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[git] / 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 static void report(const char *name, unsigned int count, size_t size)
55 {
56         fprintf(stderr, "%10s: %8u (%"PRIuMAX" kB)\n",
57                         name, count, (uintmax_t) size);
58 }
59
60 #define REPORT(name)    \
61     report(#name, name##_allocs, name##_allocs * sizeof(struct name) >> 10)
62
63 void alloc_report(void)
64 {
65         REPORT(blob);
66         REPORT(tree);
67         REPORT(commit);
68         REPORT(tag);
69 }