C++ IndexAccessMethod类代码示例

    // page in pages needed for all index lookups on a given object
    void prefetchIndexPages(Collection* collection,
                            const repl::ReplSetImpl::IndexPrefetchConfig& prefetchConfig,
                            const BSONObj& obj) {
        DiskLoc unusedDl; // unused
        BSONObjSet unusedKeys;

        // do we want prefetchConfig to be (1) as-is, (2) for update ops only, or (3) configured per op type?  
        // One might want PREFETCH_NONE for updates, but it's more rare that it is a bad idea for inserts.  
        // #3 (per op), a big issue would be "too many knobs".
        switch (prefetchConfig) {
        case repl::ReplSetImpl::PREFETCH_NONE:
            return;
        case repl::ReplSetImpl::PREFETCH_ID_ONLY:
        {
            TimerHolder timer( &prefetchIndexStats);
            // on the update op case, the call to prefetchRecordPages will touch the _id index.
            // thus perhaps this option isn't very useful?
            try {
                IndexDescriptor* desc = collection->getIndexCatalog()->findIdIndex();
                if ( !desc )
                    return;
                IndexAccessMethod* iam = collection->getIndexCatalog()->getIndex( desc );
                verify( iam );
                iam->touch(obj);
            }
            catch (const DBException& e) {
                LOG(2) << "ignoring exception in prefetchIndexPages(): " << e.what() << endl;
            }
            break;
        }
        case repl::ReplSetImpl::PREFETCH_ALL:
        {
            // indexCount includes all indexes, including ones
            // in the process of being built
            IndexCatalog::IndexIterator ii = collection->getIndexCatalog()->getIndexIterator( true );
            while ( ii.more() ) {
                TimerHolder timer( &prefetchIndexStats);
                // This will page in all index pages for the given object.
                try {
                    IndexDescriptor* desc = ii.next();
                    IndexAccessMethod* iam = collection->getIndexCatalog()->getIndex( desc );
                    verify( iam );
                    iam->touch(obj);
                }
                catch (const DBException& e) {
                    LOG(2) << "ignoring exception in prefetchIndexPages(): " << e.what() << endl;
                }
                unusedKeys.clear();
            }
            break;
        }
        default:
            fassertFailed(16427);
        }
    }

    Status Collection::validate( OperationContext* txn,
                                 bool full, bool scanData,
                                 ValidateResults* results, BSONObjBuilder* output ){

        MyValidateAdaptor adaptor;
        Status status = _recordStore->validate( txn, full, scanData, &adaptor, results, output );
        if ( !status.isOK() )
            return status;

        { // indexes
            output->append("nIndexes", _indexCatalog.numIndexesReady( txn ) );
            int idxn = 0;
            try  {
                // Only applicable when 'full' validation is requested.
                boost::scoped_ptr<BSONObjBuilder> indexDetails(full ? new BSONObjBuilder() : NULL);
                BSONObjBuilder indexes; // not using subObjStart to be exception safe

                IndexCatalog::IndexIterator i = _indexCatalog.getIndexIterator(txn, false);
                while( i.more() ) {
                    const IndexDescriptor* descriptor = i.next();
                    log(LogComponent::kIndex) << "validating index " << descriptor->indexNamespace() << endl;
                    IndexAccessMethod* iam = _indexCatalog.getIndex( descriptor );
                    invariant( iam );

                    boost::scoped_ptr<BSONObjBuilder> bob(
                        indexDetails.get() ? new BSONObjBuilder(
                            indexDetails->subobjStart(descriptor->indexNamespace())) :
                        NULL);

                    int64_t keys;
                    iam->validate(txn, full, &keys, bob.get());
                    indexes.appendNumber(descriptor->indexNamespace(),
                                         static_cast<long long>(keys));
                    idxn++;
                }

                output->append("keysPerIndex", indexes.done());
                if (indexDetails.get()) {
                    output->append("indexDetails", indexDetails->done());
                }
            }
            catch ( DBException& exc ) {
                string err = str::stream() <<
                    "exception during index validate idxn "<<
                    BSONObjBuilder::numStr(idxn) <<
                    ": " << exc.toString();
                results->errors.push_back( err );
                results->valid = false;
            }
        }

        return Status::OK();
    }

    /**
     * Add the provided (obj, dl) pair to the provided index.
     */
    static void addKeysToIndex( Collection* collection, int idxNo,
                                const BSONObj& obj, const DiskLoc &recordLoc ) {

        IndexDetails& id = collection->details()->idx(idxNo);

        IndexDescriptor* desc = collection->getIndexCatalog()->getDescriptor( idxNo );
        verify( desc );

        IndexAccessMethod* iam = collection->getIndexCatalog()->getIndex( desc );
        verify( iam );

        InsertDeleteOptions options;
        options.logIfError = false;
        options.dupsAllowed = (!KeyPattern::isIdKeyPattern(id.keyPattern()) && !id.unique())
            || ignoreUniqueIndex(id);

        int64_t inserted;
        Status ret = iam->insert(obj, recordLoc, options, &inserted);
        uassertStatusOK( ret );
    }

uint64_t Collection::getIndexSize(OperationContext* opCtx, BSONObjBuilder* details, int scale) {
    IndexCatalog* idxCatalog = getIndexCatalog();

    IndexCatalog::IndexIterator ii = idxCatalog->getIndexIterator(opCtx, true);

    uint64_t totalSize = 0;

    while (ii.more()) {
        IndexDescriptor* d = ii.next();
        IndexAccessMethod* iam = idxCatalog->getIndex(d);

        long long ds = iam->getSpaceUsedBytes(opCtx);

        totalSize += ds;
        if (details) {
            details->appendNumber(d->indexName(), ds / scale);
        }
    }

    return totalSize;
}

    Status Collection::validate( bool full, bool scanData,
                                 ValidateResults* results, BSONObjBuilder* output ){

