///////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  Note:
//

using System;
using System.Collections;
using System.Threading;

namespace Microsoft.Singularity.Applications
{
    public class HeapTest
    {
        // GC threshold is around 8MB.
        private const  long TotalToAllocate    = 8L * 1024 * 1024 * 1024;
        private const  int LargeStringLength   = 1023;
        private const  int SmallStringLength   = 64;

        private static object!   monitor;
        private static int       threadCount = 0;
        private static AutoResetEvent! exitEvent;
        private static int       stringLength;
        private static int       allocationsPerThread = 0;

        private static void ThreadMain()
        {
            lock (HeapTest.monitor) {
                HeapTest.threadCount++;
            }

            for (int i = 0; i < HeapTest.allocationsPerThread; i++) {
                new String('a', HeapTest.stringLength);
            }

            lock (HeapTest.monitor) {
                HeapTest.threadCount--;
                if (HeapTest.threadCount == 0) {
                    HeapTest.exitEvent.Set();
                }
            }
        }

        private static void Test(int stringLength)
        {
            HeapTest.monitor     = new object();
            HeapTest.exitEvent   = new AutoResetEvent(false);
            HeapTest.threadCount = 0;
            HeapTest.stringLength = stringLength;
            HeapTest.allocationsPerThread = unchecked((int)(TotalToAllocate / (Settings.MaxThreads * stringLength)));

            for (int i = 0; i < Settings.MaxThreads; i++) {
                Thread t = new Thread(new ThreadStart(ThreadMain));
                t.Start();
            }
            HeapTest.exitEvent.WaitOne();
        }

        public static void TestLargeAllocs()
        {
            Test(LargeStringLength);
        }

        public static void TestSmallAllocs()
        {
            Test(SmallStringLength);
        }
    }
}