如何在更新对象状态时使命令同步?
本文关键字：使命 命令 同步 状态 更新 对象 | 更新日期: 2023-09-27 18:14:00
我正在开发一个游戏引擎。angularjs前端与运行在IIS上的。net WebAPI项目中的端点通信。这个web api是一个门面，它只是针对游戏的领域逻辑运行命令，这是一个单独的项目。我有一个工作单元目前正在使用实体框架。
因此，angularjs代码调用IIS上的webapi网站中的端点，创建一个针对游戏运行的命令。例如:open bank account.该命令将从数据存储中加载游戏实例，检查完成情况，然后执行命令打开银行账户。在执行命令中有很多事件会改变游戏实例数据。
我有很多这样的命令，它们都有相同的基类，但是一次只应该调用一个。
public abstract class GameInstanceCommandHandler<T>
: CommandHandlerBase<T, GameInstanceIDCommandResult>
where T : GameInstanceCommand
{
protected GameInstance GameInstance { get; private set; }
protected GameInstanceCommandHandler() { }
public GameInstanceCommandHandler(IUnitOfWork uow)
: base(uow)
{
}
public override GameInstanceIDCommandResult Execute(T command)
{
Check.Null(command, "command");
GameInstance = UnitOfWork.GetGameInstance(command.GameInstanceID);
if (GameInstance == null)
return GetResult(false, "Could not find game instance.");
if (GameInstance.IsComplete)
{
var completeResult = GetResult(GameInstance.ID);
completeResult.Messages.Add("Game is complete, you cannot update the game state.");
completeResult.Success = false;
completeResult.IsGameComplete = true;
return completeResult;
}
UnitOfWork.LoadCollection(GameInstance, p => p.AppInstances);
var result = ExecuteCommand(command);
UnitOfWork.Save();
return result;
}
protected GameInstanceIDCommandResult GetResult(bool success, string message)
{
return new GameInstanceIDCommandResult(success, message);
}
protected GameInstanceIDCommandResult GetResult(Guid id)
{
return new GameInstanceIDCommandResult(id);
}
protected void LoadGameAndGameApps()
{
UnitOfWork.LoadReference(GameInstance, p => p.Game);
UnitOfWork.LoadCollection(GameInstance.Game, p => p.GameApps);
}
protected abstract GameInstanceIDCommandResult ExecuteCommand(T command);
}
所有基类都覆盖抽象的ExecuteCommand。一切都运行良好，我可以使用控制台项目或IIS或任何地方运行我的引擎，这很好。
问题是当多个命令想要同时改变游戏实例状态时。如果我在游戏中调用一个命令来计算银行账户的利息，目前对同一命令的5次调用将创建5次计算。
我想确保在给定的游戏实例中一次只允许执行一个命令。由于这是一个单独的库，而不仅仅是为了在IIS进程中运行而构建的，我知道这个问题应该在这个文件中处理。我考虑过更新代码以匹配下面的内容:
public abstract class GameInstanceCommandHandler<T>
: CommandHandlerBase<T, GameInstanceIDCommandResult>
where T : GameInstanceCommand
{
private static readonly object @lock = new object();
private static volatile List<Guid> GameInstanceIDs = new List<Guid>();
protected GameInstance GameInstance { get; private set; }
protected GameInstanceCommandHandler() { }
public GameInstanceCommandHandler(IUnitOfWork uow)
: base(uow)
{
}
public override GameInstanceIDCommandResult Execute(T command)
{
Check.Null(command, "command");
lock(@lock)
{
// if game id is updating then return
if(GameInstanceIDs.Any(p => p == command.GameInstanceID))
return GetResult(false, "The game is already being updated.");
// (lock for update)
GameInstanceIDs.Add(command.GameInstanceID);
}
try
{
GameInstance = UnitOfWork.GetGameInstance(command.GameInstanceID);
if (GameInstance == null)
return GetResult(false, "Could not find game instance.");
if (GameInstance.IsComplete)
{
var completeResult = GetResult(GameInstance.ID);
completeResult.Messages.Add("Game is complete, you cannot update the game state.");
completeResult.Success = false;
completeResult.IsGameComplete = true;
return completeResult;
}
UnitOfWork.LoadCollection(GameInstance, p => p.AppInstances);
var result = ExecuteCommand(command);
UnitOfWork.Save();
return result;
}
catch (Exception ex)
{ }
finally
{
lock (@lock)
{
GameInstanceIDs.Remove(command.GameInstanceID);
}
}
return GetResult(false, "There was an error.");
}
protected GameInstanceIDCommandResult GetResult(bool success, string message)
{
return new GameInstanceIDCommandResult(success, message);
}
protected GameInstanceIDCommandResult GetResult(Guid id)
{
return new GameInstanceIDCommandResult(id);
}
protected void LoadGameAndGameApps()
{
UnitOfWork.LoadReference(GameInstance, p => p.Game);
UnitOfWork.LoadCollection(GameInstance.Game, p => p.GameApps);
}
protected abstract GameInstanceIDCommandResult ExecuteCommand(T command);
}
这完全解决了我的问题，但还有一些问题。
- 当我在IIS中运行它时会导致我头痛吗?
