mirror of
https://github.com/mozilla/gecko-dev.git
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405 lines
14 KiB
C++
405 lines
14 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "nsCache.h"
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#include "nsDiskCache.h"
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#include "nsDiskCacheBlockFile.h"
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#include "mozilla/FileUtils.h"
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#include "mozilla/MemoryReporting.h"
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#include <algorithm>
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using namespace mozilla;
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/******************************************************************************
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* nsDiskCacheBlockFile -
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*****************************************************************************/
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/******************************************************************************
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* Open
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*****************************************************************************/
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nsresult
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nsDiskCacheBlockFile::Open(nsIFile * blockFile,
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uint32_t blockSize,
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uint32_t bitMapSize,
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nsDiskCache::CorruptCacheInfo * corruptInfo)
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{
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NS_ENSURE_ARG_POINTER(corruptInfo);
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*corruptInfo = nsDiskCache::kUnexpectedError;
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if (bitMapSize % 32) {
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*corruptInfo = nsDiskCache::kInvalidArgPointer;
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return NS_ERROR_INVALID_ARG;
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}
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mBlockSize = blockSize;
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mBitMapWords = bitMapSize / 32;
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uint32_t bitMapBytes = mBitMapWords * 4;
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// open the file - restricted to user, the data could be confidential
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nsresult rv = blockFile->OpenNSPRFileDesc(PR_RDWR | PR_CREATE_FILE, 00600, &mFD);
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if (NS_FAILED(rv)) {
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*corruptInfo = nsDiskCache::kCouldNotCreateBlockFile;
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CACHE_LOG_DEBUG(("CACHE: nsDiskCacheBlockFile::Open "
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"[this=%p] unable to open or create file: %d",
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this, rv));
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return rv; // unable to open or create file
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}
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// allocate bit map buffer
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mBitMap = new uint32_t[mBitMapWords];
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// check if we just creating the file
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mFileSize = PR_Available(mFD);
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if (mFileSize < 0) {
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// XXX an error occurred. We could call PR_GetError(), but how would that help?
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*corruptInfo = nsDiskCache::kBlockFileSizeError;
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rv = NS_ERROR_UNEXPECTED;
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goto error_exit;
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}
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if (mFileSize == 0) {
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// initialize bit map and write it
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memset(mBitMap, 0, bitMapBytes);
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if (!Write(0, mBitMap, bitMapBytes)) {
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*corruptInfo = nsDiskCache::kBlockFileBitMapWriteError;
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goto error_exit;
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}
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} else if ((uint32_t)mFileSize < bitMapBytes) {
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*corruptInfo = nsDiskCache::kBlockFileSizeLessThanBitMap;
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rv = NS_ERROR_UNEXPECTED; // XXX NS_ERROR_CACHE_INVALID;
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goto error_exit;
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} else {
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// read the bit map
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const int32_t bytesRead = PR_Read(mFD, mBitMap, bitMapBytes);
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if ((bytesRead < 0) || ((uint32_t)bytesRead < bitMapBytes)) {
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*corruptInfo = nsDiskCache::kBlockFileBitMapReadError;
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rv = NS_ERROR_UNEXPECTED;
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goto error_exit;
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}
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#if defined(IS_LITTLE_ENDIAN)
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// Swap from network format
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for (unsigned int i = 0; i < mBitMapWords; ++i)
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mBitMap[i] = ntohl(mBitMap[i]);
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#endif
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// validate block file size
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// Because not whole blocks are written, the size may be a
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// little bit smaller than used blocks times blocksize,
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// because the last block will generally not be 'whole'.
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const uint32_t estimatedSize = CalcBlockFileSize();
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if ((uint32_t)mFileSize + blockSize < estimatedSize) {
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*corruptInfo = nsDiskCache::kBlockFileEstimatedSizeError;
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rv = NS_ERROR_UNEXPECTED;
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goto error_exit;
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}
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}
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CACHE_LOG_DEBUG(("CACHE: nsDiskCacheBlockFile::Open [this=%p] succeeded",
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this));
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return NS_OK;
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error_exit:
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CACHE_LOG_DEBUG(("CACHE: nsDiskCacheBlockFile::Open [this=%p] failed with "
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"error %d", this, rv));
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Close(false);
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return rv;
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}
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/******************************************************************************
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* Close
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*****************************************************************************/
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nsresult
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nsDiskCacheBlockFile::Close(bool flush)
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{
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nsresult rv = NS_OK;
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if (mFD) {
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if (flush)
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rv = FlushBitMap();
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PRStatus err = PR_Close(mFD);
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if (NS_SUCCEEDED(rv) && (err != PR_SUCCESS))
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rv = NS_ERROR_UNEXPECTED;
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mFD = nullptr;
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}
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if (mBitMap) {
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delete [] mBitMap;
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mBitMap = nullptr;
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}
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return rv;
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}
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/******************************************************************************
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* AllocateBlocks
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*
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* Allocates 1-4 blocks, using a first fit strategy,
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* so that no group of blocks spans a quad block boundary.
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*
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* Returns block number of first block allocated or -1 on failure.
