C++ Extent::validates方法代码示例

    /** @return number of skipped (invalid) documents */
    unsigned compactExtent(const char *ns, NamespaceDetails *d, const DiskLoc ext, int n,
                const scoped_array<IndexSpec> &indexSpecs,
                scoped_array<SortPhaseOne>& phase1, int nidx, bool validate, 
                double pf, int pb)
    {
        log() << "compact extent #" << n << endl;
        unsigned oldObjSize = 0; // we'll report what the old padding was
        unsigned oldObjSizeWithPadding = 0;

        Extent *e = ext.ext();
        e->assertOk();
        assert( e->validates() );
        unsigned skipped = 0;

        {
            // the next/prev pointers within the extent might not be in order so we first page the whole thing in 
            // sequentially
            log() << "compact paging in len=" << e->length/1000000.0 << "MB" << endl;
            Timer t;
            MAdvise adv(e, e->length, MAdvise::Sequential);
            const char *p = (const char *) e;
            for( int i = 0; i < e->length; i += 4096 ) { 
                faux += p[i];
            }
            int ms = t.millis();
            if( ms > 1000 ) 
                log() << "compact end paging in " << ms << "ms " << e->length/1000000.0/ms << "MB/sec" << endl;
        }

        {
            log() << "compact copying records" << endl;
            unsigned totalSize = 0;
            int nrecs = 0;
            DiskLoc L = e->firstRecord;
            if( !L.isNull() ) {
                while( 1 ) {
                    Record *recOld = L.rec();
                    L = recOld->nextInExtent(L);
                    nrecs++;
                    BSONObj objOld(recOld);

                    if( !validate || objOld.valid() ) {
                        unsigned sz = objOld.objsize();

                        oldObjSize += sz;
                        oldObjSizeWithPadding += recOld->netLength();

                        unsigned lenWHdr = sz + Record::HeaderSize;
                        unsigned lenWPadding = lenWHdr;
                        {
                            lenWPadding = static_cast<unsigned>(pf*lenWPadding);
                            lenWPadding += pb;
                            lenWPadding = lenWPadding & quantizeMask(lenWPadding);
                            if( lenWPadding < lenWHdr || lenWPadding > BSONObjMaxUserSize / 2 ) { 
                                lenWPadding = lenWHdr;
                            }
                        }
                        totalSize += lenWPadding;
                        DiskLoc loc = allocateSpaceForANewRecord(ns, d, lenWPadding, false);
                        uassert(14024, "compact error out of space during compaction", !loc.isNull());
                        Record *recNew = loc.rec();
                        recNew = (Record *) getDur().writingPtr(recNew, lenWHdr);
                        addRecordToRecListInExtent(recNew, loc);
                        memcpy(recNew->data, objOld.objdata(), sz);

                        {
                            // extract keys for all indexes we will be rebuilding
                            for( int x = 0; x < nidx; x++ ) { 
                                phase1[x].addKeys(indexSpecs[x], objOld, loc);
                            }
                        }
                    }
                    else { 
                        if( ++skipped <= 10 )
                            log() << "compact skipping invalid object" << endl;
                    }

                    if( L.isNull() ) { 
                        // we just did the very last record from the old extent.  it's still pointed to 
                        // by the old extent ext, but that will be fixed below after this loop
                        break;
                    }

                    // remove the old records (orphan them) periodically so our commit block doesn't get too large
                    bool stopping = false;
                    RARELY stopping = *killCurrentOp.checkForInterruptNoAssert() != 0;
                    if( stopping || getDur().aCommitIsNeeded() ) {
                        e->firstRecord.writing() = L;
                        Record *r = L.rec();
                        getDur().writingInt(r->prevOfs) = DiskLoc::NullOfs;
                        getDur().commitIfNeeded();
                        killCurrentOp.checkForInterrupt(false);
                    }
                }
            } // if !L.isNull()

            assert( d->firstExtent == ext );
            assert( d->lastExtent != ext );
            DiskLoc newFirst = e->xnext;
//.........这里部分代码省略.........