        MyValidateAdaptor adaptor;
        Status status = _recordStore->validate( full, scanData, &adaptor, results, output );
        if ( !status.isOK() )
            return status;

        { // indexes
            output->append("nIndexes", _indexCatalog.numIndexesReady() );
            int idxn = 0;
            try  {
                BSONObjBuilder indexes; // not using subObjStart to be exception safe
                IndexCatalog::IndexIterator i = _indexCatalog.getIndexIterator(false);
                while( i.more() ) {
                    const IndexDescriptor* descriptor = i.next();
                    log() << "validating index " << descriptor->indexNamespace() << endl;
                    IndexAccessMethod* iam = _indexCatalog.getIndex( descriptor );
                    invariant( iam );

                    int64_t keys;
                    iam->validate(&keys);
                    indexes.appendNumber(descriptor->indexNamespace(),
                                         static_cast<long long>(keys));
                    idxn++;
                }
                output->append("keysPerIndex", indexes.done());
            }
            catch ( DBException& exc ) {
                string err = str::stream() <<
                    "exception during index validate idxn "<<
                    BSONObjBuilder::numStr(idxn) <<
                    ": " << exc.toString();
                results->errors.push_back( err );
                results->valid = false;
            }
        }

        return Status::OK();
    }

StatusWith<RecordId> Collection::updateDocument(OperationContext* txn,
                                                const RecordId& oldLocation,
                                                const Snapshotted<BSONObj>& oldDoc,
                                                const BSONObj& newDoc,
                                                bool enforceQuota,
                                                bool indexesAffected,
                                                OpDebug* debug,
                                                oplogUpdateEntryArgs& args) {
    {
        auto status = checkValidation(txn, newDoc);
        if (!status.isOK()) {
            if (_validationLevel == STRICT_V) {
                return status;
            }
            // moderate means we have to check the old doc
            auto oldDocStatus = checkValidation(txn, oldDoc.value());
            if (oldDocStatus.isOK()) {
                // transitioning from good -> bad is not ok
                return status;
            }
            // bad -> bad is ok in moderate mode
        }
    }

    dassert(txn->lockState()->isCollectionLockedForMode(ns().toString(), MODE_IX));
    invariant(oldDoc.snapshotId() == txn->recoveryUnit()->getSnapshotId());

    if (_needCappedLock) {
        // X-lock the metadata resource for this capped collection until the end of the WUOW. This
        // prevents the primary from executing with more concurrency than secondaries.
        // See SERVER-21646.
        Lock::ResourceLock{txn->lockState(), ResourceId(RESOURCE_METADATA, _ns.ns()), MODE_X};
    }

    SnapshotId sid = txn->recoveryUnit()->getSnapshotId();

    BSONElement oldId = oldDoc.value()["_id"];
    if (!oldId.eoo() && (oldId != newDoc["_id"]))
        return StatusWith<RecordId>(
            ErrorCodes::InternalError, "in Collection::updateDocument _id mismatch", 13596);

    // The MMAPv1 storage engine implements capped collections in a way that does not allow records
    // to grow beyond their original size. If MMAPv1 part of a replicaset with storage engines that
    // do not have this limitation, replication could result in errors, so it is necessary to set a
    // uniform rule here. Similarly, it is not sufficient to disallow growing records, because this
    // happens when secondaries roll back an update shrunk a record. Exactly replicating legacy
    // MMAPv1 behavior would require padding shrunk documents on all storage engines. Instead forbid
    // all size changes.
    const auto oldSize = oldDoc.value().objsize();
    if (_recordStore->isCapped() && oldSize != newDoc.objsize())
        return {ErrorCodes::CannotGrowDocumentInCappedNamespace,
                str::stream() << "Cannot change the size of a document in a capped collection: "
                              << oldSize << " != " << newDoc.objsize()};

    // At the end of this step, we will have a map of UpdateTickets, one per index, which
    // represent the index updates needed to be done, based on the changes between oldDoc and
    // newDoc.
    OwnedPointerMap<IndexDescriptor*, UpdateTicket> updateTickets;
    if (indexesAffected) {
        IndexCatalog::IndexIterator ii = _indexCatalog.getIndexIterator(txn, true);
        while (ii.more()) {
            IndexDescriptor* descriptor = ii.next();
            IndexCatalogEntry* entry = ii.catalogEntry(descriptor);
            IndexAccessMethod* iam = ii.accessMethod(descriptor);

            InsertDeleteOptions options;
            options.logIfError = false;
            options.dupsAllowed =
                !(KeyPattern::isIdKeyPattern(descriptor->keyPattern()) || descriptor->unique()) ||
                repl::getGlobalReplicationCoordinator()->shouldIgnoreUniqueIndex(descriptor);
            UpdateTicket* updateTicket = new UpdateTicket();
            updateTickets.mutableMap()[descriptor] = updateTicket;
            Status ret = iam->validateUpdate(txn,
                                             oldDoc.value(),
                                             newDoc,
                                             oldLocation,
                                             options,
                                             updateTicket,
                                             entry->getFilterExpression());
            if (!ret.isOK()) {
                return StatusWith<RecordId>(ret);
            }
        }
    }

    // This can call back into Collection::recordStoreGoingToMove.  If that happens, the old
    // object is removed from all indexes.
    StatusWith<RecordId> newLocation = _recordStore->updateRecord(
        txn, oldLocation, newDoc.objdata(), newDoc.objsize(), _enforceQuota(enforceQuota), this);

    if (!newLocation.isOK()) {
        return newLocation;
    }

    // At this point, the old object may or may not still be indexed, depending on if it was
    // moved. If the object did move, we need to add the new location to all indexes.
    if (newLocation.getValue() != oldLocation) {
        if (debug) {
            if (debug->nmoved == -1)  // default of -1 rather than 0
                debug->nmoved = 1;
//.........这里部分代码省略.........

