com.yahoo.prelude.fastsearch

Class PacketCache

java.lang.Object

java.util.AbstractMap<K,V>

java.util.HashMap<K,V>

java.util.LinkedHashMap<CacheKey,PacketWrapper>

com.yahoo.prelude.fastsearch.PacketCache

All Implemented Interfaces:

Serializable, Cloneable, Map<CacheKey,PacketWrapper>

public class PacketCache
extends LinkedHashMap<CacheKey,PacketWrapper>

An LRU cache using number of hits cached inside the results as size limiting factor. Directly modelled after com.yahoo.collections.Cache.

Author:

Steinar Knutsen, bratseth

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.util.AbstractMap

AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>

Field Summary

Fields

Modifier and Type	Field and Description
private int	capacity The maximum number of bytes of packets in this cache
private static Logger	log
private long	maxAge The max age for a valid cache entry, 0 mean infinite
private int	maxCacheItemPercentage The max size of a cached item compared to the total size
private static long	serialVersionUID
private int	totalSize The current number of bytes of packets in this cache

Constructor Summary

Constructors

Constructor and Description
PacketCache(int capacityMegaBytes, int capacityBytes, double maxAge) Creates a cache with a size given by cachesizemegabytes*2^20+cachesizebytes

Method Summary

Modifier and Type	Method and Description
void	clear()
PacketWrapper	get(CacheKey key)
PacketWrapper	get(CacheKey key, long now)
int	getByteCapacity()
int	getCapacity()
PacketWrapper	put(CacheKey key, PacketWrapper value) Adds a PacketWrapper object to this cache, unless the size is more than maxCacheItemPercentage of the total size
PacketWrapper	put(CacheKey key, PacketWrapper result, long timestamp) Adds a BasicPacket array to this cache, unless the size is more than maxCacheItemPercentage of the total size
PacketWrapper	remove(CacheKey key)
protected boolean	removeEldestEntry(Map.Entry<CacheKey,PacketWrapper> eldest) Overrides LinkedHashMap.removeEldestEntry as suggested to implement LRU cache.
private void	removeOverflow()
void	setMaxCacheItemPercentage(int maxCapacityPercentage) Sets the max size of a cached item compared to the total size Cache requests for larger objects will be ignored
int	totalPacketSize()

Methods inherited from class java.util.LinkedHashMap

containsValue, entrySet, forEach, get, getOrDefault, keySet, replaceAll, values

Methods inherited from class java.util.HashMap

clone, compute, computeIfAbsent, computeIfPresent, containsKey, isEmpty, merge, putAll, putIfAbsent, remove, remove, replace, replace, size

Methods inherited from class java.util.AbstractMap

equals, hashCode, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, containsKey, equals, hashCode, isEmpty, merge, putAll, putIfAbsent, remove, remove, replace, replace, size

Field Detail

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

totalSize

private int totalSize

The current number of bytes of packets in this cache

capacity

private final int capacity

The maximum number of bytes of packets in this cache

maxCacheItemPercentage

private int maxCacheItemPercentage

The max size of a cached item compared to the total size

maxAge

private final long maxAge

The max age for a valid cache entry, 0 mean infinite

log

private static final Logger log

Constructor Detail

PacketCache

public PacketCache(int capacityMegaBytes,
                   int capacityBytes,
                   double maxAge)

Creates a cache with a size given by cachesizemegabytes*2^20+cachesizebytes

Parameters:

capacityMegaBytes - the cache size, measured in megabytes

capacityBytes - additional number of bytes to add to the cache size

maxAge - seconds a cache entry is valid, 0 or less are illegal arguments

Method Detail

clear

public void clear()

Specified by:

clear in interface Map<CacheKey,PacketWrapper>

Overrides:

clear in class LinkedHashMap<CacheKey,PacketWrapper>

setMaxCacheItemPercentage

public void setMaxCacheItemPercentage(int maxCapacityPercentage)

Sets the max size of a cached item compared to the total size Cache requests for larger objects will be ignored

removeEldestEntry

protected boolean removeEldestEntry(Map.Entry<CacheKey,PacketWrapper> eldest)

Overrides LinkedHashMap.removeEldestEntry as suggested to implement LRU cache.

Overrides:

removeEldestEntry in class LinkedHashMap<CacheKey,PacketWrapper>

removeOverflow

private void removeOverflow()

getCapacity

public int getCapacity()

getByteCapacity

public int getByteCapacity()

put

public PacketWrapper put(CacheKey key,
                         PacketWrapper value)

Adds a PacketWrapper object to this cache, unless the size is more than maxCacheItemPercentage of the total size

Specified by:

put in interface Map<CacheKey,PacketWrapper>

Overrides:

put in class HashMap<CacheKey,PacketWrapper>

put

public PacketWrapper put(CacheKey key,
                         PacketWrapper result,
                         long timestamp)

Adds a BasicPacket array to this cache, unless the size is more than maxCacheItemPercentage of the total size

Parameters:

timestamp - the timestamp for the first packet in the array, unit milliseconds

get

public PacketWrapper get(CacheKey key)

get

public PacketWrapper get(CacheKey key,
                         long now)

remove

public PacketWrapper remove(CacheKey key)

totalPacketSize

public int totalPacketSize()