using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
namespace Samples.Terminal
{
///
/// Implements a bounded queue that won't block on overflow; instead the oldest item is discarded.
///
///
public class ConcurrentBoundedQueue : ConcurrentQueue
{
public ConcurrentBoundedQueue(int capacity)
{
Capacity = GetAlignedCapacity(capacity);
}
public ConcurrentBoundedQueue(IEnumerable collection, int capacity) : base(collection)
{
Capacity = GetAlignedCapacity(capacity);
}
private int GetAlignedCapacity(int n)
{
if (n < 2)
{
throw new ArgumentException("Capacity must be at least 2");
}
var f = Math.Log(n, 2);
var p = Math.Ceiling(f);
return (int) Math.Pow(2, p);
}
public new void Enqueue(T item)
{
// if we're about to overflow, dump oldest item
if (Count >= Capacity)
{
lock (this)
{
while (Count >= Capacity)
{
TryDequeue(out _);
}
}
}
base.Enqueue(item);
}
public int Capacity
{
get; private set;
}
}
}