mirror of
https://github.com/mongodb/mongo.git
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465 lines
15 KiB
C++
465 lines
15 KiB
C++
/**
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* Copyright (C) 2008 10gen Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License, version 3,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/* pdfile.h
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Files:
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database.ns - namespace index
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database.1 - data files
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database.2
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...
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*/
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#pragma once
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#include "../stdafx.h"
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#include "../util/mmap.h"
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#include "storage.h"
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#include "jsobj.h"
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#include "namespace.h"
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// see version, versionMinor, below.
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const int VERSION = 4;
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const int VERSION_MINOR = 4;
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namespace mongo {
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class MDFHeader;
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class Extent;
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class Record;
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class Cursor;
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void dropDatabase(const char *ns);
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bool repairDatabase(const char *ns, string &errmsg, bool preserveClonedFilesOnFailure = false, bool backupOriginalFiles = false);
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void dropNS(const string& dropNs);;
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bool userCreateNS(const char *ns, BSONObj j, string& err, bool logForReplication);
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auto_ptr<Cursor> findTableScan(const char *ns, const BSONObj& order, bool *isSorted=0);
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// -1 if library unavailable.
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boost::intmax_t freeSpace();
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/*---------------------------------------------------------------------*/
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class MDFHeader;
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class MongoDataFile {
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friend class DataFileMgr;
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friend class BasicCursor;
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public:
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MongoDataFile(int fn) : fileNo(fn) { }
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void open(const char *filename, int requestedDataSize = 0);
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/* allocate a new extent from this datafile.
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@param capped - true if capped collection
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@param loops is our recursion check variable - you want to pass in zero
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*/
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Extent* createExtent(const char *ns, int approxSize, bool capped = false, int loops = 0);
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/* see if we can find an extent of the right size in the freelist. if not,
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createExtent.
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*/
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Extent* allocExtent(const char *ns, int approxSize, bool capped = false);
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MDFHeader *getHeader() {
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return header;
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}
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/* return max size an extent may be */
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static int maxSize();
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private:
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int defaultSize( const char *filename ) const;
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Extent* getExtent(DiskLoc loc);
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Extent* _getExtent(DiskLoc loc);
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Record* recordAt(DiskLoc dl);
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MemoryMappedFile mmf;
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MDFHeader *header;
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int fileNo;
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};
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class DataFileMgr {
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friend class BasicCursor;
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public:
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void init(const char *);
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void update(
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const char *ns,
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Record *toupdate, const DiskLoc& dl,
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const char *buf, int len, stringstream& profiling);
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// The object o may be updated if modified on insert.
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DiskLoc insert(const char *ns, BSONObj &o);
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DiskLoc insert(const char *ns, const void *buf, int len, bool god = false, const BSONElement &writeId = BSONElement());
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void deleteRecord(const char *ns, Record *todelete, const DiskLoc& dl, bool cappedOK = false);
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static auto_ptr<Cursor> findAll(const char *ns);
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/* special version of insert for transaction logging -- streamlined a bit.
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assumes ns is capped and no indexes
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no _id field check
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*/
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Record* fast_oplog_insert(NamespaceDetails *d, const char *ns, int len);
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static Extent* getExtent(const DiskLoc& dl);
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static Record* getRecord(const DiskLoc& dl);
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private:
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void _deleteRecord(NamespaceDetails *d, const char *ns, Record *todelete, const DiskLoc& dl);
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vector<MongoDataFile *> files;
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};
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extern DataFileMgr theDataFileMgr;
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#pragma pack(1)
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class DeletedRecord {
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public:
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int lengthWithHeaders;
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int extentOfs;
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DiskLoc nextDeleted;
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Extent* myExtent(const DiskLoc& myLoc) {
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return DataFileMgr::getExtent(DiskLoc(myLoc.a(), extentOfs));
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}
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};
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/* Record is a record in a datafile. DeletedRecord is similar but for deleted space.
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*11:03:20 AM) dm10gen: regarding extentOfs...
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(11:03:42 AM) dm10gen: an extent is a continugous disk area, which contains many Records and DeleteRecords
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(11:03:56 AM) dm10gen: a DiskLoc has two pieces, the fileno and ofs. (64 bit total)
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(11:04:16 AM) dm10gen: to keep the headesr small, instead of storing a 64 bit ptr to the full extent address, we keep just the offset
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(11:04:29 AM) dm10gen: we can do this as we know the record's address, and it has the same fileNo
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(11:04:33 AM) dm10gen: see class DiskLoc for more info
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(11:04:43 AM) dm10gen: so that is how Record::myExtent() works
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(11:04:53 AM) dm10gen: on an alloc(), when we build a new Record, we must popular its extentOfs then
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*/
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class Record {
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public:
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enum { HeaderSize = 16 };
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int lengthWithHeaders;
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int extentOfs;
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int nextOfs;
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int prevOfs;
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char data[4];
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int netLength() {
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return lengthWithHeaders - HeaderSize;
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}
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//void setNewLength(int netlen) { lengthWithHeaders = netlen + HeaderSize; }
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/* use this when a record is deleted. basically a union with next/prev fields */
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DeletedRecord& asDeleted() {
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return *((DeletedRecord*) this);
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}
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Extent* myExtent(const DiskLoc& myLoc) {
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return DataFileMgr::getExtent(DiskLoc(myLoc.a(), extentOfs));
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}
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/* get the next record in the namespace, traversing extents as necessary */
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DiskLoc getNext(const DiskLoc& myLoc);
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DiskLoc getPrev(const DiskLoc& myLoc);
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};
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/* extents are datafile regions where all the records within the region
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belong to the same namespace.
