Implement Reliable Actors back up and restore

  • Article

Note

Azure recommends to use Periodic back up and restore for configuring data backup of Reliable Stateful services and Reliable Actors.

In the following example, a custom actor service exposes a method to back up actor data by taking advantage of the remoting listener already present in ActorService:

public interface IMyActorService : IService
{
    Task BackupActorsAsync();
}

class MyActorService : ActorService, IMyActorService
{
    public MyActorService(StatefulServiceContext context, ActorTypeInformation typeInfo, Func<ActorBase> newActor)
        : base(context, typeInfo, newActor)
    { }

    public Task BackupActorsAsync()
    {
        return this.BackupAsync(new BackupDescription(PerformBackupAsync));
    }

    private async Task<bool> PerformBackupAsync(BackupInfo backupInfo, CancellationToken cancellationToken)
    {
        try
        {
           // store the contents of backupInfo.Directory
           return true;
        }
        finally
        {
           Directory.Delete(backupInfo.Directory, recursive: true);
        }
    }
}

public interface MyActorService extends Service
{
    CompletableFuture<?> backupActorsAsync();
}

class MyActorServiceImpl extends ActorService implements MyActorService
{
    public MyActorService(StatefulServiceContext context, ActorTypeInformation typeInfo, Func<FabricActorService, ActorId, ActorBase> newActor)
    {
       super(context, typeInfo, newActor);
    }

    public CompletableFuture backupActorsAsync()
    {
        return this.backupAsync(new BackupDescription((backupInfo, cancellationToken) -> performBackupAsync(backupInfo, cancellationToken)));
    }

    private CompletableFuture<Boolean> performBackupAsync(BackupInfo backupInfo, CancellationToken cancellationToken)
    {
        try
        {
           // store the contents of backupInfo.Directory
           return true;
        }
        finally
        {
           deleteDirectory(backupInfo.Directory)
        }
    }

    void deleteDirectory(File file) {
        File[] contents = file.listFiles();
        if (contents != null) {
            for (File f : contents) {
               deleteDirectory(f);
             }
        }
        file.delete();
    }
}

In this example, IMyActorService is a remoting contract that implements IService (C#) and Service (Java), and is then implemented by MyActorService. By adding this remoting contract, methods on IMyActorService are now also available to a client by creating a remoting proxy via ActorServiceProxy:

IMyActorService myActorServiceProxy = ActorServiceProxy.Create<IMyActorService>(
    new Uri("fabric:/MyApp/MyService"), ActorId.CreateRandom());

await myActorServiceProxy.BackupActorsAsync();

MyActorService myActorServiceProxy = ActorServiceProxy.create(MyActorService.class,
    new URI("fabric:/MyApp/MyService"), actorId);

myActorServiceProxy.backupActorsAsync();

For more information on Reliable Actors, read the following articles: