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redis - a node redis client

This is a Redis client for node. It is designed for node 0.2.2+ and redis 2.0.1+. It probably won't work on earlier versions of either.

This client supports MULTI and PUBLISH/SUBSCRIBE.

Why?

node_redis works in the latest versions of node, is published in npm, and is very fast, particularly for small responses.

The most popular Redis client, redis-node-client by fictorial, is very mature and well tested. If you are running an older version of node or value the maturity and stability of redis-node-client, I encourage you to use that one instead.

node_redis is designed with performance in mind. The included bench.js runs similar tests to redis-benchmark, included with the Redis distribution, and bench.js is as fast as redis-benchmark for some patterns and slower for others.

Usage

Simple example, included as example.js:

var redis = require("redis"),
    client = redis.createClient();

client.set("string key", "string val", redis.print);
client.hset("hash key", "hashtest 1", "some value", redis.print);
client.hset(["hash key", "hashtest 2", "some other value"], redis.print);
client.hkeys("hash key", function (err, replies) {
    console.log(replies.length + " replies:");
    replies.forEach(function (reply, i) {
        console.log("    " + i + ": " + reply);
    });
    client.end();
});

This will display:

mjr:~/work/node_redis (master)$ node example.js 
Reply: OK
Reply: 0
Reply: 0
2 replies:
    0: hashtest 1
    1: hashtest 2
mjr:~/work/node_redis (master)$

Sending Commands

Each Redis command is exposed as a function on the client object. All functions take either take either an args Array plus optional callback Function or a variable number of individual arguments followed by an optional callback. Here is an example of passing an array of arguments and a callback:

client.mset(["test keys 1", "test val 1", "test keys 2", "test val 2"], function (err, res) {});

Here is that same call in the second style:

client.mset("test keys 1", "test val 1", "test keys 2", "test val 2", function (err, res) {});

Note that in either form the callback is optional:

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

For a list of Redis commands, see Redis Command Reference

The commands can be specified in uppercase or lowercase for convenience. client.get() is the same as client.GET().

Minimal parsing is done on the replies. Commands that return a single line reply return JavaScript Strings, integer replies return JavaScript Numbers, "bulk" replies return node Buffers, and "multi bulk" replies return a JavaScript Array of node Buffers. HGETALL returns an Object with Buffers keyed by the hash keys.

API

Connection Events

client will emit some events about the state of the connection to the Redis server.

"connect"

client will emit connect when a connection is established to the Redis server.

Commands issued before the connect event are queued, then replayed when a connection is established.

"error"

client will emit error when encountering an error connecting to the Redis server.

This may change at some point, because it would be nice to send back error events for things in the reply parser.

"end"

client will emit end when an established Redis server connection has closed.

redis.createClient(port, host)

Create a new client connection. port defaults to 6379 and host defaults to 127.0.0.1. If you have Redis running on the same computer as node, then the defaults are probably fine.

createClient returns a RedisClient object that is named client in all of the examples here.

client.end()

Forcibly close the connection to the Redis server. Note that this does not wait until all replies have been parsed. If you want to exit cleanly, call client.quit() to send the QUIT command.

var redis = require("redis"),
    client = redis.createClient();

client.set("foo_rand000000000000", "some fantastic value");
client.get("foo_rand000000000000", function (err, reply) {
  console.log(reply.toString());
});
client.quit();

Here is a simple example of the API for publish / subscribe. This program opens two client connections, subscribes to a channel on one of them, and publishes to that channel on the other:

var redis = require("redis"),
    client1 = redis.createClient(), client2 = redis.createClient(),
    msg_count = 0;

client1.on("subscribe", function (channel, count) {
    client2.publish("a nice channel", "I am sending a message.");
    client2.publish("a nice channel", "I am sending a second message.");
    client2.publish("a nice channel", "I am sending my last message.");
});

client1.on("message", function (channel, message) {
    console.log("client1 channel " + channel + ": " + message);
    msg_count += 1;
    if (msg_count === 3) {
        client1.unsubscribe();
        client1.end();
        client2.end();
    }
});

client1.incr("did a thing");
client1.subscribe("a nice channel");

When a client issues a SUBSCRIBE or PSUBSCRIBE, that connection is put into "pub/sub" mode. At that point, only commands that modify the subscription set are valid. When the subscription set is empty, the connection is put back into regular mode.

If you need to send regular commands to Redis while in pub/sub mode, just open another connection.

Pub / Sub Events

If a client has subscriptions active, it may emit these events:

"message" (channel, message)

Client will emit message for every message received that matches an active subscription. Listeners are passed the channel name as channel and the message Buffer as message.

