mirror of https://github.com/Sonarr/Sonarr
129 lines
3.9 KiB
C#
129 lines
3.9 KiB
C#
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace Marr.Data
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{
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/// <summary>
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/// The UnitOfWork class can be used to manage the lifetime of an IDataMapper, from creation to disposal.
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/// When used in a "using" statement, the UnitOfWork will create and dispose an IDataMapper.
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/// When the SharedContext property is used in a "using" statement,
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/// it will create a parent unit of work that will share a single IDataMapper with other units of work,
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/// and the IDataMapper will not be disposed until the shared context is disposed.
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/// If more than one shared context is created, the IDataMapper will be disposed when the outer most
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/// shared context is disposed.
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/// </summary>
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/// <remarks>
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/// It should be noted that the Dispose method on the UnitOfWork class only affects the managed IDataMapper.
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/// The UnitOfWork instance itself is not affected by the Dispose method.
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/// </remarks>
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public class UnitOfWork : IDisposable
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{
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private Func<IDataMapper> _dbConstructor;
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private IDataMapper _lazyLoadedDB;
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private short _transactionCount;
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public UnitOfWork(Func<IDataMapper> dbConstructor)
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{
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_dbConstructor = dbConstructor;
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}
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/// <summary>
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/// Gets an IDataMapper object whose lifetime is managed by the UnitOfWork class.
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/// </summary>
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public IDataMapper DB
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{
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get
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{
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if (_lazyLoadedDB == null)
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{
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_lazyLoadedDB = _dbConstructor.Invoke();
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}
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return _lazyLoadedDB;
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}
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}
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/// <summary>
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/// Instructs the UnitOfWork to share a single IDataMapper instance.
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/// </summary>
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public UnitOfWorkSharedContext SharedContext
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{
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get
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{
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return new UnitOfWorkSharedContext(this);
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}
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}
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public void BeginTransaction()
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{
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// Only allow one transaction to begin
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if (_transactionCount < 1)
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{
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DB.BeginTransaction();
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}
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_transactionCount++;
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}
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public void Commit()
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{
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// Only allow the outermost transaction to commit (all nested transactions must succeed)
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if (_transactionCount == 1)
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{
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DB.Commit();
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}
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_transactionCount--;
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}
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public void RollBack()
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{
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// Any level transaction should be allowed to rollback
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DB.RollBack();
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// Throw an exception if a nested ShareContext transaction rolls back
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if (_transactionCount > 1)
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{
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throw new NestedSharedContextRollBackException();
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}
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_transactionCount--;
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}
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public void Dispose()
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{
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if (!IsShared)
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{
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ForceDispose();
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}
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}
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internal bool IsShared { get; set; }
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private void ForceDispose()
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{
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_transactionCount = 0;
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if (_lazyLoadedDB != null)
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{
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_lazyLoadedDB.Dispose();
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_lazyLoadedDB = null;
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}
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}
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}
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[Serializable]
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public class NestedSharedContextRollBackException : Exception
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{
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public NestedSharedContextRollBackException() { }
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public NestedSharedContextRollBackException(string message) : base(message) { }
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public NestedSharedContextRollBackException(string message, Exception inner) : base(message, inner) { }
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protected NestedSharedContextRollBackException(
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System.Runtime.Serialization.SerializationInfo info,
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System.Runtime.Serialization.StreamingContext context)
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: base(info, context) { }
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}
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}
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