1 /*
2 * CDDL HEADER START
3 *
4 * This file and its contents are supplied under the terms of the
5 * Common Development and Distribution License ("CDDL"), version 1.0.
6 * You may only use this file in accordance with the terms of version
7 * 1.0 of the CDDL.
8 *
9 * A full copy of the text of the CDDL should have accompanied this
10 * source. A copy of the CDDL is also available via the Internet at
11 * http://www.illumos.org/license/CDDL.
12 *
13 * CDDL HEADER END
14 */
15
16 /*
17 * Copyright (c) 2012 by Delphix. All rights reserved.
18 */
19
20 #include <dtrace.h>
21 #include <dt_impl.h>
22 #include <dt_pq.h>
23 #include <assert.h>
24
25 /*
26 * Create a new priority queue.
27 *
28 * size is the maximum number of items that will be stored in the priority
29 * queue at one time.
30 */
31 dt_pq_t *
dt_pq_init(dtrace_hdl_t * dtp,uint_t size,dt_pq_value_f value_cb,void * cb_arg)32 dt_pq_init(dtrace_hdl_t *dtp, uint_t size, dt_pq_value_f value_cb, void *cb_arg)
33 {
34 dt_pq_t *p;
35 assert(size > 1);
36
37 if ((p = dt_zalloc(dtp, sizeof (dt_pq_t))) == NULL)
38 return (NULL);
39
40 p->dtpq_items = dt_zalloc(dtp, size * sizeof (p->dtpq_items[0]));
41 if (p->dtpq_items == NULL) {
42 dt_free(dtp, p);
43 return (NULL);
44 }
45
46 p->dtpq_hdl = dtp;
47 p->dtpq_size = size;
48 p->dtpq_last = 1;
49 p->dtpq_value = value_cb;
50 p->dtpq_arg = cb_arg;
51
52 return (p);
53 }
54
55 void
dt_pq_fini(dt_pq_t * p)56 dt_pq_fini(dt_pq_t *p)
57 {
58 dtrace_hdl_t *dtp = p->dtpq_hdl;
59
60 dt_free(dtp, p->dtpq_items);
61 dt_free(dtp, p);
62 }
63
64 static uint64_t
dt_pq_getvalue(dt_pq_t * p,uint_t index)65 dt_pq_getvalue(dt_pq_t *p, uint_t index)
66 {
67 void *item = p->dtpq_items[index];
68 return (p->dtpq_value(item, p->dtpq_arg));
69 }
70
71 void
dt_pq_insert(dt_pq_t * p,void * item)72 dt_pq_insert(dt_pq_t *p, void *item)
73 {
74 uint_t i;
75
76 assert(p->dtpq_last < p->dtpq_size);
77
78 i = p->dtpq_last++;
79 p->dtpq_items[i] = item;
80
81 while (i > 1 && dt_pq_getvalue(p, i) < dt_pq_getvalue(p, i / 2)) {
82 void *tmp = p->dtpq_items[i];
83 p->dtpq_items[i] = p->dtpq_items[i / 2];
84 p->dtpq_items[i / 2] = tmp;
85 i /= 2;
86 }
87 }
88
89 /*
90 * Return elements from the priority queue. *cookie should be zero when first
91 * called. Returns NULL when there are no more elements.
92 */
93 void *
dt_pq_walk(dt_pq_t * p,uint_t * cookie)94 dt_pq_walk(dt_pq_t *p, uint_t *cookie)
95 {
96 (*cookie)++;
97 if (*cookie >= p->dtpq_last)
98 return (NULL);
99
100 return (p->dtpq_items[*cookie]);
101 }
102
103 void *
dt_pq_pop(dt_pq_t * p)104 dt_pq_pop(dt_pq_t *p)
105 {
106 uint_t i = 1;
107 void *ret;
108
109 assert(p->dtpq_last > 0);
110
111 if (p->dtpq_last == 1)
112 return (NULL);
113
114 ret = p->dtpq_items[1];
115
116 p->dtpq_last--;
117 p->dtpq_items[1] = p->dtpq_items[p->dtpq_last];
118 p->dtpq_items[p->dtpq_last] = NULL;
119
120 for (;;) {
121 uint_t lc = i * 2;
122 uint_t rc = i * 2 + 1;
123 uint_t c;
124 uint64_t v;
125 void *tmp;
126
127 if (lc >= p->dtpq_last)
128 break;
129
130 if (rc >= p->dtpq_last) {
131 c = lc;
132 v = dt_pq_getvalue(p, lc);
133 } else {
134 uint64_t lv = dt_pq_getvalue(p, lc);
135 uint64_t rv = dt_pq_getvalue(p, rc);
136
137 if (lv < rv) {
138 c = lc;
139 v = lv;
140 } else {
141 c = rc;
142 v = rv;
143 }
144 }
145
146 if (v >= dt_pq_getvalue(p, i))
147 break;
148
149 tmp = p->dtpq_items[i];
150 p->dtpq_items[i] = p->dtpq_items[c];
151 p->dtpq_items[c] = tmp;
152
153 i = c;
154 }
155
156 return (ret);
157 }
158