log: add "log.follow" configuration variable

2015-07-09T17:24:23Z

People who work on projects with mostly linear history with frequent whole file renames may want to always use "git log --follow" when inspecting the life of the content that live in a single path. Teach the command to behave as if "--follow" was given from the command line when log.follow configuration variable is set *and* there is one (and only one) path on the command line. Signed-off-by: David Turner Signed-off-by: Junio C Hamano

Merge branch 'jk/color-diff-plain-is-context'

2015-06-11T16:29:53Z

"color.diff.plain" was a misnomer; give it 'color.diff.context' as a more logical synonym. * jk/color-diff-plain-is-context: diff.h: rename DIFF_PLAIN color slot to DIFF_CONTEXT diff: accept color.diff.context as a synonym for "plain"

Merge branch 'jc/diff-ws-error-highlight'

2015-06-11T16:29:51Z

Allow whitespace breakages in deleted and context lines to be also painted in the output. * jc/diff-ws-error-highlight: diff.c: --ws-error-highlight= option diff.c: add emit_del_line() and emit_context_line() t4015: separate common setup and per-test expectation t4015: modernise style

diff.h: rename DIFF_PLAIN color slot to DIFF_CONTEXT

2015-05-27T20:54:42Z

The latter is a much more descriptive name (and we support "color.diff.context" now). This also updates the name of any local variables which were used to store the color. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

diff.c: --ws-error-highlight= option

2015-05-27T06:00:01Z

Traditionally, we only cared about whitespace breakages introduced in new lines. Some people want to paint whitespace breakages on old lines, too. When they see a whitespace breakage on a new line, they can spot the same kind of whitespace breakage on the corresponding old line and want to say "Ah, those breakages are there but they were inherited from the original, so let's not touch them for now." Introduce `--ws-error-highlight=` option, that lets them pass a comma separated list of `old`, `new`, and `context` to specify what lines to highlight whitespace errors on. Signed-off-by: Junio C Hamano

diff: convert struct combine_diff_path to object_id

2015-03-14T05:43:13Z

Also, convert a constant to GIT_SHA1_HEXSZ. Signed-off-by: brian m. carlson Signed-off-by: Junio C Hamano

Merge branch 'ks/tree-diff-nway'

2014-06-03T19:06:40Z

Instead of running N pair-wise diff-trees when inspecting a N-parent merge, find the set of paths that were touched by walking N+1 trees in parallel. These set of paths can then be turned into N pair-wise diff-tree results to be processed through rename detections and such. And N=2 case nicely degenerates to the usual 2-way diff-tree, which is very nice. * ks/tree-diff-nway: mingw: activate alloca combine-diff: speed it up, by using multiparent diff tree-walker directly tree-diff: rework diff_tree() to generate diffs for multiparent cases as well Portable alloca for Git tree-diff: reuse base str(buf) memory on sub-tree recursion tree-diff: no need to call "full" diff_tree_sha1 from show_path() tree-diff: rework diff_tree interface to be sha1 based tree-diff: diff_tree() should now be static tree-diff: remove special-case diff-emitting code for empty-tree cases tree-diff: simplify tree_entry_pathcmp tree-diff: show_path prototype is not needed anymore tree-diff: rename compare_tree_entry -> tree_entry_pathcmp tree-diff: move all action-taking code out of compare_tree_entry() tree-diff: don't assume compare_tree_entry() returns -1,0,1 tree-diff: consolidate code for emitting diffs and recursion in one place tree-diff: show_tree() is not needed tree-diff: no need to pass match to skip_uninteresting() tree-diff: no need to manually verify that there is no mode change for a path combine-diff: move changed-paths scanning logic into its own function combine-diff: move show_log_first logic/action out of paths scanning

