/*
* Copyright (c) 2002-2009 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.kernel.impl.util;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Map.Entry;
public class ArrayMap<K,V>
{
private ArrayEntry<K,V>[] arrayEntries;
private volatile int arrayCount = 0;
private int toMapThreshold = 5;
private Map<K,V> propertyMap = null;
private final boolean useThreadSafeMap;
private boolean switchBackToArray = false;
public ArrayMap()
{
useThreadSafeMap = false;
arrayEntries = new ArrayEntry[toMapThreshold];
}
public ArrayMap( int mapThreshold, boolean threadSafe, boolean shrinkToArray )
{
this.toMapThreshold = mapThreshold;
this.useThreadSafeMap = threadSafe;
this.switchBackToArray = shrinkToArray;
arrayEntries = new ArrayEntry[toMapThreshold];
}
public void put( K key, V value )
{
if ( useThreadSafeMap )
{
synchronizedPut( key, value );
return;
}
for ( int i = 0; i < arrayCount; i++ )
{
if ( arrayEntries[i].getKey().equals( key ) )
{
arrayEntries[i].setNewValue( value );
return;
}
}
if ( arrayCount != -1 )
{
if ( arrayCount < arrayEntries.length )
{
arrayEntries[arrayCount++] = new ArrayEntry<K,V>( key, value );
}
else
{
propertyMap = new HashMap<K,V>( arrayEntries.length * 2 );
for ( int i = 0; i < arrayCount; i++ )
{
propertyMap.put( arrayEntries[i].getKey(), arrayEntries[i]
.getValue() );
}
arrayCount = -1;
propertyMap.put( key, value );
}
}
else
{
propertyMap.put( key, value );
}
}
private synchronized void synchronizedPut( K key, V value )
{
for ( int i = 0; i < arrayCount; i++ )
{
if ( arrayEntries[i].getKey().equals( key ) )
{
arrayEntries[i].setNewValue( value );
return;
}
}
if ( arrayCount != -1 )
{
if ( arrayCount < arrayEntries.length )
{
arrayEntries[arrayCount++] = new ArrayEntry<K,V>( key, value );
}
else
{
propertyMap = new HashMap<K,V>( arrayEntries.length * 2 );
for ( int i = 0; i < arrayCount; i++ )
{
propertyMap.put( arrayEntries[i].getKey(), arrayEntries[i]
.getValue() );
}
arrayEntries = null;
arrayCount = -1;
propertyMap.put( key, value );
}
}
else
{
propertyMap.put( key, value );
}
}
public V get( K key )
{
if ( key == null )
{
return null;
}
if ( useThreadSafeMap )
{
return synchronizedGet( key );
}
int count = arrayCount;
for ( int i = 0; i < count; i++ )
{
if ( key.equals( arrayEntries[i].getKey() ) )
{
return arrayEntries[i].getValue();
}
}
if ( arrayCount == -1 )
{
return propertyMap.get( key );
}
return null;
}
private synchronized V synchronizedGet( K key )
{
for ( int i = 0; i < arrayCount; i++ )
{
if ( key.equals( arrayEntries[i].getKey() ) )
{
return arrayEntries[i].getValue();
}
}
if ( arrayCount == -1 )
{
return propertyMap.get( key );
}
return null;
}
private synchronized V synchronizedRemove( K key )
{
for ( int i = 0; i < arrayCount; i++ )
{
if ( arrayEntries[i].getKey().equals( key ) )
{
V removedProperty = arrayEntries[i].getValue();
arrayCount--;
System.arraycopy( arrayEntries, i + 1, arrayEntries, i,
arrayCount - i );
return removedProperty;
}
}
if ( arrayCount == -1 )
{
V value = propertyMap.remove( key );
if ( switchBackToArray && propertyMap.size() < toMapThreshold )
{
arrayEntries = new ArrayEntry[toMapThreshold];
int tmpCount = 0;
for ( Entry<K,V> entry : propertyMap.entrySet() )
{
arrayEntries[tmpCount++] = new ArrayEntry<K,V>( entry
.getKey(), entry.getValue() );
}
arrayCount = tmpCount;
}
return value;
}
return null;
}
public V remove( K key )
{
if ( useThreadSafeMap )
{
return synchronizedRemove( key );
}
for ( int i = 0; i < arrayCount; i++ )
{
if ( arrayEntries[i].getKey().equals( key ) )
{
V removedProperty = arrayEntries[i].getValue();
arrayCount--;
System.arraycopy( arrayEntries, i + 1, arrayEntries, i,
arrayCount - i );
return removedProperty;
}
}
if ( arrayCount == -1 )
{
V value = propertyMap.remove( key );
if ( switchBackToArray && propertyMap.size() < toMapThreshold )
{
arrayEntries = new ArrayEntry[toMapThreshold];
int tmpCount = 0;
for ( Entry<K,V> entry : propertyMap.entrySet() )
{
arrayEntries[tmpCount++] = new ArrayEntry<K,V>( entry
.getKey(), entry.getValue() );
}
arrayCount = tmpCount;
}
return value;
}
return null;
}
static class ArrayEntry<K,V> implements Entry<K,V>
{
private K key;
private V value;
ArrayEntry( K key, V value )
{
this.key = key;
this.value = value;
}
public K getKey()
{
return key;
}
public V getValue()
{
return value;
}
void setNewValue( V value )
{
this.value = value;
}
public V setValue( V value )
{
V oldValue = value;
this.value = value;
return oldValue;
}
}
public Iterable<K> keySet()
{
if ( arrayCount == -1 )
{
return propertyMap.keySet();
}
List<K> keys = new LinkedList<K>();
for ( int i = 0; i < arrayCount; i++ )
{
keys.add( arrayEntries[i].getKey() );
}
return keys;
}
public Iterable<V> values()
{
if ( arrayCount == -1 )
{
return propertyMap.values();
}
List<V> values = new LinkedList<V>();
for ( int i = 0; i < arrayCount; i++ )
{
values.add( arrayEntries[i].getValue() );
}
return values;
}
public Set<Entry<K,V>> entrySet()
{
if ( arrayCount == -1 )
{
return propertyMap.entrySet();
}
Set<Entry<K,V>> entries = new HashSet<Entry<K,V>>();
for ( int i = 0; i < arrayCount; i++ )
{
entries.add( arrayEntries[i] );
}
return entries;
}
public int size()
{
if ( arrayCount != -1 )
{
return arrayCount;
}
return propertyMap.size();
}
public void clear()
{
if ( arrayCount != -1 )
{
arrayCount = 0;
}
else
{
propertyMap.clear();
}
}
}