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261 lines
7.5 KiB
261 lines
7.5 KiB
/*
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This file is part of the KDE libraries
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Copyright (C) 1999 Waldo Bastian (bastian@kde.org)
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Copyright (C) 2002 Michael Matz (matz@kde.org)
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public License
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along with this library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, USA.
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*/
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/* Fast zone memory allocator with deallocation support, for use as obstack
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or as general purpose allocator. It does no compaction. If the usage
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pattern is non-optimal it might waste some memory while running. E.g.
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allocating many small things at once, and then deallocating only every
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second one, there is a high chance, that actually no memory is freed. */
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// $Id$
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#include "kallocator.h"
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#include <kdebug.h>
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class KZoneAllocator::MemBlock
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{
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public:
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MemBlock(size_t s) : size(s), ref(0), older(0), newer(0)
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{ begin = new char[s]; }
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~MemBlock() { delete [] begin; }
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bool is_in(void *ptr) const {return !(begin > (char *)ptr
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|| (begin + size) <= (char *)ptr); }
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size_t size;
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unsigned int ref;
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char *begin;
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MemBlock *older;
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MemBlock *newer;
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};
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KZoneAllocator::KZoneAllocator(unsigned long _blockSize)
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: currentBlock(0), blockSize(1), blockOffset(0), log2(0), num_blocks(0),
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hashList(0), hashSize(0), hashDirty(true)
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{
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while (blockSize < _blockSize)
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blockSize <<= 1, log2++;
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/* Make sure, that a block is allocated at the first time allocate()
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is called (even with a 0 size). */
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blockOffset = blockSize + 1;
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}
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KZoneAllocator::~KZoneAllocator()
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{
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unsigned int count = 0;
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if (hashList) {
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/* No need to maintain the different lists in hashList[] anymore.
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I.e. no need to use delBlock(). */
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for (unsigned int i = 0; i < hashSize; i++)
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delete hashList[i];
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delete [] hashList;
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hashList = 0;
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}
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MemBlock *next;
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for (; currentBlock; currentBlock = next) {
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next = currentBlock->older;
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delete currentBlock;
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count++;
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}
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#ifndef NDEBUG // as this is called quite late in the app, we don't care
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// to use kdDebug
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if (count > 1)
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qDebug("zone still contained %d blocks", count);
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#endif
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}
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void KZoneAllocator::insertHash(MemBlock *b)
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{
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unsigned long adr = ((unsigned long)b->begin) & (~(blockSize - 1));
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unsigned long end = ((unsigned long)b->begin) + blockSize;
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while (adr < end) {
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unsigned long key = adr >> log2;
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key = key & (hashSize - 1);
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if (!hashList[key])
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hashList[key] = new TQValueList<MemBlock *>;
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hashList[key]->append(b);
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adr += blockSize;
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}
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}
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/** Add a new memory block to the pool of blocks,
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and reorganize the hash lists if needed.
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@param b block to add
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@internal
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*/
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void KZoneAllocator::addBlock(MemBlock *b)
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{
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b->newer = 0;
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b->older = currentBlock;
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if (currentBlock)
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b->older->newer = b;
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currentBlock = b;
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num_blocks++;
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/* If we either have no hashList at all, or since it's last construction
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there are now many more blocks we reconstruct the list. But don't
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make it larger than a certain maximum. */
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if (hashList && ((num_blocks / 4) > hashSize && hashSize < 64*1024))
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hashDirty = true;
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/* Only insert this block into the hashlists, if we aren't going to
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reconstruct them anyway. */
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if (hashList && !hashDirty)
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insertHash (b);
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}
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/** Reinitialize hash list. @internal */
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void KZoneAllocator::initHash()
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{
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if (hashList) {
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for (unsigned int i = 0; i < hashSize; i++)
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delete hashList[i];
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delete [] hashList;
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hashList = 0;
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}
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hashSize = 1;
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while (hashSize < num_blocks)
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hashSize <<= 1;
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if (hashSize < 1024)
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hashSize = 1024;
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if (hashSize > 64*1024)
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hashSize = 64*1024;
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hashList = new TQValueList<MemBlock *> *[hashSize];
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memset (hashList, 0, sizeof(TQValueList<MemBlock*> *) * hashSize);
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hashDirty = false;
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for (MemBlock *b = currentBlock; b; b = b->older)
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insertHash(b);
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}
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/** Delete a memory block. This @em really returns the memory to the heap.
