E ff ortless Eventual Consistency Gossip, CRDTs, and Weave Mesh - PowerPoint PPT Presentation

E ff ortless Eventual Consistency Gossip, CRDTs, and Weave Mesh weave works -

Outline • Theory • Practice • Extension 
 weave works -

Outline • Theory 
 Gossip 
 CRDT • Practice 
 Weave Mesh 
 Weave Net • Extension 
 User data types 
 Strong consistency weave works -

Motivating Example 0 Increment-only counter weave works -

Increment Motivating Example 0 Increment-only counter weave works -

Increment Motivating Example 1 Increment-only counter weave works -

Motivating Example 1 Increment-only counter weave works -

Increment Motivating Example 1 Increment-only counter weave works -

Increment Motivating Example 2 Increment-only counter weave works -

Motivating Example 2 Increment-only counter weave works -

Increment Increment Motivating Example 2 Increment-only counter Increment Increment weave works -

Increment Increment Motivating Example ☹ Increment-only counter Increment Increment weave works -

Increment Increment Motivating Example 😰 Increment-only counter Increment Increment weave works -

Increment Increment Motivating Example 2 Increment-only counter Increment Increment weave works -

Increment Increment Motivating Example 2 Increment-only counter Increment Increment weave works -

Increment Increment Motivating Example 3 Increment-only counter Increment Increment weave works -

Increment Motivating Example 3 Increment-only counter Increment Increment weave works -

Increment Motivating Example 3 Increment-only counter Increment Increment weave works -

Increment Motivating Example 4 Increment-only counter Increment Increment weave works -

Increment Motivating Example 4 Increment-only counter Increment weave works -

Increment Motivating Example 4 Increment-only counter Increment weave works -

Increment Motivating Example 5 Increment-only counter Increment weave works -

Increment Motivating Example 5 Increment-only counter weave works -

Increment Motivating Example 5 Increment-only counter weave works -

Increment Motivating Example 6 Increment-only counter weave works -

Motivating Example 6 Increment-only counter weave works -

Motivating Example 6 Increment-only counter weave works -

weave works -

weave works -

1x 1x weave works -

weave works -

1x weave works -

1x weave works -

☹ ☹ ☹ ☹ ☹ ☹ ☹ 1x weave works -

Theory: Gossip weave works -

Gossip solves… • Information dissemination in irregular networks • Unreliable links • Dynamic, changing topologies weave works -

Gossip requires… • Periodic and pairwise communication • Frequency of interaction ≪ individual message latency • Redundancy in delivered information weave works -

Gossip requires… • Periodic and pairwise communication • Frequency of interaction ≪ individual message latency • Redundancy in delivered information weave works -

Gossip modes • Push — if we know X, every round, tell a peer about X • Pull — every round, ask a peer about all possible X • Push/pull — push for some cycles, then pull for some cycles weave works -

Rumor weave works -

Rumor weave works -

Rumor weave works -

Rumor weave works -

Rumor weave works -

Rumor weave works -

Anti-entropy weave works -

Anti-entropy weave works -

Anti-entropy weave works -

Anti-entropy weave works -

Anti-entropy gossip weave works -

Aggregate weave works -

0 0 0 Motivating Example 0 0 0 Increment-only counter 0 0 0 weave works -

0 0 0 Motivating Example 0 0 0 Increment-only counter 0 0 0 weave works -

Increment 0 0 0 Motivating Example 0 0 0 Increment-only counter 0 0 0 weave works -

Increment 1 0 0 Motivating Example 0 0 0 Increment-only counter 0 0 0 weave works -

