memcached.scala

A simple and hopefully fast memcached client for scala. It uses java nio and implements the binary protocol. This client has not been exercised in production yet, so there are probably bugs. I did my best to expose the correct semantics per my interpretation of the protocol and looking at other clients, but it may not be perfect, so feel free to disagree with me and we can fix it.

A few obvious things that are currently TODOs:

• Pipelining
• Sharding (should probably use this)

Setup

Just add it to your sbt project definition:

val memcached = "com.bitlove" %%
                  "memcached" %
                    "0.0.1" from
                      "http://cloud.github.com/downloads/jakedouglas/memcached.scala/memcached.scala_2.8.1-0.0.1.jar"

Or you can clone the repo and build it for whatever version of scala you are using. Beware that running the tests will flush your local memcached instance.

Simple usage

import com.bitlove.memcached.Memcached

val c     = new Memcached("localhost", 11211)
val key   = "some key".getBytes
val value = "my value".getBytes

c.set(key, value)

c.get match {
  case None        => println("nothing there!")
  case Some(bytes) => println(new String(bytes))
}

Multiple threads

The client itself is not intended to be used by multiple threads at once, so you need to use a connection pool for a multi-threaded program. You can use your own favorite connection pool, or a simple one is included:

import com.bitlove.memcached.pool.MemcachedPool

val pool = new MemcachedPool("localhost", 11211)

pool { c =>
  c.get(...)
}

Transcoding

Transcoders allow you to to pass and receive objects of your own type, and accomodate custom serialization, compression, etc. These are intended to be chainable. The 'outermost' transcoder needs to be able to produce and decode values of Array[Byte]. Transcoders have access to the "flags" field that get stored in memcached, used for designating whether a value is serialized or compressed, etc.

See these files to understand how transcoders are assembled and chained.

Transcoders can be put to use at different levels of granularity:

• Provide a transcoder to the Memcached constructor to be used by default for all requests.
• Define an implicit transcoder to use in a certain scope.
• Pass in a transcoder on a per-request basis.

API / Docs

For now, please refer to the scala docs. Eventually there will be more here.

Issues

I'll try to fix problems when I have time. Pull requests are welcome and encouraged. If you submit a pull request, please include tests.

Thanks

@al3x, @jamesgolick and @moonpolysoft all helped answer some questions at one point or another.