- 如果我想在许多应用服务器上负载平衡这个库，那么这将不起作用。
- 如果有100万个游戏实例，那么列表将变得巨大，性能将受到影响。
public abstract class GameInstanceCommandHandler<T>
: CommandHandlerBase<T, GameInstanceIDCommandResult>
where T : GameInstanceCommand
{
private static readonly object @lock = new object();
protected GameInstance GameInstance { get; private set; }
protected GameInstanceCommandHandler() { }
public GameInstanceCommandHandler(IUnitOfWork uow)
: base(uow)
{
}
public override GameInstanceIDCommandResult Execute(T command)
{
Check.Null(command, "command");
lock(@lock)
{
GameInstance = UnitOfWork.GetGameInstance(command.GameInstanceID);
if (GameInstance == null)
return GetResult(false, "Could not find game instance.");
if(GameInstance.IsLocked)
return GetResult(false, "Game is locked by another command.");
// Lock the game in the database or datastore
GameInstance.Lock();
UnitOfWork.Save();
// Unlock only local copy
GameInstance.UnLock();
}
try
{
if (GameInstance.IsComplete)
{
var completeResult = GetResult(GameInstance.ID);
completeResult.Messages.Add("Game is complete, you cannot update the game state.");
completeResult.Success = false;
completeResult.IsGameComplete = true;
return completeResult;
}
UnitOfWork.LoadCollection(GameInstance, p => p.AppInstances);
var result = ExecuteCommand(command);
// this will unlock the gameinstance on the save
UnitOfWork.Save();
return result;
}
catch (Exception ex)
{ }
return GetResult(false, "There was an error.");
}
protected GameInstanceIDCommandResult GetResult(bool success, string message)
{
return new GameInstanceIDCommandResult(success, message);
}
protected GameInstanceIDCommandResult GetResult(Guid id)
{
return new GameInstanceIDCommandResult(id);
}
protected void LoadGameAndGameApps()
{
UnitOfWork.LoadReference(GameInstance, p => p.Game);
UnitOfWork.LoadCollection(GameInstance.Game, p => p.GameApps);
}
protected abstract GameInstanceIDCommandResult ExecuteCommand(T command);
}
也许我想错了。
我已经决定，目前最好的方法是有一个id队列。我尝试立即输入游戏实例id，如果插入是OK的，然后继续。完成工作后，从列表中删除id。如果id插入失败，说明id已经存在。
这个修复与锁几乎相同，但我依赖于唯一的键值存储。我可能会创建一个接口和类来处理这个问题，所以如果数据库失败，我可以将失败存储在文件或其他地方，以确保稍后清除id。
我绝对希望得到更多的建议，因为它确实有一种糟糕的代码气味。
public abstract class GameInstanceCommandHandler<T>
: CommandHandlerBase<T, GameInstanceIDCommandResult>
where T : GameInstanceCommand
{
protected GameInstance GameInstance { get; private set; }
protected GameInstanceCommandHandler() { }
public GameInstanceCommandHandler(IUnitOfWork uow)
: base(uow)
{
}
public override GameInstanceIDCommandResult Execute(T command)
{
Check.Null(command, "command");
try
{
AddCommandInstance(command.GameInstanceID);
}
catch(Exception ex)
{
return GetResult(false, "Only one command can be ran on an instance at a time.");
}
GameInstance = UnitOfWork.GameInstances.FirstOrDefault(p => p.ID == command.GameInstanceID);
if (GameInstance == null)
{
RemoveCommandInstance(command.GameInstanceID);
return GetResult(false, "Could not find game instance.");
}
if (GameInstance.IsComplete)
{
var completeResult = GetResult(GameInstance.ID);
completeResult.Messages.Add("Game is complete, you cannot update the game state.");
completeResult.Success = false;
completeResult.IsGameComplete = true;
RemoveCommandInstance(command.GameInstanceID);
return completeResult;
}
UnitOfWork.LoadCollection(GameInstance, p => p.AppInstances);
GameInstanceIDCommandResult result = null;
try
{
result = ExecuteCommand(command);
UnitOfWork.Save();
}
catch(Exception ex)
{
result = GetResult(false, ex.Message);
}
finally
{
RemoveCommandInstance(command.GameInstanceID);
}
return result;
}
private void AddCommandInstance(Guid gameInstanceID)
{
UnitOfWork.Add(new CommandInstance() { ID = gameInstanceID });
UnitOfWork.Save();
}
private void RemoveCommandInstance(Guid gameInstanceID)
{
UnitOfWork.Remove(UnitOfWork.CommandInstances.First(p => p.ID == gameInstanceID));
UnitOfWork.Save();
}
protected GameInstanceIDCommandResult GetResult(bool success, string message)
{
return new GameInstanceIDCommandResult(success, message);
}
protected GameInstanceIDCommandResult GetResult(Guid id)
{
return new GameInstanceIDCommandResult(id);
}
protected void LoadGameAndGameApps()
{
UnitOfWork.LoadReference(GameInstance, p => p.Game);
UnitOfWork.LoadCollection(GameInstance.Game, p => p.GameApps);
}
protected abstract GameInstanceIDCommandResult ExecuteCommand(T command);
}