coordinator.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / Common / internal / materialization / coordinator.cs / 1305376 / coordinator.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
// [....]
//----------------------------------------------------------------------------- 
 
using System.Collections.Generic;
using System.Diagnostics; 
using System.Linq;
using System.Text;
using System.Globalization;
using System.Data.Objects.Internal; 

namespace System.Data.Common.Internal.Materialization 
{ 

    ///  
    /// A coordinator is responsible for tracking state and processing result in a root or nested query
    /// result collection. The coordinator exists within a graph, and knows its Parent, (First)Child,
    /// and Next sibling. This allows the Shaper to use the coordinator as a simple state machine when
    /// consuming store reader results. 
    /// 
    internal abstract class Coordinator 
    { 
        #region state
 
        /// 
        /// The factory used to generate this coordinator instance. Contains delegates used
        /// by the Shaper during result enumeration.
        ///  
        internal readonly CoordinatorFactory CoordinatorFactory;
 
        ///  
        /// Parent coordinator (the coordinator producing rows containing this collection).
        /// If this is the root, null. 
        /// 
        internal readonly Coordinator Parent;

        ///  
        /// First coordinator for nested results below this collection. When reading a new row
        /// for this coordinator, we walk down to the Child. 
        /// 
        /// NOTE:: this cannot be readonly because we can't know both the parent and the child
        /// at initialization time; we set the Child in the parent's constructor. 
        /// 
        public Coordinator Child
        {
            get { return _child; } 
            protected set { _child = value; }
        } 
        private Coordinator _child; 

        ///  
        /// Next coordinator at this depth. Once we're done consuming results for this reader,
        /// we move on to this.Next.
        /// 
        internal readonly Coordinator Next; 

        ///  
        /// Indicates whether data has been read for the collection being aggregated or yielded 
        /// by this coordinator.
        ///  
        public bool IsEntered
        {
            get { return _isEntered; }
            protected set { _isEntered = value; } 
        }
        private bool _isEntered; 
 
        /// 
        /// Indicates whether this is the top level coordinator for a query. 
        /// 
        internal bool IsRoot
        {
            get { return null == Parent; } 
        }
 
        #endregion 

        #region constructor 

        protected Coordinator(CoordinatorFactory coordinatorFactory, Coordinator parent, Coordinator next)
        {
            this.CoordinatorFactory = coordinatorFactory; 
            this.Parent = parent;
            this.Next = next; 
        } 

        #endregion 

        #region "public" surface area

        ///  
        /// Registers this hierarchy of coordinators in the given shaper.
        ///  
        internal void Initialize(Shaper shaper) 
        {
            ResetCollection(shaper); 

            // Add this coordinator to the appropriate state slot in the
            // shaper so that it is available to materialization delegates.
            shaper.State[this.CoordinatorFactory.StateSlot] = this; 

            if (null != this.Child) 
            { 
                this.Child.Initialize(shaper);
            } 
            if (null != this.Next)
            {
                this.Next.Initialize(shaper);
            } 
        }
 
        ///  
        /// Determines the maximum depth of this subtree.
        ///  
        internal int MaxDistanceToLeaf()
        {
            int maxDistance = 0;
            Coordinator child = this.Child; 
            while (null != child)
            { 
                maxDistance = Math.Max(maxDistance, child.MaxDistanceToLeaf() + 1); 
                child = child.Next;
            } 
            return maxDistance;
        }

        ///  
        /// This method is called when the current collection is finished and it's time to move to the next collection.
        /// Recursively initializes children and siblings as well. 
        ///  
        internal abstract void ResetCollection(Shaper shaper);
 
        /// 
        /// Precondition: the current row has data for the coordinator.
        /// Side-effects: updates keys currently stored in state and updates IsEntered if a new value is encountered.
        /// Determines whether the row contains the next element in this collection. 
        /// 
        internal bool HasNextElement(Shaper shaper) 
        { 
            // check if this row contains a new element for this coordinator
            bool result = false; 

            if (!this.IsEntered || !this.CoordinatorFactory.CheckKeys(shaper))
            {
                // remember initial keys values 
                this.CoordinatorFactory.SetKeys(shaper);
                this.IsEntered = true; 
                result = true; 
            }
 
            return result;
        }

        ///  
        /// Precondition: the current row has data and contains a new element for the coordinator.
        /// Reads the next element in this collection. 
        ///  
        internal abstract void ReadNextElement(Shaper shaper);
 
        #endregion
    }

    ///  
    /// Typed 
    ///  
    internal class Coordinator : Coordinator 
    {
        #region state 

        internal readonly CoordinatorFactory TypedCoordinatorFactory;

        ///  
        /// Exposes the Current element that has been materialized (and is being populated) by this coordinator.
        ///  
        internal T Current 
        {
            get { return _current; } 
        }
        private T _current;

