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 (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)                            \
  22 static unsigned int name##_allocs;                              \
  23 void *alloc_##name##_node(void)                                 \
  24 {                                                               \
  25         static int nr;                                          \
  26         static type *block;                                     \
  27         void *ret;                                              \
  28                                                                 \
  29         if (!nr) {                                              \
  30                 nr = BLOCKING;                                  \
  31                 block = xmalloc(BLOCKING * sizeof(type));       \
  32         }                                                       \
  33         nr--;                                                   \
  34         name##_allocs++;                                        \
  35         ret = block++;                                          \
  36         memset(ret, 0, sizeof(type));                           \
  37         return ret;                                             \
  38 }
  39
  40 union any_object {
  41         struct object object;
  42         struct blob blob;
  43         struct tree tree;
  44         struct commit commit;
  45         struct tag tag;
  46 };
  47
  48 DEFINE_ALLOCATOR(blob, struct blob)
  49 DEFINE_ALLOCATOR(tree, struct tree)
  50 DEFINE_ALLOCATOR(commit, struct commit)
  51 DEFINE_ALLOCATOR(tag, struct tag)
  52 DEFINE_ALLOCATOR(object, union any_object)
  53
  54 #ifdef NO_C99_FORMAT
  55 #define SZ_FMT "%u"
  56 #else
  57 #define SZ_FMT "%zu"
  58 #endif
  59
  60 static void report(const char *name, unsigned int count, size_t size)
  61 {
  62     fprintf(stderr, "%10s: %8u (" SZ_FMT " kB)\n", name, count, size);
  63 }
  64
  65 #undef SZ_FMT
  66
  67 #define REPORT(name)    \
  68     report(#name, name##_allocs, name##_allocs*sizeof(struct name) >> 10)
  69
  70 void alloc_report(void)
  71 {
  72         REPORT(blob);
  73         REPORT(tree);
  74         REPORT(commit);
  75         REPORT(tag);
  76 }