/// <summary>
/// Stops the partition pump. In case it hasn't been started, nothing happens.
/// </summary>
///
/// <param name="reason">The reason why the partition pump is being closed.</param>
///
/// <returns>A task to be resolved on when the operation has completed.</returns>
///
private async Task StopAsync(PartitionProcessorCloseReason reason)
{
if (RunningTask != null)
{
await RunningTaskSemaphore.WaitAsync().ConfigureAwait(false);
try
{
if (RunningTask != null)
{
RunningTaskTokenSource.Cancel();
RunningTaskTokenSource = null;
try
{
await RunningTask.ConfigureAwait(false);
}
finally
{
RunningTask = null;
}
await InnerConsumer.CloseAsync().ConfigureAwait(false);
InnerConsumer = null;
await PartitionProcessor.CloseAsync(reason).ConfigureAwait(false);
}
}
finally
{
RunningTaskSemaphore.Release();
}
}
}
/// <summary>
/// Stops the partition pump. In case it isn't running, nothing happens.
/// </summary>
///
/// <param name="reason">The reason why the associated partition processor is being closed. In case it's <c>null</c>, the internal close reason set by this pump is used.</param>
///
/// <returns>A task to be resolved on when the operation has completed.</returns>
///
public async Task StopAsync(PartitionProcessorCloseReason?reason)
{
if (RunningTask != null)
{
await RunningTaskSemaphore.WaitAsync().ConfigureAwait(false);
try
{
if (RunningTask != null)
{
RunningTaskTokenSource.Cancel();
RunningTaskTokenSource = null;
try
{
// RunningTask is only expected to fail when the partition processor throws while processing
// an error, but unforeseen scenarios might happen.
await RunningTask.ConfigureAwait(false);
}
catch (Exception)
{
// TODO: delegate the exception handling to an Exception Callback.
}
RunningTask = null;
// It's important to close the consumer as soon as possible. Failing to do so multiple times
// would make it impossible to create more consumers for the associated partition as there's a
// limit per client.
await InnerConsumer.CloseAsync().ConfigureAwait(false);
// In case an exception is encountered while partition processor is closing, don't catch it and
// let the event processor handle it. The pump has no way to guess when a partition was lost or
// when a shutdown request was sent to the event processor, so it expects a "reason" parameter to
// provide this information. However, in case of pump failure, the external event processor does
// not have enough information to figure out what failure reason to use, as this information is
// only known by the pump. In this case, we expect the processor-provided reason to be null, and
// the private CloseReason is used instead.
await PartitionProcessor.CloseAsync(Context, reason ?? CloseReason).ConfigureAwait(false);
}
}
finally
{
RunningTaskSemaphore.Release();
}
}
}
