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Game Server on MS Orleans - Part 3: Summary



Hello, Habr! I continue to study MS Orleans and make a simple online game with a console client and server working with Orleans grains. This time I will tell you how it all ended and what conclusions I made for myself. For details, welcome to cat.

So yes, if you are interested at all how game servers for dynamic games are made, and not my experiment with MS Orleans, I recommend that you look at this repository (UDP) and read these articles:

  1. habr.com/en/post/303006
  2. habr.com/en/post/328118
  3. habr.com/en/company/pixonic/blog/499642
  4. habr.com/en/company/pixonic/blog/420019

Content



Source code


MsOrleansOnlineGame

About the game


The result was a simple shooter. Green # are opponents. Yellow # is your character. Red $ is a bullet. Shooting is in the direction where you are going. The direction of movement is controlled by the WASD buttons or arrows. The space bar is used for the shot. I do not see the point of describing the client code in detail because it needs to be replaced with a normal one. Graphic.

About actors (grains)


In short: My IMHO that Orleans is a gRPC on steroids honed under Azure, scaling and working with an memorial. With a cache for example. Although without a state, like a regular RPC, he knows how to work through Stateless Worker Grains. Grain (Actor) in Orleans can act as an entry point as a Controller in Asp.Net. But unlike the Controller, the grain has one single instance that has its own identifier. Grains are good when you need to work with some state at the same time from several threads or from several users. They provide thread safe operation with it.

For example, here is an actor for a basket of goods. At the first call, it will be created and will hang in memory playing the role of a cache. At the same time, thousands of users from thousands of different streams can simultaneously make requests to it for adding and removing items. All work with his condition inside him will be absolutely thread safe. In this case, of course, it would be useful to make an actor Shop with the List GetBaskets () method to get a list of all the baskets available in the system. At the same time, the Shop will also hang in the memory as a cache and all work with it will be thread safe.

    public interface IBasket : IGrainWithGuidKey
    {
        Task Add(string item);
        Task Remove(string item);
        Task<List<string>> GetItems();
    }

    public class BasketGrain : Grain, IBasket
    {
        private readonly ILogger<BasketGrain> _logger;
        private readonly IPersistentState<List<string>> _store;

        public BasketGrain(
            ILogger<BasketGrain> logger,
            [PersistentState("basket", "shopState")] IPersistentState<List<string>> store
        )
        {
            _logger = logger;
            _store = store;
        }

         public override Task OnActivateAsync()
        {
             var shop = GrainFactory.GetGrain<IShop>();
           //          .
            await shop.AddBasketIfNotContains(this.GetPrimaryKey())
            return base.OnActivateAsync();
        }

        public override async Task OnDeactivateAsync()
        {
          //       
         //    Asp.Net  . 
        //           - .
        //    -      .
        //         .
     //        
            await _store.WriteStateAsync();
            await base.OnDeactivateAsync();
        }


        public Task Add(string item)
        {
            _store.State.Add(item);
            return Task.CompletedTask;
        }

        public Task Remove(string item)
        {
            _store.State.Remove(item);
            return Task.CompletedTask;
        }

        public Task<List<string>> GetItems()
        {
           //      .
          //        
         //           
            return Task.FromResult(new List<string>(_store.State));
        }
    }

An example of use in some console application:

         private static async Task DoClientWork(IClusterClient client, Guid baskeId)
        {
            var basket = client.GetGrain<IBasket>(baskeId);
           //   gRPC -                
            await basket.Add("Apple");
        }

Game code



The map on which the players fight:

   public interface IFrame : IGrainWithIntegerKey
    {
        Task Update(Frame frame);
        Task<Frame> GetState();
    }

    public class FrameGrain : Grain, IFrame
    {
        private readonly ILogger<FrameGrain> _logger;
        private readonly IPersistentState<Frame> _store;

        public FrameGrain(
            ILogger<FrameGrain> logger,
            [PersistentState("frame", "gameState")] IPersistentState<Frame> store
        )
        {
            _logger = logger;
            _store = store;
        }

        public override Task OnActivateAsync()
        {
            _logger.LogInformation("ACTIVATED");
           //    1  1      .
            _store.State.GameId = this.GetPrimaryKeyLong();
            return base.OnActivateAsync();
        }

        public override async Task OnDeactivateAsync()
        {
            _logger.LogInformation("DEACTIVATED");
            await _store.WriteStateAsync();
            await base.OnDeactivateAsync();
        }

        public Task Update(Frame frame)
        {
            _store.State = frame;
            return Task.CompletedTask;
        }

        public Task<Frame> GetState() => Task.FromResult(_store.State.Clone());
    }

Grain of the game which stores the general state of the current game and sends it to the client 20 times per second via SignalR.

