Lasp: Distributed, Eventually Consistent Computations

PaPoC 2015, co-located with EuroSys 2015
Christopher Meiklejohn
Peter Van Roy

Transcript

1. DISTRIBUTED, EVENTUALLY CONSISTENT COMPUTATIONS LASP 1 CHRISTOPHER MEIKLEJOHN (BASHO TECHNOLOGIES, INC.) PETER VAN ROY (UNIVERSITÉ CATHOLIQUE DE LOUVAIN)
2. MOTIVATION 2
3. EXPENSIVE / IMPRACTICAL SYNCHRONIZATION IS 3
4. MOBILE GAMES: SHARED STATE BETWEEN CLIENTS CLIENTS GO OFFLINE 4 http://www.rovio.com/en/news/blog/261/263-million-monthly-active-users-in-december/
5. DISJOINT STATE AGGREGATED UPSTREAM CLIENTS GO OFFLINE “INTERNET OF THINGS”: 5 Gubbi, Jayavardhana, et al. "Internet of Things (IoT): A vision, architectural elements, and future directions." Future Generation Computer Systems 29.7 (2013): 1645-1660.
6. NO TOTAL ORDER: REPLICATED SHARED STATE WITH OFFLINE CLIENTS CLIENTS NEED TO MAKE PROGRESS 6 Gilbert, Seth, and Nancy Lynch. "Brewer's conjecture and the feasibility of consistent, available, partition-tolerant web services." ACM SIGACT News 33.2 (2002): 51-59.
7. WALL CLOCKS: UNRELIABLE AT BEST NON-DETERMINISTIC IF USED IN COMPUTATIONS 7 Corbett, James C., et al. "Spanner: Google’s globally distributed database." ACM Transactions on Computer Systems (TOCS) 31.3 (2013): 8.
8. RECONCILED BY USER CONCURRENCY 8
9. RA RB 1 3 2 ? ? set(1) set(2) set(3) 9
10. RA RB 1 3 2 ? ? set(1) set(2) set(3) 10
11. RA RB 1 3 2 ? ? set(1) set(2) set(3) 11
12. RA RB 1 3 2 ? ? set(1) set(2) set(3) 12
13. CRDTs 13
14. DETERMINISTIC RESOLUTION CRDTs PROVIDE 14
15. CRDTs: MAPS, SETS, COUNTERS, REGISTERS, GRAPHS DETERMINISTIC RESOLUTION 15
16. “CORRECT REPLICAS THAT HAVE DELIVERED THE SAME UPDATES HAVE EQUIVALENT STATE” Shapiro, Marc, et al. "Conflict-free replicated data types." Stabilization, Safety, and Security of Distributed Systems. Springer Berlin Heidelberg, 2011. 386-400. STRONG EVENTUAL CONSISTENCY CRDTs REALIZE 16
17. ‘MAX’ REGISTER CRDTs EXAMPLE 17
18. RA RB 1 3 2 3 3 set(1) set(2) set(3) max(2,3) max(2,3) 18
19. ‘ORSET’ SET CRDTs EXAMPLE 19
20. RA RB RC {1} (1, {a}, {}) {1} (1, {b}, {}) {} (1, {b}, {b}) {1} {1} {1} (1, {a, b}, {b}) (1, {a, b}, {b}) (1, {a, b}, {b}) add(1) add(1) remove(1) 20
21. RA RB RC {1} (1, {a}, {}) {1} (1, {b}, {}) {} (1, {b}, {b}) {1} {1} {1} (1, {a, b}, {b}) (1, {a, b}, {b}) (1, {a, b}, {b}) add(1) add(1) remove(1) 21
22. RA RB RC {1} (1, {a}, {}) {1} (1, {b}, {}) {} (1, {b}, {b}) {1} {1} {1} (1, {a, b}, {b}) (1, {a, b}, {b}) (1, {a, b}, {b}) add(1) add(1) remove(1) 22
23. RA RB RC {1} (1, {a}, {}) {1} (1, {b}, {}) {} (1, {b}, {b}) {1} {1} {1} (1, {a, b}, {b}) (1, {a, b}, {b}) (1, {a, b}, {b}) add(1) add(1) remove(1) 23
24. NONTRIVIAL COMPOSITION IS 24
25. RA RB RC {1} (1, {a}, {}) {1} (1, {b}, {}) {} (1, {b}, {b}) {1} {1} {1} (1, {a, b}, {b}) (1, {a, b}, {b}) (1, {a, b}, {b}) add(1) add(1) remove(1) F(RC) {2} fun(X) -> 2 end {2} {} 25
26. RA RC {1} (1, {a}, {}) {1} (1, {b}, {}) {} (1, {b}, {b}) {1} {1} (1, {a, b}, {b}) (1, {a, b}, {b}) add(1) add(1) remove(1) F(RC) {2} fun(X) -> 2 end {2} {} F(RA) {2} fun(X) -> 2 end {2} {2} {2} 26
27. RA RC {1} (1, {a}, {}) {1} (1, {b}, {}) {} (1, {b}, {b}) {1} {1} (1, {a, b}, {b}) (1, {a, b}, {b}) add(1) add(1) remove(1) F(RC) {2} fun(X) -> 2 end {2} {} F(RA) {2} fun(X) -> 2 end {2} {2} {2} 27
28. RA RC {1} (1, {a}, {}) {1} (1, {b}, {}) {} (1, {b}, {b}) {1} {1} (1, {a, b}, {b}) (1, {a, b}, {b}) add(1) add(1) remove(1) F(RC) {2} fun(X) -> 2 end {2} {} F(RA) {2} fun(X) -> 2 end {2} {2} {2} 28