    /** @return number of skipped (invalid) documents */
    unsigned compactExtent(const char *ns, NamespaceDetails *d, const DiskLoc diskloc, int n,
                const scoped_array<IndexSpec> &indexSpecs,
                scoped_array<SortPhaseOne>& phase1, int nidx, bool validate, 
                double pf, int pb)
    {
        log() << "compact begin extent #" << n << " for namespace " << ns << endl;
        unsigned oldObjSize = 0; // we'll report what the old padding was
        unsigned oldObjSizeWithPadding = 0;

        Extent *e = diskloc.ext();
        e->assertOk();
        verify( e->validates() );
        unsigned skipped = 0;

        {
            // the next/prev pointers within the extent might not be in order so we first page the whole thing in 
            // sequentially
            log() << "compact paging in len=" << e->length/1000000.0 << "MB" << endl;
            Timer t;
            MongoDataFile* mdf = cc().database()->getFile( diskloc.a() );
            HANDLE fd = mdf->getFd();
            int offset = diskloc.getOfs();
            Extent* ext = diskloc.ext();
            size_t length = ext->length;
                
            touch_pages(fd, offset, length, ext);
            int ms = t.millis();
            if( ms > 1000 ) 
                log() << "compact end paging in " << ms << "ms " << e->length/1000000.0/ms << "MB/sec" << endl;
        }

        {
            log() << "compact copying records" << endl;
            long long datasize = 0;
            long long nrecords = 0;
            DiskLoc L = e->firstRecord;
            if( !L.isNull() ) {
                while( 1 ) {
                    Record *recOld = L.rec();
                    L = recOld->nextInExtent(L);
                    BSONObj objOld = BSONObj::make(recOld);

                    if( !validate || objOld.valid() ) {
                        nrecords++;
                        unsigned sz = objOld.objsize();

                        oldObjSize += sz;
                        oldObjSizeWithPadding += recOld->netLength();

                        unsigned lenWHdr = sz + Record::HeaderSize;
                        unsigned lenWPadding = lenWHdr;
                        {
                            lenWPadding = static_cast<unsigned>(pf*lenWPadding);
                            lenWPadding += pb;
                            lenWPadding = lenWPadding & quantizeMask(lenWPadding);
                            if( lenWPadding < lenWHdr || lenWPadding > BSONObjMaxUserSize / 2 ) { 
                                lenWPadding = lenWHdr;
                            }
                        }
                        DiskLoc loc = allocateSpaceForANewRecord(ns, d, lenWPadding, false);
                        uassert(14024, "compact error out of space during compaction", !loc.isNull());
                        Record *recNew = loc.rec();
                        datasize += recNew->netLength();
                        recNew = (Record *) getDur().writingPtr(recNew, lenWHdr);
                        addRecordToRecListInExtent(recNew, loc);
                        memcpy(recNew->data(), objOld.objdata(), sz);

                        {
                            // extract keys for all indexes we will be rebuilding
                            for( int x = 0; x < nidx; x++ ) { 
                                phase1[x].addKeys(indexSpecs[x], objOld, loc);
                            }
                        }
                    }
                    else { 
                        if( ++skipped <= 10 )
                            log() << "compact skipping invalid object" << endl;
                    }

                    if( L.isNull() ) { 
                        // we just did the very last record from the old extent.  it's still pointed to 
                        // by the old extent ext, but that will be fixed below after this loop
                        break;
                    }

                    // remove the old records (orphan them) periodically so our commit block doesn't get too large
                    bool stopping = false;
                    RARELY stopping = *killCurrentOp.checkForInterruptNoAssert() != 0;
                    if( stopping || getDur().aCommitIsNeeded() ) {
                        e->firstRecord.writing() = L;
                        Record *r = L.rec();
                        getDur().writingInt(r->prevOfs()) = DiskLoc::NullOfs;
                        getDur().commitIfNeeded();
                        killCurrentOp.checkForInterrupt(false);
                    }
                }
            } // if !L.isNull()

            verify( d->firstExtent == diskloc );
//.........这里部分代码省略.........

