tmrts / teracache

Scalable, fault-tolerant, highly-available cache

Teracache

Teracache is a scalable, decentralized, highly-available in-memory cache for read-asymmetrical workflows.

Workflow

The workflow diagram depicts a system with multiple topics and nodes where each color represents the topic they're in.

What is Read-Asymmetrical?

In a read-asymmetrical workflow, reads are frequent while the writes are rare. For example a newsfeed will resize and optimize a thumbnail when a new article arrives and then serve the optimized thumbnail to thousands or millions of users.

In such cases, it is very profitable to use a cache that doesn't sacrifice performance to allow write operations. Teracache does exactly this trade-off.

How to use invalidations?

Cache entries are immutable and no entry is considered stale. Entries are evicted only to admit more popular entries.

Inspired By

• groupcache
• SWIM Membership Protocol
• Microsoft Orleans
• Amazon Dynamo
• Consistent Hashing and Random Trees