Add rewind to point functionality

[lucaslorentz]

Implement a rewind to point functionality where you chose the point in history that you want to rewind to.

Algorithm:

• Find last execution
• Retrieve all events from last execution
• Replace all events after the desired point by generic nop events
• For every removed event of types: TaskCompleted, TaskFailed:
  • Find the corresponding TaskScheduled event and add it to activity queue
• For every removed event of type: TimerFired
  • Find the corresponding TimerCreated event and add it to orchestration queue
• For every removed event of types: SubOrchestrationInstanceCompleted, SubOrchestrationInstanceFailed:
  • Find the corresponding SubOrchestrationInstanceCreated event and add it to orchestration queue.
• If it is a suborchestration, rewind parent orchestration from the suborchestration completed/failed event forward

Concerns:

• Would this repeat the instanceId of suborchestrations and give it a new execution?

[lucaslorentz]

The algorithm was improved and implemented at

durabletask-extensions/src/LLL.DurableTask.EFCore/EFCoreOrchestrationServiceClient.cs

Line 284 in fb014b5

private async Task RewindInstanceAsync(OrchestrationDbContext dbContext, string instanceId, string reason, bool rewindParents, Func<IList<HistoryEvent>, HistoryEvent> findRewindPoint)

It also rewinds suborchestrations that had their completion event rewound in the current orchestration.
It also rewinds parent orchestrations to before the current orchestration completion event.

There is no API yet though that allows us to chose the rewind point.

[nathan815]

Is it possible to use this improved Rewind algorithm with the AzureStorage backend?

I am hitting durabletask#811 and noticed you had replied there. But it looks like this improved Rewind only works with EFCore. Is my understanding correct?

Also, thanks for your work on this @lucaslorentz. durabletask-extensions looks great.

[lucaslorentz]

@nathan815 You understood correctly. The rewind logic is specific to each storage implementation, it is not possible to use the implementation I did with AzureStorage backend.