1#define	JEMALLOC_RTREE_C_
2#include "jemalloc/internal/jemalloc_internal.h"
3
4static unsigned
5hmin(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. */
12bool
13rtree_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
62static void
63rtree_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
79void
80rtree_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
91static rtree_node_elm_t *
92rtree_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
115rtree_node_elm_t *
116rtree_subtree_read_hard(rtree_t *rtree, unsigned level)
117{
118
119	return (rtree_node_init(rtree, level, &rtree->levels[level].subtree));
120}
121
122rtree_node_elm_t *
123rtree_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}
128