console-proxy/src/com/cloud/consoleproxy/AjaxFIFOImageCache.java

// Copyright 2012 Citrix Systems, Inc. Licensed under the
// Apache License, Version 2.0 (the "License"); you may not use this
// file except in compliance with the License.  Citrix Systems, Inc.
// reserves all rights not expressly granted by the License.
// You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// 
// Automatically generated by addcopyright.py at 04/03/2012
package com.cloud.consoleproxy;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.cloud.consoleproxy.util.Logger;

public class AjaxFIFOImageCache {
	private static final Logger s_logger = Logger.getLogger(AjaxFIFOImageCache.class);
	
	private List<Integer> fifoQueue;
	private Map<Integer, byte[]> cache;
	private int cacheSize;
	private int nextKey = 1;
	
	public AjaxFIFOImageCache(int cacheSize) {
		this.cacheSize = cacheSize;
		fifoQueue = new ArrayList<Integer>();
		cache = new HashMap<Integer, byte[]>();
	}
	
	public synchronized void clear() {
		fifoQueue.clear();
		cache.clear();
	}
	
	public synchronized int putImage(byte[] image) {
		while(cache.size() >= cacheSize) {
			Integer keyToRemove = fifoQueue.remove(0);
			cache.remove(keyToRemove);
			
			if(s_logger.isTraceEnabled())
				s_logger.trace("Remove image from cache, key: " + keyToRemove);
		}
		
		int key = getNextKey();
		
		if(s_logger.isTraceEnabled())
			s_logger.trace("Add image to cache, key: " + key);
		
		cache.put(key, image);
		fifoQueue.add(key);
		return key;
	}
	
	public synchronized byte[] getImage(int key) {
		if(cache.containsKey(key)) {
			if(s_logger.isTraceEnabled())
				s_logger.trace("Retrieve image from cache, key: " + key);
			
			return cache.get(key);
		}
		
		if(s_logger.isTraceEnabled())
			s_logger.trace("Image is no long in cache, key: " + key);
		return null;
	}
	
	public synchronized int getNextKey() {
		return nextKey++;
	}
}