зеркало из https://github.com/mozilla/gecko-dev.git
80 строки
2.3 KiB
C++
80 строки
2.3 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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*
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* The contents of this file are subject to the Netscape Public
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* License Version 1.1 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.mozilla.org/NPL/
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*
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* Software distributed under the License is distributed on an "AS
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* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
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* implied. See the License for the specific language governing
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* rights and limitations under the License.
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*
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* The Original Code is mozilla.org code.
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*
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* The Initial Developer of the Original Code is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 1998 Netscape Communications Corporation. All
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* Rights Reserved.
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*
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* Contributor(s):
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*/
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#ifndef POOL_H
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#define POOL_H
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#include "Fundamentals.h"
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// Pooled memory allocation
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class NS_EXTERN Pool
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{
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struct BlockHeader
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{
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BlockHeader *next; // Linked list of all memory blocks in pool
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size_t size; // Physical size of this block, including header
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};
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enum {blockHeaderSize = sizeof(BlockHeader) + 7 & -8}; // BlockHeader size rounded up to a doubleword multiple
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const size_t initialSize; // Size of first chunk to allocate
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const size_t chunkSize; // Size of other chunks to allocate
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ptr buffer; // Doubleword-aligned pointer to free memory buffer
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ptr bufferEnd; // Doubleword-aligned pointer to end of free memory buffer
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BlockHeader *headerList; // Root of linked list of all allocated blocks in this pool
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public:
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explicit Pool(size_t initialSize = 8192, size_t chunkSize = 1024);
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~Pool();
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private:
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Pool(const Pool &); // Copying forbidden
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void operator=(const Pool &); // Copying forbidden
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void *allocateOverflow(size_t size);
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public:
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void *allocate(size_t size);
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void clear();
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// Return the total amount of memory allocated by this pool
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size_t totalSize();
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};
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//
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// Allocate a block of the given size from the pool.
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//
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inline void *Pool::allocate(size_t size)
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{
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size = size + 7 & -8; // Round up to a doubleword multiple
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if ((size_t)(bufferEnd - buffer) >= size) {
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ptr result = buffer;
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buffer += size;
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return result;
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}
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return allocateOverflow(size);
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}
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#endif
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