1 0 0 Motivating Example 0 0 0 Increment-only counter 0 0 0 weave works -

t=1 1 0 0 Motivating Example 0 0 0 Increment-only counter 0 0 0 weave works -

t=2 1 1 0 Motivating Example 0 0 0 Increment-only counter 0 0 0 weave works -

t=3 1 1 0 Motivating Example 1 1 0 Increment-only counter 0 0 0 weave works -

t=4 1 1 0 Motivating Example 1 1 0 Increment-only counter 1 1 0 weave works -

t=5 1 1 0 Motivating Example 1 1 0 Increment-only counter 1 1 1 weave works -

t=6 1 1 0 Motivating Example 1 1 1 Increment-only counter 1 1 1 weave works -

t=7 1 1 1 Motivating Example 1 1 1 Increment-only counter 1 1 1 weave works -

t=7 1 1 1 Motivating Example 1 1 1 Increment-only counter 1 1 1 weave works -

Motivating Example 0 Increment-only counter weave works -

Motivating Example 0 Increment-only counter weave works -

Motivating Example 1 Increment-only counter weave works -

Motivating Example 2 Increment-only counter weave works -

Motivating Example 2 Increment-only counter weave works -

1 1 1 Motivating Example 1 2 1 Increment-only counter 🤕 1 1 1 weave works -

👒 Motivating Example Increment-only counter weave works -

Increment 👒 Motivating Example 0 Increment-only counter weave works -

Increment 👒 Motivating Example 0 Increment-only counter weave works -

Increment 👒 Motivating Example 1 Increment-only counter weave works -

Read 👒 Motivating Example 1 Increment-only counter weave works -

😧 😧 😧 Motivating Example 👒 😧 😧 x Increment-only counter 😧 😧 😧 weave works -

Theory: CRDT weave works -

CRDTs solve… • Shared state in a distributed system • Provide availability (A) • Provide partition tolerance (P) weave works -

weave works -

weave works -

CRDTs require... • Operations that are • Associative — A • (B • C) = (A • B) • C • Commutative — A • B = B • A • Idempotent* — A • A = A weave works -

CRDTs require... • Operations that are • Associative — A • (B • C) = (A • B) • C • Commutative — A • B = B • A • Idempotent* — A • A = A 😍 weave works -

CRDT • Conflict-free • Replicated • Data • Type weave works -

CmRDT • Commutative Replicated Data Type • Operation-based: transmit the op itself — "edge trigger" • Assumes reliable, exactly-once delivery (ha!) weave works -


 0 Motivating Example 0 Increment-only counter CmRDT 0 weave works -


 0 0 0 Motivating Example 0 0 0 Increment-only counter CmRDT 0 0 0 weave works -


 Increment 0 0 0 Motivating Example 0 0 0 Increment-only counter CmRDT 0 0 0 weave works -


 Increment 1 0 0 Motivating Example 0 0 0 Increment-only counter CmRDT 0 0 0 weave works -


 1 0 0 Motivating Example 0 0 0 Increment-only counter CmRDT 0 0 0 weave works -


 1 0 0 A++ Motivating Example 0 0 0 Increment-only counter CmRDT 0 0 0 weave works -


 1 0 0 A++ Motivating Example 1 0 0 Increment-only counter CmRDT 0 0 0 weave works -


 1 0 0 Motivating Example 1 0 0 Increment-only counter CmRDT 0 0 0 weave works -


 1 0 0 Motivating Example A++ 1 0 0 Increment-only counter CmRDT 0 0 0 weave works -


 1 0 0 Motivating Example A++ 1 0 0 Increment-only counter CmRDT 1 0 0 weave works -


 1 0 0 Motivating Example 1 0 0 Increment-only counter CmRDT 1 0 0 weave works -


 1 0 0 Read Motivating Example 1 0 0 Increment-only counter CmRDT 1 0 0 weave works -


 1 0 0 Read Motivating Example Σ 1 0 0 = 1 Increment-only counter CmRDT 1 0 0 weave works -

CvRDT • Convergent Replicated Data Type • State-based: transmit the complete state — "level trigger" • Achieve idempotency in fragile networks • All CmRDT can be expressed as CvRDT (Shapiro et. al.) weave works -


 1 0 0 Motivating Example 1 0 0 Increment-only counter CmRDT 1 0 0 weave works -


 1 0 0 Increment Motivating Example 1 0 0 Increment-only counter CmRDT 1 0 0 weave works -