/src/skia/third_party/externals/harfbuzz/src/hb-pool.hh
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1 | | /* |
2 | | * Copyright © 2019 Facebook, Inc. |
3 | | * |
4 | | * This is part of HarfBuzz, a text shaping library. |
5 | | * |
6 | | * Permission is hereby granted, without written agreement and without |
7 | | * license or royalty fees, to use, copy, modify, and distribute this |
8 | | * software and its documentation for any purpose, provided that the |
9 | | * above copyright notice and the following two paragraphs appear in |
10 | | * all copies of this software. |
11 | | * |
12 | | * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR |
13 | | * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES |
14 | | * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN |
15 | | * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH |
16 | | * DAMAGE. |
17 | | * |
18 | | * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, |
19 | | * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND |
20 | | * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS |
21 | | * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO |
22 | | * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. |
23 | | * |
24 | | * Facebook Author(s): Behdad Esfahbod |
25 | | */ |
26 | | |
27 | | #ifndef HB_POOL_HH |
28 | | #define HB_POOL_HH |
29 | | |
30 | | #include "hb.hh" |
31 | | |
32 | | /* Memory pool for persistent allocation of small objects. */ |
33 | | |
34 | | template <typename T, unsigned ChunkLen = 16> |
35 | | struct hb_pool_t |
36 | | { |
37 | 0 | hb_pool_t () : next (nullptr) {} |
38 | 0 | ~hb_pool_t () { fini (); } |
39 | | |
40 | | void fini () |
41 | 0 | { |
42 | 0 | next = nullptr; |
43 | |
|
44 | 0 | for (chunk_t *_ : chunks) hb_free (_); |
45 | |
|
46 | 0 | chunks.fini (); |
47 | 0 | } |
48 | | |
49 | | T* alloc () |
50 | 0 | { |
51 | 0 | if (unlikely (!next)) |
52 | 0 | { |
53 | 0 | if (unlikely (!chunks.alloc (chunks.length + 1))) return nullptr; |
54 | 0 | chunk_t *chunk = (chunk_t *) hb_calloc (1, sizeof (chunk_t)); |
55 | 0 | if (unlikely (!chunk)) return nullptr; |
56 | 0 | chunks.push (chunk); |
57 | 0 | next = chunk->thread (); |
58 | 0 | } |
59 | |
|
60 | 0 | T* obj = next; |
61 | 0 | next = * ((T**) next); |
62 | |
|
63 | 0 | memset (obj, 0, sizeof (T)); |
64 | |
|
65 | 0 | return obj; |
66 | 0 | } |
67 | | |
68 | | void release (T* obj) |
69 | 0 | { |
70 | 0 | * (T**) obj = next; |
71 | 0 | next = obj; |
72 | 0 | } |
73 | | |
74 | | private: |
75 | | |
76 | | static_assert (ChunkLen > 1, ""); |
77 | | static_assert (sizeof (T) >= sizeof (void *), ""); |
78 | | static_assert (alignof (T) % alignof (void *) == 0, ""); |
79 | | |
80 | | struct chunk_t |
81 | | { |
82 | | T* thread () |
83 | 0 | { |
84 | 0 | for (unsigned i = 0; i < ARRAY_LENGTH (arrayZ) - 1; i++) |
85 | 0 | * (T**) &arrayZ[i] = &arrayZ[i + 1]; |
86 | |
|
87 | 0 | * (T**) &arrayZ[ARRAY_LENGTH (arrayZ) - 1] = nullptr; |
88 | |
|
89 | 0 | return arrayZ; |
90 | 0 | } |
91 | | |
92 | | T arrayZ[ChunkLen]; |
93 | | }; |
94 | | |
95 | | T* next; |
96 | | hb_vector_t<chunk_t *> chunks; |
97 | | }; |
98 | | |
99 | | |
100 | | #endif /* HB_POOL_HH */ |