org.glassfish.hk2.utilities.general

Interface WeakHashClock<K,V>

All Known Implementing Classes:

WeakHashClockImpl

public interface WeakHashClock<K,V>

This is a clock (if non-empty the next verb will always return a new value in a cycle) that can also get values in O(1) complexity. This HashClock also has Weak key references, so if the key becomes unavailable it will not be retrievable from the get operation and the next operation will remove it from the clock

Author:

jwells

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Sets the clock size back to zero, no entries
void	clearStaleReferences() Causes stale references to be cleared from the data structures.
V	get(K key) Gets the given key, returning null if not found
boolean	hasWeakKeys() Tells if this WeakHashClock has Weak keys
Map.Entry<K,V>	next() Returns the next key/value pair in the clock, or null if the clock has no members.
void	put(K key, V value) Adds the given pair to the clock.
void	releaseMatching(CacheKeyFilter<K> filter) Releases all key/value pairs that match the filter
V	remove(K key) Removes the given key from the clock, if found
int	size() Returns the number of elements currently in the clock.

Method Detail

put

void put(K key,
       V value)

Adds the given pair to the clock. It will be placed at the current tail of the clock

Parameters:

key - Must not be null

value - May not be null

get

V get(K key)

Gets the given key, returning null if not found

Parameters:

key - The key to search for, may not be null

Returns:

The value found, or null if not found

remove

V remove(K key)

Removes the given key from the clock, if found

Parameters:

key - The key to remove, may not be null

Returns:

The value removed if found, or null if not found

releaseMatching

void releaseMatching(CacheKeyFilter<K> filter)

Releases all key/value pairs that match the filter

Parameters:

filter - A non-null filter that can be used to delete every key/value pair that matches the filter

size

int size()

Returns the number of elements currently in the clock. References that have gone away because they were weakly referenced will not be counted in the size

Returns:

The number of entries currently in the clock

next

Map.Entry<K,V> next()

Returns the next key/value pair in the clock, or null if the clock has no members. This will advance the head and tail of the clock to the next element. If the WeakReference for the returned element is null then this element will also have been removed from the clock by this operation

Returns:

The next key/value pair in the

clear

void clear()

Sets the clock size back to zero, no entries

clearStaleReferences

void clearStaleReferences()

Causes stale references to be cleared from the data structures. Since this is a weak clock the references can go away at any time, which happens whenever any operation has been performed. However, it may be the case that no operation will be performed for a while and so this method is provided to have a no-op operation to call in order to clear out any stale references

hasWeakKeys

boolean hasWeakKeys()

Tells if this WeakHashClock has Weak keys

Returns:

true if this map has weak keys, true otherwise