    void Collection::_compactExtent(const DiskLoc diskloc, int extentNumber,
                                    MultiIndexBlock& indexesToInsertTo,
                                    const CompactOptions* compactOptions, CompactStats* stats ) {

        log() << "compact begin extent #" << extentNumber
              << " for namespace " << _ns << " " << diskloc;

        unsigned oldObjSize = 0; // we'll report what the old padding was
        unsigned oldObjSizeWithPadding = 0;

        Extent *e = diskloc.ext();
        e->assertOk();
        verify( e->validates(diskloc) );

        {
            // the next/prev pointers within the extent might not be in order so we first
            // page the whole thing in sequentially
            log() << "compact paging in len=" << e->length/1000000.0 << "MB" << endl;
            Timer t;
            size_t length = e->length;

            touch_pages( reinterpret_cast<const char*>(e), length );
            int ms = t.millis();
            if( ms > 1000 )
                log() << "compact end paging in " << ms << "ms "
                      << e->length/1000000.0/t.seconds() << "MB/sec" << endl;
        }

        {
            log() << "compact copying records" << endl;
            long long datasize = 0;
            long long nrecords = 0;
            DiskLoc L = e->firstRecord;
            if( !L.isNull() ) {
                while( 1 ) {
                    Record *recOld = L.rec();
                    L = getExtentManager()->getNextRecordInExtent(L);
                    BSONObj objOld = BSONObj::make(recOld);

                    if ( compactOptions->validateDocuments && !objOld.valid() ) {
                        // object is corrupt!
                        log() << "compact skipping corrupt document!";
                        stats->corruptDocuments++;
                    }
                    else {
                        unsigned docSize = objOld.objsize();

                        nrecords++;
                        oldObjSize += docSize;
                        oldObjSizeWithPadding += recOld->netLength();

                        unsigned lenWHdr = docSize + Record::HeaderSize;
                        unsigned lenWPadding = lenWHdr;

                        switch( compactOptions->paddingMode ) {
                        case CompactOptions::NONE:
                            if ( details()->isUserFlagSet(NamespaceDetails::Flag_UsePowerOf2Sizes) )
                                lenWPadding = details()->quantizePowerOf2AllocationSpace(lenWPadding);
                            break;
                        case CompactOptions::PRESERVE:
                            // if we are preserving the padding, the record should not change size
                            lenWPadding = recOld->lengthWithHeaders();
                            break;
                        case CompactOptions::MANUAL:
                            lenWPadding = compactOptions->computeRecordSize(lenWPadding);
                            if (lenWPadding < lenWHdr || lenWPadding > BSONObjMaxUserSize / 2 ) {
                                lenWPadding = lenWHdr;
                            }
                            break;
                        }

                        CompactDocWriter writer( objOld, lenWPadding );
                        StatusWith<DiskLoc> status = _recordStore->insertRecord( &writer, 0 );
                        uassertStatusOK( status.getStatus() );
                        datasize += _recordStore->recordFor( status.getValue() )->netLength();

                        InsertDeleteOptions options;
                        options.logIfError = false;
                        options.dupsAllowed = true; // in compact we should be doing no checking

                        indexesToInsertTo.insert( objOld, status.getValue(), options );
                    }

                    if( L.isNull() ) {
                        // we just did the very last record from the old extent.  it's still pointed to
                        // by the old extent ext, but that will be fixed below after this loop
                        break;
                    }

                    // remove the old records (orphan them) periodically so our commit block doesn't get too large
                    bool stopping = false;
                    RARELY stopping = *killCurrentOp.checkForInterruptNoAssert() != 0;
                    if( stopping || getDur().aCommitIsNeeded() ) {
                        e->firstRecord.writing() = L;
                        Record *r = L.rec();
                        getDur().writingInt(r->prevOfs()) = DiskLoc::NullOfs;
                        getDur().commitIfNeeded();
                        killCurrentOp.checkForInterrupt();
                    }
                }
//.........这里部分代码省略.........

