Commit | Line | Data |
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9f36eaed MJ |
1 | /* SPDX-License-Identifier: MIT |
2 | * | |
a88db018 | 3 | * lttng_prio_heap.c |
162769ef | 4 | * |
7369e702 | 5 | * Priority heap containing pointers. Based on CLRS, chapter 6. |
162769ef MD |
6 | * |
7 | * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
f3bc08c5 MD |
8 | */ |
9 | ||
10 | #include <linux/slab.h> | |
a071f25d | 11 | #include <lttng/prio_heap.h> |
48f5e0b5 | 12 | #include <wrapper/vmalloc.h> |
f3bc08c5 | 13 | |
0b6d2ab3 | 14 | #ifdef DEBUG_HEAP |
a88db018 | 15 | void lttng_check_heap(const struct lttng_ptr_heap *heap) |
0b6d2ab3 MD |
16 | { |
17 | size_t i; | |
18 | ||
19 | if (!heap->len) | |
20 | return; | |
21 | ||
22 | for (i = 1; i < heap->len; i++) | |
23 | WARN_ON_ONCE(!heap->gt(heap->ptrs[i], heap->ptrs[0])); | |
24 | } | |
25 | #endif | |
26 | ||
a29e892a | 27 | static |
7369e702 | 28 | size_t parent(size_t i) |
c9891db2 | 29 | { |
0b6d2ab3 | 30 | return (i -1) >> 1; |
7369e702 MD |
31 | } |
32 | ||
33 | static | |
34 | size_t left(size_t i) | |
35 | { | |
0b6d2ab3 | 36 | return (i << 1) + 1; |
7369e702 MD |
37 | } |
38 | ||
39 | static | |
40 | size_t right(size_t i) | |
41 | { | |
0b6d2ab3 | 42 | return (i << 1) + 2; |
7369e702 MD |
43 | } |
44 | ||
a29e892a MD |
45 | /* |
46 | * Copy of heap->ptrs pointer is invalid after heap_grow. | |
47 | */ | |
7369e702 | 48 | static |
a88db018 | 49 | int heap_grow(struct lttng_ptr_heap *heap, size_t new_len) |
7369e702 MD |
50 | { |
51 | void **new_ptrs; | |
52 | ||
53 | if (heap->alloc_len >= new_len) | |
54 | return 0; | |
55 | ||
56 | heap->alloc_len = max_t(size_t, new_len, heap->alloc_len << 1); | |
48f5e0b5 | 57 | new_ptrs = lttng_kvmalloc(heap->alloc_len * sizeof(void *), heap->gfpmask); |
7369e702 | 58 | if (!new_ptrs) |
c9891db2 | 59 | return -ENOMEM; |
7369e702 MD |
60 | if (heap->ptrs) |
61 | memcpy(new_ptrs, heap->ptrs, heap->len * sizeof(void *)); | |
48f5e0b5 | 62 | lttng_kvfree(heap->ptrs); |
7369e702 MD |
63 | heap->ptrs = new_ptrs; |
64 | return 0; | |
65 | } | |
66 | ||
67 | static | |
a88db018 | 68 | int heap_set_len(struct lttng_ptr_heap *heap, size_t new_len) |
7369e702 MD |
69 | { |
70 | int ret; | |
71 | ||
72 | ret = heap_grow(heap, new_len); | |
73 | if (ret) | |
74 | return ret; | |
75 | heap->len = new_len; | |
c9891db2 MD |
76 | return 0; |
77 | } | |
78 | ||
a88db018 | 79 | int lttng_heap_init(struct lttng_ptr_heap *heap, size_t alloc_len, |
7369e702 MD |
80 | gfp_t gfpmask, int gt(void *a, void *b)) |
81 | { | |
82 | heap->ptrs = NULL; | |
83 | heap->len = 0; | |
84 | heap->alloc_len = 0; | |
85 | heap->gt = gt; | |
ff77b142 | 86 | heap->gfpmask = gfpmask; |
7369e702 MD |
87 | /* |
88 | * Minimum size allocated is 1 entry to ensure memory allocation | |
89 | * never fails within heap_replace_max. | |
90 | */ | |
c8d547f0 | 91 | return heap_grow(heap, max_t(size_t, 1, alloc_len)); |
7369e702 MD |
92 | } |
93 | ||
a88db018 | 94 | void lttng_heap_free(struct lttng_ptr_heap *heap) |
c9891db2 | 95 | { |
48f5e0b5 | 96 | lttng_kvfree(heap->ptrs); |
c9891db2 | 97 | } |
f3bc08c5 | 98 | |
a88db018 | 99 | static void heapify(struct lttng_ptr_heap *heap, size_t i) |
f3bc08c5 | 100 | { |
7369e702 MD |
101 | void **ptrs = heap->ptrs; |
102 | size_t l, r, largest; | |
103 | ||
104 | for (;;) { | |
0b6d2ab3 MD |
105 | void *tmp; |
106 | ||
7369e702 MD |
