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a84b794a JH |
1 | #ifndef COMMIT_SLAB_H |
2 | #define COMMIT_SLAB_H | |
3 | ||
4 | /* | |
5 | * define_commit_slab(slabname, elemtype) creates boilerplate code to define | |
6 | * a new struct (struct slabname) that is used to associate a piece of data | |
7 | * of elemtype to commits, and a few functions to use that struct. | |
8 | * | |
9 | * After including this header file, using: | |
10 | * | |
2e3a16b2 | 11 | * define_commit_slab(indegree, int); |
a84b794a JH |
12 | * |
13 | * will let you call the following functions: | |
14 | * | |
15 | * - int *indegree_at(struct indegree *, struct commit *); | |
16 | * | |
17 | * This function locates the data associated with the given commit in | |
862e730e JH |
18 | * the indegree slab, and returns the pointer to it. The location to |
19 | * store the data is allocated as necessary. | |
20 | * | |
21 | * - int *indegree_peek(struct indegree *, struct commit *); | |
22 | * | |
23 | * This function is similar to indegree_at(), but it will return NULL | |
24 | * until a call to indegree_at() was made for the commit. | |
a84b794a JH |
25 | * |
26 | * - void init_indegree(struct indegree *); | |
27 | * void init_indegree_with_stride(struct indegree *, int); | |
28 | * | |
29 | * Initializes the indegree slab that associates an array of integers | |
30 | * to each commit. 'stride' specifies how big each array is. The slab | |
dcbbc8fa | 31 | * that is initialized by the variant without "_with_stride" associates |
a84b794a | 32 | * each commit with an array of one integer. |
dcbbc8fa TR |
33 | * |
34 | * - void clear_indegree(struct indegree *); | |
35 | * | |
36 | * Empties the slab. The slab can be reused with the same stride | |
37 | * without calling init_indegree() again or can be reconfigured to a | |
38 | * different stride by calling init_indegree_with_stride(). | |
39 | * | |
40 | * Call this function before the slab falls out of scope to avoid | |
41 | * leaking memory. | |
a84b794a JH |
42 | */ |
43 | ||
44 | /* allocate ~512kB at once, allowing for malloc overhead */ | |
45 | #ifndef COMMIT_SLAB_SIZE | |
46 | #define COMMIT_SLAB_SIZE (512*1024-32) | |
47 | #endif | |
48 | ||
e9e03a77 TR |
49 | #define MAYBE_UNUSED __attribute__((__unused__)) |
50 | ||
a84b794a JH |
51 | #define define_commit_slab(slabname, elemtype) \ |
52 | \ | |
53 | struct slabname { \ | |
54 | unsigned slab_size; \ | |
55 | unsigned stride; \ | |
56 | unsigned slab_count; \ | |
57 | elemtype **slab; \ | |
58 | }; \ | |
59 | static int stat_ ##slabname## realloc; \ | |
60 | \ | |
e9e03a77 TR |
61 | static MAYBE_UNUSED void init_ ##slabname## _with_stride(struct slabname *s, \ |
62 | unsigned stride) \ | |
a84b794a JH |
63 | { \ |
64 | unsigned int elem_size; \ | |
65 | if (!stride) \ | |
66 | stride = 1; \ | |
67 | s->stride = stride; \ | |
d7a1d629 | 68 | elem_size = sizeof(elemtype) * stride; \ |
a84b794a JH |
69 | s->slab_size = COMMIT_SLAB_SIZE / elem_size; \ |
70 | s->slab_count = 0; \ | |
71 | s->slab = NULL; \ | |
72 | } \ | |
73 | \ | |
e9e03a77 | 74 | static MAYBE_UNUSED void init_ ##slabname(struct slabname *s) \ |