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@param b block to delete
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@internal
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*/
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void KZoneAllocator::delBlock(MemBlock *b)
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{
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/* Update also the hashlists if we aren't going to reconstruct them
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soon. */
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if (hashList && !hashDirty) {
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unsigned long adr = ((unsigned long)b->begin) & (~(blockSize - 1));
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unsigned long end = ((unsigned long)b->begin) + blockSize;
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while (adr < end) {
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unsigned long key = adr >> log2;
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key = key & (hashSize - 1);
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if (hashList[key]) {
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TQValueList<MemBlock *> *list = hashList[key];
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TQValueList<MemBlock *>::Iterator it = list->begin();
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TQValueList<MemBlock *>::Iterator endit = list->end();
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for (; it != endit; ++it)
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if (*it == b) {
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list->remove(it);
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break;
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}
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}
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adr += blockSize;
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}
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}
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if (b->older)
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b->older->newer = b->newer;
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if (b->newer)
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b->newer->older = b->older;
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if (b == currentBlock) {
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currentBlock = 0;
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blockOffset = blockSize;
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}
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delete b;
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num_blocks--;
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}
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void *
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KZoneAllocator::allocate(size_t _size)
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{
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// Use the size of (void *) as alignment
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const size_t alignment = sizeof(void *) - 1;
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_size = (_size + alignment) & ~alignment;
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if ((unsigned long) _size + blockOffset > blockSize)
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{
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if (_size > blockSize) {
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qDebug("KZoneAllocator: allocating more than %lu bytes", blockSize);
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return 0;
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}
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addBlock(new MemBlock(blockSize));
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blockOffset = 0;
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//qDebug ("Allocating block #%d (%x)\n", num_blocks, currentBlock->begin);
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}
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void *result = (void *)(currentBlock->begin+blockOffset);
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currentBlock->ref++;
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blockOffset += _size;
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return result;
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}
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void
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KZoneAllocator::deallocate(void *ptr)
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{
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if (hashDirty)
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initHash();
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unsigned long key = (((unsigned long)ptr) >> log2) & (hashSize - 1);
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TQValueList<MemBlock *> *list = hashList[key];
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if (!list) {
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/* Can happen with certain usage pattern of intermixed free_since()
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and deallocate(). */
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//qDebug("Uhoh");
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return;
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}
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TQValueList<MemBlock*>::ConstIterator it = list->begin();
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TQValueList<MemBlock*>::ConstIterator endit = list->end();
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for (; it != endit; ++it) {
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MemBlock *cur = *it;
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if (cur->is_in(ptr)) {
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if (!--cur->ref) {
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if (cur != currentBlock)
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delBlock (cur);
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else
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blockOffset = 0;
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}
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return;
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}
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}
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/* Can happen with certain usage pattern of intermixed free_since()
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and deallocate(). */
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//qDebug("Uhoh2");
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}
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void
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KZoneAllocator::free_since(void *ptr)
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{
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/* If we have a hashList and it's not yet dirty, see, if we will dirty
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it by removing too many blocks. This will make the below delBlock()s
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faster. */
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if (hashList && !hashDirty)
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{
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const MemBlock *b;
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unsigned int removed = 0;
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for (b = currentBlock; b; b = b->older, removed++)
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if (b->is_in (ptr))
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break;
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if (hashSize >= 4 * (num_blocks - removed))
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hashDirty = true;
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}
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while (currentBlock && !currentBlock->is_in(ptr)) {
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currentBlock = currentBlock->older;
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delBlock (currentBlock->newer);
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}
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blockOffset = ((char*)ptr) - currentBlock->begin;
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}
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