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name-rev: put struct rev_name into commit slab 

The commit slab commit_rev_name contains a pointer to a struct rev_name,
and the actual struct is allocated separatly.  Avoid that allocation and
pointer indirection by storing the full struct in the commit slab.  Use
the tip_name member pointer to determine if the returned struct is
initialized.

Performance in the Linux repository measured with hyperfine before:

Benchmark #1: ./git -C ../linux/ name-rev --all
  Time (mean ± σ):     953.5 ms ±   6.3 ms    [User: 901.2 ms, System: 52.1 ms]
  Range (min … max):   945.2 ms … 968.5 ms    10 runs

... and with this patch:

Benchmark #1: ./git -C ../linux/ name-rev --all
  Time (mean ± σ):     851.0 ms ±   3.1 ms    [User: 807.4 ms, System: 43.6 ms]
  Range (min … max):   846.7 ms … 857.0 ms    10 runs

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
René Scharfe 2020-02-04 22:22:36 +01:00 committed by Junio C Hamano
parent d689d6d82f
commit f13ca7cef5
1 changed files with 11 additions and 9 deletions
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20
builtin/name-rev.c
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@ -24,7 +24,7 @@ struct rev_name {
int from_tag;
};
define_commit_slab(commit_rev_name, struct rev_name *);
define_commit_slab(commit_rev_name, struct rev_name);
static timestamp_t cutoff = TIME_MAX;
static struct commit_rev_name rev_names;
@ -32,11 +32,16 @@ static struct commit_rev_name rev_names;
/* How many generations are maximally preferred over _one_ merge traversal? */
#define MERGE_TRAVERSAL_WEIGHT 65535
static int is_valid_rev_name(const struct rev_name *name)
{
return name && name->tip_name;
}
static struct rev_name *get_commit_rev_name(const struct commit *commit)
{
struct rev_name **slot = commit_rev_name_peek(&rev_names, commit);
struct rev_name *name = commit_rev_name_peek(&rev_names, commit);
return slot ? *slot : NULL;
return is_valid_rev_name(name) ? name : NULL;
}
static int is_better_name(struct rev_name *name,
@ -81,15 +86,12 @@ static struct rev_name *create_or_update_name(struct commit *commit,
int generation, int distance,
int from_tag)
{
struct rev_name **slot = commit_rev_name_at(&rev_names, commit);
struct rev_name *name = *slot;
struct rev_name *name = commit_rev_name_at(&rev_names, commit);
if (name && !is_better_name(name, taggerdate, distance, from_tag))
if (is_valid_rev_name(name) &&
!is_better_name(name, taggerdate, distance, from_tag))
return NULL;
if (!name)
name = *slot = xmalloc(sizeof(*name));
name->tip_name = tip_name;
name->taggerdate = taggerdate;
name->generation = generation;