public IFdbAsyncEnumerator <TResult> GetEnumerator(FdbAsyncMode mode)
{
IFdbAsyncEnumerator <TSource> inner = null;
try
{
inner = this.Source.GetEnumerator(mode);
Contract.Requires(inner != null, "The underlying async sequence returned an empty enumerator");
var outer = this.Factory(inner);
if (outer == null)
{
throw new InvalidOperationException("The async factory returned en empty enumerator");
}
return(outer);
}
catch (Exception)
{
//make sure that the inner iterator gets disposed if something went wrong
if (inner != null)
{
inner.Dispose();
}
throw;
}
}
protected override Task <bool> OnFirstAsync(CancellationToken ct)
{
// on the first call to MoveNext, we have to hook up with the source iterator
IFdbAsyncEnumerator <TSource> iterator = null;
try
{
iterator = StartInner();
if (iterator == null)
{
return(TaskHelpers.FalseTask);
}
OnStarted(iterator);
return(TaskHelpers.TrueTask);
}
catch (Exception)
{
// whatever happens, make sure that we released the iterator...
if (iterator != null)
{
iterator.Dispose();
iterator = null;
}
throw;
}
finally
{
m_iterator = iterator;
}
}
public void Dispose()
{
try
{
m_iterator.Dispose();
}
finally
{
m_transaction.Dispose();
}
}
protected override void Cleanup()
{
try
{
m_chunkIterator?.Dispose();
}
finally
{
m_chunkIterator = null;
m_chunk = null;
m_outOfChunks = true;
m_currentOffsetInChunk = 0;
m_itemsRemainingInChunk = 0;
}
}
internal static IFdbAsyncEnumerator <T> GetEnumerator([NotNull] FdbAsyncSequenceQuery <T> sequence, FdbAsyncMode mode)
{
var generator = sequence.CompileSequence(sequence.Expression);
if (sequence.Transaction != null)
{
return(generator(sequence.Transaction).GetEnumerator(mode));
}
//BUGBUG: how do we get a CancellationToken without a transaction?
var ct = CancellationToken.None;
IFdbTransaction trans = null;
IFdbAsyncEnumerator <T> iterator = null;
bool success = true;
try
{
trans = sequence.Database.BeginTransaction(ct);
iterator = generator(trans).GetEnumerator();
return(new TransactionIterator(trans, iterator));
}
catch (Exception)
{
success = false;
throw;
}
finally
{
if (!success)
{
if (iterator != null)
{
iterator.Dispose();
}
if (trans != null)
{
trans.Dispose();
}
}
}
}