51a62a559c
* Added doc for leases and the lease lifecycle. * Documentation: addressed comments for leases. + minor code cleanup * Documentation: language review. + decomposed shard sync UML into two separate diagrams (initialization, loop) * Documentation: language review touch-ups.
33 lines
No EOL
844 B
Text
33 lines
No EOL
844 B
Text
@startuml
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'https://plantuml.com/sequence-diagram
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autonumber
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title KCL Lease Taking
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participant LeaseCoordinator as LC
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participant LeaseTaker as LT
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participant LeaseRefresher as LR
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participant "Lease Table\n(DynamoDB)" as DDB
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loop every 2*(leaseDurationMillis + epsilonMillis)
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LC->LT: takeLeases()
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LT->LT: updateAllLeases()
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LT->LR: listLeases()
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LR->DDB: scan(:streamName=streamName)
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DDB->LR: leases from table
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LR->LT: leases from table
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LT->LT: evict from memory any lease not returned from table
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LT->LT: getExpiredLeases()
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note over LT
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Leases are "expired" if their last scan time exceeds the max lease duration.
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end note
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LT->LT: calculate lease count per host
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LT->LT: chooseLeasesToSteal()
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loop for each lease to take/steal
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LT->LR: takeLease(lease, worker)
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LR->DDB: updateItem(lease)
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end
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end
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@enduml |