        ///  
        /// For ObjectResult, aggregates all elements for in the nested collection handled by this coordinator.
        ///  
        private ICollection _elements; 

        ///  
        /// For ObjectResult, aggregates all elements as wrapped entities for in the nested collection handled by this coordinator.
        /// 
        private List _wrappedElements;
 
        /// 
        /// Delegate called when the current nested collection has been consumed. This is necessary in Span 
        /// scenarios where an EntityCollection RelatedEnd is populated only when all related entities have 
        /// been materialized.  This version of the close handler works with wrapped entities.
        ///  
        private Action> _handleClose;

        /// 
        /// For nested, object-layer coordinators we want to collect all the elements we find and handle them 
        /// when the root coordinator advances.  Otherwise we just want to return them as we find them.
        ///  
        private readonly bool IsUsingElementCollection; 

        #endregion 

        #region constructors

        internal Coordinator(CoordinatorFactory coordinator, Coordinator parent, Coordinator next) 
            : base(coordinator, parent, next)
        { 
            this.TypedCoordinatorFactory = coordinator; 

            // generate all children 
            Coordinator nextChild = null;
            foreach (var nestedCoordinator in coordinator.NestedCoordinators.Reverse())
            {
                // last child processed is first child... 
                this.Child = nestedCoordinator.CreateCoordinator(this, nextChild);
                nextChild = this.Child; 
            } 

            this.IsUsingElementCollection = (!this.IsRoot && typeof(T) != typeof(RecordState)); 
        }

        #endregion
 
        #region "public" surface area
 
        internal override void ResetCollection(Shaper shaper) 
        {
            // Check to see if anyone has registered for notification when the current coordinator 
            // is reset.
            if (null != _handleClose)
            {
                _handleClose(shaper, _wrappedElements); 
                _handleClose = null;
            } 
 
            // Reset is entered for this collection.
            this.IsEntered = false; 

            if (IsUsingElementCollection)
            {
                _elements = this.TypedCoordinatorFactory.InitializeCollection(shaper); 
                _wrappedElements = new List();
            } 
 
            if (null != this.Child)
            { 
                this.Child.ResetCollection(shaper);
            }
            if (null != this.Next)
            { 
                this.Next.ResetCollection(shaper);
            } 
        } 

        internal override void ReadNextElement(Shaper shaper) 
        {
            T element;
            IEntityWrapper wrappedElement = null;
            try 
            {
                if (this.TypedCoordinatorFactory.WrappedElement == null) 
                { 
                    element = this.TypedCoordinatorFactory.Element(shaper);
                } 
                else
                {
                    wrappedElement = this.TypedCoordinatorFactory.WrappedElement(shaper);
                    // This cast may throw, in which case it will be immediately caught 
                    // and the error handling expression will be used to get the appropriate error message.
                    element = (T)wrappedElement.Entity; 
                } 
            }
            catch (Exception e) 
            {
                if (EntityUtil.IsCatchableExceptionType(e))
                {
                    // Some errors can occur while a close handler is registered.  This clears 
                    // out the handler so that ElementWithErrorHandling will report the correct
                    // error rather than asserting on the missing close handler. 
                    ResetCollection(shaper); 
                    // call a variation of the "Element" delegate with more detailed
                    // error handling (to produce a better exception message) 
                    element = this.TypedCoordinatorFactory.ElementWithErrorHandling(shaper);
                }

                // rethrow 
                throw;
            } 
            if (IsUsingElementCollection) 
            {
                _elements.Add(element); 
                if (wrappedElement != null)
                {
                    _wrappedElements.Add(wrappedElement);
                } 
            }
            else 
            { 
                _current = element;
            } 
        }

        /// 
        /// Sets the delegate called when this collection is closed.  This close handler works on 
        /// a collection of wrapped entities, rather than on the raw entity objects.
        ///  
        internal void RegisterCloseHandler(Action> closeHandler) 
        {
            Debug.Assert(null == _handleClose, "more than one handler for a collection close 'event'"); 
            _handleClose = closeHandler;
        }

        ///  
        /// Called when we're disposing the enumerator;
        ///  
        internal void SetCurrentToDefault() 
        {
            _current = default(T); 
        }

        #endregion
 
        #region runtime callable code
 
        // Code in this section is called from the delegates produced by the Translator.  It may 
        // not show up if you search using Find All References
 
        /// 
        /// Returns a handle to the element aggregator for this nested collection.
        /// 
        private IEnumerable GetElements() 
        {
            return _elements; 
        } 

        #endregion 
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

Link Menu

Network programming in C#, Network Programming in VB.NET, Network Programming in .NET
This book is available now!
Buy at Amazon US or
Buy at Amazon UK