Tracing A Method Signature

Over the past three weeks I have discovered that many performance problems with Windows Forms applications are down to certain events being fired very rapidly, usually these are down to layout operations being triggered by updates to controls.

Without the use of RedGate Software’s excellent performance profiler I have been forced back into the habit of temporarily peppering the code I suspect of being a problem with trace messages.

For a while I was quite disorganised using trace messages such as “Entered SoAndSoMethod”, “OnSomeEvent Triggered”, etc. Over time I have settled into using the declaring class and method name to identify which method was being called.

Thinking about it today I decided this was still too much work (yeah, I am that lazy), I wondered if System.Reflection could help me:

public static void Trace()
{
    var stackTrace = new StackTrace();
    var frame = stackTrace.GetFrame(1);
    var method = frame.GetMethod();
    var parameters = FormatParameters(method.GetParameters());
    var declaringType = method.DeclaringType.ToString().Replace("EVEMon.", String.Empty);
 
    Trace("{0}.{1}({2})", declaringType, method.Name, parameters);
}

private static string FormatParameters(ParameterInfo[] parameters)
{
    var paramDetail = new StringBuilder();
 
    foreach (var param in parameters)
    {
        if (paramDetail.Length != 0)
            paramDetail.Append(", ");
 
        paramDetail.AppendFormat("{0} {1}", param.GetType().Name, param.Name);
    }
 
    return paramDetail.ToString();
}

This means that with liberal application of:

EveClient.Trace();

Will output the following to the trace:

0d 0h 00m 03s > CharacterMonitor.OnLoad(ParameterInfo e)
0d 0h 00m 03s > CharacterMonitor.multiPanel_SelectionChange(ParameterInfo sender, ParameterInfo e)
0d 0h 00m 03s > CharacterMonitor.multiPanel_SelectionChange(ParameterInfo sender, ParameterInfo e)

Hopefully that will save a few seconds here and there. It is a shame that reflection can’t get the actual values of the parameters from the frame, as that would be even more useful.

Posted in Programming | No Comments »

ASP.net 3.5 GridView RowCommand event fired twice

I am writing this up to hopefully save someone else time in the future, this particular problem took up six hours of my day yesterday causing quite a bit of frustration for me, as the developer, and the users of the application.

If you are searching for the solution scroll down to the bottom of the page where I will outline the solution I used to resolve the problem. It is also worth pointing out that this does appear to be fixed in .NET 4. Certainly I was able to consistently reproduce the problem with VS2008/.NET 3.5 on multiple different computers. However after converting the project to VS2010/.NET 5 I haven’t seen the issue.

Explanation of the problem

I wrote and maintain an application that publishes a list of courses and allows users to book onto these courses, what I have listed below is a simplified version of this application.

The administration console contains two lists:

• Published Courses – courses visible to all employees.
• Unpublished Courses - courses waiting to be published, only visible from the administration console.

Courses can be freely published (i.e. moved from Unpublished to Published) by clicking green tick. Courses that have not had any bookings made can be unpublished by clicking the red cross.

The cross and the tick are implemented as GridView ButtonFields:

<asp:ButtonField ButtonType="Image" CommandName="UnpublishCourse"
    ImageUrl="~/images/unpublish.png" InsertVisible="False" Text="Unpublish" />

This application has been running for six months, the issue had not been observed up until yesterday. The user explained to me that when they were publishing courses they were always published in pairs, equally when unpublishing courses it was being done in pairs, concealingly unpublishing a course with bookings.

Investigating the problem

Initially I tried to reproduce this on my local machine, backed up and subsequently restored the database locally made sure I was running the same revision as the server and fired it up. Couldn’t reproduce the problem, no matter how fast I clicked it wouldn’t happen. Tried various permutations of code and database but could only reproduce on the server.

Refreshed the binaries on the server with the HEAD from subversion, problem was still happening most of the time. I confirmed that it wasn’t an issue with the stored procedures by running them manually through LinqPad.

I started putting debug statements at the entry points to the critical parts of the code, this yielded an interesting output on my development machine, each time the cross or the tick was clicked UnpublishedGridView_RowCommand was fired twice. This gave me something to search for, seems I am not the only one to have this problem, Microsoft tried to reproduce it in 2006 but couldn’t.

Solving the problem

As it turns out there are several ways of fixing the problem, several people have used timers to “debounce” the RowCommand event, assuming that the event is always going to be fired twice a session variable can be used to filter out the second event.

Because the event is only fired twice when ButtonType=”Image” not when ButtonType=”Link” you can set the text property to the HTML to render your image. This resulted in the code above becomming:

<asp:ButtonField ButtonType="Link" CommandName="UnpublishCourse"
    InsertVisible="False" Text="<img src=images/unpublish.png />" />

This proved to be the simplest possible solution, Visual Studio 2008 throws a warning about ASP.net validation, but I can live with that as long as the application works. In addition to the simplicity of the solution it also continues to work in ASP.net 4 (which doesn’t exhibit the double event behaviour).

