如何确保Orleans中同一游戏实例的关联Grain在同一个Silo激活

核心实现思路 #

你需要通过自定义Grain放置策略，让所有关联同一个GameGuid的Grain都绑定到GameGrain所在的Silo上，具体实现步骤如下：

步骤1：实现自定义放置策略类 #

首先继承Orleans的PlacementStrategy基类，定义游戏关联放置策略，仅作为标记使用无需额外逻辑：

public class GameAffinityPlacementStrategy : PlacementStrategy
{
}

步骤2：实现放置定向器 #

继承IPlacementDirector<GameAffinityPlacementStrategy>，实现核心路由逻辑：

public class GameAffinityPlacementDirector : IPlacementDirector<GameAffinityPlacementStrategy>
{
    private readonly IManagementGrain _managementGrain;
    private readonly IGrainFactory _grainFactory;

    public GameAffinityPlacementDirector(IManagementGrain managementGrain, IGrainFactory grainFactory)
    {
        _managementGrain = managementGrain;
        _grainFactory = grainFactory;
    }

    public async Task<SiloAddress> OnAddActivation(PlacementStrategy strategy, PlacementTarget target, IPlacementContext context)
    {
        // 从当前Grain主键提取GameGuid
        var gameId = ExtractGameIdFromGrainKey(target.GrainId);
        if (gameId == Guid.Empty)
        {
            // 提取失败则降级为默认放置逻辑
            return context.GetCompatibleSilos(target).First();
        }

        // 获取对应GameGrain的激活位置
        var gameGrain = _grainFactory.GetGrain<IGameGrain>(gameId);
        var gameActivations = await _managementGrain.GetGrainActivations(new[] { gameGrain.GetGrainId() });
        
        if (gameActivations.Any())
        {
            // GameGrain已激活，直接返回其所在Silo地址
            return gameActivations.First().SiloAddress;
        }

        // GameGrain未激活时按默认规则选Silo，后续GameGrain激活时会遵循同策略保持位置一致
        return context.GetCompatibleSilos(target).First();
    }

    // 从Grain主键提取GameGuid的工具方法
    private Guid ExtractGameIdFromGrainKey(GrainId grainId)
    {
        var keyStr = grainId.Key.ToString();
        // 适配PlayerGrain主键格式：<GameGuid>-<PlayerGuid>
        if (keyStr.Contains('-') && keyStr.Split('-').Length == 2)
        {
            if (Guid.TryParse(keyStr.Split('-')[0], out var gameId))
            {
                return gameId;
            }
        }
        // 适配GameGrain/WeaponsGrain主键格式：直接为GameGuid
        if (Guid.TryParse(keyStr, out var directGameId))
        {
            return directGameId;
        }
        return Guid.Empty;
    }
}

步骤3：为需要共置的Grain绑定策略 #

给三个需要同Silo激活的Grain加上Placement特性，指定使用自定义策略：

[Placement(typeof(GameAffinityPlacementStrategy))]
public class GameGrain : Grain, IGameGrain
{
    // 业务逻辑
}

[Placement(typeof(GameAffinityPlacementStrategy))]
public class PlayerGrain : Grain, IPlayerGrain
{
    // 业务逻辑
}

[Placement(typeof(GameAffinityPlacementStrategy))]
public class WeaponsGrain : Grain, IWeaponsGrain
{
    // 业务逻辑
}

步骤4：Silo启动时注册策略 #

修改Silo配置代码，注册自定义的放置策略和定向器：

var builder = Host.CreateDefaultBuilder(args)
    .UseOrleans(siloBuilder =>
    {
        // 其他Silo配置
        siloBuilder.AddPlacementDirector<GameAffinityPlacementStrategy, GameAffinityPlacementDirector>();
    });

异常场景适配 #

如果出现Silo宕机导致GameGrain迁移的情况，该策略会自动识别新的GameGrain激活位置，后续新拉起的关联Grain会自动绑定到新Silo，无需额外手动处理迁移逻辑。

内容的提问来源于stack exchange，提问作者Monku