First step of “Chord”

First step of “Chord”

Transcript

1. First step of “Chord” 2016-09-23 ࣾ಺ษڧձ @kakakakakku
2. Cloud Computing Concepts, Part 1 by
3. ࠷ۙ Coursera Ͱ ཤमͯ͠ΔߨٛͰֶΜͩ “Chord” ΛβοΫϦͱ঺հ͠·͢
4. What is “Chord” ?
6. (
   ƅшƅ) ŴƅŜŖƃ ?
7. εέʔϥϏϦςΟͷ͋Δ P2P ୳ࡧΞϧΰϦζϜʢҙ༁ʣ → ൃද͸2001೥
8. [Related Algorithms] Tapestry Pastry Kademlia ʘ ࠓ೔͸঺հ͠ͳ͍͚Ͳଞʹ΋͋Δ ʗ
9. [Related Implementation] Cassandra Dynamo Riak Voldemort ʘ ϛυϧ΢ΣΞΛΠϝʔδ͢Δͱ਌ۙײ༙͘ ʗ
10. ʘ Dynamo ͷ࿦จ΋·ͨผͷػձʹ঺հ͠·͢ ʗ
11. P2P Λ෼ྨ͢Δͱ...
12. Unstructured Overlay Structured Overlay Chord Napster / Gnutella
13. Goal of “Chord”
14. େྔͷΩʔΛͲ͏෼ࢄͤ͞Δ ? େྔͷΩʔΛͲ͏ޮ཰తʹ୳ࡧͤ͞Δ ? ϊʔυͷ૿ݮʹͲ͏ରԠ͢Δ ?
15. “Chord” = Consistent Hashing + Finger Table
16. (
    ƅшƅ) Űō?
17. Consistent Hashing ղઆ
19. ҰݴͰද͢ͱ Ωʔͷ࠶഑ஔͷӨڹΛ࡟ݮͨ͠ ޮ཰తͳϋογϡ๏ʢҙ༁ʣ
20. Bad Example ʘ ࠷ॳʹμϝͳྫΛݟͯΈ·͠ΐ͏ ʗ
21. 3 Nodes 4 Keys ΩϨΠʹ ෼ࢄͨ͠ ??? ୯७ʹ mod ͰΩʔΛϊʔυʹ഑ஔ͢Δͱ...
22. ΋͠1୆ ނোͨ͠৔߹ ΦϨϯδҎ֎ શͯͷΩʔΛ࠶഑ஔ ͢Δඞཁ͕͋Δ
23. Consistent Hashing ొ৔
24. ϊʔυͱΩʔΛϋογϡԽͯ͠ Ծ૝Ϧϯά্ʹ഑ஔ͢Δ ※Ծ૝ͷҙຯ͸ࠓճ͸ׂѪ͠·͢...
25. ֤Ωʔ͔Βݟͯ ࣌ܭճΓʹ1൪ۙ઀ͨ͠ϊʔυʹ ΩʔΛ഑ஔ͢Δͱ͍͏ߟ͑ํ ʢͦͷϊʔυ͸ Successor ͱݺͿʣ
26. Ϧϯάۭؒ ഑ஔ ഑ஔ ഑ஔ
27. Ϧϯάۭؒ ނোͰ࠶഑ஔ͕ඞཁͳΩʔ਺͸ ʹ࡟ݮ͞ΕΔ ഑ஔ ࠶഑ஔ ഑ஔ
28. Αͬͯ ϊʔυ௥Ճʗނোʢҙਤతͳݮগ΋ʣ ʹରͯ͠ ہॴతͳӨڹʹ཈͑ΒΕΔ
29. Finger Table ղઆ
30. Chord ͷಛ௃తͳ࢓૊Έ ! ҰݴͰද͢ͱγϣʔτΧοτతͳ ?
31. Bad Example ʘ ࠷ॳʹμϝͳྫΛݟͯΈ·͠ΐ͏ ʗ
32. ୳ࡧ͢Δͱ͖ʹ key ͕͋Δ ୳ࡧΛϦΫΤετ ͢Δϊʔυ
33. ϊʔυΛॱ൪ʹḷͬͯ͠·͏ͱ ઢܗ୳ࡧʹͳͬͯ͠·͏… ʘ Oh, No! ʗ
34. Finger Table ొ৔
35. ೚ҙͷϊʔυʹରͯ͠ ࢦ਺ؔ਺తʹ୳ࡧՄೳͳ ϩέʔγϣϯʢҙ༁ʣΛఆΊͯ ଟஈ֊ʹ୳ࡧͤ͞Δ
36. ͜ͷྫͩͱ m=3 ͰޮՌ͕ແͦ͞͏ʹݟ͑Δ͚Ͳ... Finger Table
37. ઢܗ୳ࡧΛճආͰ͖ΔͨΊ ۭؒͷεέʔϦϯάʹରͯ͠ ୳ࡧ࣌ؒ͸େ͖͘ࠨӈ͞Εͳ͘ͳΔ ʘ Good! ʗ
38. “Chord” = Consistent Hashing + Finger Table ʘ βοΫϦͱཧղͯ͠΋Β͑ͨ ? ʗ
39. ࣮ࡍͷ “Chord” Ͱ͸ ϊʔυΛ SHA-1(ip, port) Ͱ഑ஔͯ͠ ΩʔΛ SHA-1(key) Ͱ഑ஔ͢Δ ※SHA-1 ͳΒ 160 bit ͷۭؒͰදݱͰ͖Δ
40. ·ͱΊ
41. ೔ʑ࢖ͬͯΔٕज़͸ ੈքதͷεΰΠਓ͕ͨͪߟ͑ͨ ΞϧΰϦζϜʹࢧ͑ΒΕ͍ͯΔʂ
42. ٕज़Λͨͩ࢖͏͚ͩͰ͸ͳ͘ ཁૉٕज़Λཧղ͢Δ͜ͱ΋ॏཁʂ
43. To be continued …