git-commit-vandalism/Documentation/git-commit-graph.txt
Taylor Blau 0bd52e27e3 commit-graph.h: store an odb in 'struct write_commit_graph_context'
There are lots of places in 'commit-graph.h' where a function either has
(or almost has) a full 'struct object_directory *', accesses '->path',
and then throws away the rest of the struct.

This can cause headaches when comparing the locations of object
directories across alternates (e.g., in the case of deciding if two
commit-graph layers can be merged). These paths are normalized with
'normalize_path_copy()' which mitigates some comparison issues, but not
all [1].

Replace usage of 'char *object_dir' with 'odb->path' by storing a
'struct object_directory *' in the 'write_commit_graph_context'
structure. This is an intermediate step towards getting rid of all path
normalization in 'commit-graph.c'.

Resolving a user-provided '--object-dir' argument now requires that we
compare it to the known alternates for equality.  Prior to this patch,
an unknown '--object-dir' argument would silently exit with status zero.

This can clearly lead to unintended behavior, such as verifying
commit-graphs that aren't in a repository's own object store (or one of
its alternates), or causing a typo to mask a legitimate commit-graph
verification failure. Make this error non-silent by 'die()'-ing when the
given '--object-dir' does not match any known alternate object store.

[1]: In my testing, for example, I can get one side of the commit-graph
code to fill object_dir with "./objects" and the other with just
"objects".

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-04 11:36:37 -08:00

122 lines
3.9 KiB
Plaintext

git-commit-graph(1)
===================
NAME
----
git-commit-graph - Write and verify Git commit-graph files
SYNOPSIS
--------
[verse]
'git commit-graph verify' [--object-dir <dir>] [--shallow] [--[no-]progress]
'git commit-graph write' <options> [--object-dir <dir>] [--[no-]progress]
DESCRIPTION
-----------
Manage the serialized commit-graph file.
OPTIONS
-------
--object-dir::
Use given directory for the location of packfiles and commit-graph
file. This parameter exists to specify the location of an alternate
that only has the objects directory, not a full `.git` directory. The
commit-graph file is expected to be in the `<dir>/info` directory and
the packfiles are expected to be in `<dir>/pack`. If the directory
could not be made into an absolute path, or does not match any known
object directory, `git commit-graph ...` will exit with non-zero
status.
--[no-]progress::
Turn progress on/off explicitly. If neither is specified, progress is
shown if standard error is connected to a terminal.
COMMANDS
--------
'write'::
Write a commit-graph file based on the commits found in packfiles.
+
With the `--stdin-packs` option, generate the new commit graph by
walking objects only in the specified pack-indexes. (Cannot be combined
with `--stdin-commits` or `--reachable`.)
+
With the `--stdin-commits` option, generate the new commit graph by
walking commits starting at the commits specified in stdin as a list
of OIDs in hex, one OID per line. (Cannot be combined with
`--stdin-packs` or `--reachable`.)
+
With the `--reachable` option, generate the new commit graph by walking
commits starting at all refs. (Cannot be combined with `--stdin-commits`
or `--stdin-packs`.)
+
With the `--append` option, include all commits that are present in the
existing commit-graph file.
+
With the `--split` option, write the commit-graph as a chain of multiple
commit-graph files stored in `<dir>/info/commit-graphs`. The new commits
not already in the commit-graph are added in a new "tip" file. This file
is merged with the existing file if the following merge conditions are
met:
+
* If `--size-multiple=<X>` is not specified, let `X` equal 2. If the new
tip file would have `N` commits and the previous tip has `M` commits and
`X` times `N` is greater than `M`, instead merge the two files into a
single file.
+
* If `--max-commits=<M>` is specified with `M` a positive integer, and the
new tip file would have more than `M` commits, then instead merge the new
tip with the previous tip.
+
Finally, if `--expire-time=<datetime>` is not specified, let `datetime`
be the current time. After writing the split commit-graph, delete all
unused commit-graph whose modified times are older than `datetime`.
'verify'::
Read the commit-graph file and verify its contents against the object
database. Used to check for corrupted data.
+
With the `--shallow` option, only check the tip commit-graph file in
a chain of split commit-graphs.
EXAMPLES
--------
* Write a commit-graph file for the packed commits in your local `.git`
directory.
+
------------------------------------------------
$ git commit-graph write
------------------------------------------------
* Write a commit-graph file, extending the current commit-graph file
using commits in `<pack-index>`.
+
------------------------------------------------
$ echo <pack-index> | git commit-graph write --stdin-packs
------------------------------------------------
* Write a commit-graph file containing all reachable commits.
+
------------------------------------------------
$ git show-ref -s | git commit-graph write --stdin-commits
------------------------------------------------
* Write a commit-graph file containing all commits in the current
commit-graph file along with those reachable from `HEAD`.
+
------------------------------------------------
$ git rev-parse HEAD | git commit-graph write --stdin-commits --append
------------------------------------------------
GIT
---
Part of the linkgit:git[1] suite