What is mio

In short, mio is memcached + "range search".

mio suports range search queries like "get 10 datum which key are between key1 and key2".

N.B. At present, it is in alpha quality.

Building and Installing

1. Install a recent version of Erlang.

2. Download latest mio from github or git clone git://github.com/higepon/mio.git .

3. make

4. make install with Environment variables for configuration. TARGET_DIR: Installation target directory. SBIN_DIR: sbin direcotry.

   e.g. sudo TARGET_DIR=/user/local/mio SBIN_DIR=/usr/sbin/ make install

Running mio

# Run first node named mio1 with verbose mode on host FQDN_of_your_host (default port 11211)
% mio -v -n mio1@FQDN_of_your_host


# Run second node named mio2 on host FQDN_of_your_host2.
# With -i option, indidate the introducer node.
% mio -v -n mio2@FQDN_of_your_host2 -i mio1@FQDN_of_your_host

# Run third node named mio3 on host FQDN_of_your_host (port 11411).
% mio -v -n mio3@FQDN_of_your_host -i mio1@FQDN_of_your_host -p 11411

API

You can access to Mio using memcached protocol.

Currently the following commands are supported.

• get
• set
• delete
• quit
• stats
• range_search
  • get_multi("mio:range-search", Key1, Key2, Limit, desc/asc)

Access to mio

Use memcached client libraries to access mio.

Perl

# Example: Access to Mio.
use strict;
use warnings;
use Cache::Memcached;
use Data::Dumper;

my $m = Cache::Memcached->new( { servers => ['127.0.0.1:11211']} );
$m->set( "hello" => "world" );
$m->set( "intel" => "cpu" );
$m->set( "japan" => "Tokyo" );

warn $m->get("hello");
warn $m->get("intel");
warn $m->get("japan");

my $href = $m->get_multi("mio:range-search", "he", "j", "10", "asc");

# Should print
# $VAR1 = {
#           'hello' => 'world',
#           'intel' => 'cpu'
#         };
warn Dumper $href;

PHP

$mem = new Memcached;
$mem->addServer('127.0.0.1', 11211);
$mem->set("hello", "world");
$mem->set("intel", "cpu");
$mem->set("japan", "Tokyo");
printf("%s\n", $mem->get("hello"));
printf("%s\n", $mem->get("intel"));
printf("%s\n", $mem->get("japan"));
var_dump($mem->getMulti(array("mio:range-search", "he", "j", "10", "asc")));
?>

Java

import com.danga.MemCached.*;
import java.util.*;

public class JavaMemcachedClient
{
    public static void main(String[] args)
    {
        String[] serverlist = { "127.0.0.1:11211" };
        SockIOPool pool = SockIOPool.getInstance();
        pool.setServers(serverlist);
        pool.initialize();

        MemCachedClient mc = new MemCachedClient();
        mc.set("hello", "world");
        mc.set("intel", "cpu");
        mc.set("japan", "Tokyo");
        System.out.printf("hello => %s intel => %s japan => %s\n", mc.get("hello"), mc.get("intel"), mc.get("japan"));

        String[] keys = { "mio:range-search", "he", "j", "10", "asc" };
        Map<String, Object> ret = mc.getMulti(keys);

        for (Map.Entry<String, Object> e : ret.entrySet()) {
            System.out.println(e.getKey() + " : " + e.getValue());
        }
    }
}

Algorithm

Mio using "Skip Graph" algorithm. See following articles

• Mio - a distributed Skip Graph based orderd KVS
• PDF: Load Balancing and Locality in Range-Queries Data Structures by James Aspnes.

Author

Copyright (C) Cybozu Labs, Inc.

Written by Taro Minowa(Higepon) higepon@labs.cybozu.co.jp

License

New BSD License