    public interface IGame : IGrainWithIntegerKey
    {
        Task Update(Player player);
        Task Update(Bullet bullet);
        Task<List<Player>> GetAlivePlayers();
    }

    public class GameGrain : Grain, IGame
    {
        private const byte WIDTH = 100;
        private const byte HEIGHT = 50;
        private readonly ILogger<GameGrain> _logger;
        private readonly IPersistentState<Game> _store;
        private readonly IHubContext<GameHub> _hub;
        private IDisposable _timer;
        public GameGrain(
            ILogger<GameGrain> logger,
            [PersistentState("game", "gameState")] IPersistentState<Game> store,
            IHubContext<GameHub> hub
            )
        {
            _logger = logger;
            _store = store;
            _hub = hub;
        }

        public override async Task OnActivateAsync()
        {
            _store.State.Id = this.GetPrimaryKeyLong();
            _store.State.Frame = new Frame(WIDTH, HEIGHT) { GameId = _store.State.Id };
            var frame = GrainFactory.GetGrain<IFrame>(_store.State.Id);
            await frame.Update(_store.State.Frame.Clone());
            _logger.LogWarning("ACTIVATED");
            //      50      .       .
            _timer = RegisterTimer(Draw, null, TimeSpan.FromMilliseconds(100), TimeSpan.FromMilliseconds(50));
            await base.OnActivateAsync();
        }

        public override async Task OnDeactivateAsync()
        {
            _logger.LogWarning("DEACTIVATED");
            _timer?.Dispose();
            _timer = null;
            await _store.WriteStateAsync();
            await base.OnDeactivateAsync();
        }

        public async Task Draw(object obj)
        {
            var state = _store.State;
            state.Bullets.RemoveAll(b => !b.IsAlive);
            state.Players.RemoveAll(p => !p.IsAlive);
            try
            {
                await _hub.Clients.All.SendAsync("gameUpdated", state.Clone());
            }
            catch (Exception e)
            {
                _logger.LogError(e, "Error on send s");
            }
        }

        public Task Update(Player player)
        {
            _store.State.Players.RemoveAll(x => x.Id == player.Id);
            _store.State.Players.Add(player);
            return Task.CompletedTask;
        }
        public Task Update(Bullet bullet)
        {
            _store.State.Bullets.RemoveAll(x => x.Id == bullet.Id);
            _store.State.Bullets.Add(bullet);
            return Task.CompletedTask;
        }

        public Task<List<Player>> GetAlivePlayers() =>
            Task.FromResult(_store.State.Players.Where(p => p.IsAlive).Select(p => p.Clone()).ToList());
    }

SignalR is the hub through which we communicate with the client. It acts as a proxy between the WebGl client and Orleans. So far, the client is console and he is wildly dumb. I want to make a web client in the future in a browser on Three.js and therefore I need a connection on the SignalR web socket. The Orleans client itself is only in C #, unlike gRPC, which is available in many languages, therefore, for the web client, between the Orleans server and the clients you need to install a proxy (Gateway asp.net core).

    public class GameHub : Hub
    {
        private readonly IGrainFactory _client;

        public GameHub(IGrainFactory client)
        {
            _client = client;
        }

        public async Task GameInput(Input input)
        {
            var player = _client.GetGrain<IPlayer>(input.PlayerId);
            await player.Handle(input);
        }
    }

Grain player. It automatically moves according to the timer and responds to user commands. If a shoot command arrives, he creates a bullet graine and sets the direction of movement for him.

    public class PlayerGrain : Grain, IPlayer
    {
        private readonly ILogger<PlayerGrain> _logger;
        private readonly IPersistentState<Player> _store;
        private IDisposable _timer;
        private readonly Queue<Input> _inputs;
        public PlayerGrain(
            ILogger<PlayerGrain> logger,
            [PersistentState("player", "gameState")] IPersistentState<Player> store
        )
        {
            _logger = logger;
            _store = store;
            _inputs = new Queue<Input>();
        }

        public override Task OnActivateAsync()
        {
            _logger.LogInformation("ACTIVATED");
            // State   POCO     . Entity Player   
            _store.State.Id = this.GetPrimaryKey();
            _timer = RegisterTimer(Update, null, TimeSpan.FromMilliseconds(1), TimeSpan.FromMilliseconds(200));
            return base.OnActivateAsync();
        }

