revision.c: implement --max-count-oldest

"--max-count" is a commit limiting option and sets a maximum amount
of commits to be shown. If a user wants to see only the first N
commits of the history (the oldest commits) they'd have to do
something like

    git log $(git rev-list HEAD | tail -n N | head -n 1)

This is not very user-friendly.

Teach get_revision() the --max-count-oldest option.

Signed-off-by: Mirko Faina <mroik@delayed.space>
[jc: fixed up t4202 <xmqq7boy4o05.fsf@gitster.g>]
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/rev-list-options.adoc b/Documentation/rev-list-options.adoc
index 2d195a147456ead9f517cea18d1bfbe86c941e76..e8c88d0f1c758f83663ad925378564d8f41b2636 100644 (file)
--- a/Documentation/rev-list-options.adoc
+++ b/Documentation/rev-list-options.adoc
@@ -16,7 +16,10 @@ ordering and formatting options, such as `--reverse`.
 `-<number>`::
 `-n <number>`::
 `--max-count=<number>`::
-       Limit the output to _<number>_ commits.
+       Limit the output to the first _<number>_ commits that would be shown.
+
+`--max-count-oldest=<number>`::
+       Limit the output to the last _<number>_ commits that would be shown.
 
 `--skip=<number>`::
        Skip _<number>_ commits before starting to show the commit output.

diff --git a/revision.c b/revision.c
index 599b3a66c369ca3b0099311250cf758788fdf6ce..5d53db3152ddf02f03bb73b4cc0377fed4607b10 100644 (file)
--- a/revision.c
+++ b/revision.c
@@ -2339,10 +2339,28 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
        }
 
        if ((argcount = parse_long_opt("max-count", argv, &optarg))) {
+               if (revs->max_count_type == 1)
+                       die_for_incompatible_opt2(1, "--max-count", 1,
+                                                 "--max-count-oldest");
                revs->max_count = parse_count(optarg);
                revs->no_walk = 0;
+               revs->max_count_type = 0;
                return argcount;
+       } else if ((argcount = parse_long_opt("max-count-oldest", argv, &optarg))) {
+               if (revs->max_count_type == 0 && revs->max_count != -1)
+                       die_for_incompatible_opt2(1, "--max-count", 1,
+                                                 "--max-count-oldest");
+               if (revs->skip_count > 0)
+                       die_for_incompatible_opt2(1, "--skip", 1,
+                                                 "--max-count-oldest");
+               revs->max_count = parse_count(optarg);
+               revs->no_walk = 0;
+               revs->max_count_type = 1;
+               revs->max_count_stage = 0;
        } else if ((argcount = parse_long_opt("skip", argv, &optarg))) {
+               if (revs->max_count_type == 1)
+                       die_for_incompatible_opt2(1, "--skip", 1,
+                                                 "--max-count-oldest");
                revs->skip_count = parse_count(optarg);
                return argcount;
        } else if ((*arg == '-') && isdigit(arg[1])) {
@@ -4521,15 +4539,91 @@ static struct commit *get_revision_internal(struct rev_info *revs)
        return c;
 }
 
+static void retrieve_oldest_commits(struct rev_info *revs,
+                                   struct commit_list **queue)
+{
+       struct commit *c;
+       int max_count = revs->max_count;
+       int queuei_count = 0;
+       int queueo_count = 0;
+       struct commit_list *queueo = NULL;
+       struct commit_list *queuei = NULL;
+       struct commit_list *reversed_queue = NULL;
+       struct commit_list *p;
+
+       revs->max_count = -1;
+       while ((c = get_revision_internal(revs))) {
+               /*
+                * We need to reset SHOWN status otherwise --graph breaks.
+                * It is fine to do, get_revision_internal() doesn't consider
+                * children commits as they have been already processed and the
+                * traversal happens only child to parent.
+                *
+                * We do this because the --graph machinery relies on the status
+                * of the parents to decide how the printing will happen.
+                *
+                * We can't simply replace this instruction with a
+                * graph_update() as it doesn't do the actualy printing, we'd
+                * have to remove any commit that goes over the
+                * --max-count-oldest limit from revs->graph.
+                */
+               c->object.flags &= ~(SHOWN | CHILD_SHOWN);
+               commit_list_insert(c, &queuei);
+               if (!(c->object.flags & BOUNDARY))
+                       queuei_count++;
+               while (queuei_count + queueo_count > max_count) {
+                       if (!queueo_count) {
+                               while ((c = pop_commit(&queuei))) {
+                                       commit_list_insert(c, &queueo);
+                                       queueo_count++;
+                               }
+                               queuei_count = 0;
+                       }
+                       c = pop_commit(&queueo);
+                       queueo_count--;
+                       /* We need to do this otherwise we'll discard the
+                        * commits that go over the --max-count-oldest limit but
+                        * not their respective boundaries. This matters only if
+                        * we're discarding the commit right before the boundary.
+                        */
+                       for (p = c->parents; p; p = p->next)
+                               p->item->object.flags &= ~CHILD_SHOWN;
+               }
+       }
+
+       while ((c = pop_commit(&queueo)))
+               commit_list_insert(c, &reversed_queue);
+       while ((c = pop_commit(&queuei)))
+               commit_list_insert(c, &queueo);
+       while ((c = pop_commit(&queueo)))
+               commit_list_insert(c, &reversed_queue);
+
+       while ((c = pop_commit(&reversed_queue)))
+               commit_list_insert(c, queue);
+}
+
 struct commit *get_revision(struct rev_info *revs)
 {
        struct commit *c;
        struct commit_list *reversed;
+       struct commit_list *queue = NULL;
+       struct commit_list *p;
+
+       if (revs->max_count_type == 1 && !revs->max_count_stage) {
+               retrieve_oldest_commits(revs, &queue);
+               commit_list_free(revs->commits);
+               revs->commits = queue;
+               revs->max_count_stage = 1;
+       }
 
