public SortMerge(string fname)
{
tmpPath = "tmp" + Guid.NewGuid();
Directory.CreateDirectory(tmpPath);
// begin calculate simplified performance
stTime = DateTime.Now;
Console.WriteLine("initial dividing..");
int countFiles = DivideAndSortInitial(fname);
string fnameResult = string.Empty;
while (true)
{
// observe exist files
string[] arr = Directory.GetFiles(tmpPath, "p" + phase + "_*.txt");
// detect what sorting complete if files merged in one
if (arr.Length == 1)
{
fnameResult = arr[0];
break;
}
// begin new phase
int len = arr.Length / 2;
phase++; Console.WriteLine("phase " + phase);
// prepare data for tasks
var pairs = new List <FilePair>();
for (int i = 0; i < len; i++)
{
int idx = i * 2;
string fnameSrc1 = arr[idx];
string fnameSrc2 = arr[idx + 1];
string fnameDst = tmpPath + "\\p" + phase + "_" + i + ".txt";
FilePair pair = new FilePair(fnameSrc1, fnameSrc2, fnameDst);
pairs.Add(pair);
}
// parallel sort pairs
Parallel.ForEach(pairs, pair => { SortPair(pair); });
// odd file was migrate to next phase
if (arr.Length > len * 2)
{
File.Move(arr[arr.Length - 1], tmpPath + "\\p" + phase + "_" + len + ".txt");
}
}
// emit result file to source dirrectory
FileResult = fname + ".sorted";
if (File.Exists(FileResult))
{
FileResult += "." + Guid.NewGuid();
}
File.Move(fnameResult, FileResult);
// clean temporary files
Directory.Delete(tmpPath, true);
//begin calculate simplified performance
enTime = DateTime.Now;
}
void SortPair(object state)
{
FilePair pair = (FilePair)state;
using (StreamReader sr1 = new StreamReader(pair.fnameSrc1),
sr2 = new StreamReader(pair.fnameSrc2))
{
using (StreamWriter sw = new StreamWriter(pair.fnameDst))
{
string line1 = null;
string line2 = null;
while (true)
{
if (line1 == null)
{
if (sr1.Peek() >= 0)
{
line1 = sr1.ReadLine();
}
}
if (line2 == null)
{
if (sr2.Peek() >= 0)
{
line2 = sr2.ReadLine();
}
}
if ((line1 == null) && (line2 == null))
{
break;
}
if (String.Compare(line1, line2) > 0)
{
sw.WriteLine(line1);
line1 = null;
}
else
{
sw.WriteLine(line2);
line2 = null;
}
}
sw.Flush();
}
}
}
