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Ruby wrapper for hiredis
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examples Move untested EventMachine connection class to example Feb 4, 2011
lib Prepare to 0.6.3 Nov 8, 2018
.gitmodules Fix submodule URL Mar 27, 2014
.travis.yml pick latest revisions Nov 5, 2018
Gemfile Depend on hiredis from this repo's lib directory Dec 2, 2011 Release version 0.6.1 Dec 29, 2015
hiredis.gemspec Use minitest gem for tests Jan 23, 2015


Build Status

Ruby extension that wraps hiredis. Both the synchronous connection API and a separate protocol reader are supported. It is primarily intended to speed up parsing multi bulk replies.


Install with Rubygems:

gem install hiredis


Hiredis can be used as standalone library, or be used together with redis-rb. The latter adds in support for hiredis in 2.2.


To use hiredis from redis-rb, it needs to be available in Ruby's load path. Using Bundler, this comes down to adding the following lines:

gem "hiredis", "~> 0.6.0"
gem "redis", ">= 3.2.0"

To use hiredis with redis-rb, you need to require redis/connection/hiredis before creating a new connection. This makes sure that hiredis will be used instead of the pure Ruby connection code and protocol parser. Doing so in the Gemfile is done by adding a :require option to the line adding the redis-rb dependency:

gem "redis", ">= 3.2.0", :require => ["redis", "redis/connection/hiredis"]

You can use Redis normally, as you would with the pure Ruby version.

Standalone: Connection

A connection to Redis can be opened by creating an instance of Hiredis::Connection and calling #connect:

conn =
conn.connect("", 6379)

Commands can be written to Redis by calling #write with an array of arguments. You can call write more than once, resulting in a pipeline of commands.

conn.write ["SET", "speed", "awesome"]
conn.write ["GET", "speed"]

After commands are written, use #read to receive the subsequent replies. Make sure not to call #read more than you have replies to read, or the connection will block indefinitely. You can use this feature to implement a subscriber (for Redis Pub/Sub).

=> "OK"

=> "awesome"

When the connection was closed by the server, an error of the type Hiredis::Connection::EOFError will be raised. For all I/O related errors, the Ruby built-in Errno::XYZ errors will be raised. All other errors (such as a protocol error) result in a RuntimeError.

You can skip loading everything and just load Hiredis::Connection by requiring hiredis/connection.

Standalone: Reply parser

Only using hiredis for the reply parser can be very useful in scenarios where the I/O is already handled by another component (such as EventMachine).

You can skip loading everything and just load Hiredis::Reader by requiring hiredis/reader.

Use #feed on an instance of Hiredis::Reader to feed the stream parser with new data. Use #read to get the parsed replies one by one:

>> reader =
>> reader.feed("*2\r\n$7\r\nawesome\r\n$5\r\narray\r\n")
>> reader.gets
=> ["awesome", "array"]


These numbers were generated by running benchmark/throughput.rb against ruby 1.9.2p180 (2011-02-18 revision 30909) [x86_64-darwin10.6.0]. The benchmark compares redis-rb with the Ruby connection and protocol code against redis-rb with hiredis to handle I/O and reply parsing.

For simple line or bulk replies, the throughput improvement is insignificant, while the larger multi bulk responses will have a noticeable higher throughput.

                                                        user     system      total        real
redis-rb:  1x SET pipeline, 10000 times             0.260000   0.140000   0.400000 (  0.726216)
 hiredis:  1x SET pipeline, 10000 times             0.170000   0.130000   0.300000 (  0.602332)
redis-rb: 10x SET pipeline, 10000 times             1.550000   0.660000   2.210000 (  2.231505)
 hiredis: 10x SET pipeline, 10000 times             0.400000   0.140000   0.540000 (  0.995266)

redis-rb:  1x GET pipeline, 10000 times             0.270000   0.150000   0.420000 (  0.730322)
 hiredis:  1x GET pipeline, 10000 times             0.170000   0.130000   0.300000 (  0.604060)
redis-rb: 10x GET pipeline, 10000 times             1.480000   0.640000   2.120000 (  2.122215)
 hiredis: 10x GET pipeline, 10000 times             0.380000   0.130000   0.510000 (  0.925731)

redis-rb:  1x LPUSH pipeline, 10000 times           0.260000   0.150000   0.410000 (  0.725292)
 hiredis:  1x LPUSH pipeline, 10000 times           0.160000   0.130000   0.290000 (  0.592466)
redis-rb: 10x LPUSH pipeline, 10000 times           1.540000   0.660000   2.200000 (  2.202709)
 hiredis: 10x LPUSH pipeline, 10000 times           0.360000   0.130000   0.490000 (  0.940361)

redis-rb:  1x LRANGE(100) pipeline, 1000 times      0.240000   0.020000   0.260000 (  0.307504)
 hiredis:  1x LRANGE(100) pipeline, 1000 times      0.050000   0.020000   0.070000 (  0.100293)

redis-rb:  1x LRANGE(1000) pipeline, 1000 times     2.100000   0.030000   2.130000 (  2.353551)
 hiredis:  1x LRANGE(1000) pipeline, 1000 times     0.320000   0.030000   0.350000 (  0.472789)


This code is released under the BSD license, after the license of hiredis.

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