A Ruby client library for the Redis key-value store.
A note about versions
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+.
Information about Redis
Redis is a key-value store with some interesting features:
- It's fast.
- 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
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
albert a user?
>> redis.sismember "users", "albert" => true
isabel a user?
>> redis.sismember "users", "isabel" => false
>> 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]
Executing multiple commands atomically
You can use
MULTI/EXEC to run arbitrary commands in an atomic fashion:
redis.multi do redis.set "foo", "bar" redis.incr "baz" end
Starting with redis-rb 2.2.0, the client is thread-safe by default. To use
earlier versions safely in a multithreaded environment, be sure to initialize
the client with
:thread_safe => true. Thread-safety can be explicitly
disabled for versions 2.2 and up by initializing the client with
See the tests and benchmarks for examples.
Non-default connection drivers are only used when they are explicitly required. By default, redis-rb uses Ruby's socket library to talk with Redis.
Using redis-rb with hiredis-rb (v0.3 or higher) as backend is done by requiring
redis/connection/hiredis before requiring
redis. This will make redis-rb
pick up hiredis as default driver automatically. This driver optimizes for
speed, at the cost of portability. Since hiredis is a C extension, JRuby is not
supported (by default). Use hiredis when you have large array replies (think
ZRANGE, etc.) and/or large pipelines of commands.
Using redis-rb with hiredis from a Gemfile:
gem "hiredis", "~> 0.3.1" gem "redis", "~> 2.2.0", :require => ["redis/connection/hiredis", "redis"]
This driver adds support for
em-synchrony. Using the synchrony
backend from redis-rb is done by requiring
redis. This driver makes redis-rb work with EventMachine's
asynchronous I/O, while not changing the exposed API. The hiredis gem needs to
be available as well, because the synchrony driver uses hiredis for parsing the
Using redis-rb with synchrony from a Gemfile:
gem "hiredis", "~> 0.3.1" gem "em-synchrony" gem "redis", "~> 2.2.0", :require => ["redis/connection/synchrony", "redis"]
This library (v2.2) is tested against the following interpreters:
- MRI 1.8.7 (drivers: Ruby, hiredis)
- MRI 1.9.2 (drivers: Ruby, hiredis, em-synchrony)
- JRuby 1.6 (drivers: Ruby)
- Rubinius 1.2 (drivers: Ruby, hiredis)
Ruby 1.9 doesn't raise on socket timeouts in
IO#readbut 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#readfor 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.