Debugger Canvas

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T H U R S D A Y , A P R I L 4 , 2 0 1 3

Visual Studio Futures: Devlab's Debugger Canvas

If Software Development is an art then we (developers) should be called artists. An artist

needs canvas to bring life into lines and colors. Debugger Canvas is a Visual Studio

Extension to help debugging by providing a code bubble canvas where each bubble

represent a portion of the call hierarchy. It is a Dev Lab's Power Tool developed which is

now available as a Visual Studio Extension. In order to develop this, Microsoft's Code

Canvas and Brown University's Code Bubble team joined hands. They worked in

collaboration with Visual Studio team to come up with this amazing debugging

experience. Currently, the only option to look at the call hierarchy is to look at the Call

Stack Window. This can become really difficult for multithreaded and parallel code.

Code Canvas is a Microsoft Research Project. This project is about developing an

multi-layered and infinitely zoomable surface for software development. You can get

further information about this from their main page.

Brown University's main page for Code Bubble's team can be found here. It is a front-

end to Eclipse. The code is available on SourceForge.net and can be downloaded. The

idea of code bubble is coding for working sets. They are functions, documentations,

notes and any other information that a developer need to implement a use case. This

might be introduction of a new feature of fixing a defect in code. It works by displaying

the editable functions in the form of bubbles on the view. These bubbles are fully

editable and grouped in working sets. These bubbles are backed by code files and can bemoved across the working sets. These working sets are displayed in a large bubble area.

Kael has discussed about Code Bubble, Code Canvas and Debugger Canvas and their

differences:

http://blogs.msdn.com/b/kaelr/archive/2012/03/10/code-canvas-vs-code-bubbles-vs-


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debugger-canvas.aspx

* Code Bubbles is a trademark of Brown University.

Visual Studio Extension for Debugger Canvas

Debugger Canvas is available as a visual studio extension in Visual Studio Gallery. It is

made available by as a DEVLABS project provided from Debugger Canvas Team. The

extension was last updated on 02/15/2013 and it is available as version 1.1. The

limitation is that it is not available for Visual Studio 2012. The extension is only

supported forVisual Studio 2010. The documentation suggests that it would only

work for Ultimate Edition.

The extension can be downloaded from the following link:

http://visualstudiogallery.msdn.microsoft.com/4a979842-b9aa-4adf-bfef-

83bd428a0acb

The extension has a dependency on another extension VS Fragments.


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The documentation of the extension suggests that the extension would work only with

Visual Studio 2010 Ultimate Edition. I tried installing it on Visual Studio 2010 Premium

RTM and it installed successfully. The documentation also suggests that some features

wouldn't be available on RTM version and SP1 is required. I noticed that there is no

intellisence during debugging in code fragments / bubbles in canvas window. Since

there is no intellitrace available for Premium edition, I couldn't test the code bubble tree

created by dropping an intellitrace event on the canvas.

What is Debugger Canvas?

Debugger canvas adds features in Visual Studio 2010 to improve debugging experience.

The whole idea is to provide a single canvas. This is a pan and zoom surface i.e. it can be

zoomed in and out, plus we can pan the window by dragging it from any point in the

surface.

The canvas appears as a tabbed window. It shows the code portions in the form of

bubbles / fragments. The bubbles support stepping through the code like the already

existing debugging feature in Visual Studio. The only difference is that each call is

shown as a bubble with an arrow directing from caller to the callee code. This is a

debugging experience which is completely temporary i.e. it can not be persisted as is.

There are also other features in the surface. The greatest of all is the enhanced search.

We can search the code for any references and it would show all the patterns available in

the code bubbles in the surface. just right click anywhere in the canvas surface, you

should see the following options:


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The online MSDN forum is about discussion and announcement about the tool

[http://social.msdn.microsoft.com/Forums/en-US/debuggercanvas/threads]. Like

other MSDN forums, you can ask questions which is then discussed by other members

of the community.

Debugger Canvas Menu

Installing the extension would make the necessary features in Visual Studio. This

includes the additional Debugger menu. Notice that I can run it with Resharper. The

documentation suggests that they are not compatible.


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Please notice the options for saving the canvas to the XPS document. You can also do

this by one of the context menu options available in the canvas.

LifeTime of Debugger Canvas

As discussed above, debugger canvas is a pan and zoom surface helping debugging of

complex code. Code fragments / bubble appear on the canvas as they are called. The

lifetime of a Debugger Canvas is for a single debugging session. As we have

discussed before a debugger canvas is represented as a single tabbed window, this

window can be used for the next debugging session if this is still opened. It uses the

most recent canvas window if more than one are opened.

Intellitrace & Debugger Canvas

Intellitrace is another debugging tool to help debugging experience. It is available with

Ultimate Edition of Visual Studio. The traces generated through Intellitrace can be used

by Debugger Canvas to see the call hierarchy using code bubbles with all the parameters.

This call hierarchy can always be exported into XPS format to share it with the

concerned parties.

Debugger Canvas Settings

There are some options in Debugger Canvas which are configurable. The configuration

settings are available under [Debugging -> Debugger Canvas] in Tools -> Options

dialog. The same dialog is available under Debugger -> Options and Settings.

