summaryrefslogtreecommitdiff
path: root/commit.c
diff options
context:
space:
mode:
authorJunio C Hamano <gitster@pobox.com>2013-04-12 23:25:49 -0700
committerJunio C Hamano <gitster@pobox.com>2013-04-13 22:15:42 -0700
commit66eb375d3d334efa3f467775a5f2a647c131c4b1 (patch)
tree7c2570b1cad0876b77e69d21609d11c7a728272f /commit.c
parent96c4f4a370591b4796628abe18f27f0133b21954 (diff)
downloadgit-66eb375d3d334efa3f467775a5f2a647c131c4b1.tar.gz
commit-slab: avoid large realloc
Instead of using a single "slab" and keep reallocating it as we find that we need to deal with commits with larger values of commit->index, make a "slab" an array of many "slab_piece"s. Each access may need two levels of indirections, but we only need to reallocate the first level array of pointers when we have to grow the table this way. Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'commit.c')
-rw-r--r--commit.c62
1 files changed, 42 insertions, 20 deletions
diff --git a/commit.c b/commit.c
index 9365e3b34a..4c05b3966a 100644
--- a/commit.c
+++ b/commit.c
@@ -501,34 +501,56 @@ struct commit *pop_commit(struct commit_list **stack)
return item;
}
+struct commit_slab_piece {
+ int buf;
+};
+
struct commit_slab {
- int *buf;
- int alloc;
+ int piece_size;
+ int piece_count;
+ struct commit_slab_piece **piece;
};
static void slab_init(struct commit_slab *s)
{
- memset(s, 0, sizeof(*s));
+ /* allocate ~512kB at once, allowing for malloc overhead */
+ int size = (512*1024-32) / sizeof(struct commit_slab_piece);
+
+ s->piece_size = size;
+ s->piece_count = 0;
+ s->piece = NULL;
}
static void slab_clear(struct commit_slab *s)
{
- free(s->buf);
- slab_init(s);
+ int i;
+
+ for (i = 0; i < s->piece_count; i++)
+ free(s->piece[i]);
+ s->piece_count = 0;
+ free(s->piece);
+ s->piece = NULL;
}
-static inline int *slab_at(struct commit_slab *s, const struct commit *c)
+static inline struct commit_slab_piece *slab_at(struct commit_slab *s,
+ const struct commit *c)
{
- if (s->alloc <= c->index) {
- int new_alloc = alloc_nr(s->alloc);
- if (new_alloc <= c->index)
- new_alloc = c->index + 1;
-
- s->buf = xrealloc(s->buf, new_alloc * sizeof(*s->buf));
- memset(s->buf + s->alloc, 0, new_alloc - s->alloc);
- s->alloc = new_alloc;
+ int nth_piece, nth_slot;
+
+ nth_piece = c->index / s->piece_size;
+ nth_slot = c->index % s->piece_size;
+
+ if (s->piece_count <= nth_piece) {
+ int i;
+
+ s->piece = xrealloc(s->piece, (nth_piece + 1) * sizeof(s->piece));
+ for (i = s->piece_count; i <= nth_piece; i++)
+ s->piece[i] = NULL;
+ s->piece_count = nth_piece + 1;
}
- return s->buf + c->index;
+ if (!s->piece[nth_piece])
+ s->piece[nth_piece] = xcalloc(s->piece_size, sizeof(**s->piece));
+ return &s->piece[nth_piece][nth_slot];
}
/*
@@ -550,7 +572,7 @@ void sort_in_topological_order(struct commit_list ** list, int lifo)
/* Mark them and clear the indegree */
for (next = orig; next; next = next->next) {
struct commit *commit = next->item;
- *slab_at(&indegree, commit) = 1;
+ slab_at(&indegree, commit)->buf = 1;
}
/* update the indegree */
@@ -558,7 +580,7 @@ void sort_in_topological_order(struct commit_list ** list, int lifo)
struct commit_list * parents = next->item->parents;
while (parents) {
struct commit *parent = parents->item;
- int *pi = slab_at(&indegree, parent);
+ int *pi = &slab_at(&indegree, parent)->buf;
if (*pi)
(*pi)++;
@@ -578,7 +600,7 @@ void sort_in_topological_order(struct commit_list ** list, int lifo)
for (next = orig; next; next = next->next) {
struct commit *commit = next->item;
- if (*slab_at(&indegree, commit) == 1)
+ if (slab_at(&indegree, commit)->buf == 1)
insert = &commit_list_insert(commit, insert)->next;
}
@@ -599,7 +621,7 @@ void sort_in_topological_order(struct commit_list ** list, int lifo)
commit = work_item->item;
for (parents = commit->parents; parents ; parents = parents->next) {
struct commit *parent = parents->item;
- int *pi = slab_at(&indegree, parent);
+ int *pi = &slab_at(&indegree, parent)->buf;
if (!*pi)
continue;
@@ -620,7 +642,7 @@ void sort_in_topological_order(struct commit_list ** list, int lifo)
* work_item is a commit all of whose children
* have already been emitted. we can emit it now.
*/
- *slab_at(&indegree, commit) = 0;
+ slab_at(&indegree, commit)->buf = 0;
*pptr = work_item;
pptr = &work_item->next;
}