107 | l = left(i); |
108 | r = right(i); | |
0b6d2ab3 | 109 | if (l < heap->len && heap->gt(ptrs[l], ptrs[i])) |
7369e702 MD |
110 | largest = l; |
111 | else | |
112 | largest = i; | |
0b6d2ab3 | 113 | if (r < heap->len && heap->gt(ptrs[r], ptrs[largest])) |
7369e702 | 114 | largest = r; |
0b6d2ab3 | 115 | if (largest == i) |
7369e702 | 116 | break; |
0b6d2ab3 MD |
117 | tmp = ptrs[i]; |
118 | ptrs[i] = ptrs[largest]; | |
119 | ptrs[largest] = tmp; | |
120 | i = largest; | |
7369e702 | 121 | } |
a88db018 | 122 | lttng_check_heap(heap); |
f3bc08c5 MD |
123 | } |
124 | ||
a88db018 | 125 | void *lttng_heap_replace_max(struct lttng_ptr_heap *heap, void *p) |
f3bc08c5 MD |
126 | { |
127 | void *res; | |
f3bc08c5 | 128 | |
7369e702 MD |
129 | if (!heap->len) { |
130 | (void) heap_set_len(heap, 1); | |
a29e892a | 131 | heap->ptrs[0] = p; |
a88db018 | 132 | lttng_check_heap(heap); |
f3bc08c5 MD |
133 | return NULL; |
134 | } | |
135 | ||
136 | /* Replace the current max and heapify */ | |
a29e892a MD |
137 | res = heap->ptrs[0]; |
138 | heap->ptrs[0] = p; | |
f3bc08c5 MD |
139 | heapify(heap, 0); |
140 | return res; | |
141 | } | |
142 | ||
a88db018 | 143 | int lttng_heap_insert(struct lttng_ptr_heap *heap, void *p) |
c9891db2 | 144 | { |
a29e892a MD |
145 | void **ptrs; |
146 | size_t pos; | |
7369e702 | 147 | int ret; |
c9891db2 | 148 | |
7369e702 MD |
149 | ret = heap_set_len(heap, heap->len + 1); |
150 | if (ret) | |
151 | return ret; | |
a29e892a | 152 | ptrs = heap->ptrs; |
a29e892a | 153 | pos = heap->len - 1; |
0b6d2ab3 MD |
154 | while (pos > 0 && heap->gt(p, ptrs[parent(pos)])) { |
155 | /* Move parent down until we find the right spot */ | |
156 | ptrs[pos] = ptrs[parent(pos)]; | |
157 | pos = parent(pos); | |
a29e892a | 158 | } |
0b6d2ab3 | 159 | ptrs[pos] = p; |
a88db018 | 160 | lttng_check_heap(heap); |
7369e702 | 161 | return 0; |
c9891db2 MD |
162 | } |
163 | ||
a88db018 | 164 | void *lttng_heap_remove(struct lttng_ptr_heap *heap) |
f3bc08c5 | 165 | { |
7369e702 | 166 | switch (heap->len) { |
f3bc08c5 MD |
167 | case 0: |
168 | return NULL; | |
169 | case 1: | |
7369e702 | 170 | (void) heap_set_len(heap, 0); |
a29e892a | 171 | return heap->ptrs[0]; |
f3bc08c5 | 172 | } |
f3bc08c5 | 173 | /* Shrink, replace the current max by previous last entry and heapify */ |
7369e702 | 174 | heap_set_len(heap, heap->len - 1); |
0b6d2ab3 | 175 | /* len changed. previous last entry is at heap->len */ |
a88db018 | 176 | return lttng_heap_replace_max(heap, heap->ptrs[heap->len]); |
f3bc08c5 MD |
177 | } |
178 | ||
a88db018 | 179 | void *lttng_heap_cherrypick(struct lttng_ptr_heap *heap, void *p) |
f3bc08c5 | 180 | { |
7369e702 | 181 | size_t pos, len = heap->len; |
f3bc08c5 | 182 | |
7369e702 | 183 | for (pos = 0; pos < len; pos++) |
a29e892a | 184 | if (heap->ptrs[pos] == p) |
f3bc08c5 MD |
185 | goto found; |
186 | return NULL; | |
187 | found: | |
7369e702 MD |
188 | if (heap->len == 1) { |
189 | (void) heap_set_len(heap, 0); | |
a88db018 | 190 | lttng_check_heap(heap); |
a29e892a | 191 | return heap->ptrs[0]; |
f3bc08c5 | 192 | } |
7369e702 MD |
193 | /* Replace p with previous last entry and heapify. */ |
194 | heap_set_len(heap, heap->len - 1); | |
0b6d2ab3 MD |
195 | /* len changed. previous last entry is at heap->len */ |
196 | heap->ptrs[pos] = heap->ptrs[heap->len]; | |
f3bc08c5 MD |
197 | heapify(heap, pos); |
198 | return p; | |
199 | } |