    /** @return number of skipped (invalid) documents */
    unsigned compactExtent(const char *ns, NamespaceDetails *d, const DiskLoc diskloc, int n,
                           int nidx, bool validate, double pf, int pb, bool useDefaultPadding,
                           bool preservePadding) {

        log() << "compact begin extent #" << n << " for namespace " << ns << endl;
        unsigned oldObjSize = 0; // we'll report what the old padding was
        unsigned oldObjSizeWithPadding = 0;

        Extent *e = diskloc.ext();
        e->assertOk();
        verify( e->validates(diskloc) );
        unsigned skipped = 0;

        Database* db = cc().database();

        {
            // the next/prev pointers within the extent might not be in order so we first
            // page the whole thing in sequentially
            log() << "compact paging in len=" << e->length/1000000.0 << "MB" << endl;
            Timer t;
            Extent* ext = db->getExtentManager().getExtent( diskloc );
            size_t length = ext->length;

            touch_pages( reinterpret_cast<const char*>(ext), length );
            int ms = t.millis();
            if( ms > 1000 )
                log() << "compact end paging in " << ms << "ms "
                      << e->length/1000000.0/ms << "MB/sec" << endl;
        }

        {
            log() << "compact copying records" << endl;
            long long datasize = 0;
            long long nrecords = 0;
            DiskLoc L = e->firstRecord;
            if( !L.isNull() ) {
                while( 1 ) {
                    Record *recOld = L.rec();
                    L = db->getExtentManager().getNextRecordInExtent(L);
                    BSONObj objOld = BSONObj::make(recOld);

                    if( !validate || objOld.valid() ) {
                        nrecords++;
                        unsigned sz = objOld.objsize();

                        oldObjSize += sz;
                        oldObjSizeWithPadding += recOld->netLength();

                        unsigned lenWHdr = sz + Record::HeaderSize;
                        unsigned lenWPadding = lenWHdr;
                        // if we are preserving the padding, the record should not change size
                        if (preservePadding) {
                            lenWPadding = recOld->lengthWithHeaders();
                        }
                        // maintain UsePowerOf2Sizes if no padding values were passed in
                        else if (d->isUserFlagSet(NamespaceDetails::Flag_UsePowerOf2Sizes)
                                && useDefaultPadding) {
                            lenWPadding = d->quantizePowerOf2AllocationSpace(lenWPadding);
                        }
                        // otherwise use the padding values (pf and pb) that were passed in
                        else {
                            lenWPadding = static_cast<unsigned>(pf*lenWPadding);
                            lenWPadding += pb;
                            lenWPadding = lenWPadding & quantizeMask(lenWPadding);
                        }
                        if (lenWPadding < lenWHdr || lenWPadding > BSONObjMaxUserSize / 2 ) { 
                            lenWPadding = lenWHdr;
                        }
                        DiskLoc loc = allocateSpaceForANewRecord(ns, d, lenWPadding, false);
                        uassert(14024, "compact error out of space during compaction", !loc.isNull());
                        Record *recNew = loc.rec();
                        datasize += recNew->netLength();
                        recNew = (Record *) getDur().writingPtr(recNew, lenWHdr);
                        addRecordToRecListInExtent(recNew, loc);
                        memcpy(recNew->data(), objOld.objdata(), sz);
                    }
                    else { 
                        if( ++skipped <= 10 )
                            log() << "compact skipping invalid object" << endl;
                    }

                    if( L.isNull() ) { 
                        // we just did the very last record from the old extent.  it's still pointed to 
                        // by the old extent ext, but that will be fixed below after this loop
                        break;
                    }