29. RA RC {1} (1, {a}, {}) {1} (1, {b}, {}) {} (1, {b}, {b}) {1} {1} (1, {a, b}, {b}) (1, {a, b}, {b}) add(1) add(1) remove(1) F(RC) {2} fun(X) -> 2 end {2} {} F(RA) {2} fun(X) -> 2 end {2} {2} {2} 29
30. COMPOSITION: USER OBSERVABLE VALUE VS. STATE METADATA MAPPING IS NONTRIVIAL WITHOUT MAPPING METADATA; UNMERGABLE 30 Brown, Russell, et al. "Riak dt map: A composable, convergent replicated dictionary." Proceedings of the First Workshop on Principles and Practice of Eventual Consistency. ACM, 2014. Conway, Neil, et al. "Logic and lattices for distributed programming." Proceedings of the Third ACM Symposium on Cloud Computing. ACM, 2012. Meiklejohn, Christopher. "On the composability of the Riak DT map: expanding from embedded to multi-key structures." Proceedings of the First Workshop on Principles and Practice of Eventual Consistency. ACM, 2014.
31. LASP LANGUAGE 31
32. LASP: DISTRIBUTED RUNTIME IMPLEMENTED AS ERLANG LIBRARY USES RIAK-CORE 32
33. LASP: CRDTS AS STREAMS OF STATE CHANGES CRDTS CONNECTED BY MONOTONIC PROCESSES MANY TO ONE MAPPING OF CRDTS 33
34. PRIMITIVE OPERATIONS: MONOTONIC READ, UPDATE FUNCTIONAL: MAP, FILTER, FOLD SET-THEORETIC: PRODUCT, UNION, INTERSECTION LIFTED TO OPERATE OVER METADATA 34
35. MAP EXAMPLE 35
36. RA RB RC {1} (1, {a}, {}) {1} (1, {b}, {}) {} (1, {b}, {b}) {1} {1} {1} (1, {a, b}, {b}) (1, {a, b}, {b}) (1, {a, b}, {b}) add(1) add(1) remove(1) F(RB) {2} fun(X) -> 2 end {2} {} (2, {b}, {}) (2, {b}, {b}) {} (2, {a, b}, {b}) (2, {a, b}, {b}) F(RC) {2} fun(X) -> 2 end (2, {a, b}, {b}) {2} {} {2} (2, {b}, {}) (2, {b}, {b}) (2, {a, b}, {b}) F(RA) {2} fun(X) -> 2 end (2, {a, b}, {b}) {2} {2} {2} (2, {a}, {}) (2, {a, b}, {}) (2, {a, b}, {b}) 36
37. RA RB RC {1} (1, {a}, {}) {1} (1, {b}, {}) {} (1, {b}, {b}) {1} {1} {1} (1, {a, b}, {b}) (1, {a, b}, {b}) (1, {a, b}, {b}) add(1) add(1) remove(1) F(RB) {2} fun(X) -> 2 end {2} {} (2, {b}, {}) (2, {b}, {b}) {} (2, {a, b}, {b}) (2, {a, b}, {b}) F(RC) {2} fun(X) -> 2 end (2, {a, b}, {b}) {2} {} {2} (2, {b}, {}) (2, {b}, {b}) (2, {a, b}, {b}) F(RA) {2} fun(X) -> 2 end (2, {a, b}, {b}) {2} {2} {2} (2, {a}, {}) (2, {a, b}, {}) (2, {a, b}, {b}) 37
38. RA RB RC {1} (1, {a}, {}) {1} (1, {b}, {}) {} (1, {b}, {b}) {1} {1} {1} (1, {a, b}, {b}) (1, {a, b}, {b}) (1, {a, b}, {b}) add(1) add(1) remove(1) F(RB) {2} fun(X) -> 2 end {2} {} (2, {b}, {}) (2, {b}, {b}) {} (2, {a, b}, {b}) (2, {a, b}, {b}) F(RC) {2} fun(X) -> 2 end (2, {a, b}, {b}) {2} {} {2} (2, {b}, {}) (2, {b}, {b}) (2, {a, b}, {b}) F(RA) {2} fun(X) -> 2 end (2, {a, b}, {b}) {2} {2} {2} (2, {a}, {}) (2, {a, b}, {}) (2, {a, b}, {b}) 38
39. RA RB RC {1} (1, {a}, {}) {1} (1, {b}, {}) {} (1, {b}, {b}) {1} {1} {1} (1, {a, b}, {b}) (1, {a, b}, {b}) (1, {a, b}, {b}) add(1) add(1) remove(1) F(RB) {2} fun(X) -> 2 end {2} {} (2, {b}, {}) (2, {b}, {b}) {} (2, {a, b}, {b}) (2, {a, b}, {b}) F(RC) {2} fun(X) -> 2 end (2, {a, b}, {b}) {2} {} {2} (2, {b}, {}) (2, {b}, {b}) (2, {a, b}, {b}) F(RA) {2} fun(X) -> 2 end (2, {a, b}, {b}) {2} {2} {2} (2, {a}, {}) (2, {a, b}, {}) (2, {a, b}, {b}) 39
40. AD COUNTER 40
41. AD COUNTER: TRACKS AD IMPRESSIONS PUSHES ADVERTISEMENTS TO THE CLIENT DISABLES AD AT 50,000+ IMPRESSIONS CLIENTS DISPLAY ADS WHEN OFFLINE 41
42. INFORMATION FLOW AD COUNTER 42
