/// <summary>
/// Executes the specified operation inside the current transaction context. If there is no context, a new one will be created with a <see cref="TransactionContextAffinity.NotSupported"/> affinity.
/// </summary>
/// <typeparam name="TState">The type of the data session state.</typeparam>
/// <typeparam name="TResult">The type of the operation result.</typeparam>
/// <param name="transactionGroupName">The transaction group name.</param>
/// <param name="begin">The action to execute when the transaction context begins (before any operation).</param>
/// <param name="commit">The action to execute when committing the transaction context.</param>
/// <param name="rollback">The action to execute when rollbacking the transaction context.</param>
/// <param name="end">The action to execute when the transaction context ends (after all operations).</param>
/// <param name="operation">The operation to execute inside the current transaction context.</param>
/// <returns>The result of the operation.</returns>
public static async Task <TResult> Execute <TState, TResult>(string transactionGroupName, Func <TransactionContext, Task <TState> > begin, Func <DataSession <TState>, Task> commit, Func <DataSession <TState>, Task> rollback, Func <DataSession <TState>, Task> end, Func <DataSession <TState>, Task <TResult> > operation)
{
if (string.IsNullOrEmpty(transactionGroupName))
{
throw new ArgumentNullException(nameof(transactionGroupName));
}
if (begin == null)
{
throw new ArgumentNullException(nameof(begin));
}
if (commit == null)
{
throw new ArgumentNullException(nameof(commit));
}
if (rollback == null)
{
throw new ArgumentNullException(nameof(rollback));
}
if (end == null)
{
throw new ArgumentNullException(nameof(end));
}
if (operation == null)
{
throw new ArgumentNullException(nameof(operation));
}
var current = TransactionContext.CurrentTransactionContext;
bool ownerOfCurrent = false;
if (current == null)
{
current = new TransactionContext(TransactionContextAffinity.NotSupported);
ownerOfCurrent = true;
}
if (current.State == TransactionContextState.Exited)
{
throw new InvalidOperationException(string.Format(Resources.ExceptionMessages.Transactions_InvalidTransactionContextState, string.Join(",", new string[] { TransactionContextState.Entered.ToString(), TransactionContextState.ToBeCommitted.ToString(), TransactionContextState.ToBeRollbacked.ToString() })));
}
if (current.Affinity == TransactionContextAffinity.NotSupported)
{
try
{
var state = await begin(current).ConfigureAwait(false);
var session = new DataSession <TState>(current, transactionGroupName, state, commit, rollback, end);
try
{
var result = await operation(session).ConfigureAwait(false);
if (ownerOfCurrent)
{
current.VoteCommit();
}
return(result);
}
finally
{
await end(session).ConfigureAwait(false);
}
}
finally
{
if (ownerOfCurrent && current != null)
{
current.Exit();
}
}
}
else
{
var controller = current.GetController();
Debug.Assert(controller != null);
var sessionsByTransactionGroup = _pending.GetOrAdd(controller, new ConcurrentDictionary <string, Lazy <Task <DataSession> > >());
var session = await sessionsByTransactionGroup.GetOrAdd(transactionGroupName,
new Lazy <Task <DataSession> >(
async() =>
{
// begin the session here so that it is guaranteed to run only once
var state = await begin(current).ConfigureAwait(false);
return(new DataSession <TState>(current, transactionGroupName, state, commit, rollback, end));
}, LazyThreadSafetyMode.ExecutionAndPublication)).Value.ConfigureAwait(false);
return(await operation((DataSession <TState>) session).ConfigureAwait(false));
}
}
private Task RollbackSession(DataSession<DataSessionState> session)
{
if (session == null) throw new ArgumentNullException(nameof(session));
return Task.Run(
() =>
{
var state = session.State;
WriteOperationTrace(state, "rollbackSession");
WriteOperationTrace(state, "rollbackTransaction");
// catch any further error from DB
// in particular the case where the transaction has already been aborted by the DB itself
try
{
state.Transaction.Rollback();
}
catch (DbException ex)
{
Trace.WriteLine(ex, "NLight");
}
});
}
private Task EndSession(DataSession<DataSessionState> session)
{
if (session == null) throw new ArgumentNullException(nameof(session));
return Task.Run(
() =>
{
var state = session.State;
WriteOperationTrace(state, "endSession");
if (!state.ConnectionClosedByReader)
{
WriteOperationTrace(state, "closeConnection");
state.Connection.Close();
state.Connection.Dispose();
}
});
}
private Task CommitSession(DataSession<DataSessionState> session)
{
if (session == null) throw new ArgumentNullException(nameof(session));
return Task.Run(
() =>
{
var state = session.State;
WriteOperationTrace(state, "commitSession");
WriteOperationTrace(state, "commitTransaction");
state.Transaction.Commit();
});
}