Andrew's git - gitweb.git/blob

   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 (which isn't needed, since
   8 * we never free an object descriptor anyway), but even more because it ends
   9 * up with maximal alignment because it doesn't know what the object alignment
  10 * for the new allocation is.
  11 */
  12#include "cache.h"
  13#include "object.h"
  14#include "blob.h"
  15#include "tree.h"
  16#include "commit.h"
  17#include "tag.h"
  18
  19#define BLOCKING 1024
  20
  21#define DEFINE_ALLOCATOR(name, type)                            \
  22static struct alloc_state name##_state;                         \
  23void *alloc_##name##_node(void)                                 \
  24{                                                               \
  25        return alloc_node(&name##_state, sizeof(type));         \
  26}
  27
  28union any_object {
  29        struct object object;
  30        struct blob blob;
  31        struct tree tree;
  32        struct commit commit;
  33        struct tag tag;
  34};
  35
  36struct alloc_state {
  37        int count; /* total number of nodes allocated */
  38        int nr;    /* number of nodes left in current allocation */
  39        void *p;   /* first free node in current allocation */
  40};
  41
  42static inline void *alloc_node(struct alloc_state *s, size_t node_size)
  43{
  44        void *ret;
  45
  46        if (!s->nr) {
  47                s->nr = BLOCKING;
  48                s->p = xmalloc(BLOCKING * node_size);
  49        }
  50        s->nr--;
  51        s->count++;
  52        ret = s->p;
  53        s->p = (char *)s->p + node_size;
  54        memset(ret, 0, node_size);
  55        return ret;
  56}
  57
  58DEFINE_ALLOCATOR(blob, struct blob)
  59DEFINE_ALLOCATOR(tree, struct tree)
  60DEFINE_ALLOCATOR(tag, struct tag)
  61DEFINE_ALLOCATOR(object, union any_object)
  62
  63static struct alloc_state commit_state;
  64
  65void *alloc_commit_node(void)
  66{
  67        static int commit_count;
  68        struct commit *c = alloc_node(&commit_state, sizeof(struct commit));
  69        c->index = commit_count++;
  70        return c;
  71}
  72
  73static void report(const char *name, unsigned int count, size_t size)
  74{
  75        fprintf(stderr, "%10s: %8u (%"PRIuMAX" kB)\n",
  76                        name, count, (uintmax_t) size);
  77}
  78
  79#define REPORT(name, type)      \
  80    report(#name, name##_state.count, name##_state.count * sizeof(type) >> 10)
  81
  82void alloc_report(void)
  83{
  84        REPORT(blob, struct blob);
  85        REPORT(tree, struct tree);
  86        REPORT(commit, struct commit);
  87        REPORT(tag, struct tag);
  88        REPORT(object, union any_object);
  89}