com.amazonaws.services.kinesis.leases.impl

Class LeaseTaker<T extends Lease>

java.lang.Object

com.amazonaws.services.kinesis.leases.impl.LeaseTaker<T>

All Implemented Interfaces:

ILeaseTaker<T>

public class LeaseTaker<T extends Lease>
extends java.lang.Object
implements ILeaseTaker<T>

An implementation of ILeaseTaker that uses DynamoDB via LeaseManager.

Constructor Summary

Constructors

Constructor and Description
LeaseTaker(ILeaseManager<T> leaseManager, java.lang.String workerIdentifier, long leaseDurationMillis)

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.String	getWorkerIdentifier()
java.util.Map<java.lang.String,T>	takeLeases() Compute the set of leases available to be taken and attempt to take them.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LeaseTaker

public LeaseTaker(ILeaseManager<T> leaseManager,
          java.lang.String workerIdentifier,
          long leaseDurationMillis)

Method Detail

takeLeases

public java.util.Map<java.lang.String,T> takeLeases()
                                                           throws DependencyException,
                                                                  InvalidStateException

Compute the set of leases available to be taken and attempt to take them. Lease taking rules are: 1) If a lease's counter hasn't changed in long enough, try to take it. 2) If we see a lease we've never seen before, take it only if owner == null. If it's owned, odds are the owner is holding it. We can't tell until we see it more than once. 3) For load balancing purposes, you may violate rules 1 and 2 for EXACTLY ONE lease per call of takeLeases().

Specified by:

takeLeases in interface ILeaseTaker<T extends Lease>

Returns:

map of shardId to Lease object for leases we just successfully took.

Throws:

DependencyException - on unexpected DynamoDB failures

InvalidStateException - if lease table does not exist

getWorkerIdentifier

public java.lang.String getWorkerIdentifier()

Specified by:

getWorkerIdentifier in interface ILeaseTaker<T extends Lease>

Returns:

workerIdentifier for this LeaseTaker