Find Me On Los Techies

After a while cross-posting, I decided to retire this blog in favor of my blog on Los Techies. Hope you’ll join the conversation there!

Posted in .NET. Comments Off

posh-git Release v0.3

On a whim, I’ve decided to tag a v0.3 release of posh-git (which has been stable for a few months now). In this release…

Installer

Previously the setup process for posh-git was undefined. Daniel Hoelbling was kind enough to put together a getting-started post, but I decided to make it even easier. Assuming Git and PowerShell are configured correctly (see readme for details), getting started is trivial:

cd C:\Wherever
git clone https://github.com/dahlbyk/posh-git.git
.\posh-git\install.ps1

At this point the sample posh-git profile will be loaded as part of your PowerShell profile. If you don’t like the sample profile, feel free to grab the pieces you want and discard the rest (so you can use posh-hg too, perhaps).

Update: If you already have posh-git installed, just cd into your posh-git directory and pull from my master branch:

# If you don't already have me as a remote...
git remote add dahlbyk
git pull --rebase dahlbyk master

You don’t need to run install.ps1 again; just open a new PowerShell session and you’re good to go.

Performance

By taking a dependency on msysgit 1.7.1, all status information is now retrieved in a single call (git status -s -b). This still means git status is called for every prompt, so if status is slow for your repository your prompt will be slow too.

If it’s still too slow for your taste, you also have the option to set $GitPromptSettings.EnableFileStatus = $false. This will preserve branch information for the prompt, but skip everything else (counts and tab completion for added/modified/deleted files).

Finally, you can set $GitPromptSettings.Debug = $true to see how long the various steps take behind the scenes. If your environment is anything like mine, the majority of the time will be spent in git calls.

Tab Expansion Updates

  • Fix for git rm during deleted/updated merge conflict
  • Branch expansion for cherry-pick, diff, difftool, log and show
  • Normal expansion through simple aliases (e.g. alias.dt = difftool supports git dt <tab>)

Next Steps

  • I’d still like to get some testing in place so I don’t break things unintentionally
  • I’m considering moving away from regex to parse commands for tab expansion — anyone feel like writing a git command parser in PowerShell?
  • I’d like it to be easier to use posh-git and posh-hg together, so I may revisit how they hook into tab expansion

As always, your feedback is appreciated. If you’d like posh-git updates between release posts, you can also follow me on Twitter.

Posted in Git. Tags: . Comments Off

RenderAction with ASP.NET MVC 3 Sessionless Controllers

One of the new features of ASP.NET MVC 3 is a controller-level attribute to control the availability of session state. In the RC the attribute, which lives in the System.Web.SessionState namespace, is [ControllerSessionState]; for RTM ScottGu says it will be renamed simply [SessionState]. The attribute accepts a SessionStateBehavior argument, one of Default, Disabled, ReadOnly or Required. A question that came up during a Twitter discussion a few weeks back is how the different behaviors affect Html.RenderAction(), so I decided to find out.

The Setup

I started with an empty MVC 3 project and the Razor view engine. We’ll let a view model figure out what’s going on with our controller’s Session:

public class SessionModel
{
    public SessionModel(Controller controller, bool delaySession = false)
    {
        SessionID = delaySession ? "delayed" : GetSessionId(controller.Session);
        Controller = controller.GetType().Name;
    }

    public string SessionID { get; private set; }
    public string Controller { get; private set; }

    private static string GetSessionId(HttpSessionStateBase session)
    {
        try
        {
            return session == null ? "null" : session.SessionID;
        }
        catch (Exception ex)
        {
            return "Error: " + ex.Message;
        }
    }
}

The model is rendered by two shared views. Index.cshtml gives us some simple navigation and renders actions from our various test controllers:

