mirror of
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149 lines
3.8 KiB
C++
149 lines
3.8 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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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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* Original Author(s):
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* Chris Waterson <waterson@netscape.com
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*
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* Contributor(s):
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*/
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/*
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Implementation for nsFixedSizeAllocator
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*/
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#include "nsCRT.h"
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#include "nsFixedSizeAllocator.h"
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nsresult
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nsFixedSizeAllocator::AddBucket(size_t aSize)
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{
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void* p;
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PL_ARENA_ALLOCATE(p, &mPool, sizeof(Bucket));
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if (! p)
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return NS_ERROR_OUT_OF_MEMORY;
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Bucket* bucket = NS_STATIC_CAST(Bucket*, p);
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bucket->mSize = aSize;
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bucket->mFirst = nsnull;
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bucket->mNext = mBuckets;
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mBuckets = bucket;
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return NS_OK;
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}
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nsresult
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nsFixedSizeAllocator::Init(const char* aName,
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const size_t* aBucketSizes,
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PRInt32 aNumBuckets,
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PRInt32 aInitialSize,
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PRInt32 aAlign)
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{
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NS_PRECONDITION(aNumBuckets > 0, "no buckets");
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if (aNumBuckets <= 0)
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return NS_ERROR_INVALID_ARG;
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// Blow away the old pool if we're being re-initialized.
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if (mBuckets)
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PL_FinishArenaPool(&mPool);
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PRInt32 bucketspace = aNumBuckets * sizeof(Bucket);
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PL_InitArenaPool(&mPool, aName, bucketspace + aInitialSize, aAlign);
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mBuckets = nsnull;
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for (PRInt32 i = 0; i < aNumBuckets; ++i)
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AddBucket(aBucketSizes[i]);
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return NS_OK;
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}
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void*
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nsFixedSizeAllocator::Alloc(size_t aSize)
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{
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Bucket** link = &mBuckets;
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Bucket* bucket = mBuckets;
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while (bucket != nsnull) {
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if (aSize == bucket->mSize) {
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// Promote to the head of the list, under the assumption
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// that we'll allocate same-sized object cotemporaneously.
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*link = bucket->mNext;
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bucket->mNext = mBuckets;
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mBuckets = bucket;
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break;
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}
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link = &bucket->mNext;
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bucket = bucket->mNext;
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}
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if (! bucket) {
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// Oops, we don't carry that size. Let's fix that.
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nsresult rv = AddBucket(aSize);
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if (NS_FAILED(rv))
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return nsnull;
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bucket = mBuckets;
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}
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void* next;
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if (bucket->mFirst) {
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next = bucket->mFirst;
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bucket->mFirst = bucket->mFirst->mNext;
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}
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else {
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// Allocate headroom so we can have a backpointer. Use
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// 'sizeof double' so that the block stays well-aligned
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PL_ARENA_ALLOCATE(next, &mPool, aSize + sizeof(double));
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FreeEntry* entry = NS_STATIC_CAST(FreeEntry*, next);
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entry->mBucket = bucket;
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}
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next = NS_STATIC_CAST(void*, NS_STATIC_CAST(char*, next) + sizeof(double));
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#ifdef DEBUG
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nsCRT::memset(next, 0xc8, bucket->mSize);
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#endif
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return next;
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}
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void
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nsFixedSizeAllocator::Free(void* aPtr, size_t aSize)
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{
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FreeEntry* entry = NS_REINTERPRET_CAST(FreeEntry*, NS_STATIC_CAST(char*, aPtr) - sizeof(double));
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Bucket* bucket = entry->mBucket;
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#ifdef DEBUG
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NS_ASSERTION(bucket->mSize == aSize, "ack! corruption! bucket->mSize != aSize!");
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nsCRT::memset(aPtr, 0xd8, bucket->mSize);
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#endif
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entry->mNext = bucket->mFirst;
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bucket->mFirst = entry;
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}
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