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
|
/**************************************************************************/
/* paged_allocator.h */
/**************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/**************************************************************************/
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/**************************************************************************/
#ifndef PAGED_ALLOCATOR_H
#define PAGED_ALLOCATOR_H
#include "core/os/memory.h"
#include "core/os/spin_lock.h"
#include "core/typedefs.h"
#include <type_traits>
template <class T, bool thread_safe = false>
class PagedAllocator {
T **page_pool = nullptr;
T ***available_pool = nullptr;
uint32_t pages_allocated = 0;
uint32_t allocs_available = 0;
uint32_t page_shift = 0;
uint32_t page_mask = 0;
uint32_t page_size = 0;
SpinLock spin_lock;
public:
T *alloc() {
if (thread_safe) {
spin_lock.lock();
}
if (unlikely(allocs_available == 0)) {
uint32_t pages_used = pages_allocated;
pages_allocated++;
page_pool = (T **)memrealloc(page_pool, sizeof(T *) * pages_allocated);
available_pool = (T ***)memrealloc(available_pool, sizeof(T **) * pages_allocated);
page_pool[pages_used] = (T *)memalloc(sizeof(T) * page_size);
available_pool[pages_used] = (T **)memalloc(sizeof(T *) * page_size);
for (uint32_t i = 0; i < page_size; i++) {
available_pool[0][i] = &page_pool[pages_used][i];
}
allocs_available += page_size;
}
allocs_available--;
T *alloc = available_pool[allocs_available >> page_shift][allocs_available & page_mask];
if (thread_safe) {
spin_lock.unlock();
}
memnew_placement(alloc, T);
return alloc;
}
void free(T *p_mem) {
if (thread_safe) {
spin_lock.lock();
}
p_mem->~T();
available_pool[allocs_available >> page_shift][allocs_available & page_mask] = p_mem;
if (thread_safe) {
spin_lock.unlock();
}
allocs_available++;
}
void reset(bool p_allow_unfreed = false) {
if (!p_allow_unfreed || !std::is_trivially_destructible<T>::value) {
ERR_FAIL_COND(allocs_available < pages_allocated * page_size);
}
if (pages_allocated) {
for (uint32_t i = 0; i < pages_allocated; i++) {
memfree(page_pool[i]);
memfree(available_pool[i]);
}
memfree(page_pool);
memfree(available_pool);
page_pool = nullptr;
available_pool = nullptr;
pages_allocated = 0;
allocs_available = 0;
}
}
bool is_configured() const {
return page_size > 0;
}
void configure(uint32_t p_page_size) {
ERR_FAIL_COND(page_pool != nullptr); //sanity check
ERR_FAIL_COND(p_page_size == 0);
page_size = nearest_power_of_2_templated(p_page_size);
page_mask = page_size - 1;
page_shift = get_shift_from_power_of_2(page_size);
}
PagedAllocator(uint32_t p_page_size = 4096) { // power of 2 recommended because of alignment with OS page sizes. Even if element is bigger, its still a multiple and get rounded amount of pages
configure(p_page_size);
}
~PagedAllocator() {
ERR_FAIL_COND_MSG(allocs_available < pages_allocated * page_size, "Pages in use exist at exit in PagedAllocator");
reset();
}
};
#endif // PAGED_ALLOCATOR_H
|
