void * FixedAllocator::Allocate( void )
{
// prove either emptyChunk_ points nowhere, or points to a truly empty Chunk.
assert( ( NULL == emptyChunk_ ) || ( emptyChunk_->HasAvailable( numBlocks_ ) ) );
assert( CountEmptyChunks() < 2 );
if ( ( NULL == allocChunk_ ) || allocChunk_->IsFilled() )
{
if ( NULL != emptyChunk_ )
{
allocChunk_ = emptyChunk_;
emptyChunk_ = NULL;
}
else
{
for ( ChunkIter i( chunks_.begin() ); ; ++i )
{
if ( chunks_.end() == i )
{
if ( !MakeNewChunk() )
return NULL;
break;
}
if ( !i->IsFilled() )
{
allocChunk_ = &*i;
break;
}
}
}
}
else if ( allocChunk_ == emptyChunk_)
// detach emptyChunk_ from allocChunk_, because after
// calling allocChunk_->Allocate(blockSize_); the chunk
// is no longer empty.
emptyChunk_ = NULL;
assert( allocChunk_ != NULL );
assert( !allocChunk_->IsFilled() );
void * place = allocChunk_->Allocate( blockSize_ );
// prove either emptyChunk_ points nowhere, or points to a truly empty Chunk.
assert( ( NULL == emptyChunk_ ) || ( emptyChunk_->HasAvailable( numBlocks_ ) ) );
assert( CountEmptyChunks() < 2 );
#ifdef LOKI_CHECK_FOR_CORRUPTION
if ( allocChunk_->IsCorrupt( numBlocks_, blockSize_, true ) )
{
assert( false );
return NULL;
}
#endif
return place;
}
void FixedAllocator::DoDeallocate(void* p)
{
// Show that deallocChunk_ really owns the block at address p.
assert( deallocChunk_->HasBlock( p, numBlocks_ * blockSize_ ) );
// Either of the next two assertions may fail if somebody tries to
// delete the same block twice.
assert( emptyChunk_ != deallocChunk_ );
assert( !deallocChunk_->HasAvailable( numBlocks_ ) );
// prove either emptyChunk_ points nowhere, or points to a truly empty Chunk.
assert( ( NULL == emptyChunk_ ) || ( emptyChunk_->HasAvailable( numBlocks_ ) ) );
// call into the chunk, will adjust the inner list but won't release memory
deallocChunk_->Deallocate(p, blockSize_);
if ( deallocChunk_->HasAvailable( numBlocks_ ) )
{
assert( emptyChunk_ != deallocChunk_ );
// deallocChunk_ is empty, but a Chunk is only released if there are 2
// empty chunks. Since emptyChunk_ may only point to a previously
// cleared Chunk, if it points to something else besides deallocChunk_,
// then FixedAllocator currently has 2 empty Chunks.
if ( NULL != emptyChunk_ )
{
// If last Chunk is empty, just change what deallocChunk_
// points to, and release the last. Otherwise, swap an empty
// Chunk with the last, and then release it.
Chunk * lastChunk = &chunks_.back();
if ( lastChunk == deallocChunk_ )
deallocChunk_ = emptyChunk_;
else if ( lastChunk != emptyChunk_ )
std::swap( *emptyChunk_, *lastChunk );
assert( lastChunk->HasAvailable( numBlocks_ ) );
lastChunk->Release();
chunks_.pop_back();
if ( ( allocChunk_ == lastChunk ) || allocChunk_->IsFilled() )
allocChunk_ = deallocChunk_;
}
emptyChunk_ = deallocChunk_;
}
// prove either emptyChunk_ points nowhere, or points to a truly empty Chunk.
assert( ( NULL == emptyChunk_ ) || ( emptyChunk_->HasAvailable( numBlocks_ ) ) );
}
bool FixedAllocator::TrimEmptyChunk( void )
{
// prove either emptyChunk_ points nowhere, or points to a truly empty Chunk.
assert( ( NULL == emptyChunk_ ) || ( emptyChunk_->HasAvailable( numBlocks_ ) ) );
if ( NULL == emptyChunk_ ) return false;
// If emptyChunk_ points to valid Chunk, then chunk list is not empty.
assert( !chunks_.empty() );
// And there should be exactly 1 empty Chunk.
assert( 1 == CountEmptyChunks() );
Chunk * lastChunk = &chunks_.back();
if ( lastChunk != emptyChunk_ )
std::swap( *emptyChunk_, *lastChunk );
assert( lastChunk->HasAvailable( numBlocks_ ) );
lastChunk->Release();
chunks_.pop_back();
if ( chunks_.empty() )
{
allocChunk_ = NULL;
deallocChunk_ = NULL;
}
else
{
if ( deallocChunk_ == emptyChunk_ )
{
deallocChunk_ = &chunks_.front();
assert( deallocChunk_->blocksAvailable_ < numBlocks_ );
}
if ( allocChunk_ == emptyChunk_ )
{
allocChunk_ = &chunks_.back();
assert( allocChunk_->blocksAvailable_ < numBlocks_ );
}
}
emptyChunk_ = NULL;
assert( 0 == CountEmptyChunks() );
return true;
}
void FixedAllocator::DoDeallocate(void* p)
{
assert( deallocChunk_->HasBlock( static_cast< unsigned char * >( p ),
numBlocks_ * blockSize_ ) );
// prove either emptyChunk_ points nowhere, or points to a truly empty Chunk.