tree-diff: rework diff_tree() to generate diffs for multiparent cases as well

2014-04-07T21:40:46Z

Previously diff_tree(), which is now named ll_diff_tree_sha1(), was generating diff_filepair(s) for two trees t1 and t2, and that was usually used for a commit as t1=HEAD~, and t2=HEAD - i.e. to see changes a commit introduces. In Git, however, we have fundamentally built flexibility in that a commit can have many parents - 1 for a plain commit, 2 for a simple merge, but also more than 2 for merging several heads at once. For merges there is a so called combine-diff, which shows diff, a merge introduces by itself, omitting changes done by any parent. That works through first finding paths, that are different to all parents, and then showing generalized diff, with separate columns for +/- for each parent. The code lives in combine-diff.c . There is an impedance mismatch, however, in that a commit could generally have any number of parents, and that while diffing trees, we divide cases for 2-tree diffs and more-than-2-tree diffs. I mean there is no special casing for multiple parents commits in e.g. revision-walker . That impedance mismatch *hurts* *performance* *badly* for generating combined diffs - in "combine-diff: optimize combine_diff_path sets intersection" I've already removed some slowness from it, but from the timings provided there, it could be seen, that combined diffs still cost more than an order of magnitude more cpu time, compared to diff for usual commits, and that would only be an optimistic estimate, if we take into account that for e.g. linux.git there is only one merge for several dozens of plain commits. That slowness comes from the fact that currently, while generating combined diff, a lot of time is spent computing diff(commit,commit^2) just to only then intersect that huge diff to almost small set of files from diff(commit,commit^1). That's because at present, to compute combine-diff, for first finding paths, that "every parent touches", we use the following combine-diff property/definition: D(A,P1...Pn) = D(A,P1) ^ ... ^ D(A,Pn) (w.r.t. paths) where D(A,P1...Pn) is combined diff between commit A, and parents Pi and D(A,Pi) is usual two-tree diff Pi..A So if any of that D(A,Pi) is huge, tracting 1 n-parent combine-diff as n 1-parent diffs and intersecting results will be slow. And usually, for linux.git and other topic-based workflows, that D(A,P2) is huge, because, if merge-base of A and P2, is several dozens of merges (from A, via first parent) below, that D(A,P2) will be diffing sum of merges from several subsystems to 1 subsystem. The solution is to avoid computing n 1-parent diffs, and to find changed-to-all-parents paths via scanning A's and all Pi's trees simultaneously, at each step comparing their entries, and based on that comparison, populate paths result, and deduce we could *skip* *recursing* into subdirectories, if at least for 1 parent, sha1 of that dir tree is the same as in A. That would save us from doing significant amount of needless work. Such approach is very similar to what diff_tree() does, only there we deal with scanning only 2 trees simultaneously, and for n+1 tree, the logic is a bit more complex: D(T,P1...Pn) calculation scheme ------------------------------- D(T,P1...Pn) = D(T,P1) ^ ... ^ D(T,Pn) (regarding resulting paths set) D(T,Pj) - diff between T..Pj D(T,P1...Pn) - combined diff from T to parents P1,...,Pn We start from all trees, which are sorted, and compare their entries in lock-step: T P1 Pn - - - |t| |p1| |pn| |-| |--| ... |--| imin = argmin(p1...pn) | | | | | | |-| |--| |--| |.| |. | |. | . . . . . . at any time there could be 3 cases: 1) t < p[imin]; 2) t > p[imin]; 3) t = p[imin]. Schematic deduction of what every case means, and what to do, follows: 1) t < p[imin] -> ∀j t ∉ Pj -> "+t" ∈ D(T,Pj) -> D += "+t"; t↓ 2) t > p[imin] 2.1) ∃j: pj > p[imin] -> "-p[imin]" ∉ D(T,Pj) -> D += ø; ∀ pi=p[imin] pi↓ 2.2) ∀i pi = p[imin] -> pi ∉ T -> "-pi" ∈ D(T,Pi) -> D += "-p[imin]"; ∀i pi↓ 3) t = p[imin] 3.1) ∃j: pj > p[imin] -> "+t" ∈ D(T,Pj) -> only pi=p[imin] remains to investigate 3.2) pi = p[imin] -> investigate δ(t,pi) | | v 3.1+3.2) looking at δ(t,pi) ∀i: pi=p[imin] - if all != ø -> ⎧δ(t,pi) - if pi=p[imin] -> D += ⎨ ⎩"+t" - if pi>p[imin] in any case t↓ ∀ pi=p[imin] pi↓ ~ For comparison, here is how diff_tree() works: D(A,B) calculation scheme ------------------------- A B - - |a| |b| a < b -> a ∉ B -> D(A,B) += +a a↓ |-| |-| a > b -> b ∉ A -> D(A,B) += -b b↓ | | | | a = b -> investigate δ(a,b) a↓ b↓ |-| |-| |.| |.