Orleans.VersionedState

This project allows to Transform GrainState between versions as needed. Migrating states is done with Transforms from one to another version. An A* Algoritm looks for the most efficient Transformation path even for complex transformation chains.

Packages

Package	Version
Orleans.VersionedState

Sample Explaination

Working with grain state

The injected state for Grains that use this feature now all have to be of type: 'IPersistentState'. This implies now, that all States for grains inherit from 'VersionedState'. State is Accessed through a StateManager (see Grain setup). The supplied storeHasChanged ref variable is to indicate if the state retrieval did change the state and writing state is suggested.

public async Task<string> GetState()
{
	var hasChanged = false;
	var name = _stateManager.GetState(ref hasChanged).FullName;
	if (hasChanged)
	{
		await _stateManager.WriteStateAsync();
	}
	return name;
}

Grain setup

To work with state we now dont hold on the state, but we instanciate the appropriate StateManager.

public class TestStateGrain : Grain, ITestStateGrain
{
	#region fields
	private readonly TestStateManager _stateManager;
	#endregion

	#region ctor
	public TestStateGrain(
		[PersistentState("TestState", "STORE_NAME")]
		IPersistentState<VersionedStateContainer> state)
	{
		_stateManager = new(state);
	}
	#endregion

Transformations

The generic Argument always represents the currently used type. Transforms are simple definitions that contain the source and target version and also a 'Func<VersionedState, VersionedState>' to define how the transformation between the defined versions is done.

public class TestStateManager : VersionedStateManager<V2TestState>
{
	#region ctor
	public TestStateManager(IStorage<VersionedStateContainer> stateContainer)
		: base(stateContainer)
	{
	}
	#endregion

	#region VersionedStateManager<V1TestState>
	protected override VersionTransform[] Transforms => [
		new VersionTransform(
			1,
			2,
			s => s is V1TestState v1
				? new V2TestState
				{
					FullName = $"{v1.FirstName} {v1.LastName}"
				}
				: throw new Exception("NO!!"))
	];
	#endregion
}

Contribution

Contributions in any way are appechiated (More providers, improvements, documentation or anything else). I Kindly ask you to create a Issue to talk about the planned changes or contact me directly on the Orleans Discord.