Starting Debugger Canvas

A user can select how he wants to start the Debugger Canvas. This can be controlled


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based on the following settings:

When this option is checked, any time user starts a debugging session, Debugger

Canvas is used. The first break point hit creates the bubble. These bubbles are added /

reused as we keep stepping into the functions. This option is based on code analysis

functionality in Visual Studio which transforms code into generalized graph based

model. The same functionality is used by Architecture Explorer, available in Visual

Studio Ultimate Edition. This actually requires some extra work when debugger canvas

is used for debugging, compared to general file based debugging experience in Visual

Studio. This requires scan of the whole solution and generating a graph based model. So

selecting this as default option, it might be slower to start the debugging session.Un-

checking thiswould use the general file based session in Visual Studio. You can later

invoke the debugger canvas using the following toolbar added with the installation of

the extension. This is available when you start a debugging session.

The option is disabled when we get out of the debugging session. I have noticed that if

you have this option unchecked and start a debugging session and just have the

debugger canvas window opened in a tab, it would start using the canvas. I think this is

just to use canvas as it is definitely a better debugging experience. It might seem like a

defect for other developers as they might not expect this.

Debugging recursive code

It has been traditionally very difficult to debug recursive code because of complex call

hierarchy to the same methods. Debugger Canvas becomes specially useful for


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debugging recursive code. This allows to disable the reuse of bubbles for the same

content. This can be used to have a new bubble for each call with the exact call

hierarchy. It even provides the values of local members for each bubble in the hierarchy.

What could be better than this?

Just to show the benefit for this visually, let's uncheck the above setting and start

debugging using debugger canvas. Let's consider the example of fibnacci series. The

following is a recursive implementation of Fibnacci series. You can see that each call isrepresented in the canvas. You can also appreciate how local variables are also available

in the call hierarchy.

Actually this setting came from neither Code Canvas nor Code Bubbles individually.

Code Bubbles has a non-historical design where it doesn't reuse any bubble and every

time a new bubble is created even if the users steps into the same code. This has the

advantage of simplicity and predictability. On the other hand, Code Canvas works in

historical mode and it reuses the fragment if the same code is hit again. This keeps the

canvas real estate occupied by less number of fragments. For Debugger Canvas, user isgiven option to decide what mode he wants to select and the debugging experience is

updated based on this selection i.e. Historical Vs Non-Historical debugging using

bubbles.

If your call hierarchy are not like that then reusing the bubbles would definitely simplify


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the view.

Local Variables Snapshots:

If a code bubble is being used multiple times then we can just take a snapshot of local

variables. These snapshots are taken with time stamps. These values can then be used to

compare with the local values whenever the same bubble is used again. In the following

example we have taken a snapshot of a recursive method and compare the values from

the values when we took these snapshots.

Canvas Debugging Channels

As we discussed above, the canvas is displayed as a tab window. The bubbles for each

new session are provided in the form of horizontal channels. The canvas keeps the

channels from previous debugging channel which might help in comparing the current

session from any previous one. We can easily determine if the bubble is from a previous

session as the border turns blue as we select it. For a bubble from the current session,

the border becomes yellow. We can pan and zoom to just focus on the current channel.

It is easy to navigate between different areas in the canvas by using the Visual Selection

Pane on the top. It is based on an expander. It provides the display of the pane using a

Visual Brush.


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Call Hierarchy

The canvas supports removing the bubbles from the call hierarchy. How the display

would look like if we remove a bubble from the middle of the hierarchy. In the image

below, I have the channels from two debugging session. For the current session, I have

removed a bubble from the middle. Initially, it appeared that there is no relationship

between the ancestral code block but when I dragged the child bubble a little on the

canvas, it did create a dashed line showing an indirect caller - callee relationship.

Editing in Debugger Canvas

The canvas allows editing of code while debugging. Just put the cursor at the place in

the code that you want to modify and just update the code. This can be configured

though, which can be disabled.

When I tried this feature, I was thinking it would depend on theEdit and Continue

feature but it doesn't, even when Edit & Continue is disabled.


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Integration with Existing Debugging Tools

The debugger canvas seems to be completely integrated with the existing debugging

tools in Visual Studio. In the following, the Call Stack and Threads toolbar window is

displayed. As we double click an item in the call stack from either of these, it results in abubble in the canvas. It also creates a call relationship by using arrows.

It is also integrated with other debugging tool windows includingAutos, Locals and

Immediatewindows. Since we have the support of local members right on the canvas,

I don't think anyone would use Locals and Autos when using a Debugger Canvas. But

Immediate Window would definitely be very useful.


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It is also integrated with Quick Watch Window.

Integration with Visual Studio 2012

The major road block is that it is not supported in Visual Studio 2012. It is

understandable that this is a parallel development started somewhere in 2010 when

Visual Studio 2012 wasn't even available. There should be an real effort to supportVisual Studio 2012. I also think that this should be available in non-Ultimate editions of

Visual Studio but since it is based on some features, including code analysis feature,

which are only available in the ultimate edition, it seems obvious that it would be really

difficult or impossible to provide it for other editions.

Research Paper on Debugger Canvas

This discusses the details about the design choices with Debugger Canvas. This also

sheds some light on the initial community feedback of the tool. It mentions some of themotivations about the feature design choices. [ Kael Rowan, Robert DeLine, Andrew

Bragdon, and Jens Jacobsen, Debugger Canvas: Industrial Experience with the Code

Bubbles Paradigm, International Conference on Software Engineering, 2 June 2012].

You can get it from here:


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http://research.microsoft.com/pubs/177124/p1064-213-deline.pdf

Channel 9 Video with Kael Rowan:

Kael has a very useful conversation about this on Channel 9.

POSTED BYMUHAMMAD SHUJAAT S IDDIQIAT11:43 PM0 COMMENTS

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LABELS:DEBUGGER,DEBUGGER

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2010 ,VISUAL STUDIO ULTIMATE

Date post:	03-Apr-2018
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Debugger Canvas

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