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‎libs/newfs_msdos/ExtentManager.cpp

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/*
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* Copyright (c) 2008 Apple Inc. All rights reserved.
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*
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* @APPLE_LICENSE_HEADER_START@
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*
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* This file contains Original Code and/or Modifications of Original Code
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* as defined in and that are subject to the Apple Public Source License
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* Version 2.0 (the 'License'). You may not use this file except in
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* compliance with the License. Please obtain a copy of the License at
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* http://www.opensource.apple.com/apsl/ and read it before using this
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* file.
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*
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* The Original Code and all software distributed under the License are
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* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
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* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
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* Please see the License for the specific language governing rights and
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* limitations under the License.
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*
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* @APPLE_LICENSE_HEADER_END@
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*/
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//
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// ExtentManager.cpp
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//
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#include "ExtentManager.h"
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void
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ExtentManager::Init(uint32_t theBlockSize, uint32_t theNativeBlockSize, off_t theTotalBytes)
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{
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blockSize = theBlockSize;
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nativeBlockSize = theNativeBlockSize;
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totalBytes = theTotalBytes;
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totalBlocks = howmany(totalBytes, blockSize);
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// add sentry empty extents at both sides so empty partition doesn't need to be handled specially
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AddBlockRangeExtent(0, 0);
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AddBlockRangeExtent(totalBlocks, 0);
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}
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void
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ExtentManager::MergeExtent(const ExtentInfo &a, const ExtentInfo &b, ExtentInfo *c)
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{
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// merge ext into *curIt
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c->blockAddr = min(a.blockAddr, b.blockAddr);
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c->numBlocks = max(a.blockAddr + a.numBlocks, b.blockAddr + b.numBlocks) - c->blockAddr;
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}
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void
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ExtentManager::AddBlockRangeExtent(off_t blockAddr, off_t numBlocks)
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{
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struct ExtentInfo ext, newExt;
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ListExtIt curIt, newIt;
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bool merged = false;
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// make the range a valid range
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if ((blockAddr > totalBlocks) || (blockAddr + numBlocks < 0)) { // totally out of range, do nothing
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return;
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}
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if (blockAddr < 0) {
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numBlocks = blockAddr + numBlocks;
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blockAddr = 0;
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}
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if (blockAddr + numBlocks > totalBlocks) {
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numBlocks = totalBlocks - blockAddr;
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}
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ext.blockAddr = blockAddr;
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ext.numBlocks = numBlocks;
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for (curIt = extentList.begin(); curIt != extentList.end(); curIt++) {
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if (BeforeExtent(ext, *curIt))
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break;
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if (!BeforeExtent(*curIt, ext)) { // overlapped extents
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MergeExtent(ext, *curIt, &newExt);
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*curIt = newExt;
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merged = true;
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break;
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}
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}
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// insert ext before curIt
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if (!merged) {
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curIt = extentList.insert(curIt, ext); // throws bad_alloc when out of memory
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}
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// merge the extents
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newIt = curIt;
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curIt = extentList.begin();
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while (curIt != extentList.end()) {
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if (curIt == newIt || BeforeExtent(*curIt, *newIt)) { // curIt is before newIt
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curIt++;
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continue;
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}
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if (BeforeExtent(*newIt, *curIt)) { // curIt is after newIt now, we are done
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break;
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}
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// merge the two extents
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MergeExtent(*curIt, *newIt, &newExt);
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*newIt = newExt;
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curIt = extentList.erase(curIt);
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}
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// printf("After %s(%lld, %lld)\n", __func__, blockAddr, numBlocks); DebugPrint();
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} // ExtentManager::AddBlockRangeExtent
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void
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ExtentManager::RemoveBlockRangeExtent(off_t blockAddr, off_t numBlocks)
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{
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struct ExtentInfo ext, newExt;
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ListExtIt curIt;
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ext.blockAddr = blockAddr;
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ext.numBlocks = numBlocks;
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curIt = extentList.begin();
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while (curIt != extentList.end()) {
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if (BeforeExtent(*curIt, ext)) {
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curIt++;
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continue;
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}
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if (BeforeExtent(ext, *curIt)) // we are done
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break;
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// overlapped extents
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if (curIt->blockAddr >= ext.blockAddr &&
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curIt->blockAddr + curIt->numBlocks <= ext.blockAddr + ext.numBlocks) {
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// *curIt is totally within ext, remove curIt
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curIt = extentList.erase(curIt);
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} else if (curIt->blockAddr < ext.blockAddr &&
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curIt->blockAddr + curIt->numBlocks > ext.blockAddr + ext.numBlocks) {
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// ext is totally within *curIt, split ext into two
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newExt.blockAddr = ext.blockAddr + ext.numBlocks;
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newExt.numBlocks = curIt->blockAddr + curIt->numBlocks - newExt.blockAddr;
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curIt->numBlocks = ext.blockAddr - curIt->blockAddr;
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curIt++;
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extentList.insert(curIt, newExt); // throws bad_alloc when out of memory
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curIt++;
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} else { // remove part of ext
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if (curIt->blockAddr >= ext.blockAddr) { // remove the former part of *curIt
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assert(curIt->blockAddr + curIt->numBlocks > newExt.blockAddr);
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newExt.blockAddr = ext.blockAddr + ext.numBlocks;
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newExt.numBlocks = curIt->blockAddr + curIt->numBlocks - newExt.blockAddr;
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*curIt = newExt;
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} else { // remove the latter part of *curIt
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curIt->numBlocks = ext.blockAddr - curIt->blockAddr;
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}
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curIt++;
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}
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}
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//printf("After %s(%lld, %lld)\n", __func__, blockAddr, numBlocks); DebugPrint();
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}
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void
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ExtentManager::AddByteRangeExtent(off_t byteAddr, off_t numBytes)
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{
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off_t blockAddr = byteAddr / blockSize;
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off_t blockAddrOfLastByte = (byteAddr + numBytes - 1) / blockSize;
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off_t numBlocks = blockAddrOfLastByte - blockAddr + 1;
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AddBlockRangeExtent(blockAddr, numBlocks);
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}
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void
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ExtentManager::DebugPrint()
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{
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ListExtIt it;
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for (it = extentList.begin(); it != extentList.end(); it++) {
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printf("[%lld, %lld] ", it->blockAddr, it->numBlocks);
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}
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printf("\n");
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}