        if (revs->reverse) {
                reversed = NULL;
-               while ((c = get_revision_internal(revs)))
-                       commit_list_insert(c, &reversed);
+               if (revs->max_count_type == 1)
+                       while ((c = pop_commit(&revs->commits)))
+                               commit_list_insert(c, &reversed);
+               else
+                       while ((c = get_revision_internal(revs)))
+                               commit_list_insert(c, &reversed);
                commit_list_free(revs->commits);
                revs->commits = reversed;
                revs->reverse = 0;
@@ -4543,7 +4637,18 @@ struct commit *get_revision(struct rev_info *revs)
                return c;
        }
 
-       c = get_revision_internal(revs);
+       if (revs->max_count_stage) {
+               c = pop_commit(&revs->commits);
+               if (c) {
+                       c->object.flags |= SHOWN;
+                       if (!(c->object.flags & BOUNDARY))
+                               for (p = c->parents; p; p = p->next)
+                                       p->item->object.flags |= CHILD_SHOWN;
+               }
+       } else {
+               c = get_revision_internal(revs);
+       }
+
        if (c && revs->graph)
                graph_update(revs->graph, c);
        if (!c) {

diff --git a/revision.h b/revision.h
index 584f1338b5e323820783a20372095a235f03e4e6..e157463cb1f62caaa4189a3ca210afec1fd3f8fd 100644 (file)
--- a/revision.h
+++ b/revision.h
@@ -309,6 +309,8 @@ struct rev_info {
        /* special limits */
        int skip_count;
        int max_count;
+       unsigned int max_count_type:1;
+       unsigned int max_count_stage:1;
        timestamp_t max_age;
        timestamp_t max_age_as_filter;
        timestamp_t min_age;

diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index 05cee9e41bb48d8f04bf5780dcfb685034c1b00e..75edb0eb38c03935134765643001698ac2015e78 100755 (executable)
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -1882,6 +1882,46 @@ test_expect_success 'log --graph with --name-status' '
        test_cmp_graph --name-status tangle..reach
 '
 
+test_expect_success 'log --max-count-oldest=3 --oneline' '
+       test_when_finished rm expect &&
+       git log --oneline | tail -n3 >expect &&
+       git log --oneline --max-count-oldest=3 >actual &&
+       test_cmp expect actual
+'
+
+test_expect_success 'log --max-count-oldest=3 --reverse --oneline' '
+       test_when_finished rm expect &&
+       git log --oneline --reverse | head -n3 >expect &&
+       git log --oneline --max-count-oldest=3 --reverse >actual &&
+       test_cmp expect actual
+'
+
+test_expect_success 'log --max-count-oldest with --max-count' '
+       test_when_finished rm stderr &&
+       test_must_fail git log --max-count-oldest=3 --max-count=3 2>stderr &&
+       test_grep "cannot be used together" stderr
+'
+
+test_expect_success 'log --max-count-oldest with --skip' '
+       test_when_finished rm stderr &&
+       test_must_fail git log --max-count-oldest=3 --skip=1 2>stderr &&
+       test_grep "cannot be used together" stderr
+'
+
+test_expect_success 'log --max-count-oldest=1000 --graph --boundary' '
+       test_when_finished rm expect actual &&
+       git log --graph --boundary >expect &&
+       git log --max-count-oldest=1000 --graph --boundary >actual &&
+       test_cmp expect actual
+'
+
+test_expect_success 'log --oneline --graph --boundary --max-count-oldest=1' '
+       test_when_finished rm -f actual &&
+       git log --oneline --graph --boundary --max-count-oldest=1 \
+               HEAD~1..HEAD >actual &&
+       test_line_count = 2 actual
+'
+
 cat >expect <<-\EOF
 * reach
 |