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// **********************************************************************
//
// Copyright (c) 2004
// ZeroC, Inc.
// Billerica, MA, USA
//
// All Rights Reserved.
//
// Ice is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License version 2 as published by
// the Free Software Foundation.
//
// **********************************************************************
package IceUtil;
//
// An abstraction to efficiently populate a Cache, without holding
// a lock while loading from a database.
//
// TODO: implement efficiently!
//
public class Cache
{
public Cache(Store store)
{
_store = store;
}
public Object
getIfPinned(Object key)
{
synchronized(_map)
{
return _map.get(key);
}
}
public Object
pin(Object key)
{
synchronized(_map)
{
Object o = _map.get(key);
if(o == null)
{
o = _store.load(key);
if(o != null)
{
_map.put(key, o);
}
}
return o;
}
}
public Object
unpin(Object key)
{
synchronized(_map)
{
return _map.remove(key);
}
}
public void
clear()
{
synchronized(_map)
{
_map.clear();
}
}
public int
size()
{
synchronized(_map)
{
return _map.size();
}
}
public Object
add(Object key, Object value)
{
assert value != null;
synchronized(_map)
{
Object existingVal = _map.put(key, value);
if(existingVal != null)
{
_map.put(key, existingVal);
return existingVal;
}
//
// Let's check if it's in the store
//
existingVal = _store.load(key);
if(existingVal != null)
{
_map.put(key, existingVal);
return existingVal;
}
else
{
return null;
}
}
}
public Object
pin(Object key, Object value)
{
synchronized(_map)
{
Object existingVal = _map.put(key, value);
if(existingVal != null)
{
_map.put(key, existingVal);
}
return existingVal;
}
}
private final java.util.Map _map = new java.util.HashMap();
private final Store _store;
}
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