1. Haithem Jarraya
GerritForge
Haithem@gerritforge.com
http://www.gerritforge.com
Infinite Gerrit

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About Haithem
• Haithem Jarraya
Big Data consultant based in London, worked in different
industries telecommunication, advertisement, financial services,
travel and government.
• Expertise with real time big data ecosystem, Apache Kafka,
Apache Cassandra, Apache Spark.

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About GerritForge
Founded in 2009 in London UK
Mission:
Integrate Gerrit with
the Enterprise

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Agenda
 Vision for Infinite Gerrit
 Why Cassandra?
 DfsObjDatabase – Cassandra proposed schema
• Pack list
• Packs

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Gerrit – End Goal
 Every Gerrit mater accepts writes which in
turn will increase throughput.
 Increase flexibility for scaling up.
 Zero down time, Zero data loss.
 Reduce Gerrit operational cost by auto
scaling down instances.

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Gerrit – Challenges
 Distributed storage
 Database replication
 Concurrent Ref updates
 Indexes update
 Cache consistency
 Shared sessions
 Agreement protocol between nodes

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Gerrit – Challenges
 Distributed storage
 Database replication
 Concurrent Ref updates
 Indexes update
 Cache consistency
 Shared sessions
 Agreement protocol between nodes

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C* in brief
 Each table has its rows distributed N token ranges, and each token range replicated
R times.
 Fast writes commit log(durable writes), memtable, stored to SSTable.
 Fast reads bloom filter, row key cache, row cache, SSTable index entry.
 Compaction, repairs, materialized view(3.X)…

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DFS – Storage Layer for JGit
 org...storage.dfs.DfsObjDatabase
 org….storage.dfs.DfsRefDatabase

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Packs C* schema - Packs
 Packs
CREATE TABLE git_store.packs (
id uuid,
ext text,
offset bigint,
value blob,
PRIMARY KEY ((id, ext, offset)))

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Packs C* schema – Pack list
 Pack list
CREATE TABLE git_store.pack_list (
name text,
id uuid,
ext text,
size bigint,
PRIMARY KEY (name, id, ext))
WITH CLUSTERING ORDER BY
(id DESC, ext ASC)

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LWB – HTTP route per repo

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Questions?

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Resources
 http://cassandra.apache.org
 http://www.datastax.com
 http://eclipse.org/jgit
 Dynamo paper http://s3.amazonaws.com/AllThingsDistributed/sosp/amazon-dynamo-sosp2007.pdf
 Big Table paper http://static.googleusercontent.com/media/research.google.com/en//archive/bigtable-osdi06.pdf