/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  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.
 */
/** 
 * @author Salikh Zakirov, Vera Volynets
 */ 

package perf;

import java.util.ArrayList;

/**
 * This is a programm that generates many threads 
 * that allocate small objects. The purpose of this benchmark is to stress
 * module responsible for thread suspension. Threads should be suspended before gc starts its work.
 * That is the reason of long delays.
 */
public class MultiThreadsSimple extends Thread {

    final static int chunk_size = 512;                 // allocation unit
    final static long megabyte = 1048576;               

    // total bytes to allocate
    static long total_allocate = 400 * megabyte;  
    // live set
    static long live_size = 40 * megabyte;        

    static int thread_count = 200;
    static long thread_allocate = total_allocate / thread_count;
    static long thread_live = live_size / thread_count;

    static boolean started = false;

    public static void main (String[] args) {
      	long itime=System.currentTimeMillis();
        Thread[] threads = new Thread[thread_count];
        for (int i = 0; i < thread_count; i++) {
            threads[i] = new MultiThreadsSimple();
            threads[i].start();
        }
        synchronized (MultiThreadsSimple.class) {
            MultiThreadsSimple.class.notifyAll();
            started = true;
            System.err.println(); System.err.flush();
        }
        for (int i = 0; i < thread_count; i++) {
            try {
                threads[i].join();
                System.err.print(","); System.err.flush();
            } catch (InterruptedException e) {}
        }
        System.err.println(); System.err.flush();
	System.out.println("The test run: "+(System.currentTimeMillis()-itime)+" ms\n");
        System.out.println("PASSED");
	
    }


    public void run () {
        System.err.print("."); System.err.flush();
        synchronized (this.getClass()) {
            if (!started)
                try {
                    this.getClass().wait();
                } catch (InterruptedException e) {}
        }
        long count = thread_allocate / chunk_size;
        /* maintain live set in [live_size/2 , live_size] */
        long reset = thread_live / chunk_size / 2;
        ArrayList list = new ArrayList();
        ArrayList old = new ArrayList();
        for (long i = 0; i < count; i++) {
            list.add(allocate(chunk_size));
            if (i % reset == 0) {
                old = list;
                list = new ArrayList();
                old.add(list);
            }
        }
    }

    public Object allocate (int size) {
        final int breadth = 10;
	try {
            exception(size);
       } catch (NullPointerException e) {}
       	if (size > chunk_size) {
            ArrayList list = new ArrayList(breadth);
                for (int i=0; i<breadth; i++) {
                list.add(allocate((size-breadth*4-28) / breadth));
            }
            return list;
        } else {
            return new byte[size];
        }
    }

    /* trying to pseudo-randomize null pointer exception sites. */
    public void exception (int i) {
    
        if (i%17 == 0) {
            String s = null;
 	    s.length();
	} else if (i%11 == 0) {
            exception(i/31);
        } else {
            exception(i/2);
        }
    }
 }