Junio C Hamano <gitster@xxxxxxxxx> writes:
> For example, we have this in commit.c:
>
> const void *get_cached_commit_buffer(const struct commit *commit, unsigned long *sizep)
> {
> struct commit_buffer *v = buffer_slab_at(&buffer_slab, commit);
> if (sizep)
> *sizep = v->size;
> return v->buffer;
> }
>
> But if we do not have the "buffer" data cached for that commit (via
> an earlier call to set_commit_buffer()), we don't have to enlarge
> the slab, as we are not adding anything to the slab system with this
> call.
The change may look something like this. I do not think it would
make a difference to the get_cached_commit_buffer() codepath (when
we use the commit->buffer, we pretty much know we use that for all
commits), though.
commit-slab.h | 27 ++++++++++++++++++++++++---
commit.c | 7 ++++++-
2 files changed, 30 insertions(+), 4 deletions(-)
diff --git a/commit-slab.h b/commit-slab.h
index 375c9c7..3334ab2 100644
--- a/commit-slab.h
+++ b/commit-slab.h
@@ -15,7 +15,13 @@
* - int *indegree_at(struct indegree *, struct commit *);
*
* This function locates the data associated with the given commit in
- * the indegree slab, and returns the pointer to it.
+ * the indegree slab, and returns the pointer to it. The location to
+ * store the data is allocated as necessary.
+ *
+ * - int *indegree_peek(struct indegree *, struct commit *);
+ *
+ * This function is similar to indegree_at(), but it will return NULL
+ * until a call to indegree_at() was made for the commit.
*
* - void init_indegree(struct indegree *);
* void init_indegree_with_stride(struct indegree *, int);
@@ -80,8 +86,9 @@ static MAYBE_UNUSED void clear_ ##slabname(struct slabname *s) \
s->slab = NULL; \
} \
\
-static MAYBE_UNUSED elemtype *slabname## _at(struct slabname *s, \
- const struct commit *c) \
+static MAYBE_UNUSED elemtype *slabname## _at_peek(struct slabname *s, \
+ const struct commit *c, \
+ int add_if_missing) \
{ \
int nth_slab, nth_slot; \
\
@@ -90,6 +97,8 @@ static MAYBE_UNUSED elemtype *slabname## _at(struct slabname *s, \
\
if (s->slab_count <= nth_slab) { \
int i; \
+ if (!add_if_missing) \
+ return NULL; \
s->slab = xrealloc(s->slab, \
(nth_slab + 1) * sizeof(*s->slab)); \
stat_ ##slabname## realloc++; \
@@ -103,6 +112,18 @@ static MAYBE_UNUSED elemtype *slabname## _at(struct slabname *s, \
return &s->slab[nth_slab][nth_slot * s->stride]; \
} \
\
+static MAYBE_UNUSED elemtype *slabname## _at(struct slabname *s, \
+ const struct commit *c) \
+{ \
+ return slabname##_at_peek(s, c, 1); \
+} \
+ \
+static MAYBE_UNUSED elemtype *slabname## _peek(struct slabname *s, \
+ const struct commit *c) \
+{ \
+ return slabname##_at_peek(s, c, 0); \
+} \
+ \
static int stat_ ##slabname## realloc
/*
diff --git a/commit.c b/commit.c
index 65179f9..2d1901f 100644
--- a/commit.c
+++ b/commit.c
@@ -244,7 +244,12 @@ void set_commit_buffer(struct commit *commit, void *buffer, unsigned long size)
const void *get_cached_commit_buffer(const struct commit *commit, unsigned long *sizep)
{
- struct commit_buffer *v = buffer_slab_at(&buffer_slab, commit);
+ struct commit_buffer *v = buffer_slab_peek(&buffer_slab, commit);
+ if (!v) {
+ if (sizep)
+ *sizep = 0;
+ return NULL;
+ }
if (sizep)
*sizep = v->size;
return v->buffer;
--
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