public void Enqueue(IoTask task)
{
if (_disposed)
{
throw new ObjectDisposedException(GetType().FullName);
}
IoTask last = _last, newLast;
while (last != null && !ReferenceEquals(last, newLast = Interlocked.CompareExchange(ref _last, task, last)))
{
last = newLast;
}
if (last == null)
{
throw new IOException();
}
IoTask prev = Interlocked.Exchange(ref last.Next, task);
if (prev != null)
{
throw new IOException();
}
_wakeup.Set();
}
public WorkerState(Stream output, bool closeStream)
{
_output = output;
_closeStream = closeStream;
_first = _last = new IoTask();
_wakeup = new ManualResetEvent(false);
_stop = new ManualResetEvent(false);
_worker = new Thread(WriterThread);
_worker.IsBackground = true;
_worker.SetApartmentState(ApartmentState.MTA);
_worker.Name = GetType().Name;
_worker.Start();
}
/// <summary>
/// Returns a number of bytes up to length that is pending a write at the position specified and
/// copies those bytes into buffer the offset provided.
/// </summary>
public int Read(long position, byte[] buffer, int offset, int length)
{
IoTask work = _state.First();
int bytesFound = 0;
while (work != null)
{
if (work.Position == position)
{
Buffer.BlockCopy(work.Bytes, work.Offset, buffer, offset, bytesFound = Math.Min(length, work.Length));
}
work = work.Next;
}
return(bytesFound);
}
void WriterThread()
{
try
{
byte[] buffer = new byte[8192];
WaitHandle[] waits = new WaitHandle[] { _stop, _wakeup };
while (true)
{
int result = WaitHandle.WaitAny(waits);
_wakeup.Reset();
while (PerformWrite(ref buffer))
{
}
if (result != 1)
{
break;
}
}
_output.Flush();
// Console.WriteLine("Thread {0} write lag = {1}", Thread.CurrentThread.ManagedThreadId, _lagging);
Debug.Write(
String.Format("Thread {0} write lag = {1}", Thread.CurrentThread.ManagedThreadId, _lagging),
GetType().Name
);
}
catch (ThreadAbortException) { throw; }
catch
{
_first = null;
Interlocked.Exchange(ref _last, null);
}
finally
{
if (_closeStream)
{
_output.Close();
}
}
}
public void Enqueue(IoTask task)
{
if (_disposed)
throw new ObjectDisposedException(GetType().FullName);
IoTask last = _last, newLast;
while (last != null && !ReferenceEquals(last, newLast = Interlocked.CompareExchange(ref _last, task, last)))
last = newLast;
if (last == null)
throw new IOException();
IoTask prev = Interlocked.Exchange(ref last.Next, task);
if (prev != null)
throw new IOException();
_wakeup.Set();
}
private bool PerformWrite(ref byte[] buffer)
{
IoTask start = _first;
IoTask next = Interlocked.CompareExchange(ref start.Next, null, null);
if (next == null)
return false;//nothing to do, _first has always been processed
IoTask stop = start = next;
bool hasSignals = start.Signal != null;
int byteLen = stop.Length;
long startpos = stop.Position;
long position = stop.Position + byteLen;
while (null != (next = Interlocked.CompareExchange(ref start.Next, null, null)))
{
//see if both are append-only (position < 0)
if (startpos < 0 && next.Position >= 0)
break;
//see if the next write immediately follows this
if (startpos >= 0 && next.Position != position)
break;
//see if this write will overflow our max memory buffer limit
if (next.Length + byteLen > MemoryLimit)
break;
if (next.IoAction != null)
break;
byteLen += next.Length;
position += next.Length;
hasSignals |= next.Signal != null;
stop = next;
}
if (start.IoAction != null)
{
start.IoAction(_output);
start.IoAction = null;
}
else if (ReferenceEquals(start, stop))
{
if (startpos >= 0)
_output.Position = startpos;
_output.Write(start.Bytes, start.Offset, start.Length);
}
else //buffer and write multiple items...
