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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 | 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 | ||
35 | static inline void *alloc_node(struct alloc_state *s, size_t node_size) | |
36 | { | |
37 | void *ret; | |
38 | ||
39 | if (!s->nr) { | |
40 | s->nr = BLOCKING; | |
41 | s->p = xmalloc(BLOCKING * node_size); | |
42 | } | |
43 | s->nr--; | |
44 | s->count++; | |
45 | ret = s->p; | |
46 | s->p = (char *)s->p + node_size; | |
47 | memset(ret, 0, node_size); | |
48 | return ret; | |
49 | } | |
50 | ||
51 | static struct alloc_state blob_state; | |
52 | void *alloc_blob_node(void) | |
53 | { | |
54 | struct blob *b = alloc_node(&blob_state, sizeof(struct blob)); | |
55 | b->object.type = OBJ_BLOB; | |
56 | return b; | |
57 | } | |
58 | ||
59 | static struct alloc_state tree_state; | |
60 | void *alloc_tree_node(void) | |
61 | { | |
62 | struct tree *t = alloc_node(&tree_state, sizeof(struct tree)); | |
63 | t->object.type = OBJ_TREE; | |
64 | return t; | |
65 | } | |
66 | ||
67 | static struct alloc_state tag_state; | |
68 | void *alloc_tag_node(void) | |
69 | { | |
70 | struct tag *t = alloc_node(&tag_state, sizeof(struct tag)); | |
71 | t->object.type = OBJ_TAG; | |
72 | return t; | |
73 | } | |
74 | ||
75 | static struct alloc_state object_state; | |
76 | void *alloc_object_node(void) | |
77 | { | |
78 | struct object *obj = alloc_node(&object_state, sizeof(union any_object)); | |
79 | obj->type = OBJ_NONE; | |
80 | return obj; | |
81 | } | |
82 | ||
83 | static struct alloc_state commit_state; | |
84 | ||
85 | unsigned int alloc_commit_index(void) | |
86 | { | |
87 | static unsigned int count; | |
88 | return count++; | |
89 | } | |
90 | ||
91 | void *alloc_commit_node(void) | |
92 | { | |
93 | struct commit *c = alloc_node(&commit_state, sizeof(struct commit)); | |
94 | c->object.type = OBJ_COMMIT; | |
95 | c->index = alloc_commit_index(); | |
96 | return c; | |
97 | } | |
98 | ||
99 | static void report(const char *name, unsigned int count, size_t size) | |
100 | { | |
101 | fprintf(stderr, "%10s: %8u (%"PRIuMAX" kB)\n", | |
102 | name, count, (uintmax_t) size); | |
103 | } | |
104 | ||
105 | #define REPORT(name, type) \ | |
106 | report(#name, name##_state.count, name##_state.count * sizeof(type) >> 10) | |
107 | ||
108 | void alloc_report(void) | |
109 | { | |
110 | REPORT(blob, struct blob); | |
111 | REPORT(tree, struct tree); | |
112 | REPORT(commit, struct commit); | |
113 | REPORT(tag, struct tag); | |
114 | REPORT(object, union any_object); | |
115 | } |