* - 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 */
#define COMMIT_SLAB_SIZE (512*1024-32)
#endif
+#define MAYBE_UNUSED __attribute__((__unused__))
+
#define define_commit_slab(slabname, elemtype) \
\
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) \
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++) \
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; \
\
\
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 */