streamly/MAINTAINING.md

Maintainers' Guide

PR Merge Checklist

• All the CI tests pass
• New tests are added where applicable
• Benchmarks are added where applicable
• Run benchmarks locally if you suspect any regressions
• Documentation is added for any new combinators
  • New combinators have time and space complexity annotations
  • New combinators have since annotation
• Changelog entry is added for exposed combinators.
• Identify breaking changes, or changes that may require depndency version bound changes. See https://pvp.haskell.org/. Also see the "Breaking changes section below".
• Optionally, look at hlint output if anything in that is worth fixing.
• Merge the PR by rebasing. Note that github always creates new commits when merged with rebase, it records the committer as well as the author in the commit. This makes the local branch diverge from master. You can rebase and merge the commit manually in your local git tree and push the resulting master branch to avoid new commits and divergence from the original tree.

Release Checklist

• Check if any critical pending bugs or issues are to be included

• If this is a major release check if any previously deprecated features are to be removed in this release.

• Check pre-release APIs to be exposed, especially from streamly-examples

• PVP is ahered to, do not change pre-release APIs in a minor release

• Documentation:

  • README is updated
  • Haddock docs are consistent with the changes in the release
  • Tutorial has been updated for new changes
  • Documents in the docs directory are consistent with new changes
  • All combinators have time and space complexity annotations
  • All combinators have since annotation
  • Unreleased combinators should be marked with Pre-release or Internal annotations

• Build and Test:

  • All CIs are green
  • Manually build and test for all flags (esp. dev flag) not covered by CIs
  • Test latest GHC version with -O0 and -O1

• Benchmarks:

  • Check regressions from previous release
  • Run benchmarks with large stream size (bench.sh -- long) to check for space leaks and to ensure constant memory usage for streaming operations.
  • Run benchmarks with dev flag on. Some fileio benchmarks are disabled in regular runs.
  • Check comparative benchmarks using streaming-benchmarks

• Examples:

  • Update streamly-examples to make sure it runs with the latest release.
  • Check the performance of examples where applicable

• Update Package Metadata:

  • Update stack.yaml to latest stable resolver, cleanup extra-deps
  • Make sure the description in cabal file is in sync with README and other docs
  • Make sure CI configs include last three major releases of GHC in CI testing.
  • Update tested-with field
  • Make sure all dependency bounds can use latest versions
  • Make sure any additional files are added to extra-source-files in cabal file

• Copyrights and Contibutors

  • Make sure contributors to the release are listed in credits/CONTRIBUTORS.md.
  • Bump the release version in credits/CONTRIBUTORS.md.
  • Make sure any third party code included in the release has been listed in credits/COPYRIGHTS.md and the license is added to the repo.
  • Change the Unreleased section, if exists, at the top of credits/COPYRIGHTS.md to the new release version number.

• Update changelog & Version:

  • Make sure all the bug fixes being included in this release are marked with a target release on github. So that users can search by release if they want.
  • Change the Unreleased section at the top of changelog file to the new release version number.
  • Bump the package version in cabal file or package.yaml
  • Bump the package version in configure.ac and run autoreconf

• Upload:

  • Wait for final CI tests to pass:

    • Create a git tag corresponding to the release where X.Y.Z is the new package version (git tag vX.Y.Z && git push -f origin vX.Y.Z).
    • Mask out the build status lines from the README
    • Upload to hackage
      • Use a clean workspace to create source distribution by freshly cloning the git repository. The reason for doing this is that we use wild-cards in cabal file for extra-source-files, these wild-cards may match additional files lying around in the workspace and unintentionally ship them as well.
      • cabal v2-sdist; cabal upload --publish <tarpath>
      • stack upload .
    • Add to stackage (build-constraints.yaml in Stackage repo) if needed
    • Optionally upload package-X.Y.Z-sdist.tar.gz to github release page
      • Update release contributors on github release page (git shortlog -s prev_tag..new_tag | sed $'s/^[0-9 \t]*/* /' | sort -f)
    • Update and if needed release streaming-benchmarks package
    • Check https://matrix.hackage.haskell.org/package/streamly
    • Check haddocks on Hackage, upload if not built
    • Announce to haskell-cafe@haskell.org

Breaking Changes

This section lists what constitutes breaking changes. See https://pvp.haskell.org/ breaking changes that can be determined by the API alone. We specify some additional recommendations here:

Behavior changes, this kind of changes are nasty and should be avoided. If such changes are made they should be emphasized adequately in the changelog:

• Silent changes in the behavior of an API without any changes to the signature.
• Even fixing a bug could break things as users may have employed workarounds for the bug.
• Changes in the behavior of a dependency may also cause a change in behavior.

