ae3f36dea1
Commits that make formatting changes or function renames are often not interesting when blaming a file. A user may deem such a commit as 'not interesting' and want to ignore and its changes it when assigning blame. For example, say a file has the following git history / rev-list: ---O---A---X---B---C---D---Y---E---F Commits X and Y both touch a particular line, and the other commits do not: X: "Take a third parameter" -MyFunc(1, 2); +MyFunc(1, 2, 3); Y: "Remove camelcase" -MyFunc(1, 2, 3); +my_func(1, 2, 3); git-blame will blame Y for the change. I'd like to be able to ignore Y: both the existence of the commit as well as any changes it made. This differs from -S rev-list, which specifies the list of commits to process for the blame. We would still process Y, but just don't let the blame 'stick.' This patch adds the ability for users to ignore a revision with --ignore-rev=rev, which may be repeated. They can specify a set of files of full object names of revs, e.g. SHA-1 hashes, one per line. A single file may be specified with the blame.ignoreRevFile config option or with --ignore-rev-file=file. Both the config option and the command line option may be repeated multiple times. An empty file name "" will clear the list of revs from previously processed files. Config options are processed before command line options. For a typical use case, projects will maintain the file containing revisions for commits that perform mass reformatting, and their users have the option to ignore all of the commits in that file. Additionally, a user can use the --ignore-rev option for one-off investigation. To go back to the example above, X was a substantive change to the function, but not the change the user is interested in. The user inspected X, but wanted to find the previous change to that line - perhaps a commit that introduced that function call. To make this work, we can't simply remove all ignored commits from the rev-list. We need to diff the changes introduced by Y so that we can ignore them. We let the blames get passed to Y, just like when processing normally. When Y is the target, we make sure that Y does not *keep* any blames. Any changes that Y is responsible for get passed to its parent. Note we make one pass through all of the scapegoats (parents) to attempt to pass blame normally; we don't know if we *need* to ignore the commit until we've checked all of the parents. The blame_entry will get passed up the tree until we find a commit that has a diff chunk that affects those lines. One issue is that the ignored commit *did* make some change, and there is no general solution to finding the line in the parent commit that corresponds to a given line in the ignored commit. That makes it hard to attribute a particular line within an ignored commit's diff correctly. For example, the parent of an ignored commit has this, say at line 11: commit-a 11) #include "a.h" commit-b 12) #include "b.h" Commit X, which we will ignore, swaps these lines: commit-X 11) #include "b.h" commit-X 12) #include "a.h" We can pass that blame entry to the parent, but line 11 will be attributed to commit A, even though "include b.h" came from commit B. The blame mechanism will be looking at the parent's view of the file at line number 11. ignore_blame_entry() is set up to allow alternative algorithms for guessing per-line blames. Any line that is not attributed to the parent will continue to be blamed on the ignored commit as if that commit was not ignored. Upcoming patches have the ability to detect these lines and mark them in the blame output. The existing algorithm is simple: blame each line on the corresponding line in the parent's diff chunk. Any lines beyond that stay with the target. For example, the parent of an ignored commit has this, say at line 11: commit-a 11) void new_func_1(void *x, void *y); commit-b 12) void new_func_2(void *x, void *y); commit-c 13) some_line_c commit-d 14) some_line_d After a commit 'X', we have: commit-X 11) void new_func_1(void *x, commit-X 12) void *y); commit-X 13) void new_func_2(void *x, commit-X 14) void *y); commit-c 15) some_line_c commit-d 16) some_line_d Commit X nets two additionally lines: 13 and 14. The current guess_line_blames() algorithm will not attribute these to the parent, whose diff chunk is only two lines - not four. When we ignore with the current algorithm, we get: commit-a 11) void new_func_1(void *x, commit-b 12) void *y); commit-X 13) void new_func_2(void *x, commit-X 14) void *y); commit-c 15) some_line_c commit-d 16) some_line_d Note that line 12 was blamed on B, though B was the commit for new_func_2(), not new_func_1(). Even when guess_line_blames() finds a line in the parent, it may still be incorrect. Signed-off-by: Barret Rhoden <brho@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.txt to get started, then see
Documentation/giteveryday.txt for a useful minimum set of commands, and
Documentation/git-.txt for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with man gittutorial or git help tutorial, and the
documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.txt
(man gitcvs-migration or git help cvs-migration if git is
installed).
The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission). To subscribe to the list, send an email with just "subscribe git" in the body to majordomo@vger.kernel.org. The mailing list archives are available at https://public-inbox.org/git/, http://marc.info/?l=git and other archival sites.
Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.
The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (depending on your mood):
- random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
- stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
- "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks