Mercurial: The Definitive Guide

Managing Patches in a Repository

Because MQ’s .hg/patches directory resides outside a Mercurial repository’s working directory, the “underlying” Mercurial repository knows nothing about the management or presence of patches.

This presents the interesting possibility of managing the contents of the patch directory as a Mercurial repository in its own right. This can be a useful way to work. For example, you can work on a patch for a while, qrefresh it, then hg commit the current state of the patch. This lets you “roll back” to that version of the patch later on.

You can then share different versions of the same patch stack among multiple underlying repositories. I use this when I am developing a Linux kernel feature. I have a pristine copy of my kernel sources for each of several CPU architectures, and a cloned repository under each that contains the patches I am working on. When I want to test a change on a different architecture, I push my current patches to the patch repository associated with that kernel tree, pop and push all of my patches, and build and test that kernel.

Managing patches in a repository makes it possible for multiple developers to work on the same patch series without colliding with each other, all on top of an underlying source base that they may or may not control.

MQ Support for Patch Repositories

MQ helps you to work with the .hg/patches directory as a repository; when you prepare a repository for working with patches using qinit, you can pass the hg -c option ...