Piston

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Easy Vendor Branch Management


Categories/Tags: [Vendor branch management (category)][Synchronization with Subversion (category)]
Homepage: http://piston.rubyforge.org/ blog
Documentation: http://piston.rubyforge.org/ daily usage page


Project/Development: http://rubyforge.org/projects/piston


Description: Piston is a utility that eases [[vendor branch management (not the vendor drop kind—the other kind). This is similar to svn:externals, except you have a local copy of the files, which you can modify at will. As long as the changes are mergeable, you should have no problems. It is also similar to svn export, only unlike svn export, it remembers where you exported from so you can easily update from the remote repository at any time.]]



Authors: François Beausoleil


Contents

Comparison with svn:externals

  • Unlike svn:externals, piston stores a local copy of the remote repository directory in your local repository. This allows you to make local modifications to your local copy and commit those changes.
  • Unlike with svn:externals, when you svn update a repository containing a piston import, it doesn't automatically update your piston-imported directory. The directory will only be updated when you explicitly request an update via piston update.
  • Like svn:externals, you can tie your local copy of a remote repository directory to a specific revision. But unlike with svn:externals, it's easy to switch back and forth between being tied to a revision (piston lock) and simply using the latest revision (piston unlock).

Comparison with svn export

  • With svn export it was possible to export a copy of remote repository directory, commit it to your local repository, and then forget which repository you got the code from! That can make it difficult to update your code with the vendor's latest changes, when that happens! piston, by contrast, remembers the source repository info for you so you don't have to!

Using it for managing Rails plugins

Robby on Rails : Every Second Counts with a Piston in your Trunk (http://www.robbyonrails.com/articles/2007/01/16/every-second-counts-with-a-piston-in-your-trunk). Retrieved on 2007-05-11 11:18.


Several of my comrades in #caboose are using piston to manage external plugins for Ruby on Rails. Wait! Isn’t this what Subversion externals is meant for? Well, yes… but externals also eat away at productivity. For example, each day, we may have anywhere from 4-6 designers and developers working on one client project. When we’re in crunch mode, this could account for quite a few subversion commits throughout the day. We all know that we should run svn up on a regular basis to make sure that we’re keeping things in sync… especially when designers and developers are working really closely and fine tuning something specific in the application. Well, the one downside to this process is that each svn up not only checks our repository, but it also checks external repositories. “But wait! Can’t you just ignore externals on an update?” Of course, but who wants to type out --ignore-externals each time they run an update? ...or perhaps you could make an alias for this in your shell. In any event, everyone on the team is then left to be responsible for doing this… and an extra 30-60 seconds (if not longer) per svn update times x number of people on project… well… time wasted if you’re closely watching the svn updates. [...] Another issue with svn externals is that when a repository goes down, it really starts to slow stuff down your updates. This is always fun when you go to deploy your application with Capistrano and realize that you can’t finish the update because it can’t connect it to http://svn.lazyatom.com/public/plugins/acts_as_hasselhoff/ to make sure that your application has the latest version of [the plugin]. Then there is the whole issue of wanting to make changes to the plugin that you’re including as an external. How does that fit into the whole mix? There is Hope! Piston encourages you to keep your external plugins in your local repository. Don’t worry, it remembers where it retrieved the code from so that you can update from the external repository at any time. ...


Managing Rails Plugins with Piston (http://www.rubyinside.com/advent2006/12-piston.html). Retrieved on 2007-02-15 22:24.

With Piston, you import a remote repository and check it into your local repository. You can then go nuts modifying it or periodically sync it up with its remote origin using piston update. There's an advent calendar full of reasons why you'd want to manage Rails plugins with Piston rather than using svn:externals. For one thing, it makes checkouts and updates faster -- code is all kept in the same repository so you don't need to query foreign repositories on every svn up. It also gives you simple control over which reversion of a plugin you keep around -- it's really not ideal to have your plugins updating to the bleeding edge all the time. You could set your external to a tag, but what plugin author uses tags? Seriously. Piston makes life easier. ... Grab remote updates (plugin was updated, you want the updates):

$ piston update vendor/plugins/simply_helpful/
Updated to r5710 (4 changes)

See directories under Piston's watch in your project:

$ piston status
     vendor/plugins/simply_helpful (http://dev.rubyonrails.org/svn/rails/plugins/simply_helpful)
     vendor/plugins/annotate_models (http://svn.pragprog.com/Public/plugins/annotate_models)
M    vendor/plugins/acts_as_attachment (http://svn.techno-weenie.net/projects/plugins/acts_as_attachment/)
     vendor/plugins/acts_as_textiled (svn://errtheblog.com/svn/plugins/acts_as_textiled)
     vendor/plugins/mocha (svn://rubyforge.org/var/svn/mocha/trunk)
     vendor/plugins/has_many_polymorphs (svn://rubyforge.org/var/svn/polymorphs/has_many_polymorphs)   

Using it for vendor branch management

http://piston.rubyforge.org/

First, you need to import the remote repository location:

$ piston import http://dev.rubyonrails.org/svn/rails/trunk vendor/rails
Exported r4720 from 'http://dev.rubyonrails.org/svn/rails/trunk' to 'vendor/rails'

$ svn commit -m "Importing local copy of Rails"

When you want to get the latest changes from the remote repository location:

$ piston update vendor/rails
Updated 'vendor/rails' to r4720.

$ svn commit -m "Updates vendor/rails to the latest revision"

You can prevent a local Piston-managed folder from updating by using the lock subcommand:

$ piston lock vendor/rails
'vendor/rails' locked at r4720.

When you want to update again, you unlock:

$ piston unlock vendor/rails
'vendor/rails' unlocked.

Other useful commands

convert: Converts existing svn:externals into Piston managed folders
usage: convert [DIR [...]]

  Converts folders which have the svn:externals property set to Piston managed
  folders.
> piston status
M           plugins/rake_completion (https://secure.near-time.com/svn/plugins/trunk/rake_completion/)

> piston update
Processing 'plugins/rake_completion'...
  Fetching remote repository's latest revision and UUID
  Restoring remote repository to known state at r74
  Updating remote repository to r29
  Processing adds/deletes
  Merging local changes back in
  Removing temporary files / folders
  Updating Piston properties
  Updated to r29 (0 changes)

> piston status
            plugins/rake_completion (https://secure.near-time.com/svn/plugins/trunk/rake_completion/)

How does it work?

When you do an import from a remote repository, it stores some information about the remote repository in your local repository using Subversion's handy "custom property" feature. Observe which properties get set after doing an import:

> piston import https://secure.near-time.com/svn/plugins/trunk/rake_completion/
Exported r74 from 'https://secure.near-time.com/svn/plugins/trunk/rake_completion/' to 'rake_completion'

> svn propget piston:root rake_completion/
https://secure.near-time.com/svn/plugins/trunk/rake_completion/
> svn propget piston:local-revision rake_completion/
2377
> svn propget piston:uuid rake_completion/
7c507d47-1513-0410-95a0-a599ac62d117
> svn propget piston:remote-revision rake_completion/
74


Vendor branch management  edit   (Category  edit)


Rails plugins and libraries  edit   (Category  edit) .


Subversion  edit   (Category  edit)

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