STATUS

Twitter is no longer maintaining this project or responding to issues or PRs.

Haplocheirus

Haplocheirus is a redis-backed storage engine for timelines.

Disclaimer: This project is an experiment, and is not complete or deployed anywhere yet.

Timelines are lists of 64-bit ids, possibly with a small bit of attached metadata, in preserved order. New entries are always added at the "front". Old entries may be dropped off the "back" if the timeline exceeds a maximum size. Two timelines can be merged by assuming they're roughly sorted by id. A timeline query returns a slice of the timeline, newest first.

Goals

• Highly available, partitioned
• Structured vectors (each timeline entry is an atomic blob, not necessarily all alike)
• Homogeneous service interface
• Eliminate client side hashing
• Preserve ability to expire timelines that aren't being read
• Durable snapshots
• Idempotent/commutative

Non-goals

• Contain business logic for building timelines from scratch
• Transactionally durable timelines

Structure

Gizzard is used to handle partitioning and job queueing, and Redis is used as the backend storage for each shard.

New features from redis 2.2 are required (LPUSHX and LINSERT for example), so for now, you will need to build redis from trunk: http://github.com/antirez/redis

Building

You need:

• java 1.6
• thrift 0.2.0
• sbt 0.7.4
• redis-server (2.2 trunk; see above)

You might want:

• haplocheirus-client http://github.com/bitbckt/haplocheirus-client

A special build of jredis is used, too, but currently the jar is included in the repo.

Then:

$ sbt clean update package-dist

Running

Start up your local redis server, then:

$ ./dist/haplocheirus-1.0/scripts/setup-env.sh

Community

License: Apache 2 (see included LICENSE file)

• IRC: #twinfra on freenode (irc.freenode.net)