kernel/git - git - PowerEL Git System

Commit Graph

Author	SHA1	Message	Date
Derrick Stolee	0906ac2b54	blame: use changed-path Bloom filters The changed-path Bloom filters help reduce the amount of tree parsing required during history queries. Before calculating a diff, we can ask the filter if a path changed between a commit and its first parent. If the filter says "no" then we can move on without parsing trees. If the filter says "maybe" then we parse trees to discover if the answer is actually "yes" or "no". When computing a blame, there is a section in find_origin() that computes a diff between a commit and one of its parents. When this is the first parent, we can check the Bloom filters before calling diff_tree_oid(). In order to make this work with the blame machinery, we need to initialize a struct bloom_key with the initial path. But also, we need to add more keys to a list if a rename is detected. We then check to see if _any_ of these keys answer "maybe" in the diff. During development, I purposefully left out this "add a new key when a rename is detected" to see if the test suite would catch my error. That is how I discovered the issues with GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS from the previous change. With that change, we can feel some confidence in the coverage of this change. If a user requests copy detection using "git blame -C", then there are more places where the set of "important" files can expand. I do not know enough about how this happens in the blame machinery. Thus, the Bloom filter integration is explicitly disabled in this mode. A later change could expand the bloom_key data with an appropriate call (or calls) to add_bloom_key(). If we did not disable this mode, then the following tests would fail: t8003-blame-corner-cases.sh t8011-blame-split-file.sh Generally, this is a performance enhancement and should not change the behavior of 'git blame' in any way. If a repo has a commit-graph file with computed changed-path Bloom filters, then they should notice improved performance for their 'git blame' commands. Here are some example timings that I found by blaming some paths in the Linux kernel repository: git blame arch/x86/kernel/topology.c >/dev/null Before: 0.83s After: 0.24s git blame kernel/time/time.c >/dev/null Before: 0.72s After: 0.24s git blame tools/perf/ui/stdio/hist.c >/dev/null Before: 0.27s After: 0.11s I specifically looked for "deep" paths that were also edited many times. As a counterpoint, the MAINTAINERS file was edited many times but is located in the root tree. This means that the cost of computing a diff relative to the pathspec is very small. Here are the timings for that command: git blame MAINTAINERS >/dev/null Before: 20.1s After: 18.0s These timings are the best of five. The worst-case runs were on the order of 2.5 minutes for both cases. Note that the MAINTAINERS file has 18,740 lines across 17,000+ commits. This happens to be one of the cases where this change provides the least improvement. The lack of improvement for the MAINTAINERS file and the relatively modest improvement for the other examples can be easily explained. The blame machinery needs to compute line-level diffs to determine which lines were changed by each commit. That makes up a large proportion of the computation time, and this change does not attempt to improve on that section of the algorithm. The MAINTAINERS file is large and changed often, so it takes time to determine which lines were updated by which commit. In contrast, the code files are much smaller, and it takes longer to comute the line-by-line diff for a single patch on the Linux mailing lists. Outside of the "-C" integration, I believe there is little more to gain from the changed-path Bloom filters for 'git blame' after this patch. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	5 years ago
René Scharfe	27f182b3fc	blame: provide type of fingerprints pointer The fingerprints member of struct blame_origin is a void pointer that is only ever used to reference objects of type struct fingerprint. Declare its type to allow the compiler to do type checks. We can keep its type opaque in blame.h, though -- only functions in blame.c need to know the actual definition of struct fingerprint. Signed-off-by: René Scharfe <l.s.r@web.de> Reviewed-by: Barret Rhoden <brho@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	5 years ago
Barret Rhoden	1fc73384ba	blame: optionally track line fingerprints during fill_blame_origin() fill_blame_origin() is a convenient place to store data that we will use throughout the lifetime of a blame_origin. Some heuristics for ignoring commits during a blame session can make use of this storage. In particular, we will calculate a fingerprint for each line of a file for blame_origins involved in an ignored commit. In this commit, we only calculate the line_starts, reusing the existing code from the scoreboard's line_starts. In an upcoming commit, we will actually compute the fingerprints. This feature will be used when we attempt to pass blame entries to parents when we "ignore" a commit. Most uses of fill_blame_origin() will not require this feature, hence the flag