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From: "René Scharfe" <l.s.r@web.de>
To: Derrick Stolee <stolee@gmail.com>,
	Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>,
	git@vger.kernel.org
Cc: Junio C Hamano <gitster@pobox.com>,
	Derrick Stolee <dstolee@microsoft.com>
Subject: Re: [PATCH 15/16] commit-reach: make can_all_from_reach... linear
Date: Fri, 5 Oct 2018 00:59:02 +0200	[thread overview]
Message-ID: <7b95417a-c8fb-4f1e-cb09-c36804a3a4d0@web.de> (raw)
In-Reply-To: <223b14f7-213f-4d22-4776-22dcfd1806c2@web.de>

Am 01.10.2018 um 22:37 schrieb René Scharfe:
> Am 01.10.2018 um 21:26 schrieb Derrick Stolee:
>> On 10/1/2018 3:16 PM, René Scharfe wrote:
>>> Am 28.06.2018 um 14:31 schrieb Derrick Stolee via GitGitGadget:
>>>> diff --git a/commit-reach.c b/commit-reach.c
>>>> index c58e50fbb..ac132c8e4 100644
>>>> --- a/commit-reach.c
>>>> +++ b/commit-reach.c
>>>> @@ -513,65 +513,88 @@ int commit_contains(struct ref_filter *filter, struct commit *commit,
>>>>   	return is_descendant_of(commit, list);
>>>>   }
>>>>   
>>>> -int reachable(struct commit *from, int with_flag, int assign_flag,
>>>> -	      time_t min_commit_date)
>>>> +static int compare_commits_by_gen(const void *_a, const void *_b)
>>>>   {
>>>> -	struct prio_queue work = { compare_commits_by_commit_date };
>>>> +	const struct commit *a = (const struct commit *)_a;
>>>> +	const struct commit *b = (const struct commit *)_b;
>>> This cast is bogus.  QSORT gets handed a struct commit **, i.e. an array
>>> of pointers, and qsort(1) passes references to those pointers to the
>>> compare function, and not the pointer values.
>>
>> Good catch! I'm disappointed that we couldn't use type-checking here, as 
>> it is quite difficult to discover that the types are wrong here.
> 
> Generics in C are hard, and type checking traditionally falls by the
> wayside.  You could use macros for that, like klib [*] does, but that
> has its own downsides (more object text, debugging the sort macros
> themselves is harder).
> 
> [*] https://github.com/attractivechaos/klib/blob/master/ksort.h

We could also do something like this to reduce the amount of manual
casting, but do we want to?  (Macro at the bottom, three semi-random
examples at the top.)
---
 bisect.c          | 11 +++--------
 commit-graph.c    |  9 ++-------
 commit-reach.c    | 12 +++++-------
 git-compat-util.h | 12 ++++++++++++
 4 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/bisect.c b/bisect.c
index e8b17cf7e1..06be3a3c15 100644
--- a/bisect.c
+++ b/bisect.c
@@ -192,16 +192,11 @@ struct commit_dist {
 	int distance;
 };
 
-static int compare_commit_dist(const void *a_, const void *b_)
-{
-	struct commit_dist *a, *b;
-
-	a = (struct commit_dist *)a_;
-	b = (struct commit_dist *)b_;
+DEFINE_SORT(sort_by_commit_dist, struct commit_dist, a, b, {
 	if (a->distance != b->distance)
 		return b->distance - a->distance; /* desc sort */
 	return oidcmp(&a->commit->object.oid, &b->commit->object.oid);
-}
+})
 
 static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr)
 {
@@ -223,7 +218,7 @@ static struct commit_list *best_bisection_sorted(struct commit_list *list, int n
 		array[cnt].distance = distance;
 		cnt++;
 	}
-	QSORT(array, cnt, compare_commit_dist);
+	sort_by_commit_dist(array, cnt);
 	for (p = list, i = 0; i < cnt; i++) {
 		struct object *obj = &(array[i].commit->object);
 
diff --git a/commit-graph.c b/commit-graph.c
index 7f4519ec3b..a2202414e0 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -550,12 +550,7 @@ static void write_graph_chunk_large_edges(struct hashfile *f,
 	}
 }
 
-static int commit_compare(const void *_a, const void *_b)
-{
-	const struct object_id *a = (const struct object_id *)_a;
-	const struct object_id *b = (const struct object_id *)_b;
-	return oidcmp(a, b);
-}
+DEFINE_SORT(sort_oids, struct object_id, a, b, return oidcmp(a, b))
 
 struct packed_commit_list {
 	struct commit **list;
@@ -780,7 +775,7 @@ void write_commit_graph(const char *obj_dir,
 
 	close_reachable(&oids);
 
-	QSORT(oids.list, oids.nr, commit_compare);
+	sort_oids(oids.list, oids.nr);
 
 	count_distinct = 1;
 	for (i = 1; i < oids.nr; i++) {
diff --git a/commit-reach.c b/commit-reach.c
index 2f5e592d16..3aef47c3dd 100644
--- a/commit-reach.c
+++ b/commit-reach.c
@@ -527,17 +527,15 @@ int commit_contains(struct ref_filter *filter, struct commit *commit,
 	return is_descendant_of(commit, list);
 }
 