Be cautious about the following:

• Change in version bounds of dependencies may cause compilation failure for some programs because they may not be able to find a build plan.
• Ideally, new warnings should not be considered breaking, dependencies should never be compiled with -Werror. But packages may not be following it perfectly.
• Deprecating an API may issue new warnings, however the code can still be compiled if warnings are not treated as errors.

Internal APIs:

• Internal APIs can change without having to change the major version. However, we should try to align the Internal API changes with a major release as long as possible.

Managing Issues

We label the issues in different dimensions based on the lifecyle and different management aspects of the issue. The folowing sections discuss the labels used to manage the issues. If a new label is required, it should be discussed before creating it.

Disposition

The level-1 triaging of the issue determines the current disposition of the issue. If no change is required the issue must have one of the following labels:

• invalid
• question
• discussion
• duplicate
• wontfix

If a change is required we need to do level-2 triage of the issue, see the sections below.

Change type

When a change is required we need to put one of the change type labels as part of level-2 triaging:

• performance: User visible impact on performance.
• usability: It is not convenient to use the library.
• documentation: documentation is not correct or sufficient.
• bug: A functionality issue, not working as expected.
• enhancement: A new feature or enhancement of the product.
• maintenance: A refactor or any other change with no user visible impact.

Aspect

In addition we can put a product aspect label describing a feature name or any other product specific classification bucket.

• aspect:

Severity

Optionally we can add a severity label to indicate how severe is the impact of the bug/issue, which may determine how important it is to fix it. By default the severity is normal, if it is high we put a label:

• severity:high

Change impact

For a user visible issue whether it has a release/changelog impact:

• enhancement: includes a new feature or enhancement
• breaking: has a breaking impact on existing deployments
• deprecating: deprecates an existing functionality

RULE: Any commit that may affect the end user in some way MUST have either a changelog entry OR MUST have an issue marked with one of the above labels OR both.

Priority

By default the issues are normal priority. We use a label for high priority issues:

• priority:high

Scheduling

If the issue is assigned to someone then it is considered scheduled. Otherwise it is unscheduled. Unassigned issues may have the following labels:

• deferred: blocked on any other fix or a decision to be made, or deliberately deferred for some reason.
• help-wanted: anyone can take the issue and contribute

Correlating Changes, Issues and Releases

For planning purposes, open issues may be marked with milestones or target releases. However, it may not always be known which release a fix will finally land in. For example, we may decide to make a minor release instead of a major one if there are no breaking changes yet, so we may not always know what would be the next release version.

Trackability means that we should be able to find which issues got fixed in which release. Or what all issues got fixed in a particular release. We track significant changes using the changelog. However, there may be more changes that can only be tracked via issues, PRs or commits. When we make a release we can mark all the issues fixed in that release with a correct release target for future trackability.

For better trackability of which issue got fixed in which release we need the following:

• Before you close an issue make sure a commit or a PR fixing the issue is attached with it. In the commit message you can reference an issue like "fixes #50", you can do the same in a PR as well.
• Before we make a new release EVERY issue with a commit included in that release that affects the end user, especially bugs and breaking changes MUST have the target release correctly set.

Changelog Management

Keep the unreleased changes in the Unreleased section at the top of changelog file. Using Unreleased instead of the next release number for unreleased changes is important. First, we do not know the next release number in advance, it could be a major or minor release. Second, if we use the next release number instead, then when adding a new change to the changelog, at one look we cannot know whether the release number on top is unreleased or released.

TODO

• GPG signed releases and tags