Net6 DI源码分析Part3 CallSiteRuntimeResolver,CallSiteVisitor

CallSiteRuntimeResolver

CallSiteRuntimeResolver是实现了CallSiteVisitor之一。
提供的方法主要分三个部分

1. 自有成员方法

   1. Resolve提供服务
   2. VisitCache
   3. 私有构造函数

2. 重写父类方法

   1. VisitDisposeCache(ServiceCallSite transientCallSite, RuntimeResolverContext context)
      调用父类VisitCallSiteMain ，并把创建出来的服务添加到context.Scope.CaptureDisposable

      return context.Scope.CaptureDisposable(VisitCallSiteMain(transientCallSite, context));
      

   2. object VisitRootCache(ServiceCallSite callSite, RuntimeResolverContext context)

      1. 先找对应callSite.Value是否有值如果有直接返回
      2. 如果没有直接调用 VisitCallSiteMain创建服务并把对象rootServiceProviderEngine内。
      3. 创建的服务放入callSite.Value。

          if (callSite.Value is object value) 
          {
              return value;
          }
      
      var lockType = RuntimeResolverLock.Root;
      ServiceProviderEngineScope serviceProviderEngine = context.Scope.RootProvider.Root;
      if (callSite.Value is object resolved)
      {
          return resolved;
      }
      resolved = VisitCallSiteMain(callSite, new RuntimeResolverContext
      {
          Scope = serviceProviderEngine,
          AcquiredLocks = context.AcquiredLocks | lockType
      });
      serviceProviderEngine.CaptureDisposable(resolved);
      callSite.Value = resolved;
      return resolved;
      

   3. VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)

      1. 先去serviceProviderEngine.resolvedServices拿,有的话直接返回如果没拿到执行步骤2去创建。serviceProviderEngine.resolvedServices.TryGetValue(callSite.Cache.Key, out object resolved)
      2. VisitCallSiteMain创建对象
      3. 把创建后的对象加入对应Scope的 disposable列表
      4. 把创建后的对象加入对应Scope的 resolvedServices列表

          if (resolvedServices.TryGetValue(callSite.Cache.Key, out object resolved))
          {
              return resolved;
          }
          resolved = VisitCallSiteMain(callSite, new RuntimeResolverContext
          {
              Scope = serviceProviderEngine,
              AcquiredLocks = context.AcquiredLocks | lockType
          });
          serviceProviderEngine.CaptureDisposable(resolved);
          resolvedServices.Add(callSite.Cache.Key, resolved);
          return resolved;
      

3. 实现父类抽象方法

   1. VisitConstructor
      1. 给构造方法提供参数（如果有参数递归调用VisitCallSite创建参数对象）
      2. 直接调用ServiceCallSite的ConstructorInfo反射创建对象。

         object[] parameterValues;
          if (constructorCallSite.ParameterCallSites.Length == 0)
          {
              parameterValues = Array.Empty