Google's Distributed C++ Compiler distcc

Imagine how long would it take for compiling (a rebuild) google's web server ? 20 mintues ?..Hmm., that's a lot of time for compiling , take a look at how google research engineers solved the problem by developing an algorithm called 'pump mode' for distcc. Amazing stuff.

VS 08 SP1 and .Net FX 3.5 SP1

Woohoo!! Time to get excited..VS 08 SP1 seems to me like more of a bug fixing upgrade over features. However, .Net FX 3.5 SP1 is exciting with the following

1] ASP.Net Dynamic Data :

ASP.NET Dynamic Data, which provides a rich scaffolding framework that enables rapid data driven development without writing code, and a new addition to ASP.NET AJAX that provides support for managing browser history (back button support). For more information

2] Entity Framework

http://msdn.microsoft.com/en-us/data/aa937723.aspx

3] ADO.NET Data Services Framework

The ADO.NET Data Services Framework consists of a combination of patterns and libraries, which enable data to be exposed as a flexible REST (Representational State Transfer)-based data service that can be consumed by Web clients in a corporate network or across the Internet. The ADO.NET Data Services Framework makes data service creation over any data source. A conceptual view model of the underlying storage schema can easily be exposed through rich integration with the ADO.NET Entity Framework. Services created by using the ADO.NET Data Services Framework, and also compatible Windows Live (dev.live.com) services, can be easily accessed from any platform. For client applications that are running on Microsoft platforms, a set of client libraries are provided to make interaction with data services simple. For example, .NET Framework-based clients can use LINQ to query data services and a simple .NET Framework object layer to update data in the service

Downloads

> .NET FX 3.5 SP1

> VS 08 SP1

Visual Studio RSS Configuration

If you wanted to subscribe to a different feed from MSDN, which gets displayed in the start page, use this article here to learn configure Visual Studio to do just that.

A Concurrent Programming Primer on Code Project

 

I found a good read on PLINQ (Parallel LINQ) and TPL (Task Parallel Library) on code project. It doesn’t cover everything though but gives you good examples and common pitfalls using them.

The examples cover,

• Parallel Class - Parallel.For, Parallel.Do, AsParallel  constructs
• Exception Handling for Parallel programming constructs
• Handling of compiler side-effects.

You need the TPL CTP download and of course VS 2008 for trying out the samples.

Converting a LINQ query from sequential to parallel execution is as simple and straightforward as below :

   1: Enumerable<T> data = ...;

   2: var q = from x in data.AsParallel() where p(x) orderby k(x) select f(x);

Here’s the link

Designing an Enumerator for Business Objects

Following is my elegant enumerator design which can be used for enumerating business objects from the database. Designing an enumerator with C#, .Net 3.5 will be much more elegant simply because of LINQ and LINQ to SQL. I will write about it in my future posts. LINQ has made it extremely easy to do such things, and i will prove my point in the future posts. This is also mostly based on Enterprise patterns (Check out the most famous Martin Fowler's book) . I've used a Table Gateway and a normal Iterator pattern.

 

Product - Business Object

Product.cs

public class Product
    {
        int id;

        public int Id {
            get {
                return id;
            }
            set {
                id = value;
            }
        }
        string name;

        public string Name {
            get {
                return name;
            }
            set {
                name = value;
            }
        }
        double price;

        public double Price {
            get {
                return price;
            }
            set {
                price = value;
            }
        }

        public override bool Equals(object obj) {
            if (null==obj)
                return false;           
            else
            {
                Product p = obj as Product;
                return (p.id == this.id);
            }
        }

        public override int GetHashCode() {
            return id.GetHashCode();
        }

        public override string ToString() {
            return name.ToString();
        }

 

DBEnumerator.cs

    public abstract class DBEnumerator<T>:IEnumerator,IEnumerable
    {
        private int position;
        protected List<T> list;
        protected TableGateway  tablegateway;
        protected abstract void Read(string sql);
        public virtual void Add(T item) {
            if (!list.Contains(item))
            {
                list.Add(item);
            }
        }

        #region IEnumerable Members

        public IEnumerator GetEnumerator() {
            return (IEnumerator)this;
        }