Status appendCollectionStorageStats(OperationContext* opCtx,
                                    const NamespaceString& nss,
                                    const BSONObj& param,
                                    BSONObjBuilder* result) {
    int scale = 1;
    if (param["scale"].isNumber()) {
        scale = param["scale"].numberInt();
        if (scale < 1) {
            return {ErrorCodes::BadValue, "scale has to be >= 1"};
        }
    } else if (param["scale"].trueValue()) {
        return {ErrorCodes::BadValue, "scale has to be a number >= 1"};
    }

    bool verbose = param["verbose"].trueValue();

    AutoGetCollectionForReadCommand ctx(opCtx, nss);
    Collection* collection = ctx.getCollection();  // Will be set if present
    if (!ctx.getDb() || !collection) {
        result->appendNumber("size", 0);
        result->appendNumber("count", 0);
        result->appendNumber("storageSize", 0);
        result->append("nindexes", 0);
        result->appendNumber("totalIndexSize", 0);
        result->append("indexDetails", BSONObj());
        result->append("indexSizes", BSONObj());
        std::string errmsg = !(ctx.getDb()) ? "Database [" + nss.db().toString() + "] not found."
                                            : "Collection [" + nss.toString() + "] not found.";
        return {ErrorCodes::NamespaceNotFound, errmsg};
    }

    long long size = collection->dataSize(opCtx) / scale;
    result->appendNumber("size", size);
    long long numRecords = collection->numRecords(opCtx);
    result->appendNumber("count", numRecords);

    if (numRecords)
        result->append("avgObjSize", collection->averageObjectSize(opCtx));

    RecordStore* recordStore = collection->getRecordStore();
    result->appendNumber(
        "storageSize",
        static_cast<long long>(recordStore->storageSize(opCtx, result, verbose ? 1 : 0)) / scale);

    recordStore->appendCustomStats(opCtx, result, scale);

    IndexCatalog* indexCatalog = collection->getIndexCatalog();
    result->append("nindexes", indexCatalog->numIndexesReady(opCtx));

    BSONObjBuilder indexDetails;

    IndexCatalog::IndexIterator i = indexCatalog->getIndexIterator(opCtx, false);
    while (i.more()) {
        const IndexDescriptor* descriptor = i.next();
        IndexAccessMethod* iam = indexCatalog->getIndex(descriptor);
        invariant(iam);

        BSONObjBuilder bob;
        if (iam->appendCustomStats(opCtx, &bob, scale)) {
            indexDetails.append(descriptor->indexName(), bob.obj());
        }
    }

    result->append("indexDetails", indexDetails.obj());

    BSONObjBuilder indexSizes;
    long long indexSize = collection->getIndexSize(opCtx, &indexSizes, scale);

    result->appendNumber("totalIndexSize", indexSize / scale);
    result->append("indexSizes", indexSizes.obj());

    return Status::OK();
}

//.........这里部分代码省略.........
                int ndel = 0;
                long long delSize = 0;
                BSONArrayBuilder delBucketSizes;
                int incorrect = 0;
                for ( int i = 0; i < Buckets; i++ ) {
                    DiskLoc loc = nsd->deletedListEntry(i);
                    try {
                        int k = 0;
                        while ( !loc.isNull() ) {
                            if ( recs.count(loc) )
                                incorrect++;
                            ndel++;

                            if ( loc.questionable() ) {
                                if( nsd->isCapped() && !loc.isValid() && i == 1 ) {
                                    /* the constructor for NamespaceDetails intentionally sets deletedList[1] to invalid
                                       see comments in namespace.h
                                    */
                                    break;
                                }

                                string err( str::stream() << "bad pointer in deleted record list: "
                                                          << loc.toString()
                                                          << " bucket: " << i
                                                          << " k: " << k );
                                errors << err;
                                valid = false;
                                break;
                            }

                            DeletedRecord *d = loc.drec();
                            delSize += d->lengthWithHeaders();
                            loc = d->nextDeleted();
                            k++;
                            killCurrentOp.checkForInterrupt();
                        }
                        delBucketSizes << k;
                    }
                    catch (...) {
                        errors << ("exception in deleted chain for bucket " + BSONObjBuilder::numStr(i));
                        valid = false;
                    }
                }
                result.appendNumber("deletedCount", ndel);
                result.appendNumber("deletedSize", delSize);
                if ( full ) {
                    result << "delBucketSizes" << delBucketSizes.arr();
                }

                if ( incorrect ) {
                    errors << (BSONObjBuilder::numStr(incorrect) + " records from datafile are in deleted list");
                    valid = false;
                }

                int idxn = 0;
                try  {
                    IndexCatalog* indexCatalog = collection->getIndexCatalog();

                    result.append("nIndexes", nsd->getCompletedIndexCount());
                    BSONObjBuilder indexes; // not using subObjStart to be exception safe
                    NamespaceDetails::IndexIterator i = nsd->ii();
                    while( i.more() ) {
                        IndexDetails& id = i.next();
                        log() << "validating index " << idxn << ": " << id.indexNamespace() << endl;

