wiki:pm-svn-releases

Version 5 (modified by tkr, 15 years ago) (diff)

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Suggestions for Handling Stable Versions and Releases

This page describes how the policy for versioning suggested by COIN can be implemented within the subversion repository for your project. You might want to first read the page on understanding branches and tags, or other pages for understanding subversion. Below, the string YourProject? is to be repleaced by the name of your project.

Overview

The overall philosophy of the COIN-OR versioning and release system is to specify standard procedures for maintaining the code base of COIN-OR projects that allow various groups of users to obtain the version of the code most appropriate for them. The recommended subversion repository layout for COIN-OR projects includes the top-level directories trunk/, branches/, tags/, stable/, and releases/. At all times, the main development line is to be contained in trunk/. The code in trunk is not expected to be completely functional and is the "bleeding edge" of the project. At specified points in time, specific versions can be slit off from this main development line for the purpose of implementing special features or declaring a stable release (see below). The directories branches/ are optional directories that can contain version implementing or testing experimental features. The directory tags/ is for storing fixed and named snapshots of code for future reference. No new code should ever be committed to the tags/}} directory. The use of the {{{stable/ and releases/ directory is to create stable versions of the project for users to download and other projects to link to. This explained in more detail next.

A stable version is created whenever the PM wishes to declare a new version of the project. Creating a stable version means roughly that the feature set and API associated with that particular version should be frozen, but the code may continue to evolve through the application of patches to fix bugs, the addition of documentation, etc. Such a "stable version" is identified by a two-digit version number (i.e., 5.1) and is associated with a similarly-named subdirectory in stable/ created by branching (copying) the code in trunk/ (see below for specific commands to be used for this prupose). In subversion, such a two-digit version is not frozen once copied to stable/. It is intended to continue evolving and new code can be committed to subdirectories in the stable/ directory. However, this evolution should generally consist of bug fixes and minor tweaking only---development of new features for future versions can continue at the same time in trunk/. Bug fixes applied to versions in stable/ may also need to be merged into trunk/, as appropriate (see below).

An important notion is that declaring a new stable version is not the same as creating a new point release. A point release is a fixed snapshot of a stable version intended for distribution in source and/or binary form (i.e., a tarball). Whenever the PM deems appropriate (usually when the current stable version, along with previously applied patches, passes some sort of litmus test established by the PM), a point release, identified by a three-digit release number (i.e., 5.1.1) can be copied from stable/ to releases/. The first two digits indicate the stable version and the last number is the patch level. Such point releases are frozen and are never changed. If a bug is found in a point release, it gets fixed in stable/ and then a new point release created (i.e., 5.1.2), as appropriate.

To reiterate, the point releases are what we will distribute as tarballs and what we will use to create binaries because they are fixed versions that do not evolve. Therefore, if someone finds a bug in a binary or a version created from a tarball, we will be able to recreate the exact version of the code they are using by checking out the appropriate point release from SVN. There is probably no reason why anyone (besides a developer trying to fix a bug) would want to check out something from releases/ in SVN. Because these version never change, there is no point in using SVN because svn update will not retrieve the bug fixes. To update, a user would have to manually check a new point release, but then the user might as well have just download the tarballs since that is easier.

What to Tell Users

It is up to each developer to determine exactly what they will recommend to their users as far as how to obtain the source code or binaries for their project. However, here are some suggested categories of users and what is the recommended way for them to get the codes in COIN-OR.

  1. For casual users and those who do not want to be bothered with frequent updates or installing SVN, they should download the latest tarball (point release) in either source or binary form. To report bugs, they can use the three-digit release number of the tarball they downloaded. To get a new version containing a bug fix (or a capability they want that has been added), they will need to download a new tarball. Such users can expect the version they check out to be mature and mostly bug-free.
  1. For power users who want to get updates and bug fixes as soon as they are committed, but want a stable API that will not change out from under them, they should use SVN to check out the latest stable release in stable/*.*. Such users would have to report bugs based on the SVN version number they are using (a little more of a pain for the developers), but can get the fixes using "svn update". Such users may experience a slightly bumpier ride, as there may occasionally be incorrect patches committed to stable/ and other minor difficulties. Most of the time, however, this code should be mature and stable.
  1. Developers and any really adventurous power users who want the bleeding edge can check out trunk/. This probably not to be encouraged for users and certainly the PM won't be expected to be too responsive to bug reports from people using the code in trunk/, since it is not intended to be bug-free.

