/// <exception cref="SequenceCouldNotBeFoundException">Sequence could not be found</exception>
/// <exception cref="MaximumValueReachedException">The maximum sequence value has been reached and cycle is false</exception>
/// <exception cref="MinimumValueReachedException">The minimum sequence value has been reached and cycle is false</exception>
/// <exception cref="MaxRetryAttemptReachedException">The maximum number of retries has been reached</exception>
public async Task <long> NextAsync(SequenceKey sequenceKey)
{
if (sequenceKey == null)
{
throw new ArgumentNullException("sequenceKey");
}
if (sequenceKey.Value == null)
{
throw new ArgumentNullException("sequenceKey");
}
return(await ExecAsync(sequenceKey, 0));
}
private async Task <long> ExecAsync(SequenceKey sequenceKey, int retryAttempt)
{
var result = await TryGetSequenceValue(sequenceKey);
if (!result.Result)
{
if (retryAttempt < MaxNumberOfAttempts)
{
retryAttempt++;
result.Value = await ExecAsync(sequenceKey, retryAttempt);
}
else
{
throw new MaxRetryAttemptReachedException(MaxNumberOfAttempts);
}
}
return(result.Value);
}
private async Task <TryGetSequenceValueResult> TryGetSequenceValue(SequenceKey sequenceKey)
{
var sequence = await StateProvider.GetAsync(sequenceKey);
if (sequence == null)
{
throw new SequenceCouldNotBeFoundException();
}
var result = new TryGetSequenceValueResult
{
Value = sequence.StartAt
};
if (sequence.Increment == 0)
{
result.Result = true;
return(result);
}
var sequenceValue = sequence.CurrentValue + sequence.Increment;
sequenceValue = CycleOrFailIfGreaterThanMaximum(sequence, sequenceValue);
sequenceValue = CycleOrFailIfLessThanMinimum(sequence, sequenceValue);
sequence.CurrentValue = sequenceValue;
var updateResult = await StateProvider.UpdateAsync(sequenceKey, sequence);
if (!updateResult)
{
return(result);
}
result.Value = sequence.CurrentValue;
result.Result = true;
return(result);
}