In a Visual Studio Extension, how to detect when the debugger Continues

Question

I need my Visual Studio extension to react to debugging events. I've registered a IDebugEventCallback2 and I'm receiving events, but all I get for each event is an opaque IDebugEvent2 and a Guid, many of which are not only undocumented but don't appear anywhere on the web (or in my registry).

My specific requirement at the moment is to know when the process is Continued - ie. the user has hit Continue, Run to cursor, etc. What Guid should I be looking for?

Or is there some other event family that I should be subscribing to?

(More generally, is there some way I'm missing to find out about the events that are delivered to my IDebugEventCallback2::Event callback, when many of them don't appear in MSDN or anywhere else? Thanks!)

Answer 1

There is no easy way to do this. Actions such as Continue and Run to cursor are abstractions implemented by Visual Studio and do not correspond to any unique event(s) with respect to the debug engine. The debug engine event reporting interface IDebugEventCallback2 will enable you to get notified only on fine-grained events such as when creating a breakpoint or reaching a breakpoint.

While Visual Studio enables you to perform actions such as Continue and Run to cursor programmatically, it does not provide a direct way to get notified when they are taken.

You can use EnvDTE.DebuggerEvents.OnXxx events to get notified when something is about to happen. In particular, the OnEnterBreakMode event enables you to intercept a breakpoint hit and possibly take an action. You can also inspect all the details of the reached breakpoint(s) using the current EnvDTE.Debugger inside the event handler.

Now with some effort, you can use these constructs to implement events that correspond to all Visual Studio debugging actions including Continue and Run to cursor accurately. If you require additional events not provided by EnvDTE.DebuggerEvents (such as when a breakpoint is inserted), you have no choice but use IDebugEventCallback2.Event. In this case if you have specific events in mind, please mention them explicitly and I might be able to tell you the corresponding IDebugEventCallback2.Event GUIDs.

Answer 2

You probably got off on the wrong foot here, the IDebugXxx interfaces were really intended to create your own debugging engine. Still useful perhaps to see what is going on in the existing engine, you are suppose to use QueryInterface() to discover the specific interface that matches the event. Like IDebugEngineCreateEvent2, IDebugProcessCreateEvent2, IDebugProcessDestroyEvent2, etcetera. There are a bunch of them, they are listed in the VSSDK\VisualStudioIntegration\Common\Inc\msdbg.h header and include their IID.

Best thing to do is peek at this sample, it shows how to crack the event notification into the specific interfaces. The AD7Events.cs source file shows the wrappers. Do keep in mind that this sample was made to show how to create an engine, not how to use the one already built into VS.

But yes, you are not going to get a "continue debug" event out of this. A debugging engine does not need that event since it is already responsible for taking care of that by itself. It already knows when it calls IDebugProgram3::Continue().

Surely what you are looking for is IVsDebugger.AdviseDebuggerEvents(). That's the one that tells you what the built-in debugger is doing. You need to pass an object of a class that implements IVsDebuggerEvents, your OnModeChanged() method will be called with a DBGMODE notification. I don't see a lot of fantastic examples that demonstrate usage, this web page might be helpful.