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community/kernel/src/main/java/org/neo4j/kernel/impl/store/Scanner.java
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| /* | ||
| * Copyright (c) 2002-2016 "Neo Technology," | ||
| * Network Engine for Objects in Lund AB [http://neotechnology.com] | ||
| * | ||
| * This file is part of Neo4j. | ||
| * | ||
| * Neo4j is free software: you can redistribute it and/or modify | ||
| * it under the terms of the GNU General Public License as published by | ||
| * the Free Software Foundation, either version 3 of the License, or | ||
| * (at your option) any later version. | ||
| * | ||
| * This program is distributed in the hope that it will be useful, | ||
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| * GNU General Public License for more details. | ||
| * | ||
| * You should have received a copy of the GNU General Public License | ||
| * along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
| */ | ||
| package org.neo4j.kernel.impl.store; | ||
|
|
||
| import java.util.function.Predicate; | ||
|
|
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| import org.neo4j.collection.primitive.PrimitiveLongIterator; | ||
| import org.neo4j.graphdb.ResourceIterable; | ||
| import org.neo4j.graphdb.ResourceIterator; | ||
| import org.neo4j.helpers.collection.PrefetchingResourceIterator; | ||
| import org.neo4j.kernel.impl.store.record.AbstractBaseRecord; | ||
| import org.neo4j.kernel.impl.store.record.RecordLoad; | ||
|
|
||
| /** | ||
| * Scans all used records in a store, returned {@link ResourceIterable} must be properly used such that | ||
| * its {@link ResourceIterable#iterator() resource iterators} are {@link ResourceIterator#close() closed} | ||
| * after use. | ||
| */ | ||
| public class Scanner | ||
| { | ||
| @SafeVarargs | ||
| public static <R extends AbstractBaseRecord> ResourceIterable<R> scan( final RecordStore<R> store, | ||
| final Predicate<? super R>... filters ) | ||
| { | ||
| return scan( store, true, filters ); | ||
| } | ||
|
|
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| @SafeVarargs | ||
| public static <R extends AbstractBaseRecord> ResourceIterable<R> scan( final RecordStore<R> store, | ||
| final boolean forward, final Predicate<? super R>... filters ) | ||
| { | ||
| return () -> new Scan<>( store, forward, filters ); | ||
| } | ||
|
|
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| private static class Scan<R extends AbstractBaseRecord> extends PrefetchingResourceIterator<R> | ||
| { | ||
| private final PrimitiveLongIterator ids; | ||
| private final RecordCursor<R> cursor; | ||
| private final Predicate<? super R>[] filters; | ||
|
|
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| public Scan( RecordStore<R> store, boolean forward, final Predicate<? super R>... filters ) | ||
| { | ||
| this.filters = filters; | ||
| this.ids = new StoreIdIterator( store, forward ); | ||
| this.cursor = store.newRecordCursor( store.newRecord() ); | ||
| store.placeRecordCursor( 0, cursor, RecordLoad.CHECK ); | ||
| } | ||
|
|
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| @Override | ||
| protected R fetchNextOrNull() | ||
| { | ||
| while ( ids.hasNext() ) | ||
| { | ||
| if ( cursor.next( ids.next() ) ) | ||
| { | ||
| R record = cursor.get(); | ||
| if ( passesFilters( record ) ) | ||
| { | ||
| return record; | ||
| } | ||
| } | ||
| } | ||
| return null; | ||
| } | ||
|
|
||
| private boolean passesFilters( R record ) | ||
| { | ||
| for ( Predicate<? super R> filter : filters ) | ||
| { | ||
| if ( !filter.test( record ) ) | ||
| { | ||
| return false; | ||
| } | ||
| } | ||
| return true; | ||
| } | ||
|
|
||
| @Override | ||
| public void close() | ||
| { | ||
| cursor.close(); | ||
| } | ||
| } | ||
| } |