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 { hb_pool_thb_pool_t37 hb_pool_t () : next (nullptr) {} ~hb_pool_thb_pool_t38 ~hb_pool_t () 39 { 40 next = nullptr; 41 42 + hb_iter (chunks) 43 | hb_apply (hb_free) 44 ; 45 } 46 allochb_pool_t47 T* alloc () 48 { 49 if (unlikely (!next)) 50 { 51 if (unlikely (!chunks.alloc (chunks.length + 1))) return nullptr; 52 chunk_t *chunk = (chunk_t *) hb_calloc (1, sizeof (chunk_t)); 53 if (unlikely (!chunk)) return nullptr; 54 chunks.push (chunk); 55 next = chunk->thread (); 56 } 57 58 T* obj = next; 59 next = * ((T**) next); 60 61 hb_memset (obj, 0, sizeof (T)); 62 63 return obj; 64 } 65 releasehb_pool_t66 void release (T* obj) 67 { 68 * (T**) obj = next; 69 next = obj; 70 } 71 72 private: 73 74 static_assert (ChunkLen > 1, ""); 75 static_assert (sizeof (T) >= sizeof (void *), ""); 76 static_assert (alignof (T) % alignof (void *) == 0, ""); 77 78 struct chunk_t 79 { threadhb_pool_t::chunk_t80 T* thread () 81 { 82 for (unsigned i = 0; i < ARRAY_LENGTH (arrayZ) - 1; i++) 83 * (T**) &arrayZ[i] = &arrayZ[i + 1]; 84 85 * (T**) &arrayZ[ARRAY_LENGTH (arrayZ) - 1] = nullptr; 86 87 return arrayZ; 88 } 89 90 T arrayZ[ChunkLen]; 91 }; 92 93 T* next; 94 hb_vector_t<chunk_t *> chunks; 95 }; 96 97 98 #endif /* HB_POOL_HH */ 99