Memcached Ruby Server

This is a Memcached Ruby server (TCP/IP socket). The server listen for new connections on a TCP port, accept connections and commands from any Memcached client.

This server was develop in Ruby programming language

About Memcached

Free & open source, high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load.

Memcached is an in-memory key-value store for small chunks of arbitrary data (strings, objects) from results of database calls, API calls, or page rendering.

Commands

Memcached handles a small number of basic commands. In this server it's implement a subset of Memcached commands, with all of their allowed options.

Storage Commands

Command	Function
set	Most common command. Store this data, possibly overwriting any existing data
add	Store this data, only if it does not already exist
append	Add this data after the last byte in an existing item
prepend	Same as append, but adding new data before existing data
replace	Store this data, but only if the data already exists
cas (Check And Set or Compare And Swap)	An operation that stores data, but only if no one else has updated the data since you read it last

Retrieval commands:

Command	Function
get	Command for retrieving data. Takes one or more keys and returns all found items
gets	An alternative get command for using with CAS. Returns a CAS identifier with the item

How to use it

Download:

Clone the repository with the command line interface:

git clone https://github.com/nathsotomayor/memcached_ruby.git

Execution:

Start the server

Go to the project (repository) folder and execute the command:

memcached_ruby$ ruby bin/memcached_server.rb -p 2000
Server running and listening on port 2000...

If you no provide the port this will be the port 2000 by default.

Start the client

Go to the project (repository) folder and execute the command:

memcached_ruby$ ruby bin/memcached_client.rb -p 2000

If you no provide the port this will be the port 2000 by default.

Usage examples

Storage commands

Set: Store this data, possibly overwriting any existing data

Syntax:

set key flags timetolive
value

Example:

set any_key 1 100
any_value
STORED

Add: Store this data, only if it does not already exist

Syntax:

add key flags timetolive
value

Example:

Enter a command:
add new_key 1 100
new_value
STORED

Enter a command:
add new_key 1 200
other_value
NOT_STORED

Append: Add this data after the last byte in an existing item

Syntax:

append key flags timetolive
value

Example:

Enter a command:
append key 1 100
other
NOT_STORED

Enter a command:
add key 1 100
value
STORED

Enter a command:
append key 1 200
other
STORED

Prepend: Same as append, but adding new data before existing data

Syntax:

prepend key flags timetolive
value

Example:

Enter a command:
prepend key 1 100
other
NOT_STORED

Enter a command:
add key 1 100
value
STORED

Enter a command:
prepend key 1 200
other
STORED

Replace: Store this data, but only if the data already exists

Syntax:

replace key flags timetolive
value

Example:

Enter a command:
replace new_key 1 100
new_value
NOT_STORED

Enter a command:
add new_key 1 100
new_value
STORED

Enter a command:
replace new_key 1 200
other_value
STORED

Cas (Check and Set or Compare and Swap): An operation that stores data, but only if no one else has updated the data since you read it last

Syntax:

cas key flags timetolive token
value

Example:

Enter a command:
cas key 1 100
value
ERROR

Enter a command:
cas key 1 100 9876
value
NOT_FOUND

Enter a command:
add key 1 100
value
STORED

Enter a command:
gets key
VALUE key 1 9876
value
END

Enter a command:
cas key 0 200 9876
othervalue
STORED

Retrieval commands

Get: Command for retrieving data. Takes one or more keys and returns all found items Syntax

get key or get key1 key2 ...

Example:

Enter a command:
get key
NOT_FOUND

Enter a command:
add key 1 100
value
STORED

Enter a command:
get key
VALUE key 1
value
END

Enter a command:
add other_key 2 100
other_value
STORE

Enter a command:
get key other_key
VALUE key 1
value
VALUE other_key 2
other_value
END

Gets: An alternative get command for using with CAS. Returns a CAS identifier with the item

Syntax:

gets key or gets ke1 key2 ...

Example:

Enter a command:
gets key
NOT_FOUND

Enter a command:
add key 1 100
value
STORED

Enter a command:
get key
VALUE key 1 9876
value
END

Enter a command:
add other_key 2 100
other_value
STORE

Enter a command:
gets key other_key
VALUE key 1 9876
value
VALUE other_key 2 6789
other_value
END

Ruby unit tests

Go to the project (repository) folder and execute the command:

memcached_ruby$ ruby tests/test_name_file.rb

The output should look like this:

Run options: --seed 9374

# Running:

.................

Finished in 0.003744s, 4540.5982 runs/s, 5341.8802 assertions/s.
17 runs, 20 assertions, 0 failures, 0 errors, 0 skips

References

Memcached: http://memcached.org/

Full list of commands: http://lzone.de/cheat-sheet/memcached

The protocol specification: https://github.com/memcached/memcached/blob/master/doc/protocol.txt