[PATCH 01/10] doc: about submodule support with multiple worktrees
- From
Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
- Date
- Jan 16, 2019, 10:31 UTC
- Message-ID
- <20190116103159.9305-2-pclouds@gmail.com>
- In-Reply-To
- <20190116103159.9305-1-pclouds@gmail.com>
This lays out the very first step of making multiple worktrees and submodules work together.
The first problem is git-submodule keeps per-worktree config in $GIT_DIR/config, which is shared for all worktrees. This series makes git-submodule use extensions.worktreeConfig and write submodule.* to config.worktree instead.
The rest goes on and on about the remaining problems. But let's talk a bit more about solving the first problem. Since it relies on the experimental extensions.worktreeConfig, this support is of course also experimental. On the other hand, submodules have never really worked with multi worktrees before, this change can't bite anybody.
Second problem. That is about multiple worktrees at superproject level. At submodule level, we still can't have multiple worktrees because git-submodule writes to submodule's "config" file (again). Fixing this is not particularly hard. Absorbing submodule's git dir takes some work but is feasible. This could be addressed soon in the future.
The third problem is a big and complicaed one. Submodule clones (inside the superproject) are per-worktree. So if you have two worktrees, and these have one submodule, you need space for _two_ clones. This is definitely not elegant. The tenative plan is to move clones from $GIT_COMMON_DIR/worktrees/X/modules to $GIT_COMMON_DIR/common/modules.
The latter directory is shared across all worktrees. Once we keep the clone in a common place, the submodule's worktree can be created and managed with git-worktree[1].
Another good point about this approach is we could finally safely allow "git worktree remove" to work with submodules. With current solution, removing $GIT_COMMON_DIR/worktrees/X directory means also removing potentially precious clones inside the "modules" subdir.
But whether we can do this depends on:
- if we need separate ref namespace for submodule on each worktree
- how does submodule's worktrees (remember the second problem) interact these worktrees
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> --- Documentation/git-worktree.txt | 8 ++++++++ Documentation/gitsubmodules.txt | 17 +++++++++++++++++ 2 files changed, 25 insertions(+)
diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt index aae8e1d8b2..3510fd5331 100644 --- a/Documentation/git-worktree.txt +++ b/Documentation/git-worktree.txt @@ -267,6 +267,14 @@ configuration that you do not want to share to all working trees: - `core.sparseCheckout` is recommended per working tree, unless you are sure you always use sparse checkout for all working trees. + - Most configuration variables under `submodule` group in superproject + should not be shared. ++ +------------ +$ git config --local --move-to --worktree submodule.active +$ git config --local --move-to-regexp --worktree 'submodule\..*\..*' +------------ + DETAILS ------- Each linked working tree has a private sub-directory in the repository's diff --git a/Documentation/gitsubmodules.txt b/Documentation/gitsubmodules.txt index 57999e9f36..d91817b45d 100644 --- a/Documentation/gitsubmodules.txt +++ b/Documentation/gitsubmodules.txt @@ -222,6 +222,23 @@ submodule active pathspec, which specifies that any submodule starting with 'b' except 'baz' are also active, regardless of the presence of the .url field. +MULTIPLE WORKING TREE SUPPORT +----------------------------- +When you have more than one working tree, created by +linkgit:git-worktree[1], submodules will not work on any working tree +until `extensions.worktreeConfig` is enabled. Since this config +affects more than just submodules, please see "CONFIGURATION FILE" +section for more information before turning it on. + +Once on, submodules can be added in any working tree. The submodule +itself though cannot have more than one working tree. + +When submodules are created in a working tree, their git directory is +also per-worktree, e.g. inside +'$GIT_COMMON_DIR/worktrees/<worktree>/modules' and not shared with +other working trees. This means if you have the same submodule on +different working trees, you need disk space for multiple clones. + Workflow for a third party library ----------------------------------
-- 2.20.0.482.g66447595a7