Piper is a centralized version control system used by Google for its internal software development.
[2] For over 10 years Google relied on a single Perforce instance, using proprietary caching for scalability.
[6] Piper uses the standard Google storage infrastructure, Bigtable (now called Spanner), distributed across 10 data centers worldwide and replicated through Paxos protocol.
This system utilizes cloud backend and a local FUSE filesystem to create an illusion of changes overlaid on top of a full repository.
Due to the always-connected operation, CitC allows easy switching of the computers as well as sharing the modified code with other developers, the automated build system and testing tools.