43. Ads Rovio Ad Counter Rovio Ad Counter Riot Ad Counter Riot Ad Counter Contracts Ads Contracts Ads With Contracts Riot Ads Rovio Ads Filter Product Read 50,000 Remove Increment Read Union Lasp Operation User-Maintained CRDT Lasp-Maintained CRDT Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 43
44. Ads Rovio Ad Counter Rovio Ad Counter Riot Ad Counter Riot Ad Counter Contracts Riot Ads Rovio Ads Produ Read 50,000 Remove Increment Union 44
45. Ads Rovio Ad Counter Rovio Ad Counter Riot Ad Counter Riot Ad Counter Contracts Ads Contracts Riot Ads Rovio Ads Filter Product Read 50,000 Remove Increment Union Lasp Operation User-Maintained CRDT Lasp-Maintained CRDT 45
46. Ads Contracts Ads Contracts Ads With Contracts ds Ads Filter Product Union Lasp Operation User-Maintained CRDT Lasp-Maintained CRDT 46
47. Ads ntracts Ads Contracts Ads With Contracts Filter Product Read Lasp Operation User-Maintained CRDT Lasp-Maintained CRDT 47
48. Ads Contracts Ads With Contracts Filter Read Operation Maintained CRDT Maintained CRDT Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 48
49. Ads Rovio Ad Counter Rovio Ad Counter Riot Ad Counter Riot Ad Counter Contracts Ads Contracts Ads With Contracts Riot Ads Rovio Ads Filter Product Read 50,000 Remove Increment Read Union Lasp Operation User-Maintained CRDT Lasp-Maintained CRDT Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 49
50. Ads Rovio Ad Counter Rovio Ad Counter Riot Ad Counter Riot Ad Counter Contracts Ads Contracts Riot Ads Rovio Ads Product Read 50,000 Remove Increment Union Lasp Operation User-Maintained C Lasp-Maintained C 50
51. Ads Contracts Ads Contracts Ads With Contracts Riot Ads Rovio Ads Filter Product Read 50,000 Remove Read Union Lasp Operation User-Maintained CRDT Lasp-Maintained CRDT Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 51
52. INFORMATION FLOW: MONOTONIC METADATA TO PREVENT DUPLICATE PROPAGATION 52
53. DISTRIBUTION AD COUNTER 53
54. Ads Rovio Ad Counter Rovio Ad Counter Riot Ad Counter Riot Ad Counter Contracts Ads Contracts Ads With Contracts Riot Ads Rovio Ads Filter Product Read 50,000 Remove Increment Read Union Lasp Operation User-Maintained CRDT Lasp-Maintained CRDT Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 54
55. Ads Rovio Ad Counter Rovio Ad Counter Riot Ad Counter Riot Ad Counter Contracts Ads Contracts Ads With Contracts Riot Ads Rovio Ads Filter Product Read 50,000 Remove Increment Read Union Lasp Operation User-Maintained CRDT Lasp-Maintained CRDT Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 55
56. Ads Rovio Ad Counter Rovio Ad Counter Riot Ad Counter Riot Ad Counter Contracts Ads Contracts Ads With Contracts Riot Ads Rovio Ads Filter Product Read 50,000 Remove Increment Read Union Lasp Operation User-Maintained CRDT Lasp-Maintained CRDT Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 56
57. Ads Rovio Ad Counter Rovio Ad Counter Riot Ad Counter Riot Ad Counter Contracts Ads Contracts Ads With Contracts Riot Ads Rovio Ads Filter Product Read 50,000 Remove Increment Read Union Lasp Operation User-Maintained CRDT Lasp-Maintained CRDT Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 Counter1 Counter2 Counter3 57
58. DISTRIBUTION BOUNDARIES: ARBITRARY ALLOWS COMPOSITION OF ENTIRE SYSTEM 58
59. RELATED WORK: DISTRIBUTED OZ DERFLOW, DERFLOW L, BLOOM L LVARS D-STREAMS, SUMMINGBIRD 59
60. FUTURE WORK: DELTA, OPERATION-BASED CRDTS RESERVATIONS, ESCROW ADDITIONAL CRDTS: ORSWOT, MAP 60
61. QUESTIONS? 61