001 /*
002 * Java Genetic Algorithm Library (jenetics-6.1.0).
003 * Copyright (c) 2007-2020 Franz Wilhelmstötter
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 *
017 * Author:
018 * Franz Wilhelmstötter (franz.wilhelmstoetter@gmail.com)
019 */
020 package io.jenetics.prog.regression;
021
022 import static java.util.Objects.requireNonNull;
023
024 import java.util.Arrays;
025 import java.util.Collection;
026 import java.util.List;
027 import java.util.Objects;
028
029 import io.jenetics.ext.util.Tree;
030
031 import io.jenetics.prog.op.Op;
032
033 /**
034 * This class holds the actual sample values which are used for the symbolic
035 * regression example. This class is <em>thread-safe</em> and can be used in a
036 * <em>producer-consumer</em> setup. You can add single sample values
037 * ({@link #add(Sample)}) or a list ({@link #addAll(Collection)}) of new values.
038 * These values will be made available for evaluation after an explicit call of
039 * the {@link #publish()} method.
040 *
041 * @implNote
042 * This class is thread-safe.
043 *
044 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
045 * @version 6.0
046 * @since 6.0
047 */
048 public final class SampleBuffer<T> implements Sampling<T> {
049
050 private final RingBuffer _buffer;
051
052 private volatile SampleList<T> _snapshot = null;
053
054 public SampleBuffer(final int size) {
055 _buffer = new RingBuffer(size);
056 }
057
058 /**
059 * Adding a new sample point to the buffer. <em>You need to explicitly
060 * call {@link #publish()} to make it available for the {@link #eval(Tree)}
061 * method.</em>
062 *
063 * @param sample the sample point to add
064 * @throws NullPointerException if the given {@code sample} point is
065 * {@code null}
066 */
067 public void add(final Sample<T> sample) {
068 _buffer.add(requireNonNull(sample));
069 }
070
071 /**
072 * The the given sample points to the buffer. <em>You need to explicitly
073 * call {@link #publish()} to make it available for the {@link #eval(Tree)}
074 * method.</em>
075 *
076 * @param samples the samples to add to the buffer
077 * @throws NullPointerException if the given {@code samples} is {@code null}
078 */
079 public void addAll(final Collection<? extends Sample<T>> samples) {
080 samples.forEach(Objects::requireNonNull);
081 _buffer.addAll(samples);
082 }
083
084 /**
085 * Making the current sample points available for the {@link #eval(Tree)}
086 * function.
087 *
088 * @return the number of <em>published</em> sample points
089 */
090 @SuppressWarnings({"unchecked", "rawtypes"})
091 public int publish() {
092 final Object[] values = _buffer.snapshot();
093
094 SampleList<T> snapshot = null;
095 if (values != null && values.length > 0) {
096 final List samples = Arrays.asList(values);
097 snapshot = new SampleList(samples);
098 }
099
100 try {
101 return snapshot != null ? snapshot.size() : 0;
102 } finally {
103 _snapshot = snapshot;
104 }
105 }
106
107 /**
108 * Return the currently <em>published</em> sample points.
109 *
110 * @see #publish()
111 *
112 * @return the currently <em>published</em> sample points
113 */
114 List<Sample<T>> samples() {
115 final SampleList<T> snapshot = _snapshot;
116 return snapshot != null ? snapshot : List.of();
117 }
118
119 @Override
120 public Result<T> eval(final Tree<? extends Op<T>, ?> program) {
121 requireNonNull(program);
122
123 final SampleList<T> snapshot = _snapshot;
124 return snapshot != null && !snapshot.isEmpty()
125 ? snapshot.eval(program)
126 : null;
127 }
128
129 }
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