alloc.c

   1 /*
   2  * alloc.c  - specialized allocator for internal objects
   3  *
   4  * Copyright (C) 2006 Linus Torvalds
   5  *
   6  * The standard malloc/free wastes too much space for objects, partly because
   7  * it maintains all the allocation infrastructure, but even more because it ends
   8  * up with maximal alignment because it doesn't know what the object alignment
   9  * for the new allocation is.
  10  */
  11 #include "cache.h"
  12 #include "object.h"
  13 #include "blob.h"
  14 #include "tree.h"
  15 #include "commit.h"
  16 #include "tag.h"
  17 #include "alloc.h"
  18
  19 #define BLOCKING 1024
  20
  21 union any_object {
  22         struct object object;
  23         struct blob blob;
  24         struct tree tree;
  25         struct commit commit;
  26         struct tag tag;
  27 };
  28
  29 struct alloc_state {
  30         int count; /* total number of nodes allocated */
  31         int nr;    /* number of nodes left in current allocation */
  32         void *p;   /* first free node in current allocation */
  33
  34         /* bookkeeping of allocations */
  35         void **slabs;
  36         int slab_nr, slab_alloc;
  37 };
  38
  39 struct alloc_state *allocate_alloc_state(void)
  40 {
  41         return xcalloc(1, sizeof(struct alloc_state));
  42 }
  43
  44 void clear_alloc_state(struct alloc_state *s)
  45 {
  46         while (s->slab_nr > 0) {
  47                 s->slab_nr--;
  48                 free(s->slabs[s->slab_nr]);
  49         }
  50
  51         FREE_AND_NULL(s->slabs);
  52 }
  53
  54 static inline void *alloc_node(struct alloc_state *s, size_t node_size)
  55 {
  56         void *ret;
  57
  58         if (!s->nr) {
  59                 s->nr = BLOCKING;
  60                 s->p = xmalloc(BLOCKING * node_size);
  61
  62                 ALLOC_GROW(s->slabs, s->slab_nr + 1, s->slab_alloc);
  63                 s->slabs[s->slab_nr++] = s->p;
  64         }
  65         s->nr--;
  66         s->count++;
  67         ret = s->p;
  68         s->p = (char *)s->p + node_size;
  69         memset(ret, 0, node_size);
  70
  71         return ret;
  72 }
  73
  74 void *alloc_blob_node(struct repository *r)
  75 {
  76         struct blob *b = alloc_node(r->parsed_objects->blob_state, sizeof(struct blob));
  77         b->object.type = OBJ_BLOB;
  78         return b;
  79 }
  80
  81 void *alloc_tree_node(struct repository *r)
  82 {
  83         struct tree *t = alloc_node(r->parsed_objects->tree_state, sizeof(struct tree));
  84         t->object.type = OBJ_TREE;
  85         return t;
  86 }
  87
  88 void *alloc_tag_node(struct repository *r)
  89 {
  90         struct tag *t = alloc_node(r->parsed_objects->tag_state, sizeof(struct tag));
  91         t->object.type = OBJ_TAG;
  92         return t;
  93 }
  94
  95 void *alloc_object_node(struct repository *r)
  96 {
  97         struct object *obj = alloc_node(r->parsed_objects->object_state, sizeof(union any_object));
  98         obj->type = OBJ_NONE;
  99         return obj;
 100 }
 101
 102 /*
 103  * The returned count is to be used as an index into commit slabs,
 104  * that are *NOT* maintained per repository, and that is why a single
 105  * global counter is used.
 106  */
 107 static unsigned int alloc_commit_index(void)
 108 {
 109         static unsigned int parsed_commits_count;
 110         return parsed_commits_count++;
 111 }
 112
 113 void init_commit_node(struct commit *c)
 114 {
 115         c->object.type = OBJ_COMMIT;
 116         c->index = alloc_commit_index();
 117 }
 118
 119 void *alloc_commit_node(struct repository *r)
 120 {
 121         struct commit *c = alloc_node(r->parsed_objects->commit_state, sizeof(struct commit));
 122         init_commit_node(c);
 123         return c;
 124 }
 125
 126 static void report(const char *name, unsigned int count, size_t size)
 127 {
 128         fprintf(stderr, "%10s: %8u (%"PRIuMAX" kB)\n",
 129                         name, count, (uintmax_t) size);
 130 }
 131
 132 #define REPORT(name, type)      \
 133     report(#name, r->parsed_objects->name##_state->count, \
 134                   r->parsed_objects->name##_state->count * sizeof(type) >> 10)
 135
 136 void alloc_report(struct repository *r)
 137 {
 138         REPORT(blob, struct blob);
 139         REPORT(tree, struct tree);
 140         REPORT(commit, struct commit);
 141         REPORT(tag, struct tag);
 142         REPORT(object, union any_object);
 143 }