/// <summary>
/// Enables run-time interception support for methods and properties using dynamic proxy technique.
/// </summary>
/// <param name="services"></param>
/// <returns></returns>
public static IServiceCollection EnableDynamicProxy(this IServiceCollection services)
{
var proxyConfig = new DynamicProxyConfiguration(services);
var typesInAssembly = Assembly.GetCallingAssembly().GetTypes();
AddInterceptorMappings(proxyConfig, typesInAssembly);
services.TryAddSingleton(proxyConfig);
services.TryAddSingleton <IProxyGenerator, ProxyGenerator>();
var serviceTypes = typesInAssembly
.Where(x => x.GetCustomAttribute <InterceptAttribute>() != null);
var serviceProvider = services.BuildServiceProvider();
foreach (var type in serviceTypes)
{
var serviceType = type.GetCustomAttribute <InterceptAttribute>().ServiceType;
var targetObj = serviceProvider.GetRequiredService(serviceType);
var proxyObj = new ProxyFactory(serviceProvider, proxyConfig).CreateProxy(serviceType, targetObj);
var serviceDescriptor = services.FirstOrDefault(x => x.ServiceType == serviceType);
// Remove previous implementation and add the decorated service.
services.Remove(serviceDescriptor);
services.Add(new ServiceDescriptor(serviceType, sp => proxyObj, serviceDescriptor.Lifetime));
}
return(services);
}
private static void AddInterceptorMappings(DynamicProxyConfiguration proxyConfig, System.Type[] typesInAssembly)
{
var interceptors = typesInAssembly
.Where(x => x.GetCustomAttribute <InterceptForAttribute>() != null);
foreach (var interceptor in interceptors)
{
var attribute = interceptor.GetCustomAttribute <InterceptForAttribute>().AttributeType;
proxyConfig.AddInterceptor(attribute, interceptor);
}
}
public CoreInterceptor(IServiceProvider serviceProvider, DynamicProxyConfiguration proxyConfig)
{
this.serviceProvider = serviceProvider;
this.proxyConfig = proxyConfig;
}
public ProxyFactory(IServiceProvider serviceProvider, DynamicProxyConfiguration proxyConfig)
{
this.serviceProvider = serviceProvider;
this.proxyConfig = proxyConfig;
this.proxyGenerator = serviceProvider.GetRequiredService <IProxyGenerator>();
}
public static IEnumerable <IMethodInterceptor> FindMethodInterceptors(this Castle.DynamicProxy.IInvocation invocation, DynamicProxyConfiguration proxyConfig, IServiceProvider serviceProvider)
{
var interceptors = new List <IMethodInterceptor>();
var attributes = invocation.MethodInvocationTarget.GetCustomAttributes()
.Where(x => x.GetType().IsSubclassOf(typeof(MethodInterceptorAttribute)))
.Cast <MethodInterceptorAttribute>();
foreach (var attribute in attributes)
{
var interceptorType = proxyConfig.Interceptors.FirstOrDefault(x => x.AttributeType == attribute.GetType())?.InterceptorType;
if (interceptorType == null)
{
throw new InvalidOperationException($"No suitable interceptor found for type {attribute}");
}
var interceptorInstance = (IMethodInterceptor)ActivatorUtilities.CreateInstance(serviceProvider, interceptorType);
interceptors.Add(interceptorInstance);
}
return(interceptors);
}
