/// <summary>
/// Invokes the OnEntry method on all elements of the aspect chain.
/// </summary>
/// <param name="aspects">Aspect chain</param>
/// <param name="args">Method arguments descriptor</param>
/// <returns>Result of the execution</returns>
// ReSharper disable ParameterTypeCanBeEnumerable.Local
private static IMethodResultDescriptor OnEntry(AspectChain aspects, IMethodCallDescriptor args)
// ReSharper restore ParameterTypeCanBeEnumerable.Local
{
try
{
if (aspects == null)
{
return(null);
}
IMethodResultDescriptor result = null;
foreach (var aspect in aspects)
{
result = aspect.OnEntry(args, null);
if (result != null)
{
break;
}
}
return(result);
}
catch (Exception ex)
{
throw new AspectInfrastructureException(
"Aspect infrastructure exception caught in OnEntry", ex);
}
}
/// <summary>
/// Creates an intercepted object for the specified target using the provided aspect chain.
/// </summary>
/// <param name="serviceType">Type of service object</param>
/// <param name="target">Target object to create an intercepted object for</param>
/// <param name="aspects">Aspects to be used for the service object's method calls</param>
/// <returns>Intercepted service object</returns>
public static object GetInterceptedObject(Type serviceType, object target, AspectChain aspects)
{
if (serviceType == null)
{
throw new ArgumentNullException("serviceType");
}
// --- Check the cache
InterceptedTypeDescriptor interceptor;
if (!s_Interceptors.TryGetValue(serviceType, out interceptor))
{
lock (s_Interceptors)
{
// --- Validate again to prevent a parallel type creation
if (!s_Interceptors.TryGetValue(serviceType, out interceptor))
{
// --- Validate input parameters
if (target == null)
{
throw new ArgumentNullException("target");
}
if (!serviceType.IsInterface || !serviceType.IsInstanceOfType(target))
{
throw new InvalidOperationException("Service type must be an interface" +
" type and the target object must implement that interface.");
}
// --- No generics is accepted
if (serviceType.IsGenericType ||
serviceType.GetMethods().Any(met => met.IsGenericMethod) ||
serviceType.GetInterfaces().Any(intf => intf.IsGenericType ||
intf.GetMethods().Any(met => met.IsGenericMethod)))
{
throw new InvalidOperationException(
"Service type must not have generic parameters or methods.");
}
// --- We do not have any wrapper types for the specified service type
// --- Generate the interceptor type and save it in the cache
interceptor = new InterceptedTypeDescriptor
{
InterceptedType = serviceType,
Methods = GetInterfaceMethods(serviceType)
};
GenerateWrappedType(interceptor, serviceType);
s_Interceptors[serviceType] = interceptor;
}
}
}
// --- Instantiate the wrapped type
var wrappedInstance = Activator.CreateInstance(
interceptor.WrapperType,
new[] { target, aspects });
return(wrappedInstance);
}
/// <summary>
/// Checks whether two aspect chains are equal.
/// </summary>
/// <param name="other">The other aspect chain to check for equality</param>
protected bool Equals(AspectChain other)
{
if (_aspects.Count != other._aspects.Count)
{
return(false);
}
return(!_aspects.Where((t, i) => !t.Equals(other._aspects[i]) &&
!ReferenceEquals(t, other._aspects[i])).Any());
}
/// <summary>
/// Invokes the OnException method on all elements of the aspect chain.
/// </summary>
/// <param name="aspects">Aspect chain</param>
/// <param name="args">Method arguments descriptor</param>
/// <param name="ex">Exception instance</param>
/// <returns>Result of the execution</returns>
private static Exception OnException(AspectChain aspects, IMethodCallDescriptor args,
Exception ex)
{
try
{
return(aspects == null
? ex
: aspects.Reverse.Aggregate(ex,
(current, aspect) => aspect.OnException(args, current)));
}
catch (Exception newEx)
{
throw new AspectInfrastructureException(
"Aspect infrastructure exception caught in OnSuccess", newEx);
}
}
/// <summary>
/// Invokes the OnSuccess method on all elements of the aspect chain.