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*
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*****************************************************************************/
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int32_t
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nsDiskCacheBlockFile::AllocateBlocks(int32_t numBlocks)
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{
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const int maxPos = 32 - numBlocks;
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const uint32_t mask = (0x01 << numBlocks) - 1;
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for (unsigned int i = 0; i < mBitMapWords; ++i) {
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uint32_t mapWord = ~mBitMap[i]; // flip bits so free bits are 1
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if (mapWord) { // At least one free bit
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// Binary search for first free bit in word
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int bit = 0;
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if ((mapWord & 0x0FFFF) == 0) { bit |= 16; mapWord >>= 16; }
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if ((mapWord & 0x000FF) == 0) { bit |= 8; mapWord >>= 8; }
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if ((mapWord & 0x0000F) == 0) { bit |= 4; mapWord >>= 4; }
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if ((mapWord & 0x00003) == 0) { bit |= 2; mapWord >>= 2; }
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if ((mapWord & 0x00001) == 0) { bit |= 1; mapWord >>= 1; }
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// Find first fit for mask
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for (; bit <= maxPos; ++bit) {
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// all bits selected by mask are 1, so free
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if ((mask & mapWord) == mask) {
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mBitMap[i] |= mask << bit;
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mBitMapDirty = true;
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return (int32_t)i * 32 + bit;
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}
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}
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}
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}
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return -1;
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}
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/******************************************************************************
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* DeallocateBlocks
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*****************************************************************************/
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nsresult
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nsDiskCacheBlockFile::DeallocateBlocks( int32_t startBlock, int32_t numBlocks)
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{
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if (!mFD) return NS_ERROR_NOT_AVAILABLE;
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if ((startBlock < 0) || ((uint32_t)startBlock > mBitMapWords * 32 - 1) ||
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(numBlocks < 1) || (numBlocks > 4))
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return NS_ERROR_ILLEGAL_VALUE;
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const int32_t startWord = startBlock >> 5; // Divide by 32
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const uint32_t startBit = startBlock & 31; // Modulo by 32
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// make sure requested deallocation doesn't span a word boundary
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if (startBit + numBlocks > 32) return NS_ERROR_UNEXPECTED;
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uint32_t mask = ((0x01 << numBlocks) - 1) << startBit;
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// make sure requested deallocation is currently allocated
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if ((mBitMap[startWord] & mask) != mask) return NS_ERROR_ABORT;
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mBitMap[startWord] ^= mask; // flips the bits off;
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mBitMapDirty = true;
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// XXX rv = FlushBitMap(); // coherency vs. performance
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return NS_OK;
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}
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/******************************************************************************
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* WriteBlocks
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*****************************************************************************/
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nsresult
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nsDiskCacheBlockFile::WriteBlocks( void * buffer,
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uint32_t size,
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int32_t numBlocks,
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int32_t * startBlock)
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{
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// presume buffer != nullptr and startBlock != nullptr
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NS_ENSURE_TRUE(mFD, NS_ERROR_NOT_AVAILABLE);
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// allocate some blocks in the cache block file
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*startBlock = AllocateBlocks(numBlocks);
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if (*startBlock < 0)
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return NS_ERROR_NOT_AVAILABLE;
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// seek to block position
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int32_t blockPos = mBitMapWords * 4 + *startBlock * mBlockSize;
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// write the blocks
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return Write(blockPos, buffer, size) ? NS_OK : NS_ERROR_FAILURE;
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}
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/******************************************************************************
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* ReadBlocks
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*****************************************************************************/
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nsresult
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nsDiskCacheBlockFile::ReadBlocks( void * buffer,
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int32_t startBlock,
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int32_t numBlocks,
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int32_t * bytesRead)
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{
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// presume buffer != nullptr and bytesRead != bytesRead
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if (!mFD) return NS_ERROR_NOT_AVAILABLE;
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nsresult rv = VerifyAllocation(startBlock, numBlocks);
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if (NS_FAILED(rv)) return rv;
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// seek to block position
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int32_t blockPos = mBitMapWords * 4 + startBlock * mBlockSize;
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int32_t filePos = PR_Seek(mFD, blockPos, PR_SEEK_SET);
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if (filePos != blockPos) return NS_ERROR_UNEXPECTED;
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// read the blocks
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int32_t bytesToRead = *bytesRead;
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if ((bytesToRead <= 0) || ((uint32_t)bytesToRead > mBlockSize * numBlocks)) {
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bytesToRead = mBlockSize * numBlocks;
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}
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*bytesRead = PR_Read(mFD, buffer, bytesToRead);
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CACHE_LOG_DEBUG(("CACHE: nsDiskCacheBlockFile::Read [this=%p] "
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"returned %d / %d bytes", this, *bytesRead, bytesToRead));
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return NS_OK;
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}
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/******************************************************************************
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* FlushBitMap
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*****************************************************************************/
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nsresult
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nsDiskCacheBlockFile::FlushBitMap()
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{
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if (!mBitMapDirty) return NS_OK;
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#if defined(IS_LITTLE_ENDIAN)
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uint32_t *bitmap = new uint32_t[mBitMapWords];
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// Copy and swap to network format
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uint32_t *p = bitmap;
