/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ #include "nsDiskCache.h" #include "nsDiskCacheBlockFile.h" #include "mozilla/FileUtils.h" using namespace mozilla; /****************************************************************************** * nsDiskCacheBlockFile - *****************************************************************************/ /****************************************************************************** * Open *****************************************************************************/ nsresult nsDiskCacheBlockFile::Open(nsILocalFile * blockFile, PRUint32 blockSize, PRUint32 bitMapSize) { if (bitMapSize % 32) return NS_ERROR_INVALID_ARG; mBlockSize = blockSize; mBitMapWords = bitMapSize / 32; PRUint32 bitMapBytes = mBitMapWords * 4; // open the file - restricted to user, the data could be confidential nsresult rv = blockFile->OpenNSPRFileDesc(PR_RDWR | PR_CREATE_FILE, 00600, &mFD); if (NS_FAILED(rv)) return rv; // unable to open or create file // allocate bit map buffer mBitMap = new PRUint32[mBitMapWords]; if (!mBitMap) { rv = NS_ERROR_OUT_OF_MEMORY; goto error_exit; } // check if we just creating the file mFileSize = PR_Available(mFD); if (mFileSize < 0) { // XXX an error occurred. We could call PR_GetError(), but how would that help? rv = NS_ERROR_UNEXPECTED; goto error_exit; } if (mFileSize == 0) { // initialize bit map and write it memset(mBitMap, 0, bitMapBytes); if (!Write(0, mBitMap, bitMapBytes)) goto error_exit; } else if ((PRUint32)mFileSize < bitMapBytes) { rv = NS_ERROR_UNEXPECTED; // XXX NS_ERROR_CACHE_INVALID; goto error_exit; } else { // read the bit map const PRInt32 bytesRead = PR_Read(mFD, mBitMap, bitMapBytes); if ((bytesRead < 0) || ((PRUint32)bytesRead < bitMapBytes)) { rv = NS_ERROR_UNEXPECTED; goto error_exit; } #if defined(IS_LITTLE_ENDIAN) // Swap from network format for (unsigned int i = 0; i < mBitMapWords; ++i) mBitMap[i] = ntohl(mBitMap[i]); #endif // validate block file size // Because not whole blocks are written, the size may be a // little bit smaller than used blocks times blocksize, // because the last block will generally not be 'whole'. const PRUint32 estimatedSize = CalcBlockFileSize(); if ((PRUint32)mFileSize + blockSize < estimatedSize) { rv = NS_ERROR_UNEXPECTED; goto error_exit; } } return NS_OK; error_exit: Close(false); return rv; } /****************************************************************************** * Close *****************************************************************************/ nsresult nsDiskCacheBlockFile::Close(bool flush) { nsresult rv = NS_OK; if (mFD) { if (flush) rv = FlushBitMap(); PRStatus err = PR_Close(mFD); if (NS_SUCCEEDED(rv) && (err != PR_SUCCESS)) rv = NS_ERROR_UNEXPECTED; mFD = nsnull; } if (mBitMap) { delete [] mBitMap; mBitMap = nsnull; } return rv; } /****************************************************************************** * AllocateBlocks * * Allocates 1-4 blocks, using a first fit strategy, * so that no group of blocks spans a quad block boundary. * * Returns block number of first block allocated or -1 on failure. * *****************************************************************************/ PRInt32 nsDiskCacheBlockFile::AllocateBlocks(PRInt32 numBlocks) { const int maxPos = 32 - numBlocks; const PRUint32 mask = (0x01 << numBlocks) - 1; for (unsigned int i = 0; i < mBitMapWords; ++i) { PRUint32 mapWord = ~mBitMap[i]; // flip bits so free bits are 1 if (mapWord) { // At least one free bit // Binary search for first free bit in word int bit = 0; if ((mapWord & 0x0FFFF) == 0) { bit |= 16; mapWord >>= 16; } if ((mapWord & 0x000FF) == 0) { bit |= 