@model SessionStateTest.Models.SessionModel
@{
    View.Title = Model.Controller;
    Layout = "~/Views/Shared/_Layout.cshtml";
}
<h2>Host: @Model.Controller (@Model.SessionID)</h2>
<ul>
    <li>@Html.ActionLink("No Attribute", "Index", "Home")</li>
    <li>@Html.ActionLink("Exception", "Index", "Exception")</li>
    <li>@Html.ActionLink("Default", "Index", "DefaultSession")</li>
    <li>@Html.ActionLink("Disabled", "Index", "DisabledSession")</li>
    <li>@Html.ActionLink("ReadOnly", "Index", "ReadOnlySession")</li>
    <li>@Html.ActionLink("Required", "Index", "RequiredSession")</li>
</ul>
@{
    Html.RenderAction("Partial", "Home");
    Html.RenderAction("Partial", "Exception");
    Html.RenderAction("Partial", "DefaultSession");
    Html.RenderAction("Partial", "DisabledSession");
    Html.RenderAction("Partial", "ReadOnlySession");
    Html.RenderAction("Partial", "RequiredSession");
}

Partial.cshtml just dumps the model:

@model SessionStateTest.Models.SessionModel
<div>Partial: @Model.Controller (@Model.SessionID)</div>

Finally, we need a few test controllers which will all inherit from a simple HomeController:

public class HomeController : Controller
{
    public virtual ActionResult Index()
    {
        return View(new SessionModel(this));
    }

    public ActionResult Partial()
    {
        return View(new SessionModel(this));
    }
}

[ControllerSessionState(SessionStateBehavior.Default)]
public class DefaultSessionController : HomeController { }

[ControllerSessionState(SessionStateBehavior.Disabled)]
public class DisabledSessionController : HomeController { }

[ControllerSessionState(SessionStateBehavior.ReadOnly)]
public class ReadOnlySessionController : HomeController { }

[ControllerSessionState(SessionStateBehavior.Required)]
public class RequiredSessionController : HomeController { }

And finally, a controller that uses the SessionModel constructor’s optional delaySession parameter. This parameter allows us to test RenderAction‘s Session behavior if the host controller doesn’t use Session:

public class ExceptionController : HomeController
{
    public override ActionResult Index()
    {
        return View(new SessionModel(this, true));
    }
}

The Reveal

So what do we find? Well the short answer is that the host controller’s SessionStateBehavior takes precedence. In the case of Home, Default, ReadOnly, and Required, we have access to Session information in all rendered actions:
Sessionless Controller: RenderAction with SessionState

If the host controller is marked with SessionStateBehavior.Disabled, all the rendered actions see Session as null:
Sessionless Controller: RenderAction with Disabled SessionState

I see this is the key finding to remember: an action that depends on Session, even if its controller is marked with SessionStateBehavior.Required, will be in for a nasty NullRef surprise if it’s rendered by controller without. It would be nice if the framework either gave some sort of warning about this, or if they used a Null Object pattern instead of just letting Session return null.

Finally, things get really weird if a Session-dependent action is rendered from a host controller that doesn’t reference Session, even if SessionState is enabled:

Sessionless Controller Exception: Session state has created a session id, but cannot save it because the response was already flushed by the application.

It’s pretty clear the issue has something to do with where RenderAction() happens in the request lifecycle, but it’s unclear how to resolve it short of accessing Session in the host controller.

So there we have it…a comprehensive testing of sessionless controllers and RenderAction for the ASP.NET MVC 3 Release Candidate. Hopefully the inconsistencies of the latter two cases will be resolved or at least documented before RTM.

Code Review with Git Patches and Outlook via PowerShell

In the spirit of “simplest thing that works,” my team has a rather low-fidelity approach to code reviews: patch files and e-mail. Nothing fancy, but we find it works rather well. It’s even easier thanks to git format-patch, which lets me easily generate a patch per commit, but I was never able to get send-email to work quite like I wanted. Instead, I whipped together a PowerShell script in a few minutes that does just the trick:

function patch ($ref = 'master..', $Message = '', [switch]$KeepFiles) {
  $patchPaths = $(git format-patch -C -o C:/Temp/Patches $ref)
  if($patchPaths) {
    $outlook = New-Object -ComObject Outlook.Application
    $mail = $outlook.CreateItem(0)
    [void]$mail.Recipients.Add('myteam@mycompany.com')
    $mail.Subject = "Review - $Message"
    $commits = $(git log -C --pretty=format:'%s' --reverse $ref) | foreach {  "<li>$_</li>" }
    $mail.HTMLBody = "<ol style=`"font: 11pt Calibri`">$commits</ol>"
    $patchPaths | foreach {
      [void]$mail.Attachments.Add($_)
      if(!$KeepFiles) { Remove-Item $_ }
    }
    $mail.Display()
  } else {
    Write-Warning 'Nothing to patch!'
  }
}

Usage:

Create patch of everything on current branch since master:

patch -m "Issue 123 - This is neat"

Create patch of last two commits, without message:

patch HEAD~2..

