1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
|
#include <stdbool.h>
#include "Python.h"
#include "pycore_index_pool.h"
#include "pycore_lock.h"
#ifdef Py_GIL_DISABLED
static inline void
swap(int32_t *values, Py_ssize_t i, Py_ssize_t j)
{
int32_t tmp = values[i];
values[i] = values[j];
values[j] = tmp;
}
static bool
heap_try_swap(_PyIndexHeap *heap, Py_ssize_t i, Py_ssize_t j)
{
if (i < 0 || i >= heap->size) {
return 0;
}
if (j < 0 || j >= heap->size) {
return 0;
}
if (i <= j) {
if (heap->values[i] <= heap->values[j]) {
return 0;
}
}
else if (heap->values[j] <= heap->values[i]) {
return 0;
}
swap(heap->values, i, j);
return 1;
}
static inline Py_ssize_t
parent(Py_ssize_t i)
{
return (i - 1) / 2;
}
static inline Py_ssize_t
left_child(Py_ssize_t i)
{
return 2 * i + 1;
}
static inline Py_ssize_t
right_child(Py_ssize_t i)
{
return 2 * i + 2;
}
static void
heap_add(_PyIndexHeap *heap, int32_t val)
{
assert(heap->size < heap->capacity);
// Add val to end
heap->values[heap->size] = val;
heap->size++;
// Sift up
for (Py_ssize_t cur = heap->size - 1; cur > 0; cur = parent(cur)) {
if (!heap_try_swap(heap, cur, parent(cur))) {
break;
}
}
}
static Py_ssize_t
heap_min_child(_PyIndexHeap *heap, Py_ssize_t i)
{
if (left_child(i) < heap->size) {
if (right_child(i) < heap->size) {
Py_ssize_t lval = heap->values[left_child(i)];
Py_ssize_t rval = heap->values[right_child(i)];
return lval < rval ? left_child(i) : right_child(i);
}
return left_child(i);
}
else if (right_child(i) < heap->size) {
return right_child(i);
}
return -1;
}
static int32_t
heap_pop(_PyIndexHeap *heap)
{
assert(heap->size > 0);
// Pop smallest and replace with the last element
int32_t result = heap->values[0];
heap->values[0] = heap->values[heap->size - 1];
heap->size--;
// Sift down
for (Py_ssize_t cur = 0; cur < heap->size;) {
Py_ssize_t min_child = heap_min_child(heap, cur);
if (min_child > -1 && heap_try_swap(heap, cur, min_child)) {
cur = min_child;
}
else {
break;
}
}
return result;
}
static int
heap_ensure_capacity(_PyIndexHeap *heap, Py_ssize_t limit)
{
assert(limit > 0);
if (heap->capacity > limit) {
return 0;
}
Py_ssize_t new_capacity = heap->capacity ? heap->capacity : 1024;
while (new_capacity && new_capacity < limit) {
new_capacity <<= 1;
}
if (!new_capacity) {
return -1;
}
int32_t *new_values = PyMem_RawCalloc(new_capacity, sizeof(int32_t));
if (new_values == NULL) {
return -1;
}
if (heap->values != NULL) {
memcpy(new_values, heap->values, heap->capacity);
PyMem_RawFree(heap->values);
}
heap->values = new_values;
heap->capacity = new_capacity;
return 0;
}
static void
heap_fini(_PyIndexHeap *heap)
{
if (heap->values != NULL) {
PyMem_RawFree(heap->values);
heap->values = NULL;
}
heap->size = -1;
heap->capacity = -1;
}
#define LOCK_POOL(pool) PyMutex_LockFlags(&pool->mutex, _Py_LOCK_DONT_DETACH)
#define UNLOCK_POOL(pool) PyMutex_Unlock(&pool->mutex)
int32_t
_PyIndexPool_AllocIndex(_PyIndexPool *pool)
{
LOCK_POOL(pool);
int32_t index;
_PyIndexHeap *free_indices = &pool->free_indices;
if (free_indices->size == 0) {
// No free indices. Make sure the heap can always store all of the
// indices that have been allocated to avoid having to allocate memory
// (which can fail) when freeing an index. Freeing indices happens when
// threads are being destroyed, which makes error handling awkward /
// impossible. This arrangement shifts handling of allocation failures
// to when indices are allocated, which happens at thread creation,
// where we are better equipped to deal with failure.
if (heap_ensure_capacity(free_indices, pool->next_index + 1) < 0) {
UNLOCK_POOL(pool);
PyErr_NoMemory();
return -1;
}
index = pool->next_index++;
}
else {
index = heap_pop(free_indices);
}
UNLOCK_POOL(pool);
return index;
}
void
_PyIndexPool_FreeIndex(_PyIndexPool *pool, int32_t index)
{
LOCK_POOL(pool);
heap_add(&pool->free_indices, index);
UNLOCK_POOL(pool);
}
void
_PyIndexPool_Fini(_PyIndexPool *pool)
{
heap_fini(&pool->free_indices);
}
#endif // Py_GIL_DISABLED
|