-static int compare_commits_by_gen(const void *_a, const void *_b)
-{
-	const struct commit *a = *(const struct commit * const *)_a;
-	const struct commit *b = *(const struct commit * const *)_b;
-
+DEFINE_SORT(sort_commits_by_gen, struct commit *, ap, bp, {
+	const struct commit *a = *ap;
+	const struct commit *b = *bp;
 	if (a->generation < b->generation)
 		return -1;
 	if (a->generation > b->generation)
 		return 1;
 	return 0;
-}
+})
 
 int can_all_from_reach_with_flag(struct object_array *from,
 				 unsigned int with_flag,
@@ -580,7 +578,7 @@ int can_all_from_reach_with_flag(struct object_array *from,
 		nr_commits++;
 	}
 
-	QSORT(list, nr_commits, compare_commits_by_gen);
+	sort_commits_by_gen(list, nr_commits);
 
 	for (i = 0; i < nr_commits; i++) {
 		/* DFS from list[i] */
diff --git a/git-compat-util.h b/git-compat-util.h
index 5f2e90932f..f9e78d69a2 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -1066,6 +1066,18 @@ static inline void sane_qsort(void *base, size_t nmemb, size_t size,
 		qsort(base, nmemb, size, compar);
 }
 
+#define DEFINE_SORT(name, elemtype, one, two, code)			\
+static int name##_compare(const void *one##_v_, const void *two##_v_)	\
+{									\
+	elemtype const *one = one##_v_;					\
+	elemtype const *two = two##_v_;					\
+	code;								\
+}									\
+static void name(elemtype *array, size_t n)				\
+{									\
+	QSORT(array, n, name##_compare);				\
+}
+
 #ifndef HAVE_ISO_QSORT_S
 int git_qsort_s(void *base, size_t nmemb, size_t size,
 		int (*compar)(const void *, const void *, void *), void *ctx);
-- 
2.19.0



  reply	other threads:[~2018-10-04 22:59 UTC|newest]

