Managing Local Changes with Mercurial Queues

Repository Management Problem

gem5 users typically opt to freeze their repository at a particular changeset when starting a new research project. This approach has several downsides:

• It discourages users from contributing back any useful changes they may develop.
• If a useful change is added upstream, it's a long, tedious process to update.

If a user chooses to keep their local repository up-to-date with the source tree they typically use named branches and merge any upstream changes into their branches. This approach also has its downsides:

• If any local change needs to be updated, it requires a separate commit.
• If you have several small, unrelated changes separate branches must be maintained.
• Upstream changes must be merged into the local branches.

A powerful tool that overcomes these problems is the mercurial queue extension.

Mercurial Queues

The mercurial queue extension is a powerful tool that allows you to:

• Manage small changes easily as a set of well-defined patches.
• Edit previous patches without having a new commit.
• Keep your local changes cleanly separated from upstream changes.