diff options
Diffstat (limited to 'commit-slab.h')
| -rw-r--r-- | commit-slab.h | 82 |
1 files changed, 70 insertions, 12 deletions
diff --git a/commit-slab.h b/commit-slab.h index d4c8286470..f84b449413 100644 --- a/commit-slab.h +++ b/commit-slab.h @@ -15,15 +15,30 @@ * - 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); * * Initializes the indegree slab that associates an array of integers * to each commit. 'stride' specifies how big each array is. The slab - * that id initialied by the variant without "_with_stride" associates + * that is initialized by the variant without "_with_stride" associates * each commit with an array of one integer. + * + * - void clear_indegree(struct indegree *); + * + * Empties the slab. The slab can be reused with the same stride + * without calling init_indegree() again or can be reconfigured to a + * different stride by calling init_indegree_with_stride(). + * + * Call this function before the slab falls out of scope to avoid + * leaking memory. */ /* allocate ~512kB at once, allowing for malloc overhead */ @@ -31,6 +46,8 @@ #define COMMIT_SLAB_SIZE (512*1024-32) #endif +#define MAYBE_UNUSED __attribute__((__unused__)) + #define define_commit_slab(slabname, elemtype) \ \ struct slabname { \ @@ -41,8 +58,8 @@ struct slabname { \ }; \ static int stat_ ##slabname## realloc; \ \ -static void init_ ##slabname## _with_stride(struct slabname *s, \ - unsigned stride) \ +static MAYBE_UNUSED void init_ ##slabname## _with_stride(struct slabname *s, \ + unsigned stride) \ { \ unsigned int elem_size; \ if (!stride) \ @@ -54,12 +71,12 @@ static void init_ ##slabname## _with_stride(struct slabname *s, \ s->slab = NULL; \ } \ \ -static void init_ ##slabname(struct slabname *s) \ +static MAYBE_UNUSED void init_ ##slabname(struct slabname *s) \ { \ init_ ##slabname## _with_stride(s, 1); \ } \ \ -static void clear_ ##slabname(struct slabname *s) \ +static MAYBE_UNUSED void clear_ ##slabname(struct slabname *s) \ { \ int i; \ for (i = 0; i < s->slab_count; i++) \ @@ -69,8 +86,9 @@ static void clear_ ##slabname(struct slabname *s) \ s->slab = NULL; \ } \ \ -static 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; \ \ @@ -79,19 +97,59 @@ static elemtype *slabname## _at(struct slabname *s, \ \ if (s->slab_count <= nth_slab) { \ int i; \ - s->slab = xrealloc(s->slab, \ - (nth_slab + 1) * sizeof(s->slab)); \ + if (!add_if_missing) \ + return NULL; \ + REALLOC_ARRAY(s->slab, nth_slab + 1); \ stat_ ##slabname## realloc++; \ 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 (!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]; \ + } \ + 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 +/* + * Note that this seemingly redundant second declaration is required + * to allow a terminating semicolon, which makes instantiations look + * like function declarations. I.e., the expansion of + * + * define_commit_slab(indegree, int); + * + * ends in 'static int stat_indegreerealloc;'. 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. + */ + +/* + * Statically initialize a commit slab named "var". Note that this + * evaluates "stride" multiple times! Example: + * + * struct indegree indegrees = COMMIT_SLAB_INIT(1, indegrees); + * + */ +#define COMMIT_SLAB_INIT(stride, var) { \ + COMMIT_SLAB_SIZE / sizeof(**((var).slab)) / (stride), \ + (stride), 0, NULL \ +} + #endif /* COMMIT_SLAB_H */ |