Posted in Programming, Sys. Admin. | No Comments »

Lack of AutoEllipsis support in ToolStripSystemRenderer

AutoEllipsis is a property introduced to System.Windows.Forms.Label with .NET 3.0, which in the event of the text overflowing the rendering rectangle of the Label will trim the end and add a Ellipsis (“…”), if this does occur the ToolTip for the label will also be set to the full (untrimmed text).

Unfortunately this functionality is not available for ToolStripStatusLabel. To make things worse in the event the text overflows it disappears completely. This bug, oversight, feature or whatever you want to call it cause some confusion after the release of EVEMon 1.3.0.1912. Several people assumed the new more verbose status bar was broken, being empty and all.

We put together a kludge fix, which would set the text and if it overflowed try to guess the length with Graphics.MeasureString. This worked fairly well, it cause some flickering when resizing the window and would leave a small gap on the right hand side of the StatusStrip.

I knew there must be a better way, and seeing an article about the StringFormat class reminded me of the need to find it. Searching about a bit found me a post on Joel on Software, I refined the code a little and came up with this (which is basically identical to Tom’s solution):

public class AutoEllipsisToolStripRenderer : ToolStripSystemRenderer
{
  protected override void OnRenderItemText(ToolStripItemTextRenderEventArgs e)
  {
    ToolStripStatusLabel label = e.Item as ToolStripStatusLabel;
 
    if (label == null)
    {
      base.OnRenderItemText(e);
      return;
    }
 
    TextRenderer.DrawText(e.Graphics,
      label.Text,
      label.Font,
      e.TextRectangle,
      label.ForeColor,
      TextFormatFlags.EndEllipsis);
  }
}

You need to wire this code into your StatusStrip:

this.MainStatusStrip.Renderer = new AutoEllipsisToolStripRenderer();

To the ToolStripStatusLabel will also need it’s Spring property set to true, and if you want the text left aligned the TextAlign Property will need to be set to MiddleLeft.

If you want the ToolTip to work correctly the StatusStrip will need to have ShowItemToolTips set to work, and the ToolStripStatusLabel AutoToolTip set to true. It isn’t perfect as the ToolTip is displayed when the text is not truncated, but it is close enough for my purposes.

I am exploring WPF at the moment, I was glad to see the default behaviour of a StatusBar was to just stop rendering the text at the bounds of control, an ellipsis could be added with the TextTrimming and TextWraping properties:

<statusbar HorizontalAlignment="Left" Margin="0,102,0,0" Name="MainStatusBar" VerticalAlignment="Top">
    <statusbaritem>
        <textblock TextWrapping="NoWrap" TextTrimming="CharacterEllipsis">
            Some Text Goes Here, this text may be very long as demonstrated here. In the event we run out of space an ellipsis is used.
        </textblock>
    </statusbaritem>
</statusbar>

Posted in Programming | 1 Comment »

LINQPad Crash

Update: I never did “fix” this problem, installing .NET 4 then using LINQPad 4 seems to work well.

I found myself using LINQPad more often than creating console applications, so much so I dicided to make the small but worth while investment in the optional “Autocompletion” (Intelisense-like) component. The licence is great because I can have it installed on all three of my PCs without having to buy extra licences.

I was figuring out the limits of the Math.Pow function a few days ago on the laptop when the LINQPad upgrade message appeared, not sure what happened next because LINQPad crashed with the following exception.

System Specification:

• Windows 7 Home Premium x64
• .NET v2.0.50727 (+3.0 & 3.5)
• .NET v4.0.20506
• VisualStudio 2010 Beta1

System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

   at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
   at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Form.ShowDialog(IWin32Window owner)
   at LINQPad.Program.ProcessException(Exception ex)
   at LINQPad.Program.Start(String[] args)
   at LINQPad.ProgramStarter.Run(String[] args)
   at LINQPad.Loader.Main(String[] args)

If anyone has any theories as to how this can be fixed I would be very apprecitive if you could post in the comments.

So far I have tried:

• Reinstalling from the latest (2.10.1) from the LINQPad website.
• Restarted the computer.
• Removing LINQPad through Add/Remove Programs.
• Remove LINQPAD manually.
• Rename %APPDATA%\LINQPad.
• Looked for Native Images in C:\Windows\assembly – None there

It seems to me that LINQPad throws some exception, which it’s built in exception handler tries to handle then fails, this probably means that the above stack trace is probably not indicative of what is causing the problem. Not that I think it will make a difference but I am going to try upgrading to Visual Studio 2010 RC tomorrow then at least I wll be able to use LINQPad for .NET 4.

Posted in Programming | No Comments »

Preventing the PictureBox control from locking files

One of our more regular contributors to EVEMon posted on our forums showing that the application was incapable of updating cached files (specifically images), after a bit testing I discovered the following Exception was being thrown when trying to overwrite the file in question:

System.IO.IOException: The process cannot access the file 'path\filename' because it is being used by another process.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.File.InternalCopy(String sourceFileName, String destFileName, Boolean overwrite)
   at System.IO.File.Copy(String sourceFileName, String destFileName, Boolean overwrite)
   at EVEMon.Common.FileHelper.OverwriteOrWarnTheUser(String srcFileName, String destFileName) in EVEMon.Common\FileHelper.cs:line 108
   at EVEMon.Common.FileHelper.OverwriteOrWarnTheUser(String destFileName, Func`2 writeContentFunc) in EVEMon.Common\FileHelper.cs:line 82
   at EVEMon.Common.Controls.CharacterPortrait.SavePortraitToCache(Image newImage) in EVEMon.Common\Controls\CharacterPortrait.cs:line 248

After a bit of searching around I discovered a post on StackOverflow identifying that System.Drawing.Bitmap(string filename) would lock the filename until the Bitmap was disposed of. The post presented a solution but no code, A bit of further searching confirmed my expectation that Image.FromFile(string filename) was subject to the same locking behaviour:

The file remains locked until the Image is disposed.

A bit more searching identified another post on StackOverflow which gave me the basic syntax and structure for the code I was going to need to implement this in EVEMon. The final code looks like this:

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MemoryStream stream = new MemoryStream();
 
byte[] imageBytes = File.ReadAllBytes(cacheFileName);
stream.Write(imageBytes, 0, imageBytes.Length);
stream.Position = 0;
 
var image = Image.FromStream(stream);
return image;

It appears that GDI+ will lock any image that is loaded into a control in WinForms and WPF, several comments on StackOverflow and byte.com suggested that even disposing of the control and the FileStream was not a reliable way of being able to write to the file so the above method is seems to be be the best solution all round.

Posted in Programming | No Comments »

OneNote vs Evernote

Somewhere in the middle of 2007 I was encouraged to use OneNote to clear my desk and move to a “paperless” system, initially this was a little painful as it seemed a gargantuan task to scan in all of the bits of paper on and around my desk that appeared to contain useful information.

As it turned out I realised that if a bit of paper was covered by another (or in fact covered by anything) it wasn’t that important to the execution of my role and could probably be thrown in the bin.

At the time I was not using Microsoft Office at home, opting to use OpenOffice for the limited needs I had for productivity software. I did however want a better way of organising my paperwork at home, OneNote 2007 came in at about £70 which isn’t unreasonable for what you got. Then I discovered Evernote.

Seemed perfect, I don’t generate so much paperwork that I would bust the 40mb/month limit on the free account. In the end I decided to adopt Evernote at home and continue to use OneNote at work, it proved quite a handy separation of work and life.

Recently I have run into two problems that are pushing me towards using Evernote for everything, and ditching OneNote entirely:

1. Evernote handles PDFs really well, you drag them in and they are displayed using the Foxit rendering engine. It just works. OneNote on the other hand plain old embeds them into the note, great now how is that different from having them in a folder in My Documents.
2. Evernote 3.5 has vastly improved the synchronization mechanism meaning that I can safely put something on Evernote on my PC and it will be on my laptop shortly after it is turned on next. Microsoft has tried to get this kind of functionality into OneNote and SharePoint however it just doesn’t work that well, it is too slow and there seems to be a 10 minute refresh cycle hard coded into the product.

I am still not sure that I want to ditch OneNote entirely, the 2010 version has some nice labour saving devices built in such as quick screen clippings and image formatting with the fluid user interface. Nothing in OneNote 2010 screams “don’t leave me” though.

Posted in Diary, Misc., Programming, Sys. Admin. | 2 Comments »

Debugging “Just My Code”

Within EVEMon we have started making heavy use of LINQBridge which uses Visual Studio 2008′s Multi-Targeting capabilities to allow a .NET 2.0 applications to use the compiler functionality of C# 3.0. This reduces our need to push EVEMon towards .NET 3.5, and simplifies our dependency stack for the end user (.NET 2.0 is pre-installed on Vista and above, .NET 3.5 is pre-installed in Windows 7 and above).

One of the annoyances I have run into is every time there is a problem with a LINQ statement the debugger will stop in the LINQBridge project rather than EVEMon’s code; this usually tells you nothing useful forcing you to dig into the exception to find the stack trace to find out which line caused the exception.

I found a natty attribute in DebuggerNonUserCode that allows you to tell the debugger to treat a class as Non-User Code:

[System.Diagnostics.DebuggerNonUserCode]

So far, I have not found a disadvantage in doing this. I am being conservative with my use in case I find some glaring problem, however LINQBridge has proven a stable project, and quite frankly I would much rather be looking at my own broken code when something goes wrong, rather than LINQBridges working code.