parameter. Multiple calls to fill_blame_origin() are idempotent, and any of them can request the creation of the fingerprints structure. Suggested-by: Michael Platings <michael@platin.gs> Signed-off-by: Barret Rhoden <brho@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Barret Rhoden	8934ac8c92	blame: add config options for the output of ignored or unblamable lines When ignoring commits, the commit that is blamed might not be responsible for the change, due to the inaccuracy of our heuristic. Users might want to know when a particular line has a potentially inaccurate blame. Furthermore, guess_line_blames() may fail to find any parent commit for a given line touched by an ignored commit. Those 'unblamable' lines remain blamed on an ignored commit. Users might want to know if a line is unblamable so that they do not spend time investigating a commit they know is uninteresting. This patch adds two config options to mark these two types of lines in the output of blame. The first option can identify ignored lines by specifying blame.markIgnoredLines. When this option is set, each blame line that was blamed on a commit other than the ignored commit is marked with a '?'. For example: 278b6158d6fdb (Barret Rhoden 2016-04-11 13:57:54 -0400 26) appears as: ?278b6158d6fd (Barret Rhoden 2016-04-11 13:57:54 -0400 26) where the '?' is placed before the commit, and the hash has one fewer characters. Sometimes we are unable to even guess at what ancestor commit touched a line. These lines are 'unblamable.' The second option, blame.markUnblamableLines, will mark the line with ''. For example, say we ignore e5e8d36d04cbe, yet we are unable to blame this line on another commit: e5e8d36d04cbe (Barret Rhoden 2016-04-11 13:57:54 -0400 26) appears as: e5e8d36d04cb (Barret Rhoden 2016-04-11 13:57:54 -0400 26) When these config options are used together, every line touched by an ignored commit will be marked with either a '?' or a '*'. Signed-off-by: Barret Rhoden <brho@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Barret Rhoden	ae3f36dea1	blame: add the ability to ignore commits and their changes 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>	6 years ago
Denton Liu	554544276a	.[ch]: remove extern from function declarations using spatch There has been a push to remove extern from function declarations. Remove some instances of "extern" for function declarations which are caught by Coccinelle. Note that Coccinelle has some difficulty with processing functions with `__attribute__` or varargs so some `extern` declarations are left behind to be dealt with in a future patch. This was the Coccinelle patch used: @@ type T; identifier f; @@ - extern T f(...); and it was run with: $ git ls-files \.{c,h} \| grep -v ^compat/ \| xargs spatch --sp-file contrib/coccinelle/noextern.cocci --in-place Files under `compat/` are intentionally excluded as some are directly copied from external sources and we should avoid churning them as much as possible. Signed-off-by: Denton Liu <liu.denton@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Elijah Newren	5ec1e72823	Use 'unsigned short' for mode, like diff_filespec does struct diff_filespec defines mode to be an 'unsigned short'. Several other places in the API which we'd like to interact with using a diff_filespec used a plain unsigned (or unsigned int). This caused problems when taking addresses, so switch to unsigned short. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Nguyễn Thái Ngọc Duy	ecbbc0a53b	blame.c: remove implicit dependency on the_index Side note, since we gain access to the right repository, we can stop rely on the_repository in this code as well. Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Nguyễn Thái Ngọc Duy	fde9522747	blame.h: drop extern on func declaration Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Nguyễn Thái Ngọc Duy	4e0df4e663	blame: use commit-slab for blame suspects instead of commit->util It's done so that commit->util can be removed. See more explanation in the commit that removes commit->util. Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Jeff Smith	bd481de713	blame: move entry prepend to libgit Signed-off-by: Jeff Smith <whydoubt@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Jeff Smith	09002f1b31	blame: move scoreboard setup to libgit Signed-off-by: Jeff Smith <whydoubt@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Jeff Smith	b543bb1cdf	blame: move scoreboard-related methods to libgit Signed-off-by: Jeff Smith <whydoubt@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Jeff Smith	072bf4321f	blame: move fake-commit-related methods to libgit Signed-off-by: Jeff Smith <whydoubt@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Jeff Smith	f5dd754c36	blame: move origin-related methods to libgit Signed-off-by: Jeff Smith <whydoubt@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Jeff Smith	dc076ae5d9	blame: move core structures to header The origin, entry, and scoreboard structures are core to the blame interface and need to be exposed for blame functionality. Signed-off-by: Jeff Smith <whydoubt@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago

18 Commits (f5cdbe485f5c560eb53734a2b25309409786b636)