Create patch of everything except the current commit, with message:

patch master..HEAD~1 'Refactoring for Story 234'
Posted in Git, PowerShell. Tags: . Comments Off

Better git-svn Through Aliases: git up & git dci

I’ve been using git-svn for almost a year now, and have settled on a low-friction workflow that has been working really well. First, a few notes about how I work with Git and Subversion…

  1. For the most part, we avoid Subversion branching and merging, so I optimize for working in trunk.
  2. Forget about using Git push and pull for collaborating with others. git-svn stores extra metadata that isn’t pushed with the rest of the repository, so git-svn operations will fail on cloned repos. Furthermore, each repository’s git-svn commits are unique, so pulling from another repository will fetch its parallel history (if you have to do this, git rebase -i can help filter out the overlapping commits). That said, I do use push/pull to collaborate with myself across machines, though I always operate against Subversion from one machine.
  3. All substantial work is done in local topic branches, with master reserved exclusively for tracking what’s in (or to be immediately committed to) Subversion.

git up

First up is the alias that stands in for svn update, to make sure I’m always working from the latest changes:

!git svn fetch && git push . remotes/trunk:master && git push -f origin master:master && git rebase master

Update Nov. 30, 2010: After reports that people were having issues calling git up from master, I’ve modified the alias slightly:

!git svn fetch && git svn rebase -l && git push . remotes/trunk:master && git push -f origin master

If this is your first alias, the command to set the alias would be:

git config alias.up "!git svn fetch && git svn rebase -l && git push . remotes/trunk:master && git push -f origin master"

Step by step, this alias does the following:

  1. Fetch the latest from Subversion. I use svn fetch instead of svn rebase because the former also fetches from Subversion branches; we’ll do our own rebase later.
  2. Rebase my current branch against its Subversion parent. -l skips a remote fetch, since we just did one.
  3. Update my local master branch to match Subversion’s trunk. If you didn’t use --std-layout, you might need to replace remotes/trunk with remotes/git-svn or whatever your git-svn ref is.
  4. Push master to my origin remote, which serves as a backup and allows me to collaborate with myself between machines (if you don’t have a Git remote, feel free to omit this).
  5. Rebase my current branch against master (and therefore Subversion).

The key is item #2: automating the synchronization of master and Subversion means I never have to think about it again. I can either rebase a topic branch against master to get reasonably fresh commits, or use git up to grab the latest (mostly when preparing to commit into Subversion). Without this alias, I tended to waste a fair amount of time switching back to master periodically just to make sure it’s up-to-date enough.

When do I git up?

You can use git up pretty much any time you want — on master, on a topic branch or even with a detached HEAD — as long as your working copy and index are clean. If you have work in progress but need Subversion’s latest, you can either git stash or make a temporary commit and then git reset HEAD^ after the update. I used to favor the former, but am starting to prefer the latter because I tend to be undisciplined about cleaning up stashes that git stash pop didn’t delete due to merge conflicts.

git dci

Satisfied with this abstraction for pulling changes from Subversion, I then applied the same logic to committing into Subversion:

!git svn dcommit && git push . remotes/trunk:master && git push -f origin master && git checkout master

The dci alias (short for dcommit) does the following:

  1. Commit my local changes into Subversion, generating a Subversion commit for each new Git commit. If a modified file has also changed in Subversion since your last update, the dcommit will fail — git up, resolve conflicts and try again.
  2. Keep master in sync with Subversion…
  3. …and origin.
  4. And finally, switch back to master, which will now reference the latest git-svn commit. From here I can either delete my finished topic branch, or rebase against master (git rebase master branch-name) and get back to work.

Again, by automating most of what I was already doing I can be confident that I will always come out of a dcommit in a well-known, consistent state from which I can proceed without extra thought.

