OneCache: 一个兼容memcached分布式KV存储

OneCache

OneCache是一个分布式key/value存储，可以通过memcached协议访问。OneCache nodes原生支持集群并且尽可能的复制。 添加节点进入集群有效地增加了高速缓存的存储器内存储能力。Replication of keys minimizes the impact of a single node failure as requests will transparently be forwarded to the new key leader.

OneCache's architecture is built around the concept of a one-hop distributed hash table. Many DHT algorithms are designed for a very large number of members, such as bitorrent DHTs, and trade lookup efficiency for per-node storage and communication. However, OneCache is built for a much smaller cluster size (<100) and as such, every node holds the full state of the underlying consistent hash ring. This is advantageous because every node is capable of forwarding requests to the correct node, which is why it receives the term one-hop.

OneCache's name then becomes a play on its one-hop DHT architecture and memcached protocol support.

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Usage

Single Node

To start a single OneCache node listening on memcached's default port, simply run:

$> ./onecache

Clustered

To start a cluster of OneCache nodes on a single machine (for ease of getting started) we must bind the nodes to non-default ports to avoid collision. If clustering on different machines, the default ports can be used.

Start the first node in one terminal:

$> ./onecache -gossip_port=7946 -port=11211

In another, start the second and have it join. The output will show it added a peer node.

$> ./onecache -gossip_port=7947 -port=11212 -join="127.0.0.1:7946"  2016/01/18 12:04:30 [INFO] onecache: added peer node &{c3f48bd0-4106-43d4-9044-15cf552037f0 192.168.1.10 11211}

Usage

Standard memcached libraries can be used, which make OneCache an easy drop in replacement for memcached as code doesn't have to be changed. OneCache is also accessible via the terminal:

$> telnet 127.0.0.1 11211  Trying 127.0.0.1...  Connected to localhost.  Escape character is '^]'.  set foo 0 0 12  hello, world  STORED