Posted in EVE Online, Programming | No Comments »

Controling Code Outlining with the Keyboard

Code outlining is a feature of supported by Visual Studio and many other editors, MSDN has some good documentation for VS2005, VS2008 and VS2010. If I were asked to explain this as briefly as possible, I would probably say:

Code Outlining is the logical partitioning of code in such a way that the user interface, or editor, is able to selectively hide the body of the content (such as a class, struct, enum or method) whilst leaving the signature or some identifying comment visible.

You can see this in action in Visual Studio 2008 with the following Screenshot:

I accidentally turned off Code Outlining today by hitting some keyboard shortcut that I didn’t know how to reverse, this lead me to discover several useful keyboard shortcuts for managing the display of your code from the keyboard.

As it turns out I managed to hit Ctrl-M followed by Ctrl-P (or just P in fact) which maps to Edit.StopOutlining, by default it seems that the Visual C# 2005 mapping scheme doesn’t provide a shortcut to enable Automatic Outlining so instead you can access the command through Edit Menu -> Outlining -> Start Automatic Outlining.

Enabled again, I get to play with code outlining from the keyboard:

• To toggle (collapse an expanded block or expand a collapsed block) the closest outlined element use Ctrl-M followed by Ctrl-M.
• To toggle everything use Ctrl-M followed by Ctrl-L (I find little use for this)
• To collapse to definitions use Ctrl-M followed by Ctrl-O

The last one is the most useful when used in conjunction with Regions as after colapsing to definitions you will get something similar to this:

You might have noticed in the first screenshot that CodeRush Xpress adds a coloured line between the beginning and end of blocks of code, this is a nice feature if you have long blocks of code, which of course you shouldn’t have.

There we go, an errant key stroke can lead to learning and blogging, who would have thought it?

Posted in CodeRush, Programming | No Comments »

Adjusting Selections in CodeRush Xpress

I found this function totally accidentally when I knocked my mouse into a key when something interesting popped up on Twitter. I happened to have a variable selected like so:

The key that I knocked was the Number Pad “+” key, and it expanded the selection like this:

As any self respecting Systems Administrator would do I wondered if doing exactly the same thing repeatedly would have equal or compound effects.

Strangely enough it worked, the selection will continue to expand selecting increasingly larger sections of code. The reverse works as well if you press the Number Pad “-” key the selection will be reduced.

As I was looking for documentation on this function; I found that you could use the CamelCase select function to start selections off using Ctrl+Shift+Left (or Ctrl+Shift+Right) this will take your selection from the current cursor position to the next upper case character to the left (or right). This can be coupled with the Number Pad “+” to expand your selection from a variable to an expression, to a line then a block. Neat!

Each of these discoveries was announced with a handy little popup in the bottom right hand corner of the viewport telling me what happened, and if relevant what function was suppressed.

I am going to make a concerted effort to spend my lunch break watching some more videos on DevExpress’ training site. I got 10 minutes today and watched what appeared to be footage from a launch event or a conference which was interesting but didn’t really teach me anything specifically.

Posted in CodeRush | 2 Comments »

Find Files in CodeRush Xpress

As I mentioned in my previous entry I have started using DevExpress’s CodeRush Xpress. It is a free cut down version of CodeRush that I heard about in an episode of .NET Rocks. I have wanted add something to my Visual Studio development experience and I can’t justify the cost of either Resharper or CodeRush at the moment. There has been quite a bit of discussion about Resharper vs. CodeRush and in my experience most people I have spoken to love one and hate the other.

I hope to be able to write a series of posts about some of the features found in CodeRush Xpress which I hope will clarify their purpose and use in my mind and maybe help someone find the function they are looking for.

First off “Quick File Navigation”, this is a search function for locating a file by file name, I am finding it increasingly useful when looking through patches as it allows me to very quickly jump to a file name. Particularly as I am trying to move my projects to a one class per file so if I can remember the class name I can find the code file very quickly.

The “Quick File Navigation” dialog is accessible through the keyboard short cut Ctrl+Alt+F. Typing will filter the list box by the name of the file matching anywhere in the filename including the extension.

An additional feature for those who like me use CamelCase in their file names; if you enter your filter terms in capital letters it will search for capitalized words, in order within file names. Thus entering “AW” into the search box will also bring up the AboutWindow.cs in the above solution.

Combining the above with the Ctrl-G keyboard shortcut in Visual Studio 2008 to go to a specific line we can do the following to go to line 162 in ShipLoadoutSelectWindow.cs:

Ctrl+Alt+F  →  S,L,S,W  →  Ctrl+G →  1,6,2

DevExpress have a great training video on their tv.devexpress.com sub site.

Posted in CodeRush | 1 Comment »