cmpp3submitmmf.java

java的共享内存管理.基于MMF设计。封装了java.nio.MappedByteBuffer.在大流量实时业务系统时

/*
 * @(#)CMPP3SubmitMap.java	1.00 2007-12-6
 *
 * Copyright 2007 BCINFO. All Rights Reserved.
 */
package com.bci.commons.mmf.example;

import org.apache.log4j.Logger;

import com.bci.commons.mmf.AbstractMMF;
import com.bci.commons.mmf.MemoryMapException;
import com.bci.commons.mmf.MemoryNotMappedException;
import com.bci.commons.mmf.MemoryReadException;

import java.util.TreeSet;
import java.util.concurrent.LinkedBlockingQueue;

/**
 * CMPP 3.0提交消息的缓存
 * 
 * @author xuym
 * @version 1.00, 2007-12-6
 * @since 1.5
 */
public class CMPP3SubmitMMF extends AbstractMMF {
	/**
	 * Logger for this class
	 */
	private static final Logger logger = Logger.getLogger(CMPP3SubmitMMF.class);

	/**
	 * the map file's max length of data cell.
	 */
	private int cellCount = 0;

	public CMPP3SubmitMMF() {
		super();
	}

	public CMPP3SubmitMMF(String file, int _count) {
		super();
		load(file, _count);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see com.bci.commons.mmf.AbstractMMF#load(String, int)
	 */
	@Override
	public void load(String file, int _count) throws MemoryMapException,
			MemoryNotMappedException, MemoryReadException {
		cellCount = _count;
		super.load(file, cellCount * CMPP3Cell.CELL_LENGTH);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see com.bci.commons.mmf.AbstractMMF#initialize()
	 */
	@Override
	public void initialize() throws MemoryNotMappedException,
			MemoryReadException {
		logger.debug("initializing the cmpp3 submit map...");
		setCellLength(CMPP3Cell.CELL_LENGTH);
		freeList = new LinkedBlockingQueue<Integer>();
		usedList = new TreeSet<Integer>();
		int pos = 0;
		for (int i = 0; i < cellCount; i++) {
			pos = i * CMPP3Cell.CELL_LENGTH;
			byte b = readByte(pos);
			if (b == 0) {
				freeList.offer(pos);
			} else {
				usedList.add(pos);
			}
		}
		logger.debug("this map has " + freeList.size() + " nodes.");
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see com.bci.commons.mmf.AbstractMMF#read(int)
	 */
	@Override
	public CMPP3Cell read(int desPos) throws MemoryMapException,
			MemoryReadException {
		try {
			byte[] buf = readBytes(desPos, CMPP3Cell.CELL_LENGTH);
			CMPP3Cell sSubmit = new CMPP3Cell(buf);
			sSubmit.setPosition(desPos);
			return sSubmit;
		} catch (Exception e) {
			throw new MemoryReadException(e);
		}
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see com.bci.commons.mmf.AbstractMMF#read(int)
	 */
	@Override
	public CMPP3Cell dumpAndReset(int pos) {
		CMPP3Cell cell = this.read(pos);
		this.write(pos, new byte[CMPP3Cell.CELL_LENGTH]);
		return cell;
	}

	public int getCellCount() {
		return cellCount;
	}
}