| #ifndef COMMIT_SLAB_H |
| #define COMMIT_SLAB_H |
| |
| /* |
| * define_commit_slab(slabname, elemtype) creates boilerplate code to define |
| * a new struct (struct slabname) that is used to associate a piece of data |
| * of elemtype to commits, and a few functions to use that struct. |
| * |
| * After including this header file, using: |
| * |
| * define_commit_slab(indegee, int); |
| * |
| * will let you call the following functions: |
| * |
| * - 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. |
| * |
| * - 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 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 */ |
| #ifndef COMMIT_SLAB_SIZE |
| #define COMMIT_SLAB_SIZE (512*1024-32) |
| #endif |
| |
| #define MAYBE_UNUSED __attribute__((__unused__)) |
| |
| #define define_commit_slab(slabname, elemtype) \ |
| \ |
| struct slabname { \ |
| unsigned slab_size; \ |
| unsigned stride; \ |
| unsigned slab_count; \ |
| elemtype **slab; \ |
| }; \ |
| static int stat_ ##slabname## realloc; \ |
| \ |
| static MAYBE_UNUSED 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; \ |
| } \ |
| \ |
| static MAYBE_UNUSED void init_ ##slabname(struct slabname *s) \ |
| { \ |
| init_ ##slabname## _with_stride(s, 1); \ |
| } \ |
| \ |
| static MAYBE_UNUSED void clear_ ##slabname(struct slabname *s) \ |
| { \ |
| int i; \ |
| for (i = 0; i < s->slab_count; i++) \ |
| free(s->slab[i]); \ |
| s->slab_count = 0; \ |
| free(s->slab); \ |
| s->slab = NULL; \ |
| } \ |
| \ |
| static MAYBE_UNUSED elemtype *slabname## _at(struct slabname *s, \ |
| const struct commit *c) \ |
| { \ |
| 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) { \ |
| int i; \ |
| s->slab = xrealloc(s->slab, \ |
| (nth_slab + 1) * sizeof(*s->slab)); \ |
| 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]) \ |
| s->slab[nth_slab] = xcalloc(s->slab_size, \ |
| sizeof(**s->slab) * s->stride); \ |
| return &s->slab[nth_slab][nth_slot * s->stride]; \ |
| } \ |
| \ |
| 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 */ |