//取得する行のオフセット、取得する行数、ステップを指定
public async Task <string[]> GetLines(long offset, long num, long step = 1)
{
var start = Math.Max(0, offset);
var end = offset + num * step - 1;
step = Math.Max(step, 1);
var result = new List <string>();
await Task.Run(() =>
{
var info = Info;
if (info != null)
{
end = Math.Min(end, info.TotalLineNUM - 1);
if (start >= end)
{
return;
}
var list = new ConcurrentBag <DividedFile>();
var fileNUM = info.FileNames.Count;
Parallel.For(
0, fileNUM, i =>
{
var fileStart = (info.MaxLineNUM *i);
var fileEnd = Math.Min(fileStart + info.MaxLineNUM - 1, end);
var lineNUM = (long)(fileEnd - fileStart);
if (fileEnd >= start && lineNUM > 0)
{
var dividedFile = new DividedFile(i);
var filePath = Path.Combine(InfoFileDirectory, info.FileNames[i]);
dividedFile.Load(filePath, fileStart, start, fileEnd, step);
list.Add(dividedFile);
}
}
);
if (list.Count > 0)
{
var array = list.OrderBy(e => e.Id).ToArray();
foreach (var file in array)
{
foreach (var line in file.Lines)
{
result.Add(line);
}
}
}
}
});
return(result.ToArray());
}