public async Task <long> CreateOrRestoreAsync(IPartitionErrorHandler errorHandler, long firstInputQueuePosition)
{
EventTraceContext.Clear();
this.ErrorHandler = errorHandler;
this.TraceHelper.TraceProgress("Starting partition");
await MaxConcurrentStarts.WaitAsync();
// create or restore partition state from last snapshot
try
{
// create the state
this.State = ((IStorageProvider)this.host).CreatePartitionState();
// initialize timer for this partition
this.PendingTimers = new BatchTimer <PartitionEvent>(this.ErrorHandler.Token, this.TimersFired);
// goes to storage to create or restore the partition state
this.TraceHelper.TraceProgress("Loading partition state");
var inputQueuePosition = await this.State.CreateOrRestoreAsync(this, this.ErrorHandler, firstInputQueuePosition).ConfigureAwait(false);
// start processing the timers
this.PendingTimers.Start($"Timer{this.PartitionId:D2}");
// start processing the worker queues
this.State.StartProcessing();
this.TraceHelper.TraceProgress($"Started partition, nextInputQueuePosition={inputQueuePosition}");
return(inputQueuePosition);
}
catch (Exception e) when(!Utils.IsFatal(e))
{
this.ErrorHandler.HandleError(nameof(CreateOrRestoreAsync), "Could not start partition", e, true, false);
throw;
}
finally
{
MaxConcurrentStarts.Release();
}
}
async Task Work()
{
this.Tracer?.Invoke("started");
EventTraceContext.Clear();
int?previousBatch = null;
while (!this.cancellationToken.IsCancellationRequested)
{
int?nextBatch = this.GetNextBatch();
if (previousBatch.HasValue)
{
this.WorkLoopCompleted(previousBatch.Value, this.stopwatch.Elapsed.TotalMilliseconds, nextBatch);
}
if (!nextBatch.HasValue)
{
this.Tracer?.Invoke("no work, starting to shut down");
// no work found. Announce that we are planning to shut down.
// Using an interlocked exchange to enforce store-load fence.
int read = Interlocked.Exchange(ref this.state, SHUTTINGDOWN);
Debug.Assert(read == RUNNING); // because that's what its set to before Work is called
// but recheck so we don't miss work that was just added
nextBatch = this.GetNextBatch();
if (!nextBatch.HasValue)
{
// still no work. Try to transition to idle but revert if state has been changed.
read = Interlocked.CompareExchange(ref this.state, IDLE, SHUTTINGDOWN);
if (read == SHUTTINGDOWN)
{
// shut down is complete
this.Tracer?.Invoke("shut down");
return;
}
else
{
// shutdown was reverted by Notify()
Debug.Assert(read == RUNNING);
this.Tracer?.Invoke("was told to continue");
continue;
}
}
else
{
// we found more work. So we do not shutdown but go back to running.
this.Tracer?.Invoke("found more work after all");
this.state = RUNNING;
}
}
this.Tracer?.Invoke("processing batch");
this.stopwatch.Restart();
try
{
// recheck for cancellation right before doing work
this.cancellationToken.ThrowIfCancellationRequested();
// do the work, calling the virtual method
await this.Process(this.batch).ConfigureAwait(false);
this.Tracer?.Invoke("notifying waiters");
// notify anyone who is waiting for completion
foreach (var w in this.waiters)
{
w.TrySetResult(true);
}
}
catch (Exception e)
{
foreach (var w in this.waiters)
{
w.TrySetException(e);
}
}
this.Tracer?.Invoke("done processing batch");
this.stopwatch.Stop();
previousBatch = this.batch.Count;
}
}