ants.core
Class NodeCache

java.lang.Object
  |
  +--ants.core.NodeCache

public class NodeCache

extends java.lang.Object

implements java.lang.Runnable

Node cache of managed soft-state.

Combines hashtable and doubly linked list to implement fixed size table with LRU replacement. all public entry points are synchronized. a background gc thread cleans entries that have expired.

XXX the background GC thread is probably unnecessary since this is only per-flow state. At the least, the background thread should be configurable by the flow (e.g., its collection parameters).

XXX should this class be final? Should more methods be marked final? (e.g., get)

This differs from the original version in that it does not have a maximum time limit or a maximum number of cached items, both of which are unneeded because of per-flow resource limits.

Author:

David Wetherall, Utah Janos Team

Inner Class Summary

static class

NodeCache.EventHandler Elements of this type in the node cache will receive calls when one of a set of events occurs.

Constructor Summary

NodeCache(Node owner, int size)
Construct a new NodeCache.

Method Summary

java.lang.Object	get(int i) Overloaded get method for integer keys.
java.lang.Object	get(long l) Overloaded get method for long keys.
java.lang.Object	get(java.lang.Object key) Return the value paired with a certain key
java.lang.Object	put(int i, java.lang.Object value, int time) Overloaded put method for integer keys.
java.lang.Object	put(long l, java.lang.Object value, int time) Overloaded put method for long keys.
java.lang.Object	put(java.lang.Object key, java.lang.Object value, int time) Add a key/value pair to the cache with a given expiration time.
boolean	refresh(java.lang.Object key, int time)
java.lang.Object	remove(java.lang.Object key) Remove an association from the cache.
void	run() Run forever, collecting expired objects.
java.lang.String	toString()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

NodeCache

public NodeCache(Node owner,
                 int size)

Construct a new NodeCache. Fires up the thread associated with this object.

XXX this probably shouldn't be public.

Parameters:

owner - The Node that owns this NodeCache instance

size - The size of the hash table

duration - Maximum allowable expiration time for an association

Method Detail

get

public final java.lang.Object get(java.lang.Object key)

Return the value paired with a certain key

Parameters:

key - The key to search for

Returns:

The value associated with the key

put

public final java.lang.Object put(java.lang.Object key,
                                  java.lang.Object value,
                                  int time)

Add a key/value pair to the cache with a given expiration time. If the key is already present in the cache then it will be replaced with the parameters and the old value returned.

Parameters:

key - The key for identifying the value

value - The value to be tracked

time - The expiration time for this association

Returns:

Old value from a prior association, if it existed

refresh

public boolean refresh(java.lang.Object key,
                       int time)

remove

public java.lang.Object remove(java.lang.Object key)

Remove an association from the cache.

Parameters:

key - Key for the association to remove

Returns:

The value from the association

get

public final java.lang.Object get(int i)

Overloaded get method for integer keys.

put

public final java.lang.Object put(int i,
                                  java.lang.Object value,
                                  int time)

Overloaded put method for integer keys.

get

public final java.lang.Object get(long l)

Overloaded get method for long keys.

put

public final java.lang.Object put(long l,
                                  java.lang.Object value,
                                  int time)

Overloaded put method for long keys.

run

public void run()

Run forever, collecting expired objects.

Specified by:

run in interface java.lang.Runnable

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object