C++ BSONObjSet::clear方法代码示例

    /** add index keys for a newly inserted record 
        done in two steps/phases to allow potential deferal of write lock portion in the future
    */
    void indexRecordUsingTwoSteps(const char *ns, NamespaceDetails *d, BSONObj obj,
                                         DiskLoc loc, bool shouldBeUnlocked) {
        vector<int> multi;
        vector<BSONObjSet> multiKeys;

        IndexInterface::IndexInserter inserter;

        // Step 1, read phase.
        int n = d->nIndexesBeingBuilt();
        {
            BSONObjSet keys;
            for ( int i = 0; i < n; i++ ) {
                // this call throws on unique constraint violation.  we haven't done any writes yet so that is fine.
                fetchIndexInserters(/*out*/keys, inserter, d, i, obj, loc);
                if( keys.size() > 1 ) {
                    multi.push_back(i);
                    multiKeys.push_back(BSONObjSet());
                    multiKeys[multiKeys.size()-1].swap(keys);
                }
                keys.clear();
            }
        }

        inserter.finishAllInsertions();  // Step 2, write phase.

        // now finish adding multikeys
        for( unsigned j = 0; j < multi.size(); j++ ) {
            unsigned i = multi[j];
            BSONObjSet& keys = multiKeys[j];
            IndexDetails& idx = d->idx(i);
            IndexInterface& ii = idx.idxInterface();
            Ordering ordering = Ordering::make(idx.keyPattern());
            d->setIndexIsMultikey(ns, i);
            for( BSONObjSet::iterator k = ++keys.begin()/*skip 1*/; k != keys.end(); k++ ) {
                try {
                    ii.bt_insert(idx.head, loc, *k, ordering, !idx.unique(), idx);
                } catch (AssertionException& e) {
                    if( e.getCode() == 10287 && (int) i == d->nIndexes ) {
                        DEV log() << "info: caught key already in index on bg indexing (ok)" << endl;
                    }
                    else {
                        /* roll back previously added index entries
                           note must do self index as it is multikey and could require some cleanup itself
                        */
                        for( int j = 0; j < n; j++ ) {
                            try {
                                _unindexRecord(d->idx(j), obj, loc, false);
                            }
                            catch(...) {
                                log(3) << "unindex fails on rollback after unique key constraint prevented insert\n";
                            }
                        }
                        throw;
                    }
                }
            }
        }
    }

    // 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);
        }
    }

    void prefetchIndexPages(NamespaceDetails *nsd, const BSONObj& obj) {
        DiskLoc unusedDl; // unused
        IndexInterface::IndexInserter inserter;
        BSONObjSet unusedKeys;
        ReplSetImpl::IndexPrefetchConfig prefetchConfig = theReplSet->getIndexPrefetchConfig();

        // 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 ReplSetImpl::PREFETCH_NONE:
            return;
        case 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?
            int indexNo = nsd->findIdIndex();
            if (indexNo == -1) return;
            try {
                fetchIndexInserters(/*out*/unusedKeys, 
                                    inserter, 
                                    nsd, 
                                    indexNo, 
                                    obj, 
                                    unusedDl, 
                                    /*allowDups*/true);
            }
            catch (const DBException& e) {
                LOG(2) << "ignoring exception in prefetchIndexPages(): " << e.what() << endl;
            }
            break;
        }
        case ReplSetImpl::PREFETCH_ALL:
        {
            // indexCount includes all indexes, including ones
            // in the process of being built
            int indexCount = nsd->getTotalIndexCount();
            for ( int indexNo = 0; indexNo < indexCount; indexNo++ ) {
                TimerHolder timer( &prefetchIndexStats);
                // This will page in all index pages for the given object.
                try {
                    fetchIndexInserters(/*out*/unusedKeys, 
                                        inserter, 
                                        nsd, 
                                        indexNo, 
                                        obj, 
                                        unusedDl, 
                                        /*allowDups*/true);
                }
                catch (const DBException& e) {
                    LOG(2) << "ignoring exception in prefetchIndexPages(): " << e.what() << endl;
                }
                unusedKeys.clear();
            }
            break;
        }
        default:
            fassertFailed(16427);
        }
    }