‎libs/newfs_msdos/ExtentManager.h

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/*
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* Copyright (c) 2008 Computer, Inc. All rights reserved.
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*
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* @APPLE_LICENSE_HEADER_START@
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*
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* This file contains Original Code and/or Modifications of Original Code
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* as defined in and that are subject to the Apple Public Source License
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* Version 2.0 (the 'License'). You may not use this file except in
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* compliance with the License. Please obtain a copy of the License at
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* http://www.opensource.apple.com/apsl/ and read it before using this
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* file.
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*
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* The Original Code and all software distributed under the License are
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* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
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* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
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* Please see the License for the specific language governing rights and
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* limitations under the License.
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*
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* @APPLE_LICENSE_HEADER_END@
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*/
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//
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// ExtentManager.h
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//
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#ifndef EXTENTMANAGER_H
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#define EXTENTMANAGER_H
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#include <list>
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#include <vector>
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#include <algorithm>
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#include <sys/types.h>
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#include <sys/errno.h>
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#include <cstdio>
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#include <cassert>
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using namespace std;
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struct ExtentInfo {
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off_t blockAddr;
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off_t numBlocks;
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};
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inline bool BeforeExtent(const ExtentInfo &a, const ExtentInfo &b)
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{
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return (a.blockAddr + a.numBlocks) < b.blockAddr;
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}
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typedef list<ExtentInfo>::iterator ListExtIt;
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class ExtentManager {
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public:
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ExtentManager() : blockSize(0), totalBytes(0), totalBlocks(0) {};
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~ExtentManager() {};
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void Init(uint32_t theBlockSize, uint32_t theNativeBlockSize, off_t theTotalBytes);
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void AddBlockRangeExtent(off_t blockAddr, off_t numBlocks);
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void AddByteRangeExtent(off_t byteAddr, off_t numBytes);
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void RemoveBlockRangeExtent(off_t blockAddr, off_t numBlocks);
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void DebugPrint();
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protected:
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void MergeExtent(const ExtentInfo &a, const ExtentInfo &b, ExtentInfo *c);
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public:
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size_t blockSize;
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size_t nativeBlockSize;
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off_t totalBytes;
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off_t totalBlocks;
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list<ExtentInfo> extentList;
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};
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#endif // #ifndef EXTENTMANAGER_H

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