kreta/Framework/Session/TransactionContext.cs

using System;
using System.Data;
using SDA.DataProvider;

namespace Kreta.Framework
{
    /// <summary>
    /// Adatbázis ügylet kontextus.
    /// </summary>
    public class TransactionContext : IDisposable
    {
        private static object SyncObject = new object();

        private SDAConnection dbConnection;

        private SDATransaction dbTransaction;

        private bool IsTransactional { get; set; }

        private bool IsLocked { get; set; }

        protected string IntezmenyAzonosito { get; set; }

        /// <summary>
        /// Az osztály alapértelmezett konstruktora.
        /// </summary>
        public TransactionContext(string intezmenyAzonosito) : this(intezmenyAzonosito, true)
        {
        }

        /// <summary>
        /// Az osztály konstruktora.
        /// </summary>
        /// <param name="isTransactional">Tranzakciós legyen-e a kontextus, vagy sem.</param>
        public TransactionContext(string intezmenyAzonosito, bool isTransactional)
        {
            IsTransactional = isTransactional;
            IntezmenyAzonosito = intezmenyAzonosito;
        }

        #region Belső dolgok

        internal virtual SDAConnection CreateConnection()
        {
            if (!string.IsNullOrWhiteSpace(IntezmenyAzonosito))
            {
                var connectionString = SDAServer.Instance.GetIntezmenyConnectionString(IntezmenyAzonosito);

                return SDAServer.Instance.CreateConnection(connectionString);
            }

            return SDAServer.Instance.CreateConnection();
        }

        private void Prepare()
        {
            DoPrepareConnection();
            DoPrepareTransaction();
        }

        private void DoPrepareConnection()
        {
            if (dbConnection == null)
            {
                dbConnection = CreateConnection();
                dbConnection.Open();
            }
            else
            {
                if (dbConnection.State == ConnectionState.Closed)
                {
                    // Ide nem kéne bejönnie...
                    dbConnection.Open();
                }
            }
        }

        private void DoPrepareTransaction()
        {
            if (IsTransactional && dbTransaction == null)
            {
                dbTransaction = dbConnection.BeginTransaction();
            }
        }

        private void DisposeTransaction()
        {
            if (dbTransaction != null)
            {
                try
                {
                    dbTransaction.Dispose();
                }
                finally
                {
                    dbTransaction = null;
                }
            }
        }

        private void CloseLocked()
        {
        }

        private void CloseNotLocked()
        {
            DisposeTransaction();
            if (dbConnection != null)
            {
                try
                {
                    dbConnection.Dispose();
                }
                finally
                {
                    dbConnection = null;
                }
            }
        }

        #endregion

        #region Nyilvános felület

        /// <summary>
        /// Zárolja a munkamenet ügyletét, így a munkamenet passziválásakor nem fog elveszni.
        /// </summary>
        public bool Lock()
        {
            lock (SyncObject)
            {
                if (IsLocked)
                {
                    return false;
                }
                IsLocked = true;

                return true;
            }
        }

        /// <summary>
        /// Feloldja a munkamenet ügyletének zárolását.
        /// </summary>
        public void Unlock()
        {
            lock (SyncObject)
            {
                IsLocked = false;
            }
        }

        /// <summary>
        /// A munkamenethez tartozó adatbáziskapcsolat.
        /// </summary>
        public SDAConnection DBConnection
        {
            get
            {
                Prepare();
                return dbConnection;
            }
        }

        /// <summary>
        /// A munkamenethez tartozó ügylet.
        /// </summary>
        public SDATransaction DBTransaction
        {
            get
            {
                Prepare();
                return dbTransaction;
            }
        }

        /// <summary>
        /// Jóváhagyja az ügyletet.
        /// </summary>
        public void Commit()
        {
            if (IsTransactional && !IsLocked && dbTransaction != null)
            {
                dbTransaction.Commit();
                DisposeTransaction();
            }
        }

        /// <summary>
        /// Visszagörgeti az ügyletet.
        /// </summary>
        public void Rollback()
        {
            if (IsTransactional && dbTransaction != null)
            {
                dbTransaction.Rollback();
                DisposeTransaction();
                DoPrepareTransaction();
            }
        }

        /// <summary>
        /// Lezárja a kontextust.
        /// </summary>
        public void Close()
        {
            if (dbConnection == null && dbTransaction == null)
            {
                return;
            }
            if (IsLocked)
            {
                CloseLocked();
            }
            else
            {
                CloseNotLocked();
            }
        }

        /// <summary>
        /// Lezárja a kontextust.
        /// </summary>
        public void Dispose()
        {
            Close();
            GC.SuppressFinalize(this);
        }

        #endregion
    }
}