发送出去 if (exports.debug_mode) { console.log("Queueing " + command + " for next server connection."); } this.offline_queue.push(command_obj); return; } // 连接已经准备好了，可以立即发送数据出去了 if (command === "subscribe" || command === "psubscribe" || command === "unsubscribe" || command === "punsubscribe") { if (this.subscriptions === false && exports.debug_mode) { console.log("Entering pub/sub mode from " + command); } command_obj.sub_command = true; this.subscriptions = true; } else if (command === "monitor") { this.monitoring = true; } else if (command === "quit") { this.closing = true; } else if (this.subscriptions === true) { throw new Error("Connection in pub/sub mode, only pub/sub commands may be used"); } this.command_queue.push(command_obj); // 放入发送队列command_queue中去 this.commands_sent += 1; // 统计一下发送的命令的个数 elem_count = 1; buffer_args = false; elem_count += args.length; // Probably should just scan this like a normal person. This is clever, but might be slow. buffer_args = args.some(function (arg) { return arg instanceof Buffer; }); // Always use "Multi bulk commands", but if passed any Buffer args, then do multiple writes, one for each arg // This means that using Buffers in commands is going to be slower, so use Strings if you don't already have a Buffer. // Also, why am I putting user documentation in the library source code? command_str = "*" + elem_count + "/r/n$" + command.length + "/r/n" + command + "/r/n"; if (! stream.writable && exports.debug_mode) { console.log("send command: stream is not writeable, should get a close event next tick."); return; } if (! buffer_args) { // Build up a string and send entire command in one write for (i = 0, il = args.length, arg; i < il; i += 1) { arg = args[i]; if (typeof arg !== "string") { arg = String(arg); } command_str += "$" + Buffer.byteLength(arg) + "/r/n" + arg + "/r/n"; } if (exports.debug_mode) { console.log("send " + this.host + ":" + this.port + " fd " + this.stream.fd + ": " + command_str); } stream.write(command_str); } else { if (exports.debug_mode) { console.log("send command: " + command_str); console.log("send command has Buffer arguments"); } stream.write(command_str); for (i = 0, il = args.length, arg; i < il; i += 1) { arg = args[i]; if (!(arg instanceof Buffer || arg instanceof String)) { arg = String(arg); } if (arg instanceof Buffer) { if (arg.length === 0) { if (exports.debug_mode) { console.log("Using empty string for 0 length buffer"); } stream.write("$0/r/n/r/n"); } else { stream.write("$" + arg.length + "/r/n"); stream.write(arg); stream.write("/r/n"); } } else { stream.write("$" + Buffer.byteLength(arg) + "/r/n" + arg + "/r/n"); } } } }; RedisClient.prototype.end = function () { this.stream._events = {}; this.connected = false; // 连接结束，更新状态 this.ready = false; return this.stream.end(); }; function Multi(client, args) { this.client = client; this.queue = [["MULTI"]]; // 两个[[]]代表什么意思呢？？和[]有什么区别呢？ if (Array.isArray(args)) { this.queue = this.queue.concat(args); } } // Official source is: http://redis.io/commands.json // This list needs to be updated, and perhaps auto-updated somehow. [ // string commands "get", "set", "setnx", "setex", "append", "substr", "strlen", "del", "exists", "incr", "decr", "mget", // list commands "rpush", "lpush", "rpushx", "lpushx", "linsert", "rpop", "lpop", "brpop", "blpop", "brpoplpush", "llen", "lindex", "lset", "lrange", "ltrim", "lrem", "rpoplpush", // set commands "sadd", "srem", "smove", "sismember", "scard", "spop", "srandmember", "sinter", "sinterstore", "sunion", "sunionstore", "sdiff", "sdiffstore", "smembers", // sorted set commands "zadd", "zincrby", "zrem", "zremrangebyscore", "zremrangebyrank", "zunionstore", "zinterstore", "zrange", "zrangebyscore", "zrevrangebyscore", "zcount", "zrevrange", "zcard", "zscore", "zrank", "zrevrank", // hash commands "hset", "hsetnx", "hget", "hmget", "hincrby", "hdel", "hlen", "hkeys", "hvals", "hgetall", "hexists", "incrby", "decrby", //bit commands "getbit", "setbit", "getrange", "setrange", // misc "getset", "mset", "msetnx", "randomkey", "select", "move", "rename", "renamenx", "expire", "expireat", "keys", "dbsize", "ping", "echo", "save", "bgsave", "bgwriteaof", "shutdown", "lastsave", "type", "sync", "flushdb", "flushall", "sort", "info", "discard", "monitor", "ttl", "persist", "slaveof", "debug", "config", "subscribe", "unsubscribe", "psubscribe", "punsubscribe", "publish", "watch", "unwatch", "quit" ].forEach(function (command) { RedisClient.prototype[command] = function () { // 这样使用node-redis的人就可以调用redis.set, redis.get等等redis命令了 var args = to_array(arguments); args.unshift(command); // put command at the beginning this.send_command.apply(this, args); //其实就是调用send_command(args) }; RedisClient.prototype[command.toUpperCase()] = RedisClient.prototype[command]; // 命令的大小写通吃 Multi.prototype[command] = function () { // 后面在看看这个是干啥的！ var args = to_array(arguments); args.unshift(command); this.queue.push(args); return this; // 注意返回的还是一个Multi对象 }; Multi.prototype[command.toUpperCase()] = Multi.prototype[command]; }); // Stash auth for connect and reconnect. Send immediately if already connected. RedisClient.prototype.auth = function () { var args = to_array(arguments); this.auth_pass = args[0]; this.auth_callback = args[1]; if (exports.debug_mode) { console.log("Saving auth as " + this.auth_pass); } if (this.connected) { args.unshift("auth"); this.send_command.apply(this, args); } }; RedisClient.prototype.AUTH = RedisClient.prototype.auth; // 对redis的hmset做了一个特殊处理，允许传进来的参数是object: {age: 30, city: hangzhou} RedisClient.prototype.hmset = function () { var args = to_array(arguments), tmp_args; if (args.length >= 2 && typeof args[0] === "string" && typeof args[1] === "object") { tmp_args = [ "hmset", args[0] ]; Object.keys(args[1]).map(function (key) { tmp_args.push(key); tmp_args.push(args[1][key]); }); if (args[2]) { tmp_args.push(args[2]); } args = tmp_args; } else { args.unshift("hmset"); } this.send_command.apply(this, args); }; RedisClient.prototype.HMSET = RedisClient.prototype.hmset; Multi.prototype.hmset = function () { var args = to_array(arguments), tmp_args; if (args.length >= 2 && typeof args[0] === "string" && typeof args[1] === "object") { tmp_args = [ "hmset", args[0] ]; Object.keys(args[1]).map(function (key) { tmp_args.push(key); tmp_args.push(args[1][key]); }); if (args[2]) { tmp_args.push(args[2]); } args = tmp_args; } else { args.unshift("hmset"); } this.queue.push(args); return this; }; Multi.prototype.HMSET = Multi.prototype.hmset; Multi.prototype.exec = function (callback) { var self = this; // drain queue, callback will catch "QUEUED" or error // Can't use a for loop here, as we need closure around the index. this.queue.forEach(function (args, index) { var command = args[0], obj; if (typeof args[args.length - 1] === "function") { args = args.slice(1, -1); } else { args = args.slice(1); } if (args.length === 1 && Array.isArray(args[0])) { args = args[0]; } if (command === 'hmset' && typeof args[1] === 'object') { obj = args.pop(); Object.keys(obj).forEach(function (key) { args.push(key); args.push(obj[key]); }); } this.client.send_command(command, args, function (err, reply) { if (err) { var cur = self.queue[index]; if (typeof cur[cur.length - 1] === "function") { cur[cur.length - 1](err); } else { throw new Error(err); } self.queue.splice(index, 1); } }); }, this); this.client.send_command("EXEC", function (err, replies) { if (err) { if (callback) { callback(new Error(err)); return; } else { throw new Error(err); } } var i, il, j, jl, reply, args, obj, key, val; if (replies) { for (i = 1, il = self.queue.length; i < il; i += 1) { reply = replies[i - 1]; args = self.queue[i]; // Convert HGETALL reply to object if (reply && args[0].toLowerCase() === "hgetall") { obj = {}; for (j = 0, jl = reply.length; j < jl; j += 2) { key = reply[j].toString(); val = reply[j + 1]; obj[key] = val; } replies[i - 1] = reply = obj; } if (typeof args[args.length - 1] === "function") { args[args.length - 1](null, reply); } } } if (callback) { callback(null, replies); } }); }; RedisClient.prototype.multi = function (args) { return new Multi(this, args); }; RedisClient.prototype.MULTI = function (args) { return new Multi(this, args); }; exports.createClient = function (port_arg, host_arg, options) { var port = port_arg || default_port, host = host_arg || default_host, redis_client, net_client; net_client = net.createConnection(port, host); // 创建和redis之间的连接 redis_client = new RedisClient(net_client, options); redis_client.port = port; redis_client.host = host; return redis_client; }; exports.print = function (err, reply) { if (err) { console.log("Error: " + err); } else { console.log("Reply: " + reply); } };  

 

在node-redis首页里面已经给出了很多关于node-redis的信息，从如何使用它、benchmark测试、事件API、一些特俗的命令的解释(hgetall, hmset)、pub/sub和monitor的介绍、node-redis的一些状态信息和通用回调函数(redis.print)。

 

需要注意的两个问题：

 

关于使用node-redis的redis命令接口，传入的参数有三种情况（目前只有mgetall和hmset支持object参数情况）：

 

• 独立的参数

client.set("some key", "some val"); 

 

• 数组

client.set(["some other key", "some val"]); 

 

• 对象

client.hmset(key2, { "0123456789": "abcdefghij", "some manner of key": "a type of value" }); 

 

可以直接调用client.set, client.get (client.REDIS_CMD)来向redis来请求，也可以直接使用client.send_command来向redis请求，功能相同。