| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.rya.streams.api.queries; |
| |
| import static java.util.Objects.requireNonNull; |
| |
| import java.util.ArrayList; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.concurrent.locks.ReentrantLock; |
| |
| import com.google.common.collect.Lists; |
| |
| import edu.umd.cs.findbugs.annotations.DefaultAnnotation; |
| import edu.umd.cs.findbugs.annotations.NonNull; |
| import info.aduna.iteration.CloseableIteration; |
| |
| /** |
| * An in memory implementation of {@link QueryChangeLog}. Anything that is stored in this change log will be |
| * lost when it is cleaned up, so it is not appropriate for production environments. |
| * </p> |
| * Thread safe. |
| */ |
| @DefaultAnnotation(NonNull.class) |
| public class InMemoryQueryChangeLog implements QueryChangeLog { |
| |
| private final ReentrantLock lock = new ReentrantLock(); |
| private final List<ChangeLogEntry<QueryChange>> entries = new ArrayList<>(); |
| |
| @Override |
| public void write(final QueryChange newChange) throws QueryChangeLogException { |
| requireNonNull(newChange); |
| |
| lock.lock(); |
| try { |
| final int position = entries.size(); |
| entries.add( new ChangeLogEntry<>(position, newChange) ); |
| } finally { |
| lock.unlock(); |
| } |
| } |
| |
| @Override |
| public CloseableIteration<ChangeLogEntry<QueryChange>, QueryChangeLogException> readFromStart() throws QueryChangeLogException { |
| return readFromPosition(0); |
| } |
| |
| @Override |
| public CloseableIteration<ChangeLogEntry<QueryChange>, QueryChangeLogException> readFromPosition(final long position) throws QueryChangeLogException { |
| lock.lock(); |
| try { |
| return new ListIteration<>(entries.subList((int) position, entries.size())); |
| } finally { |
| lock.unlock(); |
| } |
| } |
| |
| @Override |
| public void close() throws Exception { |
| // Nothing to do here. |
| } |
| |
| /** |
| * A {@link CloseableIteration} that iterates over a list. |
| * |
| * @param <T> - The type of object iterated over. |
| * @param <E> - The type of exception that may be thrown. |
| */ |
| @DefaultAnnotation(NonNull.class) |
| private static class ListIteration <T, E extends Exception> implements CloseableIteration<T, E> { |
| |
| private final Iterator<T> it; |
| |
| public ListIteration(final List<T> list) { |
| it = Lists.newArrayList( list ).iterator(); |
| } |
| |
| @Override |
| public boolean hasNext() throws E { |
| return it.hasNext(); |
| } |
| |
| @Override |
| public T next() throws E { |
| return it.next(); |
| } |
| |
| @Override |
| public void remove() throws E { } |
| |
| @Override |
| public void close() throws E { } |
| } |
| } |