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(11:12:35 AM) dm10gen: when the extent is allocated, all its empty space is stuck into one big DeletedRecord
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(11:12:55 AM) dm10gen: and that is placed on the free list
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*/
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class Extent {
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public:
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unsigned magic;
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DiskLoc myLoc;
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DiskLoc xnext, xprev; /* next/prev extent for this namespace */
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Namespace ns; /* which namespace this extent is for. this is just for troubleshooting really */
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int length; /* size of the extent, including these fields */
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DiskLoc firstRecord, lastRecord;
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char extentData[4];
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bool validates() {
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return !(firstRecord.isNull() ^ lastRecord.isNull()) &&
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length >= 0 && !myLoc.isNull();
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}
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void dump(iostream& s) {
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s << " loc:" << myLoc.toString() << " xnext:" << xnext.toString() << " xprev:" << xprev.toString() << '\n';
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s << " ns:" << ns.buf << '\n';
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s << " size:" << length << " firstRecord:" << firstRecord.toString() << " lastRecord:" << lastRecord.toString() << '\n';
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}
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/* assumes already zeroed -- insufficient for block 'reuse' perhaps
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Returns a DeletedRecord location which is the data in the extent ready for us.
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Caller will need to add that to the freelist structure in namespacedetail.
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*/
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DiskLoc init(const char *nsname, int _length, int _fileNo, int _offset);
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/* like init(), but for a reuse case */
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DiskLoc reuse(const char *nsname);
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void assertOk() {
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assert(magic == 0x41424344);
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}
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Record* newRecord(int len);
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Record* getRecord(DiskLoc dl) {
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assert( !dl.isNull() );
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assert( dl.sameFile(myLoc) );
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int x = dl.getOfs() - myLoc.getOfs();
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assert( x > 0 );
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return (Record *) (((char *) this) + x);
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}
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Extent* getNextExtent() {
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return xnext.isNull() ? 0 : DataFileMgr::getExtent(xnext);
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}
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Extent* getPrevExtent() {
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return xprev.isNull() ? 0 : DataFileMgr::getExtent(xprev);
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}
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};
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/*
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----------------------
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Header
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----------------------
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Extent (for a particular namespace)
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Record
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...
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Record (some chained for unused space)
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----------------------
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more Extents...
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----------------------
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*/
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/* data file header */
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class MDFHeader {
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public:
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int version;
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int versionMinor;
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int fileLength;
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DiskLoc unused; /* unused is the portion of the file that doesn't belong to any allocated extents. -1 = no more */
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int unusedLength;
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char reserved[8192 - 4*4 - 8];
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char data[4];
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static int headerSize() {
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return sizeof(MDFHeader) - 4;
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}
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bool currentVersion() const {
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return ( version == VERSION ) && ( versionMinor == VERSION_MINOR );
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}
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bool uninitialized() {
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if ( version == 0 ) return true;
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return false;
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}
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Record* getRecord(DiskLoc dl) {
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int ofs = dl.getOfs();
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assert( ofs >= headerSize() );
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return (Record*) (((char *) this) + ofs);
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}
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void init(int fileno, int filelength) {
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if ( uninitialized() ) {
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assert(filelength > 32768 );
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assert( headerSize() == 8192 );
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fileLength = filelength;
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version = VERSION;
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versionMinor = VERSION_MINOR;
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unused.setOfs( fileno, headerSize() );
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assert( (data-(char*)this) == headerSize() );
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unusedLength = fileLength - headerSize() - 16;
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memcpy(data+unusedLength, " \nthe end\n", 16);
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}
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}
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};
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#pragma pack()
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inline Extent* MongoDataFile::_getExtent(DiskLoc loc) {
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loc.assertOk();
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Extent *e = (Extent *) (((char *)header) + loc.getOfs());
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return e;
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}
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inline Extent* MongoDataFile::getExtent(DiskLoc loc) {
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Extent *e = _getExtent(loc);
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e->assertOk();
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return e;
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}
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} // namespace mongo
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#include "cursor.h"
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namespace mongo {
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inline Record* MongoDataFile::recordAt(DiskLoc dl) {
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return header->getRecord(dl);
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}
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inline DiskLoc Record::getNext(const DiskLoc& myLoc) {
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if ( nextOfs != DiskLoc::NullOfs ) {
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/* defensive */
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if ( nextOfs >= 0 && nextOfs < 10 ) {
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sayDbContext("Assertion failure - Record::getNext() referencing a deleted record?");
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return DiskLoc();
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}
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return DiskLoc(myLoc.a(), nextOfs);
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}
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Extent *e = myExtent(myLoc);
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while ( 1 ) {
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if ( e->xnext.isNull() )
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return DiskLoc(); // end of table.