                    // remove the old records (orphan them) periodically so our commit block doesn't get too large
                    bool stopping = false;
                    RARELY stopping = *killCurrentOp.checkForInterruptNoAssert() != 0;
                    if( stopping || getDur().aCommitIsNeeded() ) {
                        e->firstRecord.writing() = L;
                        Record *r = L.rec();
                        getDur().writingInt(r->prevOfs()) = DiskLoc::NullOfs;
                        getDur().commitIfNeeded();
                        killCurrentOp.checkForInterrupt(false);
                    }
                }
            } // if !L.isNull()
//.........这里部分代码省略.........

        void validateNS(const string& ns,
                        Collection* collection,
                        const BSONObj& cmdObj,
                        BSONObjBuilder& result) {

            const bool full = cmdObj["full"].trueValue();
            const bool scanData = full || cmdObj["scandata"].trueValue();

            NamespaceDetails* nsd = collection->details();

            bool valid = true;
            BSONArrayBuilder errors; // explanation(s) for why valid = false
            if ( collection->isCapped() ){
                result.append("capped", nsd->isCapped());
                result.appendNumber("max", nsd->maxCappedDocs());
            }

            if ( nsd->firstExtent().isNull() )
                result.append( "firstExtent", "null" );
            else
                result.append( "firstExtent", str::stream() << nsd->firstExtent().toString()
                               << " ns:" << nsd->firstExtent().ext()->nsDiagnostic.toString());
            if ( nsd->lastExtent().isNull() )
                result.append( "lastExtent", "null" );
            else
                result.append( "lastExtent", str::stream() <<  nsd->lastExtent().toString()
                               << " ns:" <<  nsd->lastExtent().ext()->nsDiagnostic.toString());

            BSONArrayBuilder extentData;
            int extentCount = 0;
            try {

                if ( !nsd->firstExtent().isNull() ) {
                    nsd->firstExtent().ext()->assertOk();
                    nsd->lastExtent().ext()->assertOk();
                }

                DiskLoc extentDiskLoc = nsd->firstExtent();
                while (!extentDiskLoc.isNull()) {
                    Extent* thisExtent = extentDiskLoc.ext();
                    if (full) {
                        extentData << thisExtent->dump();
                    }
                    if (!thisExtent->validates(extentDiskLoc, &errors)) {
                        valid = false;
                    }
                    DiskLoc nextDiskLoc = thisExtent->xnext;
                    if (extentCount > 0 && !nextDiskLoc.isNull()
                                        &&  nextDiskLoc.ext()->xprev != extentDiskLoc) {
                        StringBuilder sb;
                        sb << "'xprev' pointer " << nextDiskLoc.ext()->xprev.toString()
                           << " in extent " << nextDiskLoc.toString()
                           << " does not point to extent " << extentDiskLoc.toString();
                        errors << sb.str();
                        valid = false;
                    }
                    if (nextDiskLoc.isNull() && extentDiskLoc != nsd->lastExtent()) {
                        StringBuilder sb;
                        sb << "'lastExtent' pointer " << nsd->lastExtent().toString()
                           << " does not point to last extent in list " << extentDiskLoc.toString();
                        errors << sb.str();
                        valid = false;
                    }
                    extentDiskLoc = nextDiskLoc;
                    extentCount++;
                    killCurrentOp.checkForInterrupt();
                }
            }
            catch (const DBException& e) {
                StringBuilder sb;
                sb << "exception validating extent " << extentCount
                   << ": " << e.what();
                errors << sb.str();
                valid = false;
            }
            result.append("extentCount", extentCount);

            if ( full )
                result.appendArray( "extents" , extentData.arr() );

            result.appendNumber("datasize", nsd->dataSize());
            result.appendNumber("nrecords", nsd->numRecords());
            result.appendNumber("lastExtentSize", nsd->lastExtentSize());
            result.appendNumber("padding", nsd->paddingFactor());

            try {

                bool testingLastExtent = false;
                try {
                    if (nsd->firstExtent().isNull()) {
                        // this is ok
                    }
                    else {
                        result.append("firstExtentDetails", nsd->firstExtent().ext()->dump());
                        if (!nsd->firstExtent().ext()->xprev.isNull()) {
                            StringBuilder sb;
                            sb << "'xprev' pointer in 'firstExtent' " << nsd->firstExtent().toString()
                               << " is " << nsd->firstExtent().ext()->xprev.toString()
                               << ", should be null";
                            errors << sb.str();
//.........这里部分代码省略.........