                        IndexDescriptor* descriptor = indexCatalog->getDescriptor( idxn );
                        verify( descriptor );
                        IndexAccessMethod* iam = indexCatalog->getIndex( descriptor );
                        verify( iam );

                        int64_t keys;
                        iam->validate(&keys);
                        indexes.appendNumber(id.indexNamespace(), static_cast<long long>(keys));
                        idxn++;
                    }
                    result.append("keysPerIndex", indexes.done());
                }
                catch (...) {
                    errors << ("exception during index validate idxn " + BSONObjBuilder::numStr(idxn));
                    valid=false;
                }

            }
            catch (AssertionException) {
                errors << "exception during validate";
                valid = false;
            }

            result.appendBool("valid", valid);
            result.append("errors", errors.arr());

            if ( !full ){
                result.append("warning", "Some checks omitted for speed. use {full:true} option to do more thorough scan.");
            }
            
            if ( !valid ) {
                result.append("advice", "ns corrupt, requires repair");
            }

        }

StatusWith<RecordId> Collection::updateDocument(OperationContext* txn,
                                                const RecordId& oldLocation,
                                                const Snapshotted<BSONObj>& oldDoc,
                                                const BSONObj& newDoc,
                                                bool enforceQuota,
                                                bool indexesAffected,
                                                OpDebug* debug,
                                                oplogUpdateEntryArgs& args) {
    {
        auto status = checkValidation(txn, newDoc);
        if (!status.isOK()) {
            if (_validationLevel == STRICT_V) {
                return status;
            }
            // moderate means we have to check the old doc
            auto oldDocStatus = checkValidation(txn, oldDoc.value());
            if (oldDocStatus.isOK()) {
                // transitioning from good -> bad is not ok
                return status;
            }
            // bad -> bad is ok in moderate mode
        }
    }

    dassert(txn->lockState()->isCollectionLockedForMode(ns().toString(), MODE_IX));
    invariant(oldDoc.snapshotId() == txn->recoveryUnit()->getSnapshotId());

    SnapshotId sid = txn->recoveryUnit()->getSnapshotId();

    BSONElement oldId = oldDoc.value()["_id"];
    if (!oldId.eoo() && (oldId != newDoc["_id"]))
        return StatusWith<RecordId>(
            ErrorCodes::InternalError, "in Collection::updateDocument _id mismatch", 13596);

    // At the end of this step, we will have a map of UpdateTickets, one per index, which
    // represent the index updates needed to be done, based on the changes between oldDoc and
    // newDoc.
    OwnedPointerMap<IndexDescriptor*, UpdateTicket> updateTickets;
    if (indexesAffected) {
        IndexCatalog::IndexIterator ii = _indexCatalog.getIndexIterator(txn, true);
        while (ii.more()) {
            IndexDescriptor* descriptor = ii.next();
            IndexCatalogEntry* entry = ii.catalogEntry(descriptor);
            IndexAccessMethod* iam = ii.accessMethod(descriptor);

            InsertDeleteOptions options;
            options.logIfError = false;
            options.dupsAllowed =
                !(KeyPattern::isIdKeyPattern(descriptor->keyPattern()) || descriptor->unique()) ||
                repl::getGlobalReplicationCoordinator()->shouldIgnoreUniqueIndex(descriptor);
            UpdateTicket* updateTicket = new UpdateTicket();
            updateTickets.mutableMap()[descriptor] = updateTicket;
            Status ret = iam->validateUpdate(txn,
                                             oldDoc.value(),
                                             newDoc,
                                             oldLocation,
                                             options,
                                             updateTicket,
                                             entry->getFilterExpression());
            if (!ret.isOK()) {
                return StatusWith<RecordId>(ret);
            }
        }
    }

    // This can call back into Collection::recordStoreGoingToMove.  If that happens, the old
    // object is removed from all indexes.
    StatusWith<RecordId> newLocation = _recordStore->updateRecord(
        txn, oldLocation, newDoc.objdata(), newDoc.objsize(), _enforceQuota(enforceQuota), this);

    if (!newLocation.isOK()) {
        return newLocation;
    }

    // At this point, the old object may or may not still be indexed, depending on if it was
    // moved. If the object did move, we need to add the new location to all indexes.
    if (newLocation.getValue() != oldLocation) {
        if (debug) {
            if (debug->nmoved == -1)  // default of -1 rather than 0
                debug->nmoved = 1;
            else
                debug->nmoved += 1;
        }

        Status s = _indexCatalog.indexRecord(txn, newDoc, newLocation.getValue());
        if (!s.isOK())
            return StatusWith<RecordId>(s);
        invariant(sid == txn->recoveryUnit()->getSnapshotId());
        args.ns = ns().ns();
        getGlobalServiceContext()->getOpObserver()->onUpdate(txn, args);

        return newLocation;
    }

    // Object did not move.  We update each index with each respective UpdateTicket.

    if (debug)
        debug->keyUpdates = 0;

    if (indexesAffected) {
//.........这里部分代码省略.........