"pmessage" (pattern, channel, message)

Client will emit pmessage for every message received that matches an active subscription pattern. Listeners are passed the original pattern used with PSUBSCRIBE as pattern, the sending channel name as channel, and the message Buffer as message.

Client will emit subscribe in response to a SUBSCRIBE command. Listeners are passed the channel name as channel and the new count of subscriptions for this client as count.

"psubscribe" (pattern, count)

Client will emit psubscribe in response to a PSUBSCRIBE command. Listeners are passed the original pattern as pattern, and the new count of subscriptions for this client as count.

"unsubscribe" (channel, count)

Client will emit unsubscribe in response to a UNSUBSCRIBE command. Listeners are passed the channel name as channel and the new count of subscriptions for this client as count. When count is 0, this client has left pub/sub mode and no more pub/sub events will be emitted.

"punsubscribe" (pattern, count)

Client will emit punsubscribe in response to a PUNSUBSCRIBE command. Listeners are passed the channel name as channel and the new count of subscriptions for this client as count. When count is 0, this client has left pub/sub mode and no more pub/sub events will be emitted.

client.multi(commands, callback)

MULTI is supported. The syntax is a little awkward, but it works:

var redis  = require("./index"),
    client = redis.createClient(), set_size = 20;

while (set_size > 0) {
    client.sadd("bigset", "member " + set_size);
    set_size -= 1;
}

client.MULTI([
    ["scard", ["bigset"], function (err, res) {
        console.log("An individual callback, value: " + res.toString());
    }],
    ["smembers", ["bigset"]],
    ["smembers", ["bigset"]],
    ["smembers", ["bigset"]],
    ["smembers", ["bigset"]],
    ["keys", ["*"]],
    ["dbsize", []]
], function (replies) {
    console.log("MULTI got " + replies.length + " replies");
    replies.forEach(function (reply, index) {
        console.log("Reply " + index + ": " + reply.toString());
    });
    client.quit();
});

client.multi takes an Array of 3-element Arrays. The elements are: command, args, and optionally callback. When the commands are all submitted, EXEC is called and the callbacks are invoked in order. If a command is submitted that doesn't pass the syntax check, it will be removed from the transaction.

The second argument to client.multi is an optional callback with a simple array of results.

MULTI needs some love. This way works, but it's too ugly and not progressive. Patches and suggestions are welcome.

Extras

Some other things you might like to know about.

redis.print()

A handy callback function for displaying return values when testing. Example:

var redis = require("redis"),
    client = redis.createClient();

client.on("connect", function () {
    client.set("foo_rand000000000000", "some fantastic value", redis.print);
    client.get("foo_rand000000000000", redis.print);
});

This will print:

Reply: OK
Reply: some fantastic value

Note that this program will not exit cleanly because the client is still connected.

redis.debug_mode

Boolean to enable debug mode and protocol tracing.

var redis = require("redis"),
    client = redis.createClient();

redis.debug_mode = true;

client.on("connect", function () {
    client.set("foo_rand000000000000", "some fantastic value");
});

This will display:

mjr:~/work/node_redis (master)$ node ~/example.js 
send command: *3
$3
SET
$20
foo_rand000000000000
$20
some fantastic value

on_data: +OK

send command is data sent into Redis and on_data is data received from Redis.

client.send_command(command_name, args, callback)

Used internally to send commands to Redis. For convenience, nearly all commands that are published on the Redis Wiki have been added to the client object. However, if I missed any, or if new commands are introduced before this library is updated, you can use send_command() to send arbitrary commands to Redis.

All commands are sent as multi-bulk commands. args can either be an Array of arguments, or individual arguments, or omitted completely.

client.connected

Boolean tracking the state of the connection to the Redis server.

client.command_queue.length

The number of commands that have been sent to the Redis server but not yet replied to. You can use this to enforce some kind of maximum queue depth for commands while connected.

Don't mess with client.command_queue though unless you really know what you are doing.

client.offline_queue.length

The number of commands that have been queued up for a future connection. You can use this to enforce some kind of maximum queue depth for pre-connection commands.

client.retry_delay

Current delay in milliseconds before a connection retry will be attempted. This starts at 250.

client.retry_backoff

Multiplier for future retry timeouts. This should be larger than 1 to add more time between retries. Defaults to 1.7. The default initial connection retry is 250, so the second retry will be 425, followed by 723.5, etc.

TODO

Need to implement WATCH/UNWATCH and progressive MULTI commands.

Support variable argument style for MULTI commands.

Stream binary data into and out of Redis.

Also

This library still needs a lot of work, but it is useful for many things. There are other Redis libraries available for node, and they might work better for you.

Comments and patches welcome.

LICENSE - "MIT License"

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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