a84b794a JH |
75 | { \ |
76 | init_ ##slabname## _with_stride(s, 1); \ | |
77 | } \ | |
78 | \ | |
e9e03a77 | 79 | static MAYBE_UNUSED void clear_ ##slabname(struct slabname *s) \ |
a84b794a | 80 | { \ |
fddfedc3 | 81 | unsigned int i; \ |
a84b794a JH |
82 | for (i = 0; i < s->slab_count; i++) \ |
83 | free(s->slab[i]); \ | |
84 | s->slab_count = 0; \ | |
88ce3ef6 | 85 | FREE_AND_NULL(s->slab); \ |
a84b794a JH |
86 | } \ |
87 | \ | |
862e730e JH |
88 | static MAYBE_UNUSED elemtype *slabname## _at_peek(struct slabname *s, \ |
89 | const struct commit *c, \ | |
90 | int add_if_missing) \ | |
a84b794a | 91 | { \ |
fddfedc3 | 92 | unsigned int nth_slab, nth_slot; \ |
a84b794a | 93 | \ |
d7a1d629 RJ |
94 | nth_slab = c->index / s->slab_size; \ |
95 | nth_slot = c->index % s->slab_size; \ | |
a84b794a JH |
96 | \ |
97 | if (s->slab_count <= nth_slab) { \ | |
fddfedc3 | 98 | unsigned int i; \ |
862e730e JH |
99 | if (!add_if_missing) \ |
100 | return NULL; \ | |
2756ca43 | 101 | REALLOC_ARRAY(s->slab, nth_slab + 1); \ |
a84b794a JH |
102 | stat_ ##slabname## realloc++; \ |
103 | for (i = s->slab_count; i <= nth_slab; i++) \ | |
104 | s->slab[i] = NULL; \ | |
105 | s->slab_count = nth_slab + 1; \ | |
106 | } \ | |
862e730e JH |
107 | if (!s->slab[nth_slab]) { \ |
108 | if (!add_if_missing) \ | |
109 | return NULL; \ | |
a84b794a | 110 | s->slab[nth_slab] = xcalloc(s->slab_size, \ |
d7a1d629 | 111 | sizeof(**s->slab) * s->stride); \ |
862e730e JH |
112 | } \ |
113 | return &s->slab[nth_slab][nth_slot * s->stride]; \ | |
114 | } \ | |
115 | \ | |
116 | static MAYBE_UNUSED elemtype *slabname## _at(struct slabname *s, \ | |
117 | const struct commit *c) \ | |
118 | { \ | |
119 | return slabname##_at_peek(s, c, 1); \ | |
120 | } \ | |
121 | \ | |
122 | static MAYBE_UNUSED elemtype *slabname## _peek(struct slabname *s, \ | |
123 | const struct commit *c) \ | |
124 | { \ | |
125 | return slabname##_at_peek(s, c, 0); \ | |
a84b794a JH |
126 | } \ |
127 | \ | |
af920e36 | 128 | struct slabname |
a84b794a | 129 | |
e9e03a77 | 130 | /* |
af920e36 | 131 | * Note that this redundant forward declaration is required |
e9e03a77 TR |
132 | * to allow a terminating semicolon, which makes instantiations look |
133 | * like function declarations. I.e., the expansion of | |
134 | * | |
135 | * define_commit_slab(indegree, int); | |
136 | * | |
af920e36 | 137 | * ends in 'struct indegree;'. This would otherwise |
e9e03a77 TR |
138 | * be a syntax error according (at least) to ISO C. It's hard to |
139 | * catch because GCC silently parses it by default. | |
140 | */ | |
141 | ||
80cdaba5 JK |
142 | /* |
143 | * Statically initialize a commit slab named "var". Note that this | |
144 | * evaluates "stride" multiple times! Example: | |
145 | * | |
146 | * struct indegree indegrees = COMMIT_SLAB_INIT(1, indegrees); | |
147 | * | |
148 | */ | |
149 | #define COMMIT_SLAB_INIT(stride, var) { \ | |
150 | COMMIT_SLAB_SIZE / sizeof(**((var).slab)) / (stride), \ | |
151 | (stride), 0, NULL \ | |
152 | } | |
153 | ||
a84b794a | 154 | #endif /* COMMIT_SLAB_H */ |