Package me.ahoo.cosid.machine.lease

Class Lease

java.lang.Object

me.ahoo.cosid.machine.lease.Lease

@Immutable
public final class Lease
extends Object

A machine id held by an instance, as stored by a MachineLeaseStore.

A lease keeps three separate values:

• watermark: the last timestamp the machine id may have been used for, which the next owner must not go back to (its clock-backwards watermark). It never decreases, and renewing does not move it.
• renewed at: the store time of the last claim or renewal, which decides expiry.
• version: an opaque token that changes on every write. MachineLeaseStore.renew(me.ahoo.cosid.machine.lease.Lease, long) and MachineLeaseStore.release(me.ahoo.cosid.machine.lease.Lease, long) only succeed with the current version, so an owner whose lease was taken over in between finds out instead of overwriting the new owner.

Since:

3.4.0

Constructor Summary

Constructors

Constructor	Description
Lease(String namespace, InstanceId instanceId, int machineId, long watermark, long renewedAt, long version)	Create a lease.

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object o)
InstanceId	getInstanceId()
int	getMachineId()
String	getNamespace()
long	getRenewedAt()	The store time of the last claim or renewal: the lease expires a safe-guard duration after it.
long	getVersion()
long	getWatermark()	The last timestamp the machine id may have been used for: the owner waits until its clock passes it.
int	hashCode()
boolean	isStable()
MachineState	toMachineState()
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

Lease

public Lease(String namespace,
 InstanceId instanceId,
 int machineId,
 long watermark,
 long renewedAt,
 long version)

Create a lease.

Parameters:

watermark - the last timestamp the machine id may have been used for

renewedAt - the store time of the last claim or renewal

version - the token that changes on every write

Method Details

getNamespace

public String getNamespace()

getInstanceId

public InstanceId getInstanceId()

isStable

public boolean isStable()

getMachineId

public int getMachineId()

getWatermark

public long getWatermark()

The last timestamp the machine id may have been used for: the owner waits until its clock passes it.

getRenewedAt

public long getRenewedAt()

The store time of the last claim or renewal: the lease expires a safe-guard duration after it.

getVersion

public long getVersion()

toMachineState

public MachineState toMachineState()

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object