@matheusbsbs / matheus-bagliano / commits / 3afc679b3c

commit: use generations in paint_down_to_common()

Define compare_commits_by_gen_then_commit_date(), which uses generation numbers as a primary comparison and commit date to break ties (or as a comparison when both commits do not have computed generation numbers). Since the commit-graph file is closed under reachability, we know that all commits in the file have generation at most GENERATION_NUMBER_MAX which is less than GENERATION_NUMBER_INFINITY. This change does not affect the number of commits that are walked during the execution of paint_down_to_common(), only the order that those commits are inspected. In the case that commit dates violate topological order (i.e. a parent is "newer" than a child), the previous code could walk a commit twice: if a commit is reached with the PARENT1 bit, but later is re-visited with the PARENT2 bit, then that PARENT2 bit must be propagated to its parents. Using generation numbers avoids this extra effort, even if it is somewhat rare. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Derrick Stolee committed May 1, 2018 at 12:47 UTC 3afc679b3c13d99e4f02bceb686f11d51576d3ae

2 files changed +20 -1

commit.c

+19 -1

@@ -640,6 +640,24 @@ static int compare_commits_by_author_date(const void *a_, const void *b_,

640 return 0;

641 }

642

643 +int compare_commits_by_gen_then_commit_date(const void *a_, const void *b_, void *unused)

644 +{

645 + const struct commit *a = a_, *b = b_;

646 +

647 + /* newer commits first */

648 + if (a->generation < b->generation)

649 + return 1;

650 + else if (a->generation > b->generation)

651 + return -1;

652 +

653 + /* use date as a heuristic when generations are equal */

654 + if (a->date < b->date)

655 + return 1;

656 + else if (a->date > b->date)

657 + return -1;

658 + return 0;

659 +}

660 +

661 int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused)

662 {

663 const struct commit *a = a_, *b = b_;

@@ -789,7 +807,7 @@ static int queue_has_nonstale(struct prio_queue *queue)

807 /* all input commits in one and twos[] must have been parsed! */

808 static struct commit_list *paint_down_to_common(struct commit *one, int n, struct commit **twos)

809 {

792 - struct prio_queue queue = { compare_commits_by_commit_date };

810 + struct prio_queue queue = { compare_commits_by_gen_then_commit_date };

811 struct commit_list *result = NULL;

812 int i;

813

commit.h

@@ -341,6 +341,7 @@ extern int remove_signature(struct strbuf *buf);

341 extern int check_commit_signature(const struct commit *commit, struct signature_check *sigc);

342

343 int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused);

344 +int compare_commits_by_gen_then_commit_date(const void *a_, const void *b_, void *unused);

345

346 LAST_ARG_MUST_BE_NULL

347 extern int run_commit_hook(int editor_is_used, const char *index_file, const char *name, ...);