8; mapWord >>= 8; } if ((mapWord & 0x0000F) == 0) { bit |= 4; mapWord >>= 4; } if ((mapWord & 0x00003) == 0) { bit |= 2; mapWord >>= 2; } if ((mapWord & 0x00001) == 0) { bit |= 1; mapWord >>= 1; } // Find first fit for mask for (; bit <= maxPos; ++bit) { // all bits selected by mask are 1, so free if ((mask & mapWord) == mask) { mBitMap[i] |= mask << bit; mBitMapDirty = true; return (PRInt32)i * 32 + bit; } } } } return -1; } /****************************************************************************** * DeallocateBlocks *****************************************************************************/ nsresult nsDiskCacheBlockFile::DeallocateBlocks( PRInt32 startBlock, PRInt32 numBlocks) { if (!mFD) return NS_ERROR_NOT_AVAILABLE; if ((startBlock < 0) || ((PRUint32)startBlock > mBitMapWords * 32 - 1) || (numBlocks < 1) || (numBlocks > 4)) return NS_ERROR_ILLEGAL_VALUE; const PRInt32 startWord = startBlock >> 5; // Divide by 32 const PRUint32 startBit = startBlock & 31; // Modulo by 32 // make sure requested deallocation doesn't span a word boundary if (startBit + numBlocks > 32) return NS_ERROR_UNEXPECTED; PRUint32 mask = ((0x01 << numBlocks) - 1) << startBit; // make sure requested deallocation is currently allocated if ((mBitMap[startWord] & mask) != mask) return NS_ERROR_ABORT; mBitMap[startWord] ^= mask; // flips the bits off; mBitMapDirty = true; // XXX rv = FlushBitMap(); // coherency vs. performance return NS_OK; } /****************************************************************************** * WriteBlocks *****************************************************************************/ nsresult nsDiskCacheBlockFile::WriteBlocks( void * buffer, PRUint32 size, PRInt32 numBlocks, PRInt32 * startBlock) { // presume buffer != nsnull and startBlock != nsnull NS_ENSURE_TRUE(mFD, NS_ERROR_NOT_AVAILABLE); // allocate some blocks in the cache block file *startBlock = AllocateBlocks(numBlocks); if (*startBlock < 0) return NS_ERROR_NOT_AVAILABLE; // seek to block position PRInt32 blockPos = mBitMapWords * 4 + *startBlock * mBlockSize; // write the blocks return Write(blockPos, buffer, size) ? NS_OK : NS_ERROR_FAILURE; } /****************************************************************************** * ReadBlocks *****************************************************************************/ nsresult nsDiskCacheBlockFile::ReadBlocks( void * buffer, PRInt32 startBlock, PRInt32 numBlocks, PRInt32 * bytesRead) { // presume buffer != nsnull and bytesRead != bytesRead if (!mFD) return NS_ERROR_NOT_AVAILABLE; nsresult rv = VerifyAllocation(startBlock, numBlocks); if (NS_FAILED(rv)) return rv; // seek to block position PRInt32 blockPos = mBitMapWords * 4 + startBlock * mBlockSize; PRInt32 filePos = PR_Seek(mFD, blockPos, PR_SEEK_SET); if (filePos != blockPos) return NS_ERROR_UNEXPECTED; // read the blocks PRInt32 bytesToRead = *bytesRead; if ((bytesToRead <= 0) || ((PRUint32)bytesToRead > mBlockSize * numBlocks)) { bytesToRead = mBlockSize * numBlocks; } *bytesRead = PR_Read(mFD, buffer, bytesToRead); return NS_OK; } /****************************************************************************** * FlushBitMap *****************************************************************************/ nsresult nsDiskCacheBlockFile::FlushBitMap() { if (!mBitMapDirty) return NS_OK; #if defined(IS_LITTLE_ENDIAN) PRUint32 *bitmap = new PRUint32[mBitMapWords]; // Copy and swap to network format PRUint32 *p = bitmap; for (unsigned int i = 0; i < mBitMapWords; ++i, ++p) *p = htonl(mBitMap[i]); #else PRUint32 *bitmap = mBitMap; #endif // write bitmap bool written = Write(0, bitmap, mBitMapWords * 4); #if