A Ruby client library for the Redis key-value store.

Versions 1.0.x target all versions of Redis. You have to use this one if you are using Redis < 1.2.

Version 2.0 is a big refactoring of the previous version and makes little effort to be backwards-compatible when it shouldn't. It does not support Redis' original protocol, favoring the new, binary-safe one. You should be using this version if you're running Redis 1.2+.

Redis is a key-value store with some interesting features:

1. It's fast.
2. Keys are strings but values are typed. Currently Redis supports strings, lists, sets, sorted sets and hashes. Atomic operations can be done on all of these types.

See the Redis homepage for more information.

You can connect to Redis by instantiating the Redis class:

require "redis"

redis = Redis.new

This assumes Redis was started with default values listening on localhost, port 6379. If you need to connect to a remote server or a different port, try:

redis = Redis.new(:host => "10.0.1.1", :port => 6380)

To connect to Redis listening on a unix socket, try:

redis = Redis.new(:path => "/tmp/redis.sock")

Once connected, you can start running commands against Redis:

>> redis.set "foo", "bar"
=> "OK"

>> redis.get "foo"
=> "bar"

>> redis.sadd "users", "albert"
=> true

>> redis.sadd "users", "bernard"
=> true

>> redis.sadd "users", "charles"
=> true

How many users?

>> redis.scard "users"
=> 3

Is albert a user?

>> redis.sismember "users", "albert"
=> true

Is isabel a user?

>> redis.sismember "users", "isabel"
=> false

Handle groups:

>> redis.sadd "admins", "albert"
=> true

>> redis.sadd "admins", "isabel"
=> true

Users who are also admins:

>> redis.sinter "users", "admins"
=> ["albert"]

Users who are not admins:

>> redis.sdiff "users", "admins"
=> ["bernard", "charles"]

Admins who are not users:

>> redis.sdiff "admins", "users"
=> ["isabel"]

All users and admins:

>> redis.sunion "admins", "users"
=> ["albert", "bernard", "charles", "isabel"]

Redis only stores strings as values. If you want to store an object inside a key, you can use a serialization/deseralization mechanism like JSON:

>> redis.set "foo", [1, 2, 3].to_json
=> OK

>> JSON.parse(redis.get("foo"))
=> [1, 2, 3]

You can use MULTI/EXEC to run arbitrary commands in an atomic fashion:

redis.multi do
  redis.set "foo", "bar"
  redis.incr "baz"
end

To use Redis safely in a multithreaded environment, be sure to initialize the client with :thread_safe => true for version <= 2.1.x. The client is thread-safe by default since 2.2.

Redis.new(:thread_safe => true)

See the tests and benchmarks for examples.

• Ruby 1.9 doesn't raise on socket timeouts in IO#read but rather retries the read operation. This means socket timeouts don't work on 1.9 when using the pure Ruby I/O code. Use hiredis when you want use socket timeouts on 1.9.

• Ruby 1.8 does raise on socket timeouts in IO#read, but prints a warning that using IO#read for non blocking reads is obsolete. This is wrong, since the read is in fact blocking, but EAGAIN (which is returned on socket timeouts) is interpreted as if the read was non blocking. Use hiredis to prevent seeing this warning.

Check the Redis Command Reference or check the tests to find out how to use this client.

Fork the project and send pull requests. You can also ask for help at #redis-rb on Freenode.