Csharp/C Sharp/Generics/Generic Parameters

Two Generic parameters

 
using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
public interface IDocument {
    string Title {
        get;
    }
    string Content {
        get;
    }
}
public class Document : IDocument {
    private string title;
    public string Title {
        get {
            return title;
        }
    }
    private string content;
    public string Content {
        get {
            return content;
        }
    }
    public Document(string title, string content) {
        this.title = title;
        this.content = content;
    }
}
public class ProcessDocuments<T, U>
    where T : IDocument
    where U : IDocumentManager<T> {
    public static void Start(U dm) {
        new Thread(new ThreadStart(new ProcessDocuments<T, U>(dm).Run)).Start();
    }
    protected ProcessDocuments(U dm) {
        documentManager = dm;
    }
    private U documentManager;
    protected void Run() {
        while (true) {
            if (documentManager.IsDocumentAvailable) {
                T doc = documentManager.GetDocument();
                Console.WriteLine("Processing document {0}", doc.Title);
            }
            Thread.Sleep(new Random().Next(20));
        }
    }
}
public interface IDocumentManager<T> {
    void AddDocument(T doc);
    T GetDocument();
    bool IsDocumentAvailable {
        get;
    }
}
public class DocumentManager<T> : IDocumentManager<T> {
    private readonly Queue<T> documentQueue = new Queue<T>();
    public void AddDocument(T doc) {
        lock (this) {
            documentQueue.Enqueue(doc);
        }
    }
    public T GetDocument() {
        T doc = default(T);
        lock (this) {
            doc = documentQueue.Dequeue();
        }
        return doc;
    }
    public bool IsDocumentAvailable {
        get {
            return (documentQueue.Count > 0) ? true : false;
        }
    }
}
class Program {
    static void Main(string[] args) {
        DocumentManager<Document> dm = new DocumentManager<Document>();
        ProcessDocuments<Document, DocumentManager<Document>>.Start(dm);
        for (int i = 0; i < 1000; i++) {
            Document doc = new Document("Doc " + i.ToString(), "content");
            dm.AddDocument(doc);
            Console.WriteLine("added document {0}", doc.Title);
            Thread.Sleep(new Random().Next(20));
        }
    }
}