155 lines
4.4 KiB
C++
155 lines
4.4 KiB
C++
/*
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* Copyright (C) 2009 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <cutils/log.h>
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#include "allocator.h"
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// align all the memory blocks on a cache-line boundary
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const int SimpleBestFitAllocator::kMemoryAlign = 32;
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SimpleBestFitAllocator::SimpleBestFitAllocator(size_t size)
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{
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size_t pagesize = getpagesize();
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mHeapSize = ((size + pagesize-1) & ~(pagesize-1));
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chunk_t* node = new chunk_t(0, mHeapSize / kMemoryAlign);
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mList.insertHead(node);
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}
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SimpleBestFitAllocator::~SimpleBestFitAllocator()
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{
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while(!mList.isEmpty()) {
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delete mList.remove(mList.head());
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}
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}
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size_t SimpleBestFitAllocator::size() const
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{
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return mHeapSize;
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}
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size_t SimpleBestFitAllocator::allocate(size_t size, uint32_t flags)
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{
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Locker::Autolock _l(mLock);
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ssize_t offset = alloc(size, flags);
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return offset;
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}
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ssize_t SimpleBestFitAllocator::deallocate(size_t offset)
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{
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Locker::Autolock _l(mLock);
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chunk_t const * const freed = dealloc(offset);
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if (freed) {
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return 0;
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}
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return -ENOENT;
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}
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ssize_t SimpleBestFitAllocator::alloc(size_t size, uint32_t flags)
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{
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if (size == 0) {
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return 0;
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}
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size = (size + kMemoryAlign-1) / kMemoryAlign;
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chunk_t* free_chunk = 0;
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chunk_t* cur = mList.head();
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size_t pagesize = getpagesize();
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while (cur) {
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int extra = ( -cur->start & ((pagesize/kMemoryAlign)-1) ) ;
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// best fit
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if (cur->free && (cur->size >= (size+extra))) {
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if ((!free_chunk) || (cur->size < free_chunk->size)) {
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free_chunk = cur;
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}
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if (cur->size == size) {
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break;
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}
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}
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cur = cur->next;
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}
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if (free_chunk) {
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const size_t free_size = free_chunk->size;
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free_chunk->free = 0;
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free_chunk->size = size;
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if (free_size > size) {
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int extra = ( -free_chunk->start & ((pagesize/kMemoryAlign)-1) ) ;
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if (extra) {
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chunk_t* split = new chunk_t(free_chunk->start, extra);
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free_chunk->start += extra;
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mList.insertBefore(free_chunk, split);
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}
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LOGE_IF(((free_chunk->start*kMemoryAlign)&(pagesize-1)),
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"page is not aligned!!!");
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const ssize_t tail_free = free_size - (size+extra);
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if (tail_free > 0) {
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chunk_t* split = new chunk_t(
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free_chunk->start + free_chunk->size, tail_free);
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mList.insertAfter(free_chunk, split);
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}
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}
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return (free_chunk->start)*kMemoryAlign;
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}
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return -ENOMEM;
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}
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SimpleBestFitAllocator::chunk_t* SimpleBestFitAllocator::dealloc(size_t start)
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{
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start = start / kMemoryAlign;
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chunk_t* cur = mList.head();
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while (cur) {
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if (cur->start == start) {
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LOG_FATAL_IF(cur->free,
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"block at offset 0x%08lX of size 0x%08lX already freed",
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cur->start*kMemoryAlign, cur->size*kMemoryAlign);
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// merge freed blocks together
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chunk_t* freed = cur;
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cur->free = 1;
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do {
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chunk_t* const p = cur->prev;
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chunk_t* const n = cur->next;
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if (p && (p->free || !cur->size)) {
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freed = p;
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p->size += cur->size;
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mList.remove(cur);
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delete cur;
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}
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cur = n;
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} while (cur && cur->free);
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#ifndef NDEBUG
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if (!freed->free) {
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dump_l("dealloc (!freed->free)");
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}
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#endif
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LOG_FATAL_IF(!freed->free,
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"freed block at offset 0x%08lX of size 0x%08lX is not free!",
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freed->start * kMemoryAlign, freed->size * kMemoryAlign);
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return freed;
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}
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cur = cur->next;
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}
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return 0;
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}
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