Thread overview: 118+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-16 13:00 [PATCH 00/16] Consolidate reachability logic Derrick Stolee via GitGitGadget
2018-06-19 20:25 ` [PATCH 04/16] upload-pack: make reachable() more generic Derrick Stolee via GitGitGadget
2018-06-19 20:35 ` [PATCH 05/16] upload-pack: refactor ok_to_give_up() Derrick Stolee via GitGitGadget
2018-06-25 17:16 ` [PATCH 01/16] commit-reach: move walk methods from commit.c Derrick Stolee via GitGitGadget
2018-07-16 18:57   ` Stefan Beller
2018-07-16 21:31   ` Jonathan Tan
2018-06-25 17:35 ` [PATCH 02/16] commit-reach: move ref_newer from remote.c Derrick Stolee via GitGitGadget
2018-07-16 19:10   ` Stefan Beller
2018-06-25 18:01 ` [PATCH 03/16] commit-reach: move commit_contains from ref-filter Derrick Stolee via GitGitGadget
2018-07-16 19:14   ` Stefan Beller
2018-06-28 12:31 ` [PATCH 15/16] commit-reach: make can_all_from_reach... linear Derrick Stolee via GitGitGadget
2018-07-16 22:37   ` Stefan Beller
2018-07-17  1:16   ` Jonathan Tan
2018-10-01 19:16   ` René Scharfe
2018-10-01 19:26     ` Derrick Stolee
2018-10-01 20:37       ` René Scharfe
2018-10-04 22:59         ` René Scharfe [this message]
2018-10-05 12:15           ` Derrick Stolee
2018-10-05 16:51           ` Jeff King
2018-10-05 18:48             ` René Scharfe
2018-10-05 19:08               ` Jeff King
2018-10-05 19:36                 ` René Scharfe
2018-10-05 19:42                   ` Jeff King
2018-10-14 14:29                     ` René Scharfe
2018-10-15 15:31                       ` Derrick Stolee
2018-10-15 16:26                         ` René Scharfe
2018-10-16 23:09                       ` Junio C Hamano
2018-10-17  8:33                       ` Jeff King
2020-11-18  2:16                         ` Jonathan Nieder
2020-11-18  6:54                           ` Jeff King
2020-11-18 17:47                             ` René Scharfe
2018-10-05 19:12             ` Ævar Arnfjörð Bjarmason
2018-10-05 19:28               ` Jeff King
2018-10-05 19:42                 ` Ævar Arnfjörð Bjarmason
2018-10-05 19:44                   ` Jeff King
2018-07-12 20:47 ` [PATCH 06/16] upload-pack: generalize commit date cutoff Derrick Stolee via GitGitGadget
2018-07-16 19:38   ` Stefan Beller
2018-07-18 16:04     ` Derrick Stolee
2018-07-12 20:52 ` [PATCH 07/16] commit-reach: move can_all_from_reach_with_flags Derrick Stolee via GitGitGadget
2018-07-16 22:37   ` Jonathan Tan
2018-07-13 14:06 ` [PATCH 08/16] test-reach: create new test tool for ref_newer Derrick Stolee via GitGitGadget
2018-07-16 23:00   ` Jonathan Tan
2018-07-18 16:14     ` Derrick Stolee
2018-07-13 14:28 ` [PATCH 09/16] test-reach: test in_merge_bases Derrick Stolee via GitGitGadget
2018-07-13 14:38 ` [PATCH 10/16] test-reach: test is_descendant_of Derrick Stolee via GitGitGadget
2018-07-13 14:51 ` [PATCH 11/16] test-reach: test get_merge_bases_many Derrick Stolee via GitGitGadget
2018-07-16 21:24   ` Stefan Beller
2018-07-16 23:08   ` Jonathan Tan
2018-07-13 16:51 ` [PATCH 12/16] test-reach: test reduce_heads Derrick Stolee via GitGitGadget
2018-07-16 21:30   ` Stefan Beller
2018-07-16 21:59     ` Eric Sunshine
2018-07-13 17:22 ` [PATCH 13/16] test-reach: test can_all_from_reach_with_flags Derrick Stolee via GitGitGadget
2018-07-16 21:54   ` Stefan Beller
2018-07-18 16:54     ` Derrick Stolee
2018-07-17  0:10   ` Jonathan Tan
2018-07-13 18:37 ` [PATCH 14/16] commit-reach: replace ref_newer logic Derrick Stolee via GitGitGadget
2018-07-16 22:16   ` Stefan Beller
2018-07-13 19:25 ` [PATCH 16/16] commit-reach: use can_all_from_reach Derrick Stolee via GitGitGadget
2018-07-16 22:47   ` Stefan Beller
2018-07-16 13:54 ` [PATCH 00/16] Consolidate reachability logic Ramsay Jones
2018-07-16 16:18   ` Jeff King
2018-07-16 18:40     ` Eric Sunshine
2018-07-16 18:56       ` Jeff King
2018-07-16 18:59         ` Eric Sunshine
2018-07-18 12:32           ` Johannes Schindelin
2018-07-18 12:23     ` Johannes Schindelin
2018-07-18 19:21       ` Jeff King
2018-07-19 16:34         ` Johannes Schindelin
2018-07-16 17:26   ` Stefan Beller
2018-07-16 18:44     ` Eric Sunshine
2018-07-16 18:47       ` Derrick Stolee
2018-07-18 12:28         ` Johannes Schindelin
2018-07-18 15:01           ` Duy Nguyen
2018-07-18 17:01             ` Junio C Hamano
2018-07-18 17:11               ` Derrick Stolee
2018-07-19 16:37                 ` Johannes Schindelin
2018-07-19 16:32               ` Johannes Schindelin
2018-07-20 16:33 ` [PATCH v2 00/18] " Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 01/18] commit-reach: move walk methods from commit.c Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 02/18] commit.h: remove method declarations Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 03/18] commit-reach: move ref_newer from remote.c Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 04/18] commit-reach: move commit_contains from ref-filter Derrick Stolee
2018-08-28 21:24     ` Jonathan Nieder
2018-08-28 21:33       ` Derrick Stolee
2018-08-28 21:36       ` [PATCH] commit-reach: correct accidental #include of C file Jonathan Nieder
2018-08-28 21:39         ` Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 05/18] upload-pack: make reachable() more generic Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 06/18] upload-pack: refactor ok_to_give_up() Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 07/18] upload-pack: generalize commit date cutoff Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 08/18] commit-reach: move can_all_from_reach_with_flags Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 09/18] test-reach: create new test tool for ref_newer Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 10/18] test-reach: test in_merge_bases Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 11/18] test-reach: test is_descendant_of Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 12/18] test-reach: test get_merge_bases_many Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 13/18] test-reach: test reduce_heads Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 14/18] test-reach: test can_all_from_reach_with_flags Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 15/18] test-reach: test commit_contains Derrick Stolee
2018-07-23 20:35     ` Jonathan Tan
2018-07-25 18:08       ` Junio C Hamano
2018-07-25 18:30         ` Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 16/18] commit-reach: replace ref_newer logic Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 17/18] commit-reach: make can_all_from_reach... linear Derrick Stolee
2018-07-23 20:41     ` Jonathan Tan
2018-08-01 20:41       ` Derrick Stolee
2018-09-12  4:14     ` Jeff King
2018-09-12  4:29       ` Jeff King
2018-09-12 13:08         ` Derrick Stolee
2018-07-20 16:33   ` [PATCH v2 18/18] commit-reach: use can_all_from_reach Derrick Stolee
2018-07-20 17:10   ` [PATCH v2 00/18] Consolidate reachability logic Stefan Beller
2018-07-20 17:15     ` Derrick Stolee
2018-07-20 22:16       ` Stefan Beller
2018-08-01 20:33         ` Derrick Stolee
2018-07-20 17:18   ` Derrick Stolee
2018-07-20 18:09     ` Eric Sunshine
2018-07-20 19:14       ` Derrick Stolee
2018-07-20 17:41   ` Duy Nguyen
2018-07-20 19:09     ` Derrick Stolee
2018-07-20 22:45   ` Junio C Hamano

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