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This repository includes code implementing TAPIR -- the Transaction Application Protocol for Inconsistent Replication. This code was used for the SOSP 2015 paper, "Building Consistent Transactions with Inconsistent Replication."

TAPIR is a new protocol for linearizable distributed transactions built using replication with no consistency guarantees. By enforcing consistency only at the transaction layer, TAPIR eliminates coordination at the replication layer, enabling TAPIR to provide the same transaction model and consistency guarantees as existing systems, like Spanner, with better latency and throughput.

In addition to TAPIR, this repo includes several other useful implementations of distributed systems, including:

  1. An implementation of a lock server designed to work with inconsistent replication (IR), our high-performance, unordered replication protocol.

  2. An implementation of Viewstamped Replication (VR), detailed in this older paper and this more recent paper.

  3. An implementation of a scalable, distributed storage system designed to work with VR that uses two-phase commit to support distributed transactions and supports both optimistic concurrency control and strict two-phase locking.

The repo is structured as follows:

  • /lib - the transport library for communication between nodes. This includes UDP based network communcation as well as the ability to simulate network conditions on a local machine, including packet delays and reorderings.

  • /replication - replication library for the distributed stores

    • /vr - implementation of viewstamped replication protocol
    • /ir - implementation of inconsistent replication protocol
  • /store - partitioned/sharded distributed store

    • /common - common data structures, backing stores and interfaces for all of stores
    • /tapirstore - implementation of TAPIR designed to work with IR
    • /strongstore - implementation of both an OCC-based and locking-based 2PC transactional storage system, designed to work with VR
    • /weakstore - implementation of an eventually consistent storage system, using quorum writes for replication
  • /lockserver - a lock server designed to be used with IR

Compiling & Running

You can compile all of the TAPIR executables by running make in the root directory

TAPIR depends on protobufs, libevent and openssl, so you will need the following development libraries:

  • libprotobuf-dev
  • libevent-openssl
  • libevent-pthreads
  • libevent-dev
  • libssl-dev
  • protobuf-compiler

Contact and Questions

Please email Irene at, Dan at and Naveen at


TAPIR distributed transactional storage system







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