    void SimpleRecordStoreV1::_compactExtent(OperationContext* txn,
                                             const DiskLoc diskloc,
                                             int extentNumber,
                                             RecordStoreCompactAdaptor* adaptor,
                                             const CompactOptions* compactOptions,
                                             CompactStats* stats ) {

        log() << "compact begin extent #" << extentNumber
              << " for namespace " << _ns << " " << diskloc;

        unsigned oldObjSize = 0; // we'll report what the old padding was
        unsigned oldObjSizeWithPadding = 0;

        Extent *e = _extentManager->getExtent( diskloc );
        e->assertOk();
        fassert( 17437, e->validates(diskloc) );

        {
            // the next/prev pointers within the extent might not be in order so we first
            // page the whole thing in sequentially
            log() << "compact paging in len=" << e->length/1000000.0 << "MB" << endl;
            Timer t;
            size_t length = e->length;

            touch_pages( reinterpret_cast<const char*>(e), length );
            int ms = t.millis();
            if( ms > 1000 )
                log() << "compact end paging in " << ms << "ms "
                      << e->length/1000000.0/t.seconds() << "MB/sec" << endl;
        }

        {
            log() << "compact copying records" << endl;
            long long datasize = 0;
            long long nrecords = 0;
            DiskLoc L = e->firstRecord;
            if( !L.isNull() ) {
                while( 1 ) {
                    Record *recOld = recordFor(L);
                    L = getNextRecordInExtent(L);

                    if ( compactOptions->validateDocuments && !adaptor->isDataValid(recOld) ) {
                        // object is corrupt!
                        log() << "compact skipping corrupt document!";
                        stats->corruptDocuments++;
                    }
                    else {
                        unsigned dataSize = adaptor->dataSize( recOld );
                        unsigned docSize = dataSize;

                        nrecords++;
                        oldObjSize += docSize;
                        oldObjSizeWithPadding += recOld->netLength();

                        unsigned lenWHdr = docSize + Record::HeaderSize;
                        unsigned lenWPadding = lenWHdr;

                        switch( compactOptions->paddingMode ) {
                        case CompactOptions::NONE:
                            if ( _details->isUserFlagSet(Flag_UsePowerOf2Sizes) )
                                lenWPadding = quantizePowerOf2AllocationSpace(lenWPadding);
                            break;
                        case CompactOptions::PRESERVE:
                            // if we are preserving the padding, the record should not change size
                            lenWPadding = recOld->lengthWithHeaders();
                            break;
                        case CompactOptions::MANUAL:
                            lenWPadding = compactOptions->computeRecordSize(lenWPadding);
                            if (lenWPadding < lenWHdr || lenWPadding > BSONObjMaxUserSize / 2 ) {
                                lenWPadding = lenWHdr;
                            }
                            break;
                        }

                        CompactDocWriter writer( recOld, dataSize, lenWPadding );
                        StatusWith<DiskLoc> status = insertRecord( txn, &writer, 0 );
                        uassertStatusOK( status.getStatus() );
                        datasize += recordFor( status.getValue() )->netLength();

                        adaptor->inserted( recordFor( status.getValue() ), status.getValue() );
                    }

                    if( L.isNull() ) {
                        // we just did the very last record from the old extent.  it's still pointed to
                        // by the old extent ext, but that will be fixed below after this loop
                        break;
                    }

                    // remove the old records (orphan them) periodically so our commit block doesn't get too large
                    bool stopping = false;
                    RARELY stopping = !txn->checkForInterruptNoAssert().isOK();
                    if( stopping || txn->recoveryUnit()->isCommitNeeded() ) {
                        *txn->recoveryUnit()->writing(&e->firstRecord) = L;
                        Record *r = recordFor(L);
                        txn->recoveryUnit()->writingInt(r->prevOfs()) = DiskLoc::NullOfs;
                        txn->recoveryUnit()->commitIfNeeded();
                        txn->checkForInterrupt();
                    }
                }
            } // if !L.isNull()
//.........这里部分代码省略.........

