Update: The information in this post is unfortunately out of date. While much of the code samples are similar, the new method of creating new plugins has changed in subtle, but very significant ways. Until a new guide can be written, please refer to the existing plugins for code examples.
Considering that my last post on Integrating Git and SVN has garnered a fair amount of attention, I thought that it would be useful to discuss my Source Integration framework in more detail. Specifically, I’ll be covering topics such as the design and implementation of the framework and, more importantly, how developers can go about implementing support for other version control tools.
The point of this is to show that it’s quite possible to integrate just about any type of version control tool with the Source Integration system; indeed I planned from the beginning to create a generalized framework that would support many different types and paradigms for version control. This should at least be evident in that I have already created extension plugins for Git and Subversion - it should be quite possible to extend the concepts further to Mercurial, Bazaar, CVS, or any other tool.
For the point of brevity, I’ll make the assumption that the developer at least has a fair understanding of PHP, their version control tool, and how events and plugins work in MantisBT. If you are not yet familiar with the plugin system, there is currently a basic introduction in the MantisBT Developer’s Guide, which I’ll hopefully be adding more information to in the near future.
With the ongoing work towards a 1.2 release, the Mantis Bug Tracker features a brand new plugin and event system, which will allow users to implement entirely new features for MantisBT without ever needing to touch any of the core codebase. It’s a very extensible system, and allows plugin authors to implement only what they need, while still allowing advanced plugins as much flexibility as possible. Plugins can be as small as a single file with 20 lines of code, or as large as entire hierarchies of files, pages, with their own API’s.
As the core developer of the new plugin system, I have been working on a variety of plugins. In particular, I have created a vastly improved method of integrating source control repositories within MantisBT. The plugin package is named, aptly enough, Source Integration, and implements a generic framework that will allow integration with multiple repositories, each potentially using any source control systems available, simply by creating an extension plugin for each new tool. Currently, I have implemented integration packages for both Git and Subversion, my two source control tools of choice.
The Source Integration package tracks repository information based on a series of changesets, each of which may have a list of affected files. The data representation is generic enough to cover version control concepts used by all types of tools, from the ubiquitous CVS and Subversion, to modern distributed tools like Git and Hg. However, the system takes the stance of implementing as few details as possible, so it relies on existing repository-viewing tools for tasks such as viewing commit diffs, file contents, tree browsing, etc. Extension plugins handle translating tool-specific information, like history logs or checkin data, into the generalized data objects used by the framework. Extensions also generate URL’s for viewing files and diffs, but everything else is handled automatically by the core framework.
The true benefit of the Source Integration package lies in the amount of repository integration that it implements within MantisBT. When importing changesets from your repository, Source looks at the commit message of each changeset for references to bug numbers in your tracker, and sets up links in the database for any bugs mentioned. When viewing bugs mentioned in commit messages, a new section is displayed after the bugnotes called “Related Changesets”, giving a list of linked changes, including information about the changeset, such as the branch, author, timestamp, and a list of changed files.