        public override async Task OnDeactivateAsync()
        {
            _logger.LogInformation("ACTIVATED");
            _timer?.Dispose();
            _timer = null;
            await _store.WriteStateAsync();
            await base.OnDeactivateAsync();
        }

        public async Task Handle(Input input)
        {
            _store.State.GameId = input.GameId;
            _inputs.Enqueue(input);
        }

        public async Task Update(object obj)
        {
            if (!_store.State.IsAlive)
            {
                await _store.ClearStateAsync();
               //          .
             //       .       .
                DeactivateOnIdle();
                return;
            }

            while (_inputs.Count > 0)
            {
                var input = _inputs.Dequeue();
                foreach (var direction in input.Directions.Where(d => d != Direction.None))
                {
                    _store.State.Direction = direction;
                }

                foreach (var command in input.Commands.Where(c => c != Command.None))
                {
                    if (command == Command.Shoot)
                    {
                        var bulletId = Guid.NewGuid();
                        var bullet = GrainFactory.GetGrain<IBullet>(bulletId);
                        //  Shot()           .
                        bullet.Update(_store.State.Shot()).Ignore(); //Ignore()        
                    }
                }
            }
            _store.State.Move();
            if (_store.State.GameId.HasValue)
            {
                var frame = GrainFactory.GetGrain<IFrame>(_store.State.GameId.Value);
                var fs = await frame.GetState();
                if (fs.Collide(_store.State))
                    _store.State.MoveBack();
                GrainFactory.GetGrain<IGame>(_store.State.GameId.Value)
                    .Update(_store.State.Clone())
                    .Ignore();
            }
        }

        public async Task Die()
        {
            _store.State.IsAlive = false;
            if (_store.State.GameId.HasValue)
                await GrainFactory.GetGrain<IGame>(_store.State.GameId.Value).Update(_store.State.Clone());
            await _store.ClearStateAsync();
            DeactivateOnIdle();
        }
    }


Grain bullets. It automatically moves on a timer and, if it encounters a player, orders it to die. If she encounters an obstacle on the map, she dies herself.
  public interface IBullet : IGrainWithGuidKey
    {
        Task Update(Bullet dto);
    }

    public class BulletGrain : Grain, IBullet
    {
        private readonly ILogger<BulletGrain> _logger;
        private readonly IPersistentState<Bullet> _store;
        private IDisposable _timer;
        public BulletGrain(
            ILogger<BulletGrain> logger,
            [PersistentState("bullet", "gameState")] IPersistentState<Bullet> store
        )
        {
            _logger = logger;
            _store = store;
        }

        public Task Update(Bullet dto)
        {
            _store.State = dto;
            _store.State.Id = this.GetPrimaryKey();
            return Task.CompletedTask;
        }

        public override Task OnActivateAsync()
        {
            _logger.LogInformation("ACTIVATED");
            _timer = this.RegisterTimer(Update, null, TimeSpan.FromMilliseconds(1), TimeSpan.FromMilliseconds(50));
            return base.OnActivateAsync();
        }

        public override async Task OnDeactivateAsync()
        {
            _logger.LogInformation("DEACTIVATED");
            _timer?.Dispose();
            _timer = null;
            await _store.WriteStateAsync();
            await base.OnDeactivateAsync();
        }

        public async Task Update(object obj)
        {
            if (!_store.State.IsAlive)
            {
                await _store.ClearStateAsync();
                DeactivateOnIdle();
                return;
            }
            _store.State.Move();
            if (_store.State.GameId.HasValue)
            {
                var frame = GrainFactory.GetGrain<IFrame>(_store.State.GameId.Value);
                var fs = await frame.GetState();
                if (fs.Collide(_store.State))
                    _store.State.IsAlive = false;
                if (_store.State.Point.X > fs.Width || _store.State.Point.Y > fs.Height)
                    _store.State.IsAlive = false;
                var game = GrainFactory.GetGrain<IGame>(_store.State.GameId.Value);
                var players = await game.GetAlivePlayers();
                foreach (var player in players)
                {
                    if (player.Collide(_store.State))
                    {
                        _store.State.IsAlive = false;
                        GrainFactory.GetGrain<IPlayer>(player.Id).Die().Ignore();
                        break;
                    }
                }
                game.Update(_store.State.Clone()).Ignore();
            }
        }
    }

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