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using System;
using System.Threading;
namespace Pfz.Threading
{
/// <summary>
/// A semaphore class that uses only Monitor class for synchronization, avoiding
/// operating system events.
/// </summary>
public sealed class ManagedSemaphore:
IAdvancedDisposable
{
private readonly object _lock = new object();
private int _availableCount;
/// <summary>
/// Creates a new semaphore with the given availableCount.
/// </summary>
public ManagedSemaphore(int availableCount)
{
if (availableCount < 1)
throw new ArgumentException("availableCount must be at least 1.", "availableCount");
_availableCount = availableCount;
}
/// <summary>
/// Disposes this semaphore.
/// If you try to enter or exit it after this, the action will always return immediately.
/// </summary>
public void Dispose()
{
lock(_lock)
{
_availableCount = -1;
Monitor.PulseAll(_lock);
}
}
/// <summary>
/// Gets a value indicating if this semaphore was disposed.
/// </summary>
public bool WasDisposed
{
get
{
return _availableCount == -1;
}
}
/// <summary>
/// Enters the actual semaphore.
/// </summary>
public void Enter()
{
lock(_lock)
{
while(true)
{
if (_availableCount == -1)
return;
if (_availableCount > 0)
{
_availableCount--;
return;
}
Monitor.Wait(_lock);
}
}
}
/// <summary>
/// Enters the actual semaphore with the given count value.
/// If you pass a value higher than the one used to create it, you will dead-lock (at least until
/// the semaphore is disposed).
/// </summary>
public void Enter(int count)
{
if (count <= 0)
throw new ArgumentException("count of semaphores to enter must be at least 1.", "count");
lock(_lock)
{
while(true)
{
if (_availableCount == -1)
return;
if (_availableCount >= count)
{
_availableCount -= count;
return;
}
Monitor.Wait(_lock);
}
}
}
/// <summary>
/// Exits the semaphore. One thread can enter it and another one exit it. There is no check for that.
/// </summary>
public void Exit()
{
lock(_lock)
{
if (_availableCount == -1)
return;
_availableCount++;
Monitor.Pulse(_lock);
}
}
/// <summary>
/// Exits the semaphore the given amount. One thread can enter it and another one exit it. There is no check for that.
/// </summary>
public void Exit(int count)
{
if (count <= 0)
throw new ArgumentException("count of semaphores to exit must be at least 1.", "count");
if (count == -1)
{
Exit();
return;
}
lock(_lock)
{
if (_availableCount == -1)
return;
_availableCount += count;
Monitor.PulseAll(_lock);
}
}
}
}
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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).