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using System;
using System.IO.MemoryMappedFiles;
using System.Threading;
namespace Pfz.Remoting
{
/// <summary>
/// This class represents a communication stream based on MemoryMappedFiles. It only works locally, but
/// is faster than TCP/IP or NamedPipes.
/// </summary>
public sealed class MemoryMappedFileWriter:
IDisposable
{
private MemoryMappedFile _file;
private MemoryMappedViewAccessor _accessor;
private EventWaitHandle _sentEvent;
private EventWaitHandle _readEvent;
private int _mappedFileLength;
private unsafe byte *_pointer;
private unsafe MemoryMappedFileReaderWriterData *_data;
private bool _eventSet;
/// <summary>
/// Creates a new MemoryMappedFileWriter with the given name and length, and optionally with the given
/// timeout, which will be the time it will wait for client connections.
/// </summary>
public MemoryMappedFileWriter(string name, int length, int connectionTimeout = -1)
{
if (name == null)
throw new ArgumentNullException("name");
if (length <= 0)
throw new ArgumentOutOfRangeException("length");
if (connectionTimeout < -1)
throw new ArgumentOutOfRangeException("connectionTimeout");
unsafe
{
_file = MemoryMappedFile.CreateNew(name, length + sizeof(MemoryMappedFileReaderWriterData));
_accessor = _file.CreateViewAccessor();
byte *pointer = null;
_accessor.SafeMemoryMappedViewHandle.AcquirePointer(ref pointer);
(*(int *)pointer) = length;
_mappedFileLength = length;
_pointer = pointer;
_data = (MemoryMappedFileReaderWriterData *)(pointer + length);
}
_accessor.Flush();
_sentEvent = new EventWaitHandle(false, EventResetMode.AutoReset, name + ":Sent");
_sentEvent.Set();
_readEvent = new EventWaitHandle(false, EventResetMode.AutoReset, name + ":Read");
if (!_readEvent.WaitOne(connectionTimeout))
throw new TimeoutException("Timed-out waiting for client connection.");
}
/// <summary>
/// Releases all resources used by this Memory-Mapped-File.
/// </summary>
public void Dispose()
{
var sentEvent = _sentEvent;
unsafe
{
if (_data != null && sentEvent != null)
{
_data->_ended = true;
sentEvent.Set();
}
}
var accessor = _accessor;
if (accessor != null)
{
_accessor = null;
accessor.Dispose();
}
var file = _file;
if (file != null)
{
_file = null;
file.Dispose();
}
if (sentEvent != null)
{
_sentEvent = null;
sentEvent.Dispose();
}
var readEvent = _readEvent;
if (readEvent != null)
{
_readEvent = null;
readEvent.Dispose();
}
}
private int _timeout = 60000;
/// <summary>
/// Gets or sets the time-out used for writes.
/// This is not the same as the connection time out and must be set explicity.
/// </summary>
public int Timeout
{
get
{
return _timeout;
}
set
{
if (value < -1)
throw new ArgumentOutOfRangeException("value");
_timeout = value;
}
}
/// <summary>
/// Gets the Length of the memory-mapped-file.
/// </summary>
public int MemoryMappedFileLength
{
get
{
return _mappedFileLength;
}
}
/// <summary>
/// Writes the buffer data.
/// </summary>
public void Write(byte[] buffer)
{
if (buffer == null)
throw new ArgumentNullException("buffer");
_Write(buffer, 0, buffer.Length);
}
/// <summary>
/// Writes the buffer data.
/// </summary>
public void Write(byte[] buffer, int offset)
{
if (buffer == null)
throw new ArgumentNullException("buffer");
if (offset < 0 || offset >= buffer.Length)
throw new ArgumentOutOfRangeException("offset");
_Write(buffer, offset, buffer.Length - offset);
}
/// <summary>
/// Writes the buffer data.
/// </summary>
public void Write(byte[] buffer, int offset, int count)
{
if (buffer == null)
throw new ArgumentNullException("buffer");
if (offset < 0 || offset > buffer.Length)
throw new ArgumentOutOfRangeException("offset");
if (count < 0 || offset + count > buffer.Length)
throw new ArgumentOutOfRangeException("count");
_Write(buffer, offset, count);
}
private void _Write(byte[] buffer, int offset, int count)
{
unsafe
{
while(count > 0)
{
int writerPosition = _data->_writerPosition;
bool writerState = _data->_writerState;
int readerPosition;
bool readerState;
while (true)
{
readerPosition = _data->_readerPosition;
readerState = _data->_readerState;
if (writerPosition != readerPosition || writerState == readerState)
break;
_eventSet = false;
_sentEvent.Set();
if (!_readEvent.WaitOne(_timeout))
throw new TimeoutException("Write timed-out.");
}
int remaining;
if (readerState == writerState)
remaining = _mappedFileLength - writerPosition;
else
remaining = readerPosition - writerPosition;
int toSend = Math.Min(count, remaining);
fixed(byte *sourcePointer = buffer)
UnsafeBuffer.BlockCopy(sourcePointer + offset, _pointer + writerPosition, toSend);
offset += toSend;
count -= toSend;
writerPosition += toSend;
if (writerPosition >= _mappedFileLength)
{
writerPosition = 0;
_data->_writerState = !writerState;
}
_data->_writerPosition = writerPosition;
if (!_eventSet)
{
_eventSet = true;
_sentEvent.Set();
}
}
}
}
/// <summary>
/// Tells the other side that it can start reading.
/// </summary>
public void Flush()
{
_sentEvent.Set();
}
/// <summary>
/// Writes a single byte of data.
/// </summary>
public void WriteByte(byte value)
{
unsafe
{
int writerPosition = _data->_writerPosition;
bool writerState = _data->_writerState;
while (writerPosition == _data->_readerPosition && writerState != _data->_readerState)
{
_eventSet = false;
_sentEvent.Set();
if (!_readEvent.WaitOne(_timeout))
throw new TimeoutException("Write timed-out.");
}
_pointer[writerPosition] = value;
writerPosition ++;
if (writerPosition >= _mappedFileLength)
{
writerPosition = 0;
_data->_writerState = !writerState;
}
_data->_writerPosition = writerPosition;
if (!_eventSet)
{
_eventSet = true;
_sentEvent.Set();
}
}
}
}
}
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I started to program computers when I was 11 years old, as a hobbyist, programming in AMOS Basic and Blitz Basic for Amiga.
At 12 I had my first try with assembler, but it was too difficult at the time. Then, in the same year, I learned C and, after learning C, I was finally able to learn assembler (for Motorola 680x0).
Not sure, but probably between 12 and 13, I started to learn C++. I always programmed "in an object oriented way", but using function pointers instead of virtual methods.
At 15 I started to learn Pascal at school and to use Delphi. At 16 I started my first internship (using Delphi). At 18 I started to work professionally using C++ and since then I've developed my programming skills as a professional developer in C++ and C#, generally creating libraries that help other developers do their work easier, faster and with less errors.
Want more info or simply want to contact me?
Take a look at:
http://paulozemek.azurewebsites.net/
Or e-mail me at: paulozemek@outlook.com
Codeproject MVP 2012, 2015 & 2016
Microsoft MVP 2013-2014 (in October 2014 I started working at Microsoft, so I can't be a Microsoft MVP anymore).