Examples with PrefetchingIterator org.neo4j.helpers.collection.PrefetchingIterator used on opensource projects

Example 11 with PrefetchingIterator

use of org.neo4j.helpers.collection.PrefetchingIterator in project neo4j-mobile-android by neo4j-contrib.

the class LegacyRelationshipStoreReader method readRelationshipStore.

public Iterable<RelationshipRecord> readRelationshipStore() throws IOException {
    final ByteBuffer buffer = ByteBuffer.allocateDirect(RECORD_LENGTH);
    return new Iterable<RelationshipRecord>() {

        @Override
        public Iterator<RelationshipRecord> iterator() {
            return new PrefetchingIterator<RelationshipRecord>() {

                long id = 0;

                @Override
                protected RelationshipRecord fetchNextOrNull() {
                    RelationshipRecord record = null;
                    while (record == null && id <= maxId) {
                        buffer.clear();
                        try {
                            fileChannel.read(buffer);
                        } catch (IOException e) {
                            throw new RuntimeException(e);
                        }
                        buffer.flip();
                        long inUseByte = buffer.get();
                        boolean inUse = (inUseByte & 0x1) == Record.IN_USE.intValue();
                        if (inUse) {
                            long firstNode = LegacyStore.getUnsignedInt(buffer);
                            long firstNodeMod = (inUseByte & 0xEL) << 31;
                            long secondNode = LegacyStore.getUnsignedInt(buffer);
                            // [ xxx,    ][    ,    ][    ,    ][    ,    ] second node high order bits,     0x70000000
                            // [    ,xxx ][    ,    ][    ,    ][    ,    ] first prev rel high order bits,  0xE000000
                            // [    ,   x][xx  ,    ][    ,    ][    ,    ] first next rel high order bits,  0x1C00000
                            // [    ,    ][  xx,x   ][    ,    ][    ,    ] second prev rel high order bits, 0x380000
                            // [    ,    ][    , xxx][    ,    ][    ,    ] second next rel high order bits, 0x70000
                            // [    ,    ][    ,    ][xxxx,xxxx][xxxx,xxxx] type
                            long typeInt = buffer.getInt();
                            long secondNodeMod = (typeInt & 0x70000000L) << 4;
                            int type = (int) (typeInt & 0xFFFF);
                            record = new RelationshipRecord(id, LegacyStore.longFromIntAndMod(firstNode, firstNodeMod), LegacyStore.longFromIntAndMod(secondNode, secondNodeMod), type);
                            record.setInUse(inUse);
                            long firstPrevRel = LegacyStore.getUnsignedInt(buffer);
                            long firstPrevRelMod = (typeInt & 0xE000000L) << 7;
                            record.setFirstPrevRel(LegacyStore.longFromIntAndMod(firstPrevRel, firstPrevRelMod));
                            long firstNextRel = LegacyStore.getUnsignedInt(buffer);
                            long firstNextRelMod = (typeInt & 0x1C00000L) << 10;
                            record.setFirstNextRel(LegacyStore.longFromIntAndMod(firstNextRel, firstNextRelMod));
                            long secondPrevRel = LegacyStore.getUnsignedInt(buffer);
                            long secondPrevRelMod = (typeInt & 0x380000L) << 13;
                            record.setSecondPrevRel(LegacyStore.longFromIntAndMod(secondPrevRel, secondPrevRelMod));
                            long secondNextRel = LegacyStore.getUnsignedInt(buffer);
                            long secondNextRelMod = (typeInt & 0x70000L) << 16;
                            record.setSecondNextRel(LegacyStore.longFromIntAndMod(secondNextRel, secondNextRelMod));
                            long nextProp = LegacyStore.getUnsignedInt(buffer);
                            long nextPropMod = (inUseByte & 0xF0L) << 28;
                            record.setNextProp(LegacyStore.longFromIntAndMod(nextProp, nextPropMod));
                        } else {
                            record = new RelationshipRecord(id, -1, -1, -1);
                            record.setInUse(false);
                        }
                        id++;
                    }
                    return record;
                }

                @Override
                public void remove() {
                    throw new UnsupportedOperationException();
                }
            };
        }
    };
}