private Iterator joinTxRecords()

in hugegraph-core/src/main/java/org/apache/hugegraph/backend/tx/GraphTransaction.java [1841:1888]
38 lines of code
12 McCabe index (conditional complexity)

    private <V extends HugeElement> Iterator<V> joinTxRecords(
                                    Query query,
                                    Iterator<V> records,
                                    BiFunction<Query, V, V> matchFunc,
                                    Map<Id, V> addedTxRecords,
                                    Map<Id, V> removedTxRecords,
                                    Map<Id, V> updatedTxRecords) {
        this.checkOwnerThread();
        // Return the origin results if there is no change in tx
        if (addedTxRecords.isEmpty() &&
            removedTxRecords.isEmpty() &&
            updatedTxRecords.isEmpty()) {
            return records;
        }

        Set<V> txResults = InsertionOrderUtil.newSet();

        /*
         * Collect added/updated records
         * Records in memory have higher priority than query from backend store
         */
        for (V elem : addedTxRecords.values()) {
            if (query.reachLimit(txResults.size())) {
                break;
            }
            if ((elem = matchFunc.apply(query, elem)) != null) {
                txResults.add(elem);
            }
        }
        for (V elem : updatedTxRecords.values()) {
            if (query.reachLimit(txResults.size())) {
                break;
            }
            if ((elem = matchFunc.apply(query, elem)) != null) {
                txResults.add(elem);
            }
        }

        // Filter backend record if it's updated in memory
        Iterator<V> backendResults = new FilterIterator<>(records, elem -> {
            Id id = elem.id();
            return !addedTxRecords.containsKey(id) &&
                   !updatedTxRecords.containsKey(id) &&
                   !removedTxRecords.containsKey(id);
        });

        return new ExtendableIterator<V>(txResults.iterator(), backendResults);
    }