    StatusWith<DiskLoc> Collection::updateDocument( OperationContext* txn,
                                                    const DiskLoc& oldLocation,
                                                    const BSONObj& objNew,
                                                    bool enforceQuota,
                                                    OpDebug* debug ) {

        BSONObj objOld = _recordStore->dataFor( txn, oldLocation ).toBson();

        if ( objOld.hasElement( "_id" ) ) {
            BSONElement oldId = objOld["_id"];
            BSONElement newId = objNew["_id"];
            if ( oldId != newId )
                return StatusWith<DiskLoc>( ErrorCodes::InternalError,
                                            "in Collection::updateDocument _id mismatch",
                                            13596 );
        }

        if ( ns().coll() == "system.users" ) {
            // XXX - andy and spencer think this should go away now
            V2UserDocumentParser parser;
            Status s = parser.checkValidUserDocument(objNew);
            if ( !s.isOK() )
                return StatusWith<DiskLoc>( s );
        }

        /* duplicate key check. we descend the btree twice - once for this check, and once for the actual inserts, further
           below.  that is suboptimal, but it's pretty complicated to do it the other way without rollbacks...
        */
        OwnedPointerMap<IndexDescriptor*,UpdateTicket> updateTickets;
        IndexCatalog::IndexIterator ii = _indexCatalog.getIndexIterator( txn, true );
        while ( ii.more() ) {
            IndexDescriptor* descriptor = ii.next();
            IndexAccessMethod* iam = _indexCatalog.getIndex( descriptor );

            InsertDeleteOptions options;
            options.logIfError = false;
            options.dupsAllowed =
                !(KeyPattern::isIdKeyPattern(descriptor->keyPattern()) || descriptor->unique())
                || repl::getGlobalReplicationCoordinator()->shouldIgnoreUniqueIndex(descriptor);
            UpdateTicket* updateTicket = new UpdateTicket();
            updateTickets.mutableMap()[descriptor] = updateTicket;
            Status ret = iam->validateUpdate(txn, objOld, objNew, oldLocation, options, updateTicket );
            if ( !ret.isOK() ) {
                return StatusWith<DiskLoc>( ret );
            }
        }

        // this can callback into Collection::recordStoreGoingToMove
        StatusWith<DiskLoc> newLocation = _recordStore->updateRecord( txn,
                                                                      oldLocation,
                                                                      objNew.objdata(),
                                                                      objNew.objsize(),
                                                                      _enforceQuota( enforceQuota ),
                                                                      this );

        if ( !newLocation.isOK() ) {
            return newLocation;
        }

        _infoCache.notifyOfWriteOp();

        if ( newLocation.getValue() != oldLocation ) {

            if ( debug ) {
                if (debug->nmoved == -1) // default of -1 rather than 0
                    debug->nmoved = 1;
                else
                    debug->nmoved += 1;
            }

            _indexCatalog.indexRecord(txn, objNew, newLocation.getValue());

            return newLocation;
        }

        if ( debug )
            debug->keyUpdates = 0;

        ii = _indexCatalog.getIndexIterator( txn, true );
        while ( ii.more() ) {
            IndexDescriptor* descriptor = ii.next();
            IndexAccessMethod* iam = _indexCatalog.getIndex( descriptor );

            int64_t updatedKeys;
            Status ret = iam->update(txn, *updateTickets.mutableMap()[descriptor], &updatedKeys);
            if ( !ret.isOK() )
                return StatusWith<DiskLoc>( ret );
            if ( debug )
                debug->keyUpdates += updatedKeys;
        }

        // Broadcast the mutation so that query results stay correct.
        _cursorCache.invalidateDocument(oldLocation, INVALIDATION_MUTATION);

        return newLocation;
    }

    StatusWith<CompactStats> Collection::compact( const CompactOptions* compactOptions ) {

        if ( isCapped() )
            return StatusWith<CompactStats>( ErrorCodes::BadValue,
                                             "cannot compact capped collection" );

        if ( _indexCatalog.numIndexesInProgress() )
            return StatusWith<CompactStats>( ErrorCodes::BadValue,
                                             "cannot compact when indexes in progress" );

        NamespaceDetails* d = details();

        // this is a big job, so might as well make things tidy before we start just to be nice.
        getDur().commitIfNeeded();

        list<DiskLoc> extents;
        for( DiskLoc L = d->firstExtent(); !L.isNull(); L = L.ext()->xnext )
            extents.push_back(L);
        log() << "compact " << extents.size() << " extents" << endl;

        // same data, but might perform a little different after compact?
        _infoCache.reset();

        vector<BSONObj> indexSpecs;
        {
            IndexCatalog::IndexIterator ii( _indexCatalog.getIndexIterator( false ) );
            while ( ii.more() ) {
                IndexDescriptor* descriptor = ii.next();
                indexSpecs.push_back( _compactAdjustIndexSpec( descriptor->infoObj() ) );
            }
        }

        log() << "compact orphan deleted lists" << endl;
        d->orphanDeletedList();

        // Start over from scratch with our extent sizing and growth
        d->setLastExtentSize( 0 );

        // before dropping indexes, at least make sure we can allocate one extent!
        if ( allocateSpaceForANewRecord( _ns.ns().c_str(),
                                         d,
                                         Record::HeaderSize+1,
                                         false).isNull() ) {
            return StatusWith<CompactStats>( ErrorCodes::InternalError,
                                             "compact error no space available to allocate" );
        }

        // note that the drop indexes call also invalidates all clientcursors for the namespace,
        // which is important and wanted here
        log() << "compact dropping indexes" << endl;
        Status status = _indexCatalog.dropAllIndexes( true );
        if ( !status.isOK() ) {
            return StatusWith<CompactStats>( status );
        }

        getDur().commitIfNeeded();

        CompactStats stats;

