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git/commit-slab-impl.h
SZEDER Gábor 1df15f8dee commit-slab: add a function to deep free entries on the slab
clear_##slabname() frees only the memory allocated for a commit slab
itself, but entries in the commit slab might own additional memory
outside the slab that should be freed as well.  We already have (at
least) one such commit slab, and this patch series is about to add one
more.

To free all additional memory owned by entries on the commit slab the
user of such a slab could iterate over all commits it knows about,
peek whether there is a valid entry associated with each commit, and
free the additional memory, if any.  Or it could rely on intimate
knowledge about the internals of the commit slab implementation, and
could itself iterate directly through all entries in the slab, and
free the additional memory.  Or it could just leak the additional
memory...

Introduce deep_clear_##slabname() to allow releasing memory owned by
commit slab entries by invoking the 'void free_fn(elemtype *ptr)'
function specified as parameter for each entry in the slab.

Use it in get_shallow_commits() in 'shallow.c' to replace an
open-coded iteration over a commit slab's entries.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-08 12:28:49 -07:00

107 lines
3.1 KiB
C

#ifndef COMMIT_SLAB_IMPL_H
#define COMMIT_SLAB_IMPL_H
#include "git-compat-util.h"
#define implement_static_commit_slab(slabname, elemtype) \
implement_commit_slab(slabname, elemtype, MAYBE_UNUSED static)
#define implement_shared_commit_slab(slabname, elemtype) \
implement_commit_slab(slabname, elemtype, )
#define implement_commit_slab(slabname, elemtype, scope) \
\
scope void init_ ##slabname## _with_stride(struct slabname *s, \
unsigned stride) \
{ \
unsigned int elem_size; \
if (!stride) \
stride = 1; \
s->stride = stride; \
elem_size = sizeof(elemtype) * stride; \
s->slab_size = COMMIT_SLAB_SIZE / elem_size; \
s->slab_count = 0; \
s->slab = NULL; \
} \
\
scope void init_ ##slabname(struct slabname *s) \
{ \
init_ ##slabname## _with_stride(s, 1); \
} \
\
scope void clear_ ##slabname(struct slabname *s) \
{ \
unsigned int i; \
for (i = 0; i < s->slab_count; i++) \
free(s->slab[i]); \
s->slab_count = 0; \
FREE_AND_NULL(s->slab); \
} \
\
scope void deep_clear_ ##slabname(struct slabname *s, void (*free_fn)(elemtype *)) \
{ \
unsigned int i; \
for (i = 0; i < s->slab_count; i++) { \
unsigned int j; \
if (!s->slab[i]) \
continue; \
for (j = 0; j < s->slab_size; j++) \
free_fn(&s->slab[i][j * s->stride]); \
} \
clear_ ##slabname(s); \
} \
\
scope elemtype *slabname## _at_peek(struct slabname *s, \
const struct commit *c, \
int add_if_missing) \
{ \
unsigned int nth_slab, nth_slot; \
\
nth_slab = c->index / s->slab_size; \
nth_slot = c->index % s->slab_size; \
\
if (s->slab_count <= nth_slab) { \
unsigned int i; \
if (!add_if_missing) \
return NULL; \
REALLOC_ARRAY(s->slab, nth_slab + 1); \
for (i = s->slab_count; i <= nth_slab; i++) \
s->slab[i] = NULL; \
s->slab_count = nth_slab + 1; \
} \
if (!s->slab[nth_slab]) { \
if (!add_if_missing) \
return NULL; \
s->slab[nth_slab] = xcalloc(s->slab_size, \
sizeof(**s->slab) * s->stride); \
} \
return &s->slab[nth_slab][nth_slot * s->stride]; \
} \
\
scope elemtype *slabname## _at(struct slabname *s, \
const struct commit *c) \
{ \
return slabname##_at_peek(s, c, 1); \
} \
\
scope elemtype *slabname## _peek(struct slabname *s, \
const struct commit *c) \
{ \
return slabname##_at_peek(s, c, 0); \
} \
\
struct slabname
/*
* Note that this redundant forward declaration is required
* to allow a terminating semicolon, which makes instantiations look
* like function declarations. I.e., the expansion of
*
* implement_commit_slab(indegree, int, static);
*
* ends in 'struct indegree;'. This would otherwise
* be a syntax error according (at least) to ISO C. It's hard to
* catch because GCC silently parses it by default.
*/
#endif /* COMMIT_SLAB_IMPL_H */