    Status RecordStoreV1Base::validate( OperationContext* txn,
                                        bool full, bool scanData,
                                        ValidateAdaptor* adaptor,
                                        ValidateResults* results, BSONObjBuilder* output ) const {

        // 1) basic status that require no iteration
        // 2) extent level info
        // 3) check extent start and end
        // 4) check each non-deleted record
        // 5) check deleted list

        // -------------

        // 1111111111111111111
        if ( isCapped() ){
            output->appendBool("capped", true);
            output->appendNumber("max", _details->maxCappedDocs());
        }

        output->appendNumber("datasize", _details->dataSize());
        output->appendNumber("nrecords", _details->numRecords());
        output->appendNumber("lastExtentSize", _details->lastExtentSize(txn));
        output->appendNumber("padding", _details->paddingFactor());

        if ( _details->firstExtent(txn).isNull() )
            output->append( "firstExtent", "null" );
        else
            output->append( "firstExtent",
                            str::stream() << _details->firstExtent(txn).toString()
                            << " ns:"
                            << _getExtent( txn, _details->firstExtent(txn) )->nsDiagnostic.toString());
        if ( _details->lastExtent(txn).isNull() )
            output->append( "lastExtent", "null" );
        else
            output->append( "lastExtent", str::stream() << _details->lastExtent(txn).toString()
                            << " ns:"
                            << _getExtent( txn, _details->lastExtent(txn) )->nsDiagnostic.toString());

        // 22222222222222222222222222
        { // validate extent basics
            BSONArrayBuilder extentData;
            int extentCount = 0;
            DiskLoc extentDiskLoc;
            try {
                if ( !_details->firstExtent(txn).isNull() ) {
                    _getExtent( txn, _details->firstExtent(txn) )->assertOk();
                    _getExtent( txn, _details->lastExtent(txn) )->assertOk();
                }

                extentDiskLoc = _details->firstExtent(txn);
                while (!extentDiskLoc.isNull()) {
                    Extent* thisExtent = _getExtent( txn, extentDiskLoc );
                    if (full) {
                        extentData << thisExtent->dump();
                    }
                    if (!thisExtent->validates(extentDiskLoc, &results->errors)) {
                        results->valid = false;
                    }
                    DiskLoc nextDiskLoc = thisExtent->xnext;
                    
                    if (extentCount > 0 && !nextDiskLoc.isNull()
                        &&  _getExtent( txn, nextDiskLoc )->xprev != extentDiskLoc) {
                        StringBuilder sb;
                        sb << "'xprev' pointer " << _getExtent( txn, nextDiskLoc )->xprev.toString()
                           << " in extent " << nextDiskLoc.toString()
                           << " does not point to extent " << extentDiskLoc.toString();
                        results->errors.push_back( sb.str() );
                        results->valid = false;
                    }
                    if (nextDiskLoc.isNull() && extentDiskLoc != _details->lastExtent(txn)) {
                        StringBuilder sb;
                        sb << "'lastExtent' pointer " << _details->lastExtent(txn).toString()
                           << " does not point to last extent in list " << extentDiskLoc.toString();
                        results->errors.push_back( sb.str() );
                        results->valid = false;
                    }
                    extentDiskLoc = nextDiskLoc;
                    extentCount++;
                    txn->checkForInterrupt();
                }
            }
            catch (const DBException& e) {
                StringBuilder sb;
                sb << "exception validating extent " << extentCount
                   << ": " << e.what();
                results->errors.push_back( sb.str() );
                results->valid = false;
                return Status::OK();
            }
            output->append("extentCount", extentCount);

            if ( full )
                output->appendArray( "extents" , extentData.arr() );

