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Imported Upstream version 1.9.0+dfsg1
[rustc.git] / src / jemalloc / src / rtree.c
1 #define JEMALLOC_RTREE_C_
2 #include "jemalloc/internal/jemalloc_internal.h"
3
4 static unsigned
5 hmin(unsigned ha, unsigned hb)
6 {
7
8 return (ha < hb ? ha : hb);
9 }
10
11 /* Only the most significant bits of keys passed to rtree_[gs]et() are used. */
12 bool
13 rtree_new(rtree_t *rtree, unsigned bits, rtree_node_alloc_t *alloc,
14 rtree_node_dalloc_t *dalloc)
15 {
16 unsigned bits_in_leaf, height, i;
17
18 assert(bits > 0 && bits <= (sizeof(uintptr_t) << 3));
19
20 bits_in_leaf = (bits % RTREE_BITS_PER_LEVEL) == 0 ? RTREE_BITS_PER_LEVEL
21 : (bits % RTREE_BITS_PER_LEVEL);
22 if (bits > bits_in_leaf) {
23 height = 1 + (bits - bits_in_leaf) / RTREE_BITS_PER_LEVEL;
24 if ((height-1) * RTREE_BITS_PER_LEVEL + bits_in_leaf != bits)
25 height++;
26 } else
27 height = 1;
28 assert((height-1) * RTREE_BITS_PER_LEVEL + bits_in_leaf == bits);
29
30 rtree->alloc = alloc;
31 rtree->dalloc = dalloc;
32 rtree->height = height;
33
34 /* Root level. */
35 rtree->levels[0].subtree = NULL;
36 rtree->levels[0].bits = (height > 1) ? RTREE_BITS_PER_LEVEL :
37 bits_in_leaf;
38 rtree->levels[0].cumbits = rtree->levels[0].bits;
39 /* Interior levels. */
40 for (i = 1; i < height-1; i++) {
41 rtree->levels[i].subtree = NULL;
42 rtree->levels[i].bits = RTREE_BITS_PER_LEVEL;
43 rtree->levels[i].cumbits = rtree->levels[i-1].cumbits +
44 RTREE_BITS_PER_LEVEL;
45 }
46 /* Leaf level. */
47 if (height > 1) {
48 rtree->levels[height-1].subtree = NULL;
49 rtree->levels[height-1].bits = bits_in_leaf;
50 rtree->levels[height-1].cumbits = bits;
51 }
52
53 /* Compute lookup table to be used by rtree_start_level(). */
54 for (i = 0; i < RTREE_HEIGHT_MAX; i++) {
55 rtree->start_level[i] = hmin(RTREE_HEIGHT_MAX - 1 - i, height -
56 1);
57 }
58
59 return (false);
60 }
61
62 static void
63 rtree_delete_subtree(rtree_t *rtree, rtree_node_elm_t *node, unsigned level)
64 {
65
66 if (level + 1 < rtree->height) {
67 size_t nchildren, i;
68
69 nchildren = ZU(1) << rtree->levels[level].bits;
70 for (i = 0; i < nchildren; i++) {
71 rtree_node_elm_t *child = node[i].child;
72 if (child != NULL)
73 rtree_delete_subtree(rtree, child, level + 1);
74 }
75 }
76 rtree->dalloc(node);
77 }
78
79 void
80 rtree_delete(rtree_t *rtree)
81 {
82 unsigned i;
83
84 for (i = 0; i < rtree->height; i++) {
85 rtree_node_elm_t *subtree = rtree->levels[i].subtree;
86 if (subtree != NULL)
87 rtree_delete_subtree(rtree, subtree, i);
88 }
89 }
90
91 static rtree_node_elm_t *
92 rtree_node_init(rtree_t *rtree, unsigned level, rtree_node_elm_t **elmp)
93 {
94 rtree_node_elm_t *node;
95
96 if (atomic_cas_p((void **)elmp, NULL, RTREE_NODE_INITIALIZING)) {
97 /*
98 * Another thread is already in the process of initializing.
99 * Spin-wait until initialization is complete.
100 */
101 do {
102 CPU_SPINWAIT;
103 node = atomic_read_p((void **)elmp);
104 } while (node == RTREE_NODE_INITIALIZING);
105 } else {
106 node = rtree->alloc(ZU(1) << rtree->levels[level].bits);
107 if (node == NULL)
108 return (NULL);
109 atomic_write_p((void **)elmp, node);
110 }
111
112 return (node);
113 }
114
115 rtree_node_elm_t *
116 rtree_subtree_read_hard(rtree_t *rtree, unsigned level)
117 {
118
119 return (rtree_node_init(rtree, level, &rtree->levels[level].subtree));
120 }
121
122 rtree_node_elm_t *
123 rtree_child_read_hard(rtree_t *rtree, rtree_node_elm_t *elm, unsigned level)
124 {
125
126 return (rtree_node_init(rtree, level, &elm->child));
127 }