/////////////////////////////////////////////////////////////////////
// FileLock.cs - Handle concurrent accesses to the same file       //
//                                                                 //
// Jim Fawcett, CSE681 - Software Modeling & Analysis, Summer 2003 //
/////////////////////////////////////////////////////////////////////

using System;
using System.IO;
using System.Threading;

namespace FileLocks
{
	class FileWriter
	{
      string Title(string s)
      {
        int len = s.Length;
        string underline = new string('=',len+2);
        string temp = "\n  " + s + "\n" + underline;
        return temp;
      }
      int CopyFile(string inFile, string outFile)
      {
         string writePath = Path.GetFullPath("../../..");
         writePath += "/" + outFile;
         string readPath = Path.GetFullPath("../../..");
         readPath += "/" + inFile;

         int fileSize = 0;
         try
         {
            FileStream fsr = File.Open(readPath,FileMode.Open,FileAccess.Read,FileShare.Read);
            try
            {
               FileStream fsw = File.Open(writePath,FileMode.OpenOrCreate,FileAccess.Write,FileShare.None);
               const int size = 1024;
               byte[] block = new Byte[size];
               while(true)
               {
                  int NumBytesRead = fsr.Read(block,0,size);
                  if(NumBytesRead == 0)
                     break;
                  fsw.Write(block,0,NumBytesRead);
                  fileSize += NumBytesRead;
               }
               fsw.Flush();
               fsw.Close();
            }
            catch(Exception) { /* do nothing */ }
            fsr.Close();
         }
         catch(Exception) { /* do nothing */ };
         return fileSize;
      }
		[STAThread]
		static void Main(string[] args)
		{
         FileWriter fw = new FileWriter();
         Console.Write(fw.Title("Test File Locking"));
         if(args.Length == 0)
         {
            Console.Write("\n  Please enter name of file to read");
            return;
         }
         const int NumCycles =5000;
         const int NumAttempts = 50;
         int NumFails = 0;
         int size = 0;
         for(int i=0; i<NumCycles; ++i)
         {
            for(int j=0; j<NumAttempts; ++j)
            {
               size = fw.CopyFile(args[0],args[1]);
               if(size == 0)
               {
                  Thread.Sleep(20); 
                  continue;
               }
               Console.Write("\n  {0,5}: Copied {1} bytes from {2} to {3}",i,size,args[0],args[1]);
               if(size > 0)
                  break;
            }
            if(size == 0)
               ++NumFails;
         }
         Console.Write("\n  There were {0} failures to copy\n\n",NumFails);
      }
	}
}