        OwnedPointerVector<IndexCatalog::IndexBuildBlock> indexBuildBlocks;
        vector<IndexAccessMethod*> indexesToInsertTo;
        vector< std::pair<IndexAccessMethod*,IndexAccessMethod*> > bulkToCommit;
        for ( size_t i = 0; i < indexSpecs.size(); i++ ) {
            killCurrentOp.checkForInterrupt(false);
            BSONObj info = indexSpecs[i];
            info = _compactAdjustIndexSpec( info );
            info = _indexCatalog.fixIndexSpec( info );
            auto_ptr<IndexCatalog::IndexBuildBlock> block( new IndexCatalog::IndexBuildBlock( this,info ) );
            Status status = block->init();
            if ( !status.isOK() )
                return StatusWith<CompactStats>(status);

            IndexAccessMethod* accessMethod = block->getEntry()->accessMethod();
            status = accessMethod->initializeAsEmpty();
            if ( !status.isOK() )
                return StatusWith<CompactStats>(status);

            IndexAccessMethod* bulk = accessMethod->initiateBulk();
            if ( bulk ) {
                indexesToInsertTo.push_back( bulk );
                bulkToCommit.push_back( std::pair<IndexAccessMethod*,IndexAccessMethod*>( accessMethod, bulk ) );
            }
            else {
                indexesToInsertTo.push_back( accessMethod );
            }

            indexBuildBlocks.mutableVector().push_back( block.release() );
        }

        // reset data size and record counts to 0 for this namespace
        // as we're about to tally them up again for each new extent
        d->setStats( 0, 0 );

        ProgressMeterHolder pm(cc().curop()->setMessage("compact extent",
                                                        "Extent Compacting Progress",
                                                        extents.size()));

        int extentNumber = 0;
        for( list<DiskLoc>::iterator i = extents.begin(); i != extents.end(); i++ ) {
            _compactExtent(*i, extentNumber++, indexesToInsertTo, compactOptions, &stats );
//.........这里部分代码省略.........

StatusWith<CompactStats> compactCollection(OperationContext* opCtx,
                                           Collection* collection,
                                           const CompactOptions* compactOptions) {
    dassert(opCtx->lockState()->isCollectionLockedForMode(collection->ns().toString(), MODE_X));

    DisableDocumentValidation validationDisabler(opCtx);

    auto recordStore = collection->getRecordStore();
    auto indexCatalog = collection->getIndexCatalog();

    if (!recordStore->compactSupported())
        return StatusWith<CompactStats>(ErrorCodes::CommandNotSupported,
                                        str::stream()
                                            << "cannot compact collection with record store: "
                                            << recordStore->name());

    if (recordStore->compactsInPlace()) {
        CompactStats stats;
        Status status = recordStore->compact(opCtx);
        if (!status.isOK())
            return StatusWith<CompactStats>(status);

        // Compact all indexes (not including unfinished indexes)
        std::unique_ptr<IndexCatalog::IndexIterator> ii(
            indexCatalog->getIndexIterator(opCtx, false));
        while (ii->more()) {
            IndexCatalogEntry* entry = ii->next();
            IndexDescriptor* descriptor = entry->descriptor();
            IndexAccessMethod* iam = entry->accessMethod();

            LOG(1) << "compacting index: " << descriptor->toString();
            Status status = iam->compact(opCtx);
            if (!status.isOK()) {
                error() << "failed to compact index: " << descriptor->toString();
                return status;
            }
        }

        return StatusWith<CompactStats>(stats);
    }

    if (indexCatalog->numIndexesInProgress(opCtx))
        return StatusWith<CompactStats>(ErrorCodes::BadValue,
                                        "cannot compact when indexes in progress");

    std::vector<BSONObj> indexSpecs;
    {
        std::unique_ptr<IndexCatalog::IndexIterator> ii(
            indexCatalog->getIndexIterator(opCtx, false));
        while (ii->more()) {
            IndexDescriptor* descriptor = ii->next()->descriptor();

            // Compact always creates the new index in the foreground.
            const BSONObj spec =
                descriptor->infoObj().removeField(IndexDescriptor::kBackgroundFieldName);
            const BSONObj key = spec.getObjectField("key");
            const Status keyStatus =
                index_key_validate::validateKeyPattern(key, descriptor->version());
            if (!keyStatus.isOK()) {
                return StatusWith<CompactStats>(
                    ErrorCodes::CannotCreateIndex,
                    str::stream() << "Cannot compact collection due to invalid index " << spec
                                  << ": "
                                  << keyStatus.reason()
                                  << " For more info see"
                                  << " http://dochub.mongodb.org/core/index-validation");
            }
            indexSpecs.push_back(spec);
        }
    }

    // Give a chance to be interrupted *before* we drop all indexes.
    opCtx->checkForInterrupt();

    {
        // note that the drop indexes call also invalidates all clientcursors for the namespace,
        // which is important and wanted here
        WriteUnitOfWork wunit(opCtx);
        log() << "compact dropping indexes";
        indexCatalog->dropAllIndexes(opCtx, true);
        wunit.commit();
    }

    CompactStats stats;

    MultiIndexBlockImpl indexer(opCtx, collection);
    indexer.allowInterruption();
    indexer.ignoreUniqueConstraint();  // in compact we should be doing no checking

    Status status = indexer.init(indexSpecs).getStatus();
    if (!status.isOK())
        return StatusWith<CompactStats>(status);

    status = recordStore->compact(opCtx);
    if (!status.isOK())
        return StatusWith<CompactStats>(status);

    log() << "starting index commits";
    status = indexer.dumpInsertsFromBulk();
    if (!status.isOK())
//.........这里部分代码省略.........

