diff --git a/src/Makefile.sources b/src/Makefile.sources index 5ee856583..17956c59d 100644 --- a/src/Makefile.sources +++ b/src/Makefile.sources @@ -129,6 +129,7 @@ HB_BASE_sources = \ hb-ot-var-mvar-table.hh \ hb-ot-var.cc \ hb-ot-vorg-table.hh \ + hb-pool.hh \ hb-sanitize.hh \ hb-serialize.hh \ hb-set-digest.hh \ diff --git a/src/hb-pool.hh b/src/hb-pool.hh new file mode 100644 index 000000000..7e49ad0e6 --- /dev/null +++ b/src/hb-pool.hh @@ -0,0 +1,98 @@ +/* + * Copyright © 2019 Facebook, Inc. + * + * This is part of HarfBuzz, a text shaping library. + * + * Permission is hereby granted, without written agreement and without + * license or royalty fees, to use, copy, modify, and distribute this + * software and its documentation for any purpose, provided that the + * above copyright notice and the following two paragraphs appear in + * all copies of this software. + * + * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR + * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES + * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN + * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH + * DAMAGE. + * + * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, + * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND + * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS + * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO + * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. + * + * Facebook Author(s): Behdad Esfahbod + */ + +#ifndef HB_POOL_HH +#define HB_POOL_HH + +#include "hb.hh" + +/* Memory pool for persistent allocation of small objects. */ + +template +struct hb_pool_t +{ + hb_pool_t () : next (nullptr) {} + + ~hb_pool_t () + { + next = nullptr; + + hb_iter (chunks) + | hb_apply ([] (chunk_t *_) { ::free (_); }) + ; + } + + T* alloc () + { + if (unlikely (!next)) + { + if (unlikely (!chunks.alloc (chunks.length + 1))) return nullptr; + chunk_t *chunk = (chunk_t *) malloc (sizeof (chunk_t)); + if (unlikely (!chunk)) return nullptr; + chunks.push (chunk); + next = chunk->thread (); + } + + T* obj = next; + next = * ((T**) next); + + *obj = Null (T); + + return obj; + } + + void free (T* obj) + { + * (T**) obj = next; + next = obj; + } + + private: + + static_assert (ChunkLen > 1, ""); + static_assert (sizeof (T) >= sizeof (void *), ""); + static_assert (alignof (T) % sizeof (void *) == 0, ""); + + struct chunk_t + { + T* thread () + { + for (unsigned i = 0; i < ARRAY_LENGTH (arrayZ) - 1; i++) + * (T**) &arrayZ[i] = &arrayZ[i + 1]; + + * (T**) &arrayZ[ARRAY_LENGTH (arrayZ) - 1] = nullptr; + + return arrayZ; + } + + T arrayZ[ChunkLen]; + }; + + T* next; + hb_vector_t chunks; +}; + + +#endif /* HB_POOL_HH */