{
if (buffer.Length < byteLen)
Array.Resize(ref buffer, byteLen + 8192);
int counter = 0;
int offset = 0;
IoTask current = start;
while (true)
{
counter++;
Buffer.BlockCopy(current.Bytes, current.Offset, buffer, offset, current.Length);
offset += current.Length;
if (ReferenceEquals(current, stop))
break;
current = current.Next;
}
_lagging = Math.Max(_lagging, counter);
if (startpos >= 0)
_output.Position = startpos;
_output.Write(buffer, 0, offset);
}
while (hasSignals)
{
if (start.Signal != null)
{
start.Signal.Set();
start.Signal = null;
}
if (ReferenceEquals(start, stop))
break;
start = start.Next;
}
_first = stop;
return true;
}
void WriterThread()
{
try
{
byte[] buffer = new byte[8192];
WaitHandle[] waits = new WaitHandle[] { _stop, _wakeup };
while (true)
{
int result = WaitHandle.WaitAny(waits);
_wakeup.Reset();
while (PerformWrite(ref buffer))
{ }
if (result != 1)
break;
}
_output.Flush();
// Console.WriteLine("Thread {0} write lag = {1}", Thread.CurrentThread.ManagedThreadId, _lagging);
Debug.Write(
String.Format("Thread {0} write lag = {1}", Thread.CurrentThread.ManagedThreadId, _lagging),
GetType().Name
);
}
catch (ThreadAbortException) { throw; }
catch
{
_first = null;
Interlocked.Exchange(ref _last, null);
}
finally
{
if (_closeStream)
_output.Close();
}
}
public WorkerState(Stream output, bool closeStream)
{
_output = output;
_closeStream = closeStream;
_first = _last = new IoTask();
_wakeup = new ManualResetEvent(false);
_stop = new ManualResetEvent(false);
_worker = new Thread(WriterThread);
_worker.IsBackground = true;
_worker.SetApartmentState(ApartmentState.MTA);
_worker.Name = GetType().Name;
_worker.Start();
}
private bool PerformWrite(ref byte[] buffer)
{
IoTask start = _first;
IoTask next = Interlocked.CompareExchange(ref start.Next, null, null);
if (next == null)
{
return(false);//nothing to do, _first has always been processed
}
IoTask stop = start = next;
bool hasSignals = start.Signal != null;
int byteLen = stop.Length;
long startpos = stop.Position;
long position = stop.Position + byteLen;
while (null != (next = Interlocked.CompareExchange(ref start.Next, null, null)))
{
//see if both are append-only (position < 0)
if (startpos < 0 && next.Position >= 0)
{
break;
}
//see if the next write immediately follows this
if (startpos >= 0 && next.Position != position)
{
break;
}
//see if this write will overflow our max memory buffer limit
if (next.Length + byteLen > MemoryLimit)
{
break;
}
if (next.IoAction != null)
{
break;
}
byteLen += next.Length;
position += next.Length;
hasSignals |= next.Signal != null;
stop = next;
}
if (start.IoAction != null)
{
start.IoAction(_output);
start.IoAction = null;
}
else if (ReferenceEquals(start, stop))
{
if (startpos >= 0)
{
_output.Position = startpos;
}
_output.Write(start.Bytes, start.Offset, start.Length);
}
else //buffer and write multiple items...
{
if (buffer.Length < byteLen)
{
Array.Resize(ref buffer, byteLen + 8192);
}
int counter = 0;
int offset = 0;
IoTask current = start;
while (true)
{
counter++;
Buffer.BlockCopy(current.Bytes, current.Offset, buffer, offset, current.Length);
offset += current.Length;
if (ReferenceEquals(current, stop))
{
break;
}
current = current.Next;
}
_lagging = Math.Max(_lagging, counter);
if (startpos >= 0)
{
_output.Position = startpos;
}
_output.Write(buffer, 0, offset);
}
while (hasSignals)
{
if (start.Signal != null)
{
start.Signal.Set();
start.Signal = null;
}
if (ReferenceEquals(start, stop))
{
break;
}
start = start.Next;
}
_first = stop;
return(true);
}