StatusWith<CompactStats> Collection::compact(OperationContext* txn,
                                             const CompactOptions* compactOptions) {
    dassert(txn->lockState()->isCollectionLockedForMode(ns().toString(), MODE_X));

    DisableDocumentValidation validationDisabler(txn);

    if (!_recordStore->compactSupported())
        return StatusWith<CompactStats>(ErrorCodes::CommandNotSupported,
                                        str::stream()
                                            << "cannot compact collection with record store: "
                                            << _recordStore->name());

    if (_recordStore->compactsInPlace()) {
        CompactStats stats;
        Status status = _recordStore->compact(txn, NULL, compactOptions, &stats);
        if (!status.isOK())
            return StatusWith<CompactStats>(status);

        // Compact all indexes (not including unfinished indexes)
        IndexCatalog::IndexIterator ii(_indexCatalog.getIndexIterator(txn, false));
        while (ii.more()) {
            IndexDescriptor* descriptor = ii.next();
            IndexAccessMethod* index = _indexCatalog.getIndex(descriptor);

            LOG(1) << "compacting index: " << descriptor->toString();
            Status status = index->compact(txn);
            if (!status.isOK()) {
                error() << "failed to compact index: " << descriptor->toString();
                return status;
            }
        }

        return StatusWith<CompactStats>(stats);
    }

    if (_indexCatalog.numIndexesInProgress(txn))
        return StatusWith<CompactStats>(ErrorCodes::BadValue,
                                        "cannot compact when indexes in progress");

    vector<BSONObj> indexSpecs;
    {
        IndexCatalog::IndexIterator ii(_indexCatalog.getIndexIterator(txn, false));
        while (ii.more()) {
            IndexDescriptor* descriptor = ii.next();

            const BSONObj spec = _compactAdjustIndexSpec(descriptor->infoObj());
            const BSONObj key = spec.getObjectField("key");
            const Status keyStatus = validateKeyPattern(key);
            if (!keyStatus.isOK()) {
                return StatusWith<CompactStats>(
                    ErrorCodes::CannotCreateIndex,
                    str::stream() << "Cannot compact collection due to invalid index " << spec
                                  << ": "
                                  << keyStatus.reason()
                                  << " For more info see"
                                  << " http://dochub.mongodb.org/core/index-validation");
            }
            indexSpecs.push_back(spec);
        }
    }

    // Give a chance to be interrupted *before* we drop all indexes.
    txn->checkForInterrupt();

    {
        // note that the drop indexes call also invalidates all clientcursors for the namespace,
        // which is important and wanted here
        WriteUnitOfWork wunit(txn);
        log() << "compact dropping indexes";
        Status status = _indexCatalog.dropAllIndexes(txn, true);
        if (!status.isOK()) {
            return StatusWith<CompactStats>(status);
        }
        wunit.commit();
    }

    CompactStats stats;

    MultiIndexBlock indexer(txn, this);
    indexer.allowInterruption();
    indexer.ignoreUniqueConstraint();  // in compact we should be doing no checking

    Status status = indexer.init(indexSpecs);
    if (!status.isOK())
        return StatusWith<CompactStats>(status);

    MyCompactAdaptor adaptor(this, &indexer);

    status = _recordStore->compact(txn, &adaptor, compactOptions, &stats);
    if (!status.isOK())
        return StatusWith<CompactStats>(status);

    log() << "starting index commits";
    status = indexer.doneInserting();
    if (!status.isOK())
        return StatusWith<CompactStats>(status);

    {
        WriteUnitOfWork wunit(txn);
        indexer.commit();
//.........这里部分代码省略.........

    StatusWith<DiskLoc> Collection::updateDocument( const DiskLoc& oldLocation,
                                                    const BSONObj& objNew,
                                                    bool enforceQuota,
                                                    OpDebug* debug ) {

        Record* oldRecord = getExtentManager()->recordFor( oldLocation );
        BSONObj objOld = BSONObj::make( oldRecord );

        if ( objOld.hasElement( "_id" ) ) {
            BSONElement oldId = objOld["_id"];
            BSONElement newId = objNew["_id"];
            if ( oldId != newId )
                return StatusWith<DiskLoc>( ErrorCodes::InternalError,
                                            "in Collection::updateDocument _id mismatch",
                                            13596 );
        }

        if ( ns().coll() == "system.users" ) {
            // XXX - andy and spencer think this should go away now
            V2UserDocumentParser parser;
            Status s = parser.checkValidUserDocument(objNew);
            if ( !s.isOK() )
                return StatusWith<DiskLoc>( s );
        }

        /* duplicate key check. we descend the btree twice - once for this check, and once for the actual inserts, further
           below.  that is suboptimal, but it's pretty complicated to do it the other way without rollbacks...
        */
        OwnedPointerVector<UpdateTicket> updateTickets;
        updateTickets.mutableVector().resize(_indexCatalog.numIndexesTotal());
        for (int i = 0; i < _indexCatalog.numIndexesTotal(); ++i) {
            IndexDescriptor* descriptor = _indexCatalog.getDescriptor( i );
            IndexAccessMethod* iam = _indexCatalog.getIndex( descriptor );

            InsertDeleteOptions options;
            options.logIfError = false;
            options.dupsAllowed =
                !(KeyPattern::isIdKeyPattern(descriptor->keyPattern()) || descriptor->unique())
                || ignoreUniqueIndex(descriptor);
            updateTickets.mutableVector()[i] = new UpdateTicket();
            Status ret = iam->validateUpdate(objOld, objNew, oldLocation, options,
                                             updateTickets.mutableVector()[i]);
            if ( !ret.isOK() ) {
                return StatusWith<DiskLoc>( ret );
            }
        }

        if ( oldRecord->netLength() < objNew.objsize() ) {
            // doesn't fit, have to move to new location

            if ( _details->isCapped() )
                return StatusWith<DiskLoc>( ErrorCodes::InternalError,
                                            "failing update: objects in a capped ns cannot grow",
                                            10003 );

            moveCounter.increment();
            _details->paddingTooSmall();