defined(IS_LITTLE_ENDIAN) delete [] bitmap; #endif if (!written) return NS_ERROR_UNEXPECTED; PRStatus err = PR_Sync(mFD); if (err != PR_SUCCESS) return NS_ERROR_UNEXPECTED; mBitMapDirty = false; return NS_OK; } /****************************************************************************** * VerifyAllocation * * Return values: * NS_OK if all bits are marked allocated * NS_ERROR_ILLEGAL_VALUE if parameters don't obey constraints * NS_ERROR_FAILURE if some or all the bits are marked unallocated * *****************************************************************************/ nsresult nsDiskCacheBlockFile::VerifyAllocation( PRInt32 startBlock, PRInt32 numBlocks) { if ((startBlock < 0) || ((PRUint32)startBlock > mBitMapWords * 32 - 1) || (numBlocks < 1) || (numBlocks > 4)) return NS_ERROR_ILLEGAL_VALUE; const PRInt32 startWord = startBlock >> 5; // Divide by 32 const PRUint32 startBit = startBlock & 31; // Modulo by 32 // make sure requested deallocation doesn't span a word boundary if (startBit + numBlocks > 32) return NS_ERROR_ILLEGAL_VALUE; PRUint32 mask = ((0x01 << numBlocks) - 1) << startBit; // check if all specified blocks are currently allocated if ((mBitMap[startWord] & mask) != mask) return NS_ERROR_FAILURE; return NS_OK; } /****************************************************************************** * CalcBlockFileSize * * Return size of the block file according to the bits set in mBitmap * *****************************************************************************/ PRUint32 nsDiskCacheBlockFile::CalcBlockFileSize() { // search for last byte in mBitMap with allocated bits PRUint32 estimatedSize = mBitMapWords * 4; PRInt32 i = mBitMapWords; while (--i >= 0) { if (mBitMap[i]) break; } if (i >= 0) { // binary search to find last allocated bit in byte PRUint32 mapWord = mBitMap[i]; PRUint32 lastBit = 31; if ((mapWord & 0xFFFF0000) == 0) { lastBit ^= 16; mapWord <<= 16; } if ((mapWord & 0xFF000000) == 0) { lastBit ^= 8; mapWord <<= 8; } if ((mapWord & 0xF0000000) == 0) { lastBit ^= 4; mapWord <<= 4; } if ((mapWord & 0xC0000000) == 0) { lastBit ^= 2; mapWord <<= 2; } if ((mapWord & 0x80000000) == 0) { lastBit ^= 1; mapWord <<= 1; } estimatedSize += (i * 32 + lastBit + 1) * mBlockSize; } return estimatedSize; } /****************************************************************************** * Write * * Wrapper around PR_Write that grows file in larger chunks to combat fragmentation * *****************************************************************************/ bool nsDiskCacheBlockFile::Write(PRInt32 offset, const void *buf, PRInt32 amount) { /* Grow the file to 4mb right away, then double it until the file grows to 20mb. 20mb is a magic threshold because OSX stops autodefragging files bigger than that. Beyond 20mb grow in 4mb chunks. */ const PRInt32 upTo = offset + amount; // Use a conservative definition of 20MB const PRInt32 minPreallocate = 4*1024*1024; const PRInt32 maxPreallocate = 20*1000*1000; if (mFileSize < upTo) { // maximal file size const PRInt32 maxFileSize = mBitMapWords * 4 * (mBlockSize * 8 + 1); if (upTo > maxPreallocate) { // grow the file as a multiple of minPreallocate mFileSize = ((upTo + minPreallocate - 1) / minPreallocate) * minPreallocate; } else { // Grow quickly between 1MB to 20MB if (mFileSize) while(mFileSize < upTo) mFileSize *= 2; mFileSize = clamped(mFileSize, minPreallocate, maxPreallocate); } mFileSize = NS_MIN(mFileSize, maxFileSize); // Appears to cause bug 617123? Disabled for now. //mozilla::fallocate(mFD, mFileSize); } if (PR_Seek(mFD, offset, PR_SEEK_SET) != offset) return false; return PR_Write(mFD, buf, amount) == amount; }