Package org.postgresql.util

Class LruCache<Key,Value extends CanEstimateSize>

java.lang.Object

org.postgresql.util.LruCache<Key,Value>

All Implemented Interfaces:

Gettable<Key,Value>

public class LruCache<Key,Value extends CanEstimateSize>
extends java.lang.Object
implements Gettable<Key,Value>

Caches values in simple least-recently-accessed order.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	LruCache.CreateAction<Key,Value>	When the entry is not present in cache, this create action is used to create one.
static interface	LruCache.EvictAction<Value>	Action that is invoked when the entry is removed from the cache.
private class	LruCache.LimitedMap

Field Summary

Fields

Modifier and Type	Field	Description
private java.util.Map<Key,Value>	cache
private LruCache.CreateAction<Key,Value>	createAction
private long	currentSize
private ResourceLock	lock
private long	maxSizeBytes
private int	maxSizeEntries
private LruCache.EvictAction<Value>	onEvict

Constructor Summary

Constructors

Constructor	Description
LruCache(int maxSizeEntries, long maxSizeBytes, boolean accessOrder)
LruCache(int maxSizeEntries, long maxSizeBytes, boolean accessOrder, LruCache.CreateAction<Key,Value> createAction, LruCache.EvictAction<Value> onEvict)

Method Summary

Modifier and Type	Method	Description
Value	borrow(Key key)	Borrows an entry from the cache.
private void	evictValue(Value value)
Value	get(Key key)	Returns an entry from the cache.
void	put(Key key, Value value)	Returns given value to the cache.
void	putAll(java.util.Map<Key,Value> m)	Puts all the values from the given map into the cache.

Methods inherited from class java.lang.Object

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

Field Detail

onEvict

private final LruCache.EvictAction<Value extends CanEstimateSize> onEvict

createAction

private final LruCache.CreateAction<Key,Value extends CanEstimateSize> createAction

maxSizeEntries

private final int maxSizeEntries

maxSizeBytes

private final long maxSizeBytes

currentSize

private long currentSize

cache

private final java.util.Map<Key,Value extends CanEstimateSize> cache

lock

private final ResourceLock lock

Constructor Detail

LruCache

public LruCache(int maxSizeEntries,
                long maxSizeBytes,
                boolean accessOrder)

LruCache

public LruCache(int maxSizeEntries,
                long maxSizeBytes,
                boolean accessOrder,
                LruCache.CreateAction<Key,Value> createAction,
                LruCache.EvictAction<Value> onEvict)

Method Detail

evictValue

private void evictValue(Value value)

get

public Value get(Key key)

Returns an entry from the cache.

Specified by:

get in interface Gettable<Key,Value extends CanEstimateSize>

Parameters:

key - cache key

Returns:

entry from cache or null if cache does not contain given key.

borrow

public Value borrow(Key key)
             throws java.sql.SQLException

Borrows an entry from the cache.

Parameters:

key - cache key

Returns:

entry from cache or newly created entry if cache does not contain given key.

Throws:

java.sql.SQLException - if entry creation fails

put

public void put(Key key,
                Value value)

Returns given value to the cache.

Parameters:

key - key

value - value

putAll

public void putAll(java.util.Map<Key,Value> m)

Puts all the values from the given map into the cache.

Parameters:

m - The map containing entries to put into the cache