            // unindex old record, don't delete
            // this way, if inserting new doc fails, we can re-index this one
            ClientCursor::aboutToDelete(_ns.ns(), _details, oldLocation);
            _indexCatalog.unindexRecord( objOld, oldLocation, true );

            if ( debug ) {
                if (debug->nmoved == -1) // default of -1 rather than 0
                    debug->nmoved = 1;
                else
                    debug->nmoved += 1;
            }

            StatusWith<DiskLoc> loc = insertDocument( objNew, enforceQuota );

            if ( loc.isOK() ) {
                // insert successful, now lets deallocate the old location
                // remember its already unindexed
                _recordStore.deallocRecord( oldLocation, oldRecord );
            }
            else {
                // new doc insert failed, so lets re-index the old document and location
                _indexCatalog.indexRecord( objOld, oldLocation );
            }

            return loc;
        }

        _infoCache.notifyOfWriteOp();
        _details->paddingFits();

        if ( debug )
            debug->keyUpdates = 0;

        for (int i = 0; i < _indexCatalog.numIndexesTotal(); ++i) {
            IndexDescriptor* descriptor = _indexCatalog.getDescriptor( i );
            IndexAccessMethod* iam = _indexCatalog.getIndex( descriptor );

            int64_t updatedKeys;
            Status ret = iam->update(*updateTickets.vector()[i], &updatedKeys);
            if ( !ret.isOK() )
                return StatusWith<DiskLoc>( ret );
            if ( debug )
//.........这里部分代码省略.........

    StatusWith<RecordId> Collection::updateDocument( OperationContext* txn,
                                                    const RecordId& oldLocation,
                                                    const BSONObj& objNew,
                                                    bool enforceQuota,
                                                    OpDebug* debug ) {

        BSONObj objOld = _recordStore->dataFor( txn, oldLocation ).releaseToBson();

        if ( objOld.hasElement( "_id" ) ) {
            BSONElement oldId = objOld["_id"];
            BSONElement newId = objNew["_id"];
            if ( oldId != newId )
                return StatusWith<RecordId>( ErrorCodes::InternalError,
                                            "in Collection::updateDocument _id mismatch",
                                            13596 );
        }

        /* duplicate key check. we descend the btree twice - once for this check, and once for the actual inserts, further
           below.  that is suboptimal, but it's pretty complicated to do it the other way without rollbacks...
        */

        // At the end of this step, we will have a map of UpdateTickets, one per index, which
        // represent the index updates needed to be done, based on the changes between objOld and
        // objNew.
        OwnedPointerMap<IndexDescriptor*,UpdateTicket> updateTickets;
        IndexCatalog::IndexIterator ii = _indexCatalog.getIndexIterator( txn, true );
        while ( ii.more() ) {
            IndexDescriptor* descriptor = ii.next();
            IndexAccessMethod* iam = _indexCatalog.getIndex( descriptor );

            InsertDeleteOptions options;
            options.logIfError = false;
            options.dupsAllowed =
                !(KeyPattern::isIdKeyPattern(descriptor->keyPattern()) || descriptor->unique())
                || repl::getGlobalReplicationCoordinator()->shouldIgnoreUniqueIndex(descriptor);
            UpdateTicket* updateTicket = new UpdateTicket();
            updateTickets.mutableMap()[descriptor] = updateTicket;
            Status ret = iam->validateUpdate(txn, objOld, objNew, oldLocation, options, updateTicket );
            if ( !ret.isOK() ) {
                return StatusWith<RecordId>( ret );
            }
        }

        // This can call back into Collection::recordStoreGoingToMove.  If that happens, the old
        // object is removed from all indexes.
        StatusWith<RecordId> newLocation = _recordStore->updateRecord( txn,
                                                                      oldLocation,
                                                                      objNew.objdata(),
                                                                      objNew.objsize(),
                                                                      _enforceQuota( enforceQuota ),
                                                                      this );

        if ( !newLocation.isOK() ) {
            return newLocation;
        }

        // At this point, the old object may or may not still be indexed, depending on if it was
        // moved.

        _infoCache.notifyOfWriteOp();

        // If the object did move, we need to add the new location to all indexes.
        if ( newLocation.getValue() != oldLocation ) {

            if ( debug ) {
                if (debug->nmoved == -1) // default of -1 rather than 0
                    debug->nmoved = 1;
                else
                    debug->nmoved += 1;
            }

            Status s = _indexCatalog.indexRecord(txn, objNew, newLocation.getValue());
            if (!s.isOK())
                return StatusWith<RecordId>(s);

            return newLocation;
        }

        // Object did not move.  We update each index with each respective UpdateTicket.

        if ( debug )
            debug->keyUpdates = 0;

        ii = _indexCatalog.getIndexIterator( txn, true );
        while ( ii.more() ) {
            IndexDescriptor* descriptor = ii.next();
            IndexAccessMethod* iam = _indexCatalog.getIndex( descriptor );

            int64_t updatedKeys;
            Status ret = iam->update(txn, *updateTickets.mutableMap()[descriptor], &updatedKeys);
            if ( !ret.isOK() )
                return StatusWith<RecordId>( ret );
            if ( debug )
                debug->keyUpdates += updatedKeys;
        }

        // Broadcast the mutation so that query results stay correct.
        _cursorCache.invalidateDocument(txn, oldLocation, INVALIDATION_MUTATION);

        return newLocation;
//.........这里部分代码省略.........