merge-tree: batched merges
cover merge-tree: batched merges
When a branch is updated, a Git hosting provider may want to check all open code reviews targetting the given branch to determine if those code reviews can still merge cleanly into the target branch. Provide a new --stdin option to git-merge-tree to enable this capability, with each line of input providing the branches for the next merge.
Note: this still requires all the merges to be in the same repository. There is some code I noticed a while back in merge-ort that implicitly uses the_repository (indirectly), and there may be more uses that I am unaware of.
Elijah Newren (2):
merge-tree: update documentation for differences in -z output
merge-tree: support multiple batched merges with --stdin
Documentation/git-merge-tree.txt | 76 ++++++++++++++++++++++++++++---- builtin/merge-tree.c | 42 ++++++++++++++++-- t/t4301-merge-tree-write-tree.sh | 41 +++++++++++++++++ 3 files changed, 148 insertions(+), 11 deletions(-)
base-commit: 45c9f05c44b1cb6bd2d6cb95a22cf5e3d21d5b63
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1361%2Fnewren%2Fbatched-merges-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1361/newren/batched-merges-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1361
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PATCH 1/2 merge-tree: update documentation for differences in -z output
From: Elijah Newren <[email protected]>
The Informational Messages was updated in de90581141 ("merge-ort:
optionally produce machine-readable output", 2022-06-18) to provide more detailed and machine parseable output when -z is passed, but the Documentation was not updated to reflect these changes. Update it now.
--- Documentation/git-merge-tree.txt | 46 +++++++++++++++++++++++++++----- 1 file changed, 39 insertions(+), 7 deletions(-)
Documentation/git-merge-tree.txt +39 -7
@@ -108,18 +108,50 @@ character instead of a newline character. Informational messages ~~~~~~~~~~~~~~~~~~~~~~ -This always starts with a blank line (or NUL if `-z` is passed) to -separate it from the previous sections, and then has free-form -messages about the merge, such as: +This section provides informational messages, typically about +conflicts. The format of the section varies significantly depending +on whether `-z` is passed. + +If `-z` is passed: + +The output format is zero or more conflict informational records, each +of the form: + + <list-of-paths><conflict-type>NUL<conflict-message>NUL + +where <list-of-paths> is of the form + + <number-of-paths>NUL<path1>NUL<path2>NUL...<pathN>NUL + +and includes paths (or branch names) affected by the conflict or +informational message in <conflict-message>. Also, <conflict-type> is a +stable string explaining the type of conflict, such as + + * "Auto-merging" + * "CONFLICT (rename/delete)" + * "CONFLICT (submodule lacks merge base)" + * "CONFLICT (binary)" + +and <conflict-message> is a more detailed message about the conflict which often +(but not always) embeds the <stable-short-type-description> within it. These +strings may change in future Git versions. Some examples: * "Auto-merging <file>" * "CONFLICT (rename/delete): <oldfile> renamed...but deleted in..." - * "Failed to merge submodule <submodule> (<reason>)" + * "Failed to merge submodule <submodule> (no merge base)" * "Warning: cannot merge binary files: <filename>" -Note that these free-form messages will never have a NUL character -in or between them, even if -z is passed. It is simply a large block -of text taking up the remainder of the output. +If `-z` is NOT passed: + +This section starts with a blank line to separate it from the previous +sections, and then only contains the <conflict-message> information +from the previous section (separated by newlines). These are +non-stable strings that should not be parsed by scripts, and are just +meant for human consumption. Also, note that while <conflict-message> +strings usually do not contain embedded newlines, they sometimes do. +(However, the free-form messages will never have an embedded NUL +character). So, the entire block of information is meant for human +readers as an agglomeration of all conflict messages. EXIT STATUS -----------
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PATCH 2/2 merge-tree: support multiple batched merges with --stdin
In reply to Elijah Newren via GitGitGadgetFrom: Elijah Newren <[email protected]>
Add an option, --stdin, to merge-tree which will accept lines of input with two branches to merge per line, and which will perform all the merges and give output for each in turn. This option implies -z, and modifies the output to also include a merge status since the exit code of the program can no longer convey that information now that multiple merges are involved.
This could be useful, for example, by Git hosting providers. When one branch is updated, one may want to check whether all code reviews targetting that branch can still cleanly merge. Avoiding the overhead of starting up a separate process for each of those code reviews might provide significant savings in a repository with many code reviews.
--- Documentation/git-merge-tree.txt | 30 ++++++++++++++++++++++- builtin/merge-tree.c | 42 +++++++++++++++++++++++++++++--- t/t4301-merge-tree-write-tree.sh | 41 +++++++++++++++++++++++++++++++ 3 files changed, 109 insertions(+), 4 deletions(-)
Documentation/git-merge-tree.txt +29 -1
@@ -81,6 +81,31 @@ Whereas for a conflicted merge, the output is by default of the form: These are discussed individually below. +However, there is an exception. If `--stdin` is passed, then there is +an extra section at the beginning, a NUL character at the end, and then +all the sections repeat for each line of input. Thus, if the first merge +is conflicted and the second is clean, the output would be of the form: + + <Merge status> + <OID of toplevel tree> + <Conflicted file info> + <Informational messages> + NUL + <Merge status> + <OID of toplevel tree> + NUL + +[[MS]] +Merge status +~~~~~~~~~~~~ + +This is an integer status followed by a NUL character. The integer status is: + + 0: merge had conflicts + 1: merge was clean + <0: something prevented the merge from running (e.g. access to repository + objects denied by filesystem) + [[OIDTLT]] OID of toplevel tree ~~~~~~~~~~~~~~~~~~~~
@@ -159,7 +184,10 @@ EXIT STATUS For a successful, non-conflicted merge, the exit status is 0. When the merge has conflicts, the exit status is 1. If the merge is not able to complete (or start) due to some kind of error, the exit status is -something other than 0 or 1 (and the output is unspecified). +something other than 0 or 1 (and the output is unspecified). When +--stdin is passed, the return status is 0 for both successful and +conflicted merges, and something other than 0 or 1 if it cannot complete +all the requested merges. USAGE NOTES -----------
builtin/merge-tree.c +39 -3
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t/t4301-merge-tree-write-tree.sh +41 -0
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