.NET - First chance exception listener for intensive debugging?

Question

This is probably unrealistic, but would it be possible to enable a component to be notified of all first chance exceptions occuring in its process?

We have some third-party (contracted by us) components which fail to do anything but eat excepitions and the politics of the business relationship make the whole ordeal a royal pain.

We also are aware that some of our code is performing the disappointing action of letting exceptions vanish into the abyss rather than using our centralized exception logger.

I assume our application would have to be started as a child process of a debugging application to achieve the effect, but I figure it's worth asking :)

Answer 1

You can use the .net profiling API to get notifications of exceptions at all sorts of states, these are the available methods:

ExceptionThrown
ExceptionSearchFunctionEnter
ExceptionSearchFunctionLeave
ExceptionSearchFilterEnter
ExceptionSearchFilterLeave
ExceptionSearchCatcherFound
ExceptionOSHandlerEnter
ExceptionOSHandlerLeave
ExceptionUnwindFunctionEnter
ExceptionUnwindFunctionLeave
ExceptionUnwindFinallyEnter
ExceptionUnwindFinallyLeave
ExceptionCatcherEnter
ExceptionCatcherLeave
ExceptionCLRCatcherFound
ExceptionCLRCatcherExecute

Using the profiling api is not entirely for the faint of heart; have a look at http://msdn.microsoft.com/en-us/library/ms404386.aspx as an entry point for your research and http://msdn.microsoft.com/en-us/library/bb384687.aspx for exception handling specifically.

I'm not aware of a simple way to do it within your managed code such as

AppDomain.FirstChanceException += new EventHandler...

event or similar.

EDIT: A possibly better alternative is using the unamanaged debugging API instead.

Basically you can set a ICorManagedCallback/ICorManagedCallback2 callback using ICorDebug::SetManagedHandler and get callbacks when exceptions occur.

I'm not experienced enough in this area to know what the advantages/disadvantages are over the profiling api.

I just had a look at the mdgb sample which uses the ICorDebug APIs and it seems to get quite enough notifications from exceptions (to quickly see what events occur, set a breakpoint in the HandleEvent method in corapi/Debugger.cs:406)