/// <summary>Starts a worker thread to read lines from the file</summary>
public static ManualResetEventSlim BeginReadLines(string filepath, WaitHandle stop, Action <string> lines_cb, Encoding?encoding = null)
{
// Use:
// var stop = new ManualResetEventSlim(false);
// var done = FileContent.BeginReadLines(filepath, stop, s => UseLine(s));
// ...
// stop.Set();
// done.WaitOne();
var done = new ManualResetEventSlim(false);
ThreadPool.QueueUserWorkItem(async _ =>
{
var sr = (StreamReader?)null;
var mmf = (MemoryMappedFile?)null;
try
{
for (; ; Thread.Yield())
{
// Create the memory mapped file after the monitored file is created
if (sr == null)
{
// Cancelled already?
if (stop.WaitOne(0))
{
break;
}
// Wait for the file to appear.
// 'MemoryMappedFile.CreateFromFile' fails for null or zero-length files
if (!Path_.FileExists(filepath) || Path_.FileLength(filepath) == 0)
{
Thread.Sleep(100);
continue;
}
// Once the file exists, create a memory mapped file from it
mmf = mmf ?? MemoryMappedFile.CreateFromFile(filepath, FileMode.Open, Path_.SanitiseFileName($"FileContent-{filepath}"), 0, MemoryMappedFileAccess.Read);
sr = new StreamReader(mmf.CreateViewStream(), encoding ?? Encoding.UTF8);
}
// Read lines from the file
var line = await sr.ReadLineAsync();
if (line != null)
{
lines_cb(line.Trim('\0'));
continue;
}
// Only test for exit if no data was read
if (stop.WaitOne(0))
{
break;
}
// If no data was read from the file, wait a bit longer
Thread.Sleep(10);
}
}
finally
{
sr?.Dispose();
mmf?.Dispose();
done.Set();
}
});
return(done);
}
/// <summary>Starts a worker thread to read bytes from a memory mapped file</summary>
public static ManualResetEventSlim BeginRead(string filepath, WaitHandle stop, Action <ArraySegment <byte> > data_cb, int block_size = 1024)
{
// Use:
// var stop = new ManualResetEventSlim(false);
// var done = FileContent.BeginRead(filepath, stop, s => UseBytes(s));
// ...
// stop.Set();
// done.WaitOne();
var done = new ManualResetEventSlim(false);
ThreadPool.QueueUserWorkItem(async _ =>
{
var sr = (Stream?)null;
var mmf = (MemoryMappedFile?)null;
try
{
var buffer = new byte[block_size];
for (; ; Thread.Yield())
{
// Create the memory mapped file after the monitored file is created
if (sr == null)
{
try
{
// Cancelled already?
if (stop.WaitOne(0))
{
break;
}
// Wait for the file to appear.
// 'MemoryMappedFile.CreateFromFile' fails for null or zero-length files
if (!Path_.FileExists(filepath) || Path_.FileLength(filepath) == 0)
{
Thread.Sleep(100);
continue;
}
// Once the file exists, create a memory mapped file from it
mmf = mmf ?? MemoryMappedFile.CreateFromFile(filepath, FileMode.Open, Path_.SanitiseFileName($"FileContent-{filepath}"), 0, MemoryMappedFileAccess.Read);
sr = mmf.CreateViewStream();
}
catch (UnauthorizedAccessException)
{
Thread.Sleep(100);
continue;
}
}
// Read blocks of data from the file
var read = await sr.ReadAsync(buffer, 0, buffer.Length);
if (read != 0)
{
data_cb(new ArraySegment <byte>(buffer, 0, read));
continue;
}
// Only test for exit if no data was read
if (stop.WaitOne(0))
{
break;
}
// If no data was read from the file, wait a bit longer
Thread.Sleep(10);
}
}
finally
{
sr?.Dispose();
mmf?.Dispose();
done.Set();
}
});
return(done);
}