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