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for (unsigned int i = 0; i < mBitMapWords; ++i, ++p)
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*p = htonl(mBitMap[i]);
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#else
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uint32_t *bitmap = mBitMap;
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#endif
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// write bitmap
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bool written = Write(0, bitmap, mBitMapWords * 4);
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#if defined(IS_LITTLE_ENDIAN)
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delete [] bitmap;
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#endif
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if (!written)
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return NS_ERROR_UNEXPECTED;
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PRStatus err = PR_Sync(mFD);
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if (err != PR_SUCCESS) return NS_ERROR_UNEXPECTED;
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mBitMapDirty = false;
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return NS_OK;
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}
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/******************************************************************************
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* VerifyAllocation
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*
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* Return values:
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* NS_OK if all bits are marked allocated
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* NS_ERROR_ILLEGAL_VALUE if parameters don't obey constraints
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* NS_ERROR_FAILURE if some or all the bits are marked unallocated
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*
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*****************************************************************************/
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nsresult
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nsDiskCacheBlockFile::VerifyAllocation( int32_t startBlock, int32_t numBlocks)
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{
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if ((startBlock < 0) || ((uint32_t)startBlock > mBitMapWords * 32 - 1) ||
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(numBlocks < 1) || (numBlocks > 4))
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return NS_ERROR_ILLEGAL_VALUE;
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const int32_t startWord = startBlock >> 5; // Divide by 32
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const uint32_t startBit = startBlock & 31; // Modulo by 32
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// make sure requested deallocation doesn't span a word boundary
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if (startBit + numBlocks > 32) return NS_ERROR_ILLEGAL_VALUE;
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uint32_t mask = ((0x01 << numBlocks) - 1) << startBit;
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// check if all specified blocks are currently allocated
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if ((mBitMap[startWord] & mask) != mask) return NS_ERROR_FAILURE;
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return NS_OK;
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}
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/******************************************************************************
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* CalcBlockFileSize
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*
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* Return size of the block file according to the bits set in mBitmap
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*
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*****************************************************************************/
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uint32_t
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nsDiskCacheBlockFile::CalcBlockFileSize()
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{
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// search for last byte in mBitMap with allocated bits
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uint32_t estimatedSize = mBitMapWords * 4;
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int32_t i = mBitMapWords;
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while (--i >= 0) {
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if (mBitMap[i]) break;
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}
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if (i >= 0) {
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// binary search to find last allocated bit in byte
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uint32_t mapWord = mBitMap[i];
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uint32_t lastBit = 31;
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if ((mapWord & 0xFFFF0000) == 0) { lastBit ^= 16; mapWord <<= 16; }
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if ((mapWord & 0xFF000000) == 0) { lastBit ^= 8; mapWord <<= 8; }
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if ((mapWord & 0xF0000000) == 0) { lastBit ^= 4; mapWord <<= 4; }
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if ((mapWord & 0xC0000000) == 0) { lastBit ^= 2; mapWord <<= 2; }
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if ((mapWord & 0x80000000) == 0) { lastBit ^= 1; mapWord <<= 1; }
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estimatedSize += (i * 32 + lastBit + 1) * mBlockSize;
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}
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return estimatedSize;
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}
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/******************************************************************************
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* Write
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*
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* Wrapper around PR_Write that grows file in larger chunks to combat fragmentation
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*
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*****************************************************************************/
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bool
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nsDiskCacheBlockFile::Write(int32_t offset, const void *buf, int32_t amount)
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{
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/* Grow the file to 4mb right away, then double it until the file grows to 20mb.
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20mb is a magic threshold because OSX stops autodefragging files bigger than that.
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Beyond 20mb grow in 4mb chunks.
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*/
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const int32_t upTo = offset + amount;
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// Use a conservative definition of 20MB
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const int32_t minPreallocate = 4*1024*1024;
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const int32_t maxPreallocate = 20*1000*1000;
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if (mFileSize < upTo) {
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// maximal file size
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const int32_t maxFileSize = mBitMapWords * 4 * (mBlockSize * 8 + 1);
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if (upTo > maxPreallocate) {
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// grow the file as a multiple of minPreallocate
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mFileSize = ((upTo + minPreallocate - 1) / minPreallocate) * minPreallocate;
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} else {
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// Grow quickly between 1MB to 20MB
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if (mFileSize)
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while(mFileSize < upTo)
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mFileSize *= 2;
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mFileSize = clamped(mFileSize, minPreallocate, maxPreallocate);
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}
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mFileSize = std::min(mFileSize, maxFileSize);
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#if !defined(XP_MACOSX)
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mozilla::fallocate(mFD, mFileSize);
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#endif
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}
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if (PR_Seek(mFD, offset, PR_SEEK_SET) != offset)
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return false;
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return PR_Write(mFD, buf, amount) == amount;
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}
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size_t
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nsDiskCacheBlockFile::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf)
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{
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return aMallocSizeOf(mBitMap) + aMallocSizeOf(mFD);
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}
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