/// </summary>
/// <param name="aspects">Aspect chain</param>
/// <param name="args">Method arguments descriptor</param>
/// <param name="result">Result of the method call</param>
/// <returns>Result of the execution</returns>
private static IMethodResultDescriptor OnSuccess(AspectChain aspects, IMethodCallDescriptor args,
IMethodResultDescriptor result)
{
try
{
if (aspects != null)
{
foreach (var aspect in aspects.Reverse)
{
aspect.OnSuccess(args, result);
}
}
return(result);
}
catch (Exception ex)
{
throw new AspectInfrastructureException(
"Aspect infrastructure exception caught in OnSuccess", ex);
}
}
/// <summary>
/// Invokes the OnExit method on all elements of the aspect chain.
/// </summary>
/// <param name="aspects">Aspect chain</param>
/// <param name="args">Method arguments descriptor</param>
/// <param name="result">Result of the method call</param>
/// <returns>Result of the execution</returns>
private static void OnExit(AspectChain aspects, IMethodCallDescriptor args,
IMethodResultDescriptor result)
{
try
{
if (aspects == null)
{
return;
}
foreach (var aspect in aspects.Reverse)
{
aspect.OnExit(args, result);
}
}
catch (Exception ex)
{
throw new AspectInfrastructureException(
"Aspect infrastructure exception caught in OnExit", ex);
}
}
/// <summary>
/// Creates an intercepted object for the specified target using the provided aspect chain.
/// </summary>
/// <typeparam name="TService">Type of service object</typeparam>
/// <param name="target">Target object to create an intercepted object for</param>
/// <param name="aspects">Aspects to be used for the service object's method calls</param>
/// <returns>Intercepted service object</returns>
public static TService GetInterceptedObject <TService>(TService target, AspectChain aspects)
{
return((TService)GetInterceptedObject(typeof(TService), target, aspects));
}
/// <summary>
/// Executes the method call on the target object and wraps it into the execution of the
/// specified object chain.
/// </summary>
/// <param name="target">Target object</param>
/// <param name="arguments">Method call arguments</param>
/// <param name="targetMethod"></param>
/// <param name="aspects">Aspect chain to execute</param>
/// <param name="methodInfo"></param>
/// <returns>Result of the method execution</returns>
public static IMethodResultDescriptor ExecuteWrappedCall <TService>(TService target, List <MethodArgument> arguments,
MethodInfo methodInfo, Func <IMethodCallDescriptor, TService, IMethodResultDescriptor> targetMethod,
AspectChain aspects)
{
// --- Use the aspects of the object, if that supports IMethodAspect
if (aspects == null)
{
var typeAspects = GetAspects(methodInfo, target.GetType());
if (typeAspects.Count > 0)
{
aspects = new AspectChain(typeAspects);
}
}
var targetAspect = target as IMethodAspect;
if (targetAspect != null)
{
var aspectList = new List <IMethodAspect> {
targetAspect
};
if (aspects != null)
{
aspectList.AddRange(aspects);
}
aspects = new AspectChain(aspectList);
}
// --- Obtain the method descriptor
var args = new MethodCallDescriptor(target, methodInfo, arguments);
var onEntryResult = OnEntry(aspects, args);
if (onEntryResult == null)
{
// --- Call original method body
IMethodResultDescriptor result;
try
{
result = targetMethod(args, target);
}
catch (Exception ex)
{
result = new MethodResultDescriptor(ex);
}
// --- Call OnExit
OnExit(aspects, args, result);
if (result.Exception == null)
{
onEntryResult = OnSuccess(aspects, args, result);
}
else
{
var newEx = OnException(aspects, args, result.Exception);
if (newEx == null)
{
throw new AspectInfrastructureException("OnException returned null.", null);
}
throw newEx;
}
}
return(onEntryResult);
}