        }

        try {
            // 333333333333333333333333333
            bool testingLastExtent = false;
            try {
//.........这里部分代码省略.........

        void validateNS(const char *ns,
                        NamespaceDetails *d,
                        const BSONObj& cmdObj,
                        BSONObjBuilder& result) {
            const bool full = cmdObj["full"].trueValue();
            const bool scanData = full || cmdObj["scandata"].trueValue();

            bool valid = true;
            BSONArrayBuilder errors; // explanation(s) for why valid = false
            if ( d->isCapped() ){
                result.append("capped", d->isCapped());
                result.appendNumber("max", d->maxCappedDocs());
            }

            result.append("firstExtent", str::stream() << d->firstExtent.toString()
                                    << " ns:" << d->firstExtent.ext()->nsDiagnostic.toString());
            result.append( "lastExtent", str::stream() <<  d->lastExtent.toString()
                                    << " ns:" <<  d->lastExtent.ext()->nsDiagnostic.toString());

            BSONArrayBuilder extentData;
            int extentCount = 0;
            try {
                d->firstExtent.ext()->assertOk();
                d->lastExtent.ext()->assertOk();

                DiskLoc extentDiskLoc = d->firstExtent;
                while (!extentDiskLoc.isNull()) {
                    Extent* thisExtent = extentDiskLoc.ext();
                    if (full) {
                        extentData << thisExtent->dump();
                    }
                    if (!thisExtent->validates(extentDiskLoc, &errors)) {
                        valid = false;
                    }
                    DiskLoc nextDiskLoc = thisExtent->xnext;
                    if (extentCount > 0 && !nextDiskLoc.isNull()
                                        &&  nextDiskLoc.ext()->xprev != extentDiskLoc) {
                        StringBuilder sb;
                        sb << "'xprev' pointer " << nextDiskLoc.ext()->xprev.toString()
                           << " in extent " << nextDiskLoc.toString()
                           << " does not point to extent " << extentDiskLoc.toString();
                        errors << sb.str();
                        valid = false;
                    }
                    if (nextDiskLoc.isNull() && extentDiskLoc != d->lastExtent) {
                        StringBuilder sb;
                        sb << "'lastExtent' pointer " << d->lastExtent.toString()
                           << " does not point to last extent in list " << extentDiskLoc.toString();
                        errors << sb.str();
                        valid = false;
                    }
                    extentDiskLoc = nextDiskLoc;
                    extentCount++;
                    killCurrentOp.checkForInterrupt();
                }
            }
            catch (const DBException& e) {
                StringBuilder sb;
                sb << "exception validating extent " << extentCount
                   << ": " << e.what();
                errors << sb.str();
                valid = false;
            }
            result.append("extentCount", extentCount);

            if ( full )
                result.appendArray( "extents" , extentData.arr() );

            result.appendNumber("datasize", d->stats.datasize);
            result.appendNumber("nrecords", d->stats.nrecords);
            result.appendNumber("lastExtentSize", d->lastExtentSize);
            result.appendNumber("padding", d->paddingFactor());

            try {

                bool testingLastExtent = false;
                try {
                    if (d->firstExtent.isNull()) {
                        errors << "'firstExtent' pointer is null";
                        valid=false;
                    }
                    else {
                        result.append("firstExtentDetails", d->firstExtent.ext()->dump());
                        if (!d->firstExtent.ext()->xprev.isNull()) {
                            StringBuilder sb;
                            sb << "'xprev' pointer in 'firstExtent' " << d->firstExtent.toString()
                               << " is " << d->firstExtent.ext()->xprev.toString()
                               << ", should be null";
                            errors << sb.str();
                            valid=false;
                        }
                    }
                    testingLastExtent = true;
                    if (d->lastExtent.isNull()) {
                        errors << "'lastExtent' pointer is null";
                        valid=false;
                    }
                    else {
                        if (d->firstExtent != d->lastExtent) {
                            result.append("lastExtentDetails", d->lastExtent.ext()->dump());
//.........这里部分代码省略.........