/// <summary>
/// Loads the specified session.
/// </summary>
/// <param name="session">The session to load.</param>
/// <returns>
/// <see cref="System.Threading.Tasks.Task{T}" /> that can be awaited.
/// </returns>
/// <exception cref="ArgumentNullException">
/// If <paramref name="session" /> is null.
/// </exception>
/// <exception cref="ArgumentException">
/// If <paramref name="session" /> has been already loaded or canceled.
/// </exception>
public async Task<Session> Load( Session session )
{
//Contract.Requires<ArgumentNullException>( session != null, "session" );
if( session.State != SessionState.Created )
{
throw new ArgumentException( "Invalid session state.", "session" );
}
ActionRegistration action;
if( !_actions.TryGetValue( session.Action, out action ) )
{
throw new Exception( "Session with invalid action." );
}
if( !action.Validate( session ) )
{
session.State = SessionState.Complete;
return session;
}
lock( _sessions )
{
if( session.Exclusive )
{
if( _sessions.Count > 0 )
{
foreach( var existingSession in _sessions )
{
existingSession.Cancel();
}
_sessions.Clear();
}
}
_sessions.Add( session );
}
OnSessionStarted( new SessionEventArgs( session ) );
if( session.IsCancellationRequested )
{
lock( _sessions )
{
_sessions.Remove( session );
}
return session;
}
session.State = SessionState.Active;
if( DataExchangeService != null )
{
DataExchangeService.BeginDataExchange();
}
Task task = null;
try
{
task = action.Process( session );
}
catch( Exception ex )
{
lock( _sessions )
{
_sessions.Remove( session );
}
if( DataExchangeService != null )
{
DataExchangeService.EndDataExchange();
}
var canceled = ex is OperationCanceledException;
var eventArgs = new SessionAbortedEventArgs( session, canceled ? null : ex );
OnSessionAborted( eventArgs );
if( !canceled && !eventArgs.Handled )
{
if( ViewModelExceptionHandlingService == null || !ViewModelExceptionHandlingService.HandleException( this, session, ex ) )
{
throw;
}
}
return session;
}
if( task == null )
{
lock( _sessions )
{
_sessions.Remove( session );
}
session.State = SessionState.Complete;
if( DataExchangeService != null )
{
DataExchangeService.EndDataExchange();
}
OnSessionComplete( new SessionEventArgs( session ) );
return session;
}
try
{
await task;
session.State = SessionState.Complete;
OnSessionComplete( new SessionEventArgs( session ) );
}
catch( Exception ex )
{
var canceled = ex is OperationCanceledException;
var eventArgs = new SessionAbortedEventArgs( session, canceled ? null : ex );
var aggregateException = ex as AggregateException;
if( aggregateException != null )
{
canceled = aggregateException.InnerExceptions.OfType<OperationCanceledException>().Any();
}
OnSessionAborted( eventArgs );
if( !canceled && !eventArgs.Handled )
{
if( ViewModelExceptionHandlingService == null || !ViewModelExceptionHandlingService.HandleException( this, session, ex ) )
{
throw;
}
}
}
finally
{
lock( _sessions )
{
_sessions.Remove( session );
}
if( DataExchangeService != null )
{
DataExchangeService.EndDataExchange();
}
}
return session;
}
/// <summary>
/// Raises the session aborted event.
/// </summary>
/// <param name="e">
/// The <see cref="Digillect.Mvvm.SessionAbortedEventArgs" /> instance containing the event data.
/// </param>
protected virtual void OnSessionAborted( SessionAbortedEventArgs e )
{
if( SessionAborted != null )
{
SessionAborted( this, e );
}
}