When do I dci?

git dci should be used when you want to commit HEAD and its uncommitted ancestors into Subversion. In my experience, this usually falls into one of three scenarios:

1. Entire Branch

You have a topic branch and want to replay all of its commits into Subversion one by one. In this case, simply checkout the branch and call git dci:

git dci Entire Branch

I use this most often, as I prefer granular commits and a linear history.

Update Dec. 4, 2010: Donn pointed out that I gloss over my use of an lg alias, which provides a concise graph of history. The alias is described here.

2. Squashed Branch

The exception to my linear history preference is if the build would break between intermediate commits. For example, I might upgrade a dependency in one commit and then fix the build in the next commit. One could certainly use a squash merge or interactive rebase, but sometimes I prefer to keep the granular history in Git.

So how do we accomplish this with git-svn? Well git-svn essentially treats merge commits as the sum of their parts, relative to the previous Subversion commit — it squashes for us. To make our single Subversion commit, we’ll just switch to master and use git merge --no-ff:

git merge --no-ff

The --no-ff flag forces the creation of a merge commit even though we should be able to fast-forward (if we up’d first, that is). You can make this the default behavior for master by setting branch.master.mergeoptions (I use --no-ff --no-commit).

Once we have our merge commit, we again use git dci to push all its changes into Subversion:

git dci After Merge

Note that the dev2 commits remain untouched by git-svn, and Subversion has the combined changes:

git-svn Merge Commit in Subversion

3. Detached HEAD

The final scenario is really no different from either #1 or #2, but it’s worth pointing out that you can use git dci from any HEAD, not just on a branch. For example, suppose I have a few refactoring commits that I created as part of feature work which I would like to share with the team now while I finish up the feature. In this case, I can checkout (or merge from) the last of the commits I want to share:

Checkout Detached HEAD

And git dci from the detached HEAD to save those changes:

git dci from Detached HEAD

Note that git dci left me on master. Now to continue on dev3, I just rebase against master so Git is aware that the dci’d commits have been updated with git-svn metadata:

git rebase master dev3

If I want to get even more sophisticated, I could cherry-pick then dci individual commits, or I could create a copy of the branch and use interactive rebase to exclude the commits that I don’t want to dci yet. Just remember to rebase the topic branch against master when you’re done.

If you have any additional git-svn tips or questions, please let me know.

Posted in Git. Tags: . 3 Comments »

Git-Achievements in PowerShell

Reading through Jason’s post on using Git-Achievements with msysGit, I couldn’t help but get it working with PowerShell. The result is a single PowerShell script added to my Git-Achievements repository, tagged here on the off chance I decided to upload my achievements.

To install posh-git-achievements…

  1. Fork my repository on GitHub (or if you have an existing repository, add me as a remote and pull)
  2. Clone your fork of the repository (into C:\Git\git-achievements, for this example)
  3. Open your PowerShell profile and add the following:
    Set-Alias git C:\Git\git-achievements\git-achievements.ps1
  4. “dot source” your profile to reload it in your current session (or just start a new session):
    . $PROFILE
  5. Check the install:
    git achievements --help

If all goes according to plan, this should unlock your first achievement.

Note that this will pass every git call through a few extra layers, including calls made for the posh-git prompt. But if you can tolerate the performance hit, it’s a rather fun way to expand your working knowledge of Git. Enjoy!

Posted in Git, PowerShell. Tags: . Comments Off

msysGit error setting certificate verify locations

I had never had any problems using msysGit with SSL until last night, when I came across the following error:

$ git pull
Password:
error: error setting certificate verify locations:
 CAfile: /bin/curl-ca-bundle.crt
 CApath: none
 while accessing https://dahlbyk@github.com/dahlbyk/posh-git.git/info/refs

fatal: HTTP request failed

There were a number of suggestions in the comments on GitHub’s Smart HTTP post, but they mostly seemed like hacks (most common: copy file from msysGit elsewhere, or turn off http.sslverify). A much easier fix is just to set http.sslcainfo to the absolute path of the curl-ca-bundle.crt file in your msysGit install’s bin folder:

$ git config --global http.sslcainfo "/c/Program Files (x86)/Git/bin/curl-ca-bundle.crt"

I chose to do this at the --global level so the setting won’t be overwritten by future msysGit installs.

Posted in Git. Tags: . Comments Off
Follow

Get every new post delivered to your Inbox.