assert( ( NULL == emptyChunk_ ) || ( emptyChunk_->HasAvailable( numBlocks_ ) ) );
// call into the chunk, will adjust the inner list but won't release memory
deallocChunk_->Deallocate(p, blockSize_);
if ( deallocChunk_->HasAvailable( numBlocks_ ) )
{
assert( emptyChunk_ != deallocChunk_ );
// deallocChunk_ is empty, but a Chunk is only released if there are 2
// empty chunks. Since emptyChunk_ may only point to a previously
// cleared Chunk, if it points to something else besides deallocChunk_,
// then FixedAllocator currently has 2 empty Chunks.
if ( NULL != emptyChunk_ )
{
// If last Chunk is empty, just change what deallocChunk_
// points to, and release the last. Otherwise, swap an empty
// Chunk with the last, and then release it.
Chunk * lastChunk = &chunks_.back();
if ( lastChunk == deallocChunk_ )
deallocChunk_ = emptyChunk_;
else if ( lastChunk != emptyChunk_ )
std::swap( *emptyChunk_, *lastChunk );
assert( lastChunk->HasAvailable( numBlocks_ ) );
lastChunk->Release();
chunks_.pop_back();
allocChunk_ = deallocChunk_;
}
emptyChunk_ = deallocChunk_;
}
// prove either emptyChunk_ points nowhere, or points to a truly empty Chunk.
assert( ( NULL == emptyChunk_ ) || ( emptyChunk_->HasAvailable( numBlocks_ ) ) );
}
void * FixedAllocator::Allocate( void )
{
// prove either emptyChunk_ points nowhere, or points to a truly empty Chunk.
assert( ( NULL == emptyChunk_ ) || ( emptyChunk_->HasAvailable( numBlocks_ ) ) );
if ( ( NULL == allocChunk_ ) || allocChunk_->IsFilled() )
{
if ( NULL != emptyChunk_ )
{
allocChunk_ = emptyChunk_;
emptyChunk_ = NULL;
}
else
{
for ( ChunkIter i( chunks_.begin() ); ; ++i )
{
if ( chunks_.end() == i )
{
if ( !MakeNewChunk() )
return NULL;
break;
}
if ( !i->IsFilled() )
{
allocChunk_ = &*i;
break;
}
}
}
}
assert( allocChunk_ != NULL );
assert( !allocChunk_->IsFilled() );
// prove either emptyChunk_ points nowhere, or points to a truly empty Chunk.
assert( ( NULL == emptyChunk_ ) || ( emptyChunk_->HasAvailable( numBlocks_ ) ) );
return allocChunk_->Allocate(blockSize_);
}
bool FixedAllocator::IsCorrupt( void ) const
{
const bool isEmpty = chunks_.empty();
ChunkCIter start( chunks_.begin() );
ChunkCIter last( chunks_.end() );
const size_t emptyChunkCount = CountEmptyChunks();
if ( isEmpty )
{
if ( start != last )
{
assert( false );
return true;
}
if ( 0 < emptyChunkCount )
{
assert( false );
return true;
}
if ( NULL != deallocChunk_ )
{
assert( false );
return true;
}
if ( NULL != allocChunk_ )
{
assert( false );
return true;
}
if ( NULL != emptyChunk_ )
{
assert( false );
return true;
}
}
else
{
const Chunk * front = &chunks_.front();
const Chunk * back = &chunks_.back();
if ( start >= last )
{
assert( false );
return true;
}
if ( back < deallocChunk_ )
{
assert( false );
return true;
}
if ( back < allocChunk_ )
{
assert( false );
return true;
}
if ( front > deallocChunk_ )
{
assert( false );
return true;
}
if ( front > allocChunk_ )
{
assert( false );
return true;
}
switch ( emptyChunkCount )
{
case 0:
if ( emptyChunk_ != NULL )
{
assert( false );
return true;
}
break;
case 1:
if ( emptyChunk_ == NULL )
{
assert( false );
return true;
}
if ( back < emptyChunk_ )
{
assert( false );
return true;
}
if ( front > emptyChunk_ )
{
assert( false );
return true;
}
if ( !emptyChunk_->HasAvailable( numBlocks_ ) )
{
// This may imply somebody tried to delete a block twice.
assert( false );
return true;
}
break;
default:
assert( false );
return true;
}
for ( ChunkCIter it( start ); it != last; ++it )
{
const Chunk & chunk = *it;
if ( chunk.IsCorrupt( numBlocks_, blockSize_, true ) )
return true;
}
}
return false;
}