        #endregion

        #region IEnumerator Members

        public object Current {
            get {
                return (object)list[position];
            }
        }

        public bool MoveNext() {
            position++;
            return (position < list.Count);
        }

        public void Reset() {
            position = -1;
        }

        #endregion
    }

ProductEnumerator.cs

    public class ProductEnumerator:DBEnumerator<Product>
    {
        public ProductEnumerator(string sql) {
            this.tablegateway = new TableGateway();
            this.list = new List<Product>();
            Read(sql);
            this.Reset();
        }

        internal TableGateway TableGateway {
            get {
                return tablegateway;
            }
        }

        protected override void Read(string sql) {
            DataTable dt = new DataTable();
            dt = tablegateway.ExecuteNonQuery(sql);
            foreach (DataRow row in dt.Rows)
            {
                Product p = new Product();
                p.Id = Convert.ToInt32(row["Id"].ToString());
                p.Name = row["Name"].ToString();
                p.Price = Convert.ToDouble(row["Price"].ToString());
                Add(p);
            }
        }
    }

TableGateway.cs

   public class TableGateway
    {
        private string connstring;
        private IDbCommand command;
        private Collection<IDataParameter> parameters;

        public TableGateway() {
            connstring = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\\Projects\\C#Projects"+
                         "\\BusinessObjectEnumerator\\Inventory.mdb;";
            parameters = new Collection<IDataParameter>();
        }

        public void AddParameters(string parameterName, string parameterValue) {
            IDataParameter param = command.CreateParameter();
            param.ParameterName = parameterName;
            param.Value = parameterValue;
        }


        public string TableName{
            get {return "Tablegateway";}
        }

        public DataTable ExecuteNonQuery(string sql)
        {
            using (IDbConnection conn = GetConnection())
            {
                command = conn.CreateCommand();
                foreach (IDataParameter param in parameters){
                    command.Parameters.Add(param);
                }

                OleDbDataAdapter oledbdataadapter = new OleDbDataAdapter(sql,(OleDbConnection)                                                                           conn);
                DataSet dataset = new DataSet();
                try
                {
                    oledbdataadapter.Fill(dataset, this.TableName);
                }
                catch
                {
                    throw;

                } 
                finally
                {
                    conn.Close();
                }
                return dataset.Tables[TableName];
            }            
        }

        private IDbConnection GetConnection() {
            return new  OleDbConnection(connstring);
        }

    }

Putting the ProductEnumerator to test

  static void Main(string[] args) {

            ProductEnumerator myproducts = new ProductEnumerator   ("select * from products");

            Console.WriteLine("Enumerating products..\n");

            foreach (Product p in myproducts){
                Console.WriteLine("ID: ,"+p.Id+ 
                                  "Name: ,"+ p.Name+
                                  "Price: ,"+p.Price);
            }

            Console.WriteLine("\nPress any key to exit..");
            Console.ReadKey();
        }

Notice, Since we have implemented the IEnumerable and IEnumerator interfaces, we can use the ProductEnumerator in a foreach statement. This will be the cool part of Enumerators. The MSIL generation for the foreach statement would do something like the following:

IEnumerator ienum = myproducts.GetEnumerator();

while(ienum.MoveNext()) {

...

}

Also, We can  provide mechanisms to add stuff into the List<T> of the DBEnumerator. By doing this we will need to have some mechanisms to persist the newly added object to the DB. In other words instantaneously serialize the object. This will require some kind of an EventHandler to track the List<T> added event. Hmm... reminds me of a 1000 patterns from Martin Fowler , just to do this.. :) (Oh, my brave attempt to write a DataMapper in 3 days, i paid the price in the ACW..Thanks to Dr.Grey for enlightening me about my deed)

Output

Enumerating products..

ID: ,1Name: ,Product APrice: ,10.99

ID: ,2Name: ,Product BPrice: ,12.99


ID: ,3Name: ,Product CPrice: ,10.99


ID: ,4Name: ,Product DPrice: ,14.99


ID: ,5Name: ,Product EPrice: ,19


ID: ,6Name: ,Product FPrice: ,19.99


ID: ,7Name: ,Product GPrice: ,7.99


ID: ,8Name: ,Product HPrice: ,5.45


ID: ,9Name: ,Product IPrice: ,3.44


ID: ,10Name: ,Product JPrice: ,0.99

Press any key to exit..

The DB (for proof)