Setting up your Repository

First you want to make sure that the directories trunk, stable, and releases exist for your project. An easy way to do this is to load the webpage https://projects.coin-or.org/svn/YourProject (such as https://projects.coin-or.org/svn/BuildTools). This lists the base directories in your project.

If a directory, say releases, does not yet exist, you can create it directly in the svn repository with the svn mkdir command, giving it the full URL. For example:

svn mkdir https://projects.coin-or.org/svn/YourProject/releases \
           -m "creating releases directory"

Working with Stable Versions

The idea of a stable branch is that you maintain a stable line of your code here, that can be used by a user who wants to be up-to-date with your "official" version of the code. You start with a version that you think is good enough to be made "official". Later, you update the code in a particular stable branch, for example to include bug fixes, or because you add some improvements. Typically, when you fixed a bug reported by a user, you would fix it in the corresonding stable release, and tell the user how to get it. When it seems to work, you should probably make a new release (see below).

Note: We strongly suggest to create a new stable branch when the user interface for your code changes in a way, so that users of your code would have to change their code in order to use the new code. By creating a new stable branch, a user will not find any bad surprises when updating his/her local copy of a stable branch, and can instead switch to a new stable branch later, whenever (s)he is ready.

Creating a New Stable Version

You usually create a new stable branch, with a version number x,y, say 2.3, from some version of your code that exists in the repository. Typically, you would have been working in trunk (where the active development takes place), and want to releases the current trunk version in the repository as a new stable branch.

A new stable branch with the chosen version number is create in the repository, using the svn copy command. In order to create stable branch 2.3 from trunk you could use

svn copy https://projects.coin-or.org/svn/YourProject/trunk \
           https://projects.coin-or.org/svn/YourProject/stable/2.3 \
           -m "Creating new stable branch 2.3 from trunk (rev 533)"

NOTE: In the commit message you should always record the subversion revision number from which you created the new branch. This information is essential for merging and some other repository operations. To find out the revision number, you can use the svn info command. For example, to determine the revision number in the above example, you could have used

svn info https://projects.coin-or.org/svn/YourProject/trunk

and looked at the line that starts with "Revision:".

Maintaining a Stable Version

To change the content for a stable version, you work with it as usual: creating a local copy of the code in that branch, making changes there (directly by editing, or by using svn merge to include changes made in a different version in the repository, such as trunk), and finally submitting the changes back to the repository.

Working With Point Releases

The release directory is the place where a user can find particular, numbered releases. The tarballs distributed on the COIN-OR website are created from those releases. It is mandatory that by checking out a release from this place in the repository always proves the identical code, so that restore older versions is possible (for example for reproducing bugs). In this context you need to be careful if you use svn:externals. Once a release has been created it must not be changed'''

Creating a New Point Release

Typically, you would have a version of your code in a stable branch, say 2.3, which you now want to make an official release.

If you are using Externals: Before creating the new releaes from the current version in the stable branch, you need to make sure that all svn:externals are pointing to releases of the dependencies so that your release can be recreated exactly at any point in time, even if the development of the dependencies progressed. So, please make sure that all URLs in your Externals file are pointing to something in the release directory of the dependencies. Also, make sure that the externals are indeed set according to the file content (verify with svn pget svn:externals https://projects.coin-or.org/svn/YourProject/stable/2.3).

To create a new release, say 2.3.6, you use the svn copy command:

svn copy https://projects.coin-or.org/svn/YourProject/stable/2.3 \
           https://projects.coin-or.org/svn/YourProject/releases/2.3.8 \
           -m "Creating new release 2.3.8 from stable/2.3 (rev 567)"

Again, it is a very good idea to log the subversion repository revision number in the commit message.