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e = e->xnext.ext();
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if ( !e->firstRecord.isNull() )
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break;
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// entire extent could be empty, keep looking
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}
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return e->firstRecord;
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}
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inline DiskLoc Record::getPrev(const DiskLoc& myLoc) {
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if ( prevOfs != DiskLoc::NullOfs )
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return DiskLoc(myLoc.a(), prevOfs);
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Extent *e = myExtent(myLoc);
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if ( e->xprev.isNull() )
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return DiskLoc();
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return e->xprev.ext()->lastRecord;
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}
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inline Record* DiskLoc::rec() const {
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return DataFileMgr::getRecord(*this);
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}
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inline BSONObj DiskLoc::obj() const {
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return BSONObj(rec());
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}
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inline DeletedRecord* DiskLoc::drec() const {
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assert( fileNo != -1 );
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return (DeletedRecord*) rec();
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}
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inline Extent* DiskLoc::ext() const {
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return DataFileMgr::getExtent(*this);
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}
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/*---------------------------------------------------------------------*/
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} // namespace mongo
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#include "rec.h"
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#include "database.h"
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namespace mongo {
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#define BOOST_CHECK_EXCEPTION( expression ) \
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try { \
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expression; \
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} catch ( const std::exception &e ) { \
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problem() << e.what() << endl; \
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assert( false ); \
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} catch ( ... ) { \
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assert( false ); \
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}
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class FileOp {
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public:
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virtual ~FileOp() {}
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virtual bool apply( const boost::filesystem::path &p ) = 0;
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virtual const char * op() const = 0;
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};
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inline void _applyOpToDataFiles( const char *database, FileOp &fo, const char *path = dbpath ) {
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string c = database;
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c += '.';
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boost::filesystem::path p(path);
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boost::filesystem::path q;
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q = p / (c+"ns");
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bool ok = false;
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BOOST_CHECK_EXCEPTION( ok = fo.apply( q ) );
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if ( ok )
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log( 1 ) << fo.op() << " file " << q.string() << '\n';
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int i = 0;
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int extra = 10; // should not be necessary, this is defensive in case there are missing files
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while ( 1 ) {
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assert( i <= DiskLoc::MaxFiles );
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stringstream ss;
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ss << c << i;
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q = p / ss.str();
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BOOST_CHECK_EXCEPTION( ok = fo.apply(q) );
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if ( ok ) {
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if ( extra != 10 ){
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log(1) << fo.op() << " file " << q.string() << '\n';
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log() << " _applyOpToDataFiles() warning: extra == " << extra << endl;
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}
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}
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else if ( --extra <= 0 )
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break;
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i++;
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}
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}
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inline void _deleteDataFiles(const char *database) {
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class : public FileOp {
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virtual bool apply( const boost::filesystem::path &p ) {
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return boost::filesystem::remove( p );
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}
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virtual const char * op() const {
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return "remove";
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}
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} deleter;
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_applyOpToDataFiles( database, deleter );
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}
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boost::intmax_t dbSize( const char *database );
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inline NamespaceIndex* nsindex(const char *ns) {
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DEV {
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char buf[256];
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nsToClient(ns, buf);
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if ( database->name != buf ) {
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out() << "ERROR: attempt to write to wrong database database\n";
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out() << " ns:" << ns << '\n';
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out() << " database->name:" << database->name << endl;
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assert( database->name == buf );
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}
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}
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return &database->namespaceIndex;
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}
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inline NamespaceDetails* nsdetails(const char *ns) {
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// if this faults, did you set the current db first? (DBContext + dblock)
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return nsindex(ns)->details(ns);
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}
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inline MongoDataFile& DiskLoc::pdf() const {
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assert( fileNo != -1 );
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return *database->getFile(fileNo);
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}
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inline Extent* DataFileMgr::getExtent(const DiskLoc& dl) {
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assert( dl.a() != -1 );
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return database->getFile(dl.a())->getExtent(dl);
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}
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inline Record* DataFileMgr::getRecord(const DiskLoc& dl) {
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assert( dl.a() != -1 );
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return database->getFile(dl.a())->recordAt(dl);
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}
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} // namespace mongo
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