使用PostSharp包装方法调用

Question

Is there any way to wrap a method call with PostSharp? I have to add code around/outside a specific call.

The OnMethodBound add the code inside the specified method and the MethodInterception aspect redirects the call to the aspect, but I have to to add code outside the call.

Example: Without aspect:

...
call();
...

With aspect:

beforePart();
call();
afterPart();

Answer 1

Currently, the only scenario in which PostSharp weaves the aspect around the call site is when you apply that aspect to a method in the referenced assembly.

When applying an aspect in your project, you can set the name of the external assembly in the AttributeTargetAssemblies property.

[Log(AttributeTargetAssemblies = "SomeLibrary", ...)]

PostSharp, of course, will not modify the existing external assembly, instead it will weave the aspect in your project's assembly around the calls to the referenced assembly.

Applying the aspect to the calls of the methods from the same assembly is not currently supported. In most scenarios this is not required, or there should be a reasonable workaround.

Maybe we'll be able to solve this if you provide more details about your synchronized method and why it's not possible to use method interception.

Update.

The possible workaround is to introduce the synchronization locks using aspects. You can write a custom OnMethodBoundaryAspect or use SynchronizedAttribute from the Threading Pattern Library.

Then you can use Aspect Dependency or Aspect Priority to make sure that the measuring aspect is introduced before the threading aspect. This way the behavior will be the same as when introducing the measuring aspect around the call site.

[Serializable]
[AspectTypeDependency(AspectDependencyAction.Order,
                      AspectDependencyPosition.Before,
                      typeof(SynchronizedAttribute))]
public class MeasureTimeAttribute : OnMethodBoundaryAspect
{
    // ...
}

Answer 2

I had similar requirement and I wrote a logging aspect for all database calls I make with external library which is Dapper. I created an aspect:

[MulticastAttributeUsage(MulticastTargets.Method)]
[AttributeUsage(AttributeTargets.Assembly | AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = true)]
public sealed class SqlLogger : MethodInterceptionAspect
{
    public override void OnInvoke(MethodInterceptionArgs args)
    {
        // logging code goes here

        base.OnInvoke(args);
    }
}

And then I registered it on assembly level:

[assembly: SqlLogger(AttributeTargetAssemblies = "Dapper", AttributePriority = 1)]