| . . . . ~~~~~~~~ This patch generalizes diff tree-walker to work with arbitrary number of parents as described above - i.e. now there is a resulting tree t, and some parents trees tp[i] i=[0..nparent). The generalization builds on the fact that usual diff D(A,B) is by definition the same as combined diff D(A,[B]), so if we could rework the code for common case and make it be not slower for nparent=1 case, usual diff(t1,t2) generation will not be slower, and multiparent diff tree-walker would greatly benefit generating combine-diff. What we do is as follows: 1) diff tree-walker ll_diff_tree_sha1() is internally reworked to be a paths generator (new name diff_tree_paths()), with each generated path being `struct combine_diff_path` with info for path, new sha1,mode and for every parent which sha1,mode it was in it. 2) From that info, we can still generate usual diff queue with struct diff_filepairs, via "exporting" generated combine_diff_path, if we know we run for nparent=1 case. (see emit_diff() which is now named emit_diff_first_parent_only()) 3) In order for diff_can_quit_early(), which checks DIFF_OPT_TST(opt, HAS_CHANGES)) to work, that exporting have to be happening not in bulk, but incrementally, one diff path at a time. For such consumers, there is a new callback in diff_options introduced: ->pathchange(opt, struct combine_diff_path *) which, if set to !NULL, is called for every generated path. (see new compat ll_diff_tree_sha1() wrapper around new paths generator for setup) 4) The paths generation itself, is reworked from previous ll_diff_tree_sha1() code according to "D(A,P1...Pn) calculation scheme" provided above: On the start we allocate [nparent] arrays in place what was earlier just for one parent tree. then we just generalize loops, and comparison according to the algorithm. Some notes(*): 1) alloca(), for small arrays, is used for "runs not slower for nparent=1 case than before" goal - if we change it to xmalloc()/free() the timings get ~1% worse. For alloca() we use just-introduced xalloca/xalloca_free compatibility wrappers, so it should not be a portability problem. 2) For every parent tree, we need to keep a tag, whether entry from that parent equals to entry from minimal parent. For performance reasons I'm keeping that tag in entry's mode field in unused bit - see S_IFXMIN_NEQ. Not doing so, we'd need to alloca another [nparent] array, which hurts performance. 3) For emitted paths, memory could be reused, if we know the path was processed via callback and will not be needed later. We use efficient hand-made realloc-style path_appendnew(), that saves us from ~1-1.5% of potential additional slowdown. 4) goto(s) are used in several places, as the code executes a little bit faster with lowered register pressure. Also - we should now check for FIND_COPIES_HARDER not only when two entries names are the same, and their hashes are equal, but also for a case, when a path was removed from some of all parents having it. The reason is, if we don't, that path won't be emitted at all (see "a > xi" case), and we'll just skip it, and FIND_COPIES_HARDER wants all paths - with diff or without - to be emitted, to be later analyzed for being copies sources. The new check is only necessary for nparent >1, as for nparent=1 case xmin_eqtotal always =1 =nparent, and a path is always added to diff as removal. ~~~~~~~~ Timings for # without -c, i.e. testing only nparent=1 case `git log --raw --no-abbrev --no-renames` before and after the patch are as follows: navy.git linux.git v3.10..v3.11 before 0.611s 1.889s after 0.619s 1.907s slowdown 1.3% 0.9% This timings show we did no harm to usual diff(tree1,tree2) generation. From the table we can see that we actually did ~1% slowdown, but I think I've "earned" that 1% in the previous patch ("tree-diff: reuse base str(buf) memory on sub-tree recursion", HEAD~~) so for nparent=1 case, net timings stays approximately the same. The output also stayed the same. (*) If we revert 1)-4) to more usual techniques, for nparent=1 case, we'll get ~2-2.5% of additional slowdown, which I've tried to avoid, as "do no harm for nparent=1 case" rule. For linux.git, combined diff will run an order of magnitude faster and appropriate timings will be provided in the next commit, as we'll be taking advantage of the new diff tree-walker for combined-diff generation there. P.S. and combined diff is not some exotic/for-play-only stuff - for example for a program I write to represent Git archives as readonly filesystem, there is initial scan with `git log --reverse --raw --no-abbrev --no-renames -c` to extract log of what was created/changed when, as a result building a map {} sha1 -> in which commit (and date) a content was added that `-c` means also show combined diff for merges, and without them, if a merge is non-trivial (merges changes from two parents with both having separate changes to a file), or an evil one, the map will not be full, i.e. some valid sha1 would be absent from it. That case was my initial motivation for combined diffs speedup. Signed-off-by: Kirill Smelkov Signed-off-by: Junio C Hamano

tree-diff: diff_tree() should now be static

2014-03-26T21:30:47Z

We reworked all its users to use the functionality through diff_tree_sha1 variant in recent patches (see "tree-diff: allow diff_tree_sha1 to accept NULL sha1" and what comes next). diff_tree() is now not used outside tree-diff.c - make it static. Signed-off-by: Kirill Smelkov Signed-off-by: Junio C Hamano

Merge branch 'jc/hold-diff-remove-q-synonym-for-no-deletion'

2014-03-07T23:17:41Z

Remove a confusing and deprecated "-q" option from "git diff-files"; "git diff-files --diff-filter=d" can be used instead.

user/sven/git.git/diff.h, branch v2.7.0-rc2