Package com.github.benmanes.caffeine.cache.simulator.policy.irr

Class ClockProPolicy

java.lang.Object

com.github.benmanes.caffeine.cache.simulator.policy.irr.ClockProPolicy

All Implemented Interfaces:

Policy, Policy.KeyOnlyPolicy

public final class ClockProPolicy
extends Object
implements Policy.KeyOnlyPolicy

The ClockPro algorithm. This algorithm differs from LIRS by replacing the LRU stacks with Clock (Second Chance) policy. This allows cache hits to be performed concurrently at the cost of a global lock on a miss and has the worst case time of O(n) on eviction due to queues being scanned.

ClockPro uses three hands that scan the queue. The hot hand points to the largest recency, the cold hand to the cold entry furthest from the hot hand, and the test hand to the last cold entry in the test period. This policy is adaptive by adjusting the percentage of hot and cold entries that may reside in the cache. It uses non-resident (ghost) entries to retain additional history, which are removed during the test hand's scan. The algorithm is explained by the authors in CLOCK-Pro: An Effective Improvement of the CLOCK Replacement and Clock-Pro: An Effective Replacement in OS Kernel.

Nested Class Summary

Nested classes/interfaces inherited from interface com.github.benmanes.caffeine.cache.simulator.policy.Policy

Policy.Characteristic, Policy.KeyOnlyPolicy, Policy.PolicySpec

Constructor Summary

Constructors

Constructor	Description
ClockProPolicy(Config config)

Method Summary

Modifier and Type	Method	Description
void	finished()	Indicates that the recording has completed.
void	record(long key)
PolicyStats	stats()	Returns the cache efficiency statistics.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.github.benmanes.caffeine.cache.simulator.policy.Policy

name

Methods inherited from interface com.github.benmanes.caffeine.cache.simulator.policy.Policy.KeyOnlyPolicy

record

Constructor Detail

ClockProPolicy

public ClockProPolicy(Config config)

Method Detail

stats

public PolicyStats stats()

Description copied from interface: Policy

Returns the cache efficiency statistics.

Specified by:

stats in interface Policy

finished

public void finished()

Description copied from interface: Policy

Indicates that the recording has completed.

Specified by:

finished in interface Policy

record

public void record(long key)

Specified by:

record in interface Policy.KeyOnlyPolicy