001 /*
002 * Java Genetic Algorithm Library (jenetics-7.2.0).
003 * Copyright (c) 2007-2023 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 import java.util.function.Function;
029
030 import io.jenetics.ext.util.Tree;
031
032 import io.jenetics.prog.op.Op;
033
034 /**
035 * This class holds the actual sample values which are used for the symbolic
036 * regression example. This class is <em>thread-safe</em> and can be used in a
037 * <em>producer-consumer</em> setup. You can add single sample values
038 * ({@link #add(Sample)}) or a list ({@link #addAll(Collection)}) of new values.
039 * These values will be made available for evaluation after an explicit call of
040 * the {@link #publish()} method.
041 *
042 * @implNote
043 * This class is thread-safe.
044 *
045 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
046 * @version 6.0
047 * @since 6.0
048 */
049 public final class SampleBuffer<T> implements Sampling<T> {
050
051 private final RingBuffer _buffer;
052
053 private volatile SampleList<T> _snapshot = null;
054
055 public SampleBuffer(final int capacity) {
056 _buffer = new RingBuffer(capacity);
057 }
058
059 /**
060 * Adding a new sample point to the buffer. <em>You need to explicitly
061 * call {@link #publish()} to make it available for the {@link #eval(Tree)}
062 * method.</em>
063 *
064 * @param sample the sample point to add
065 * @throws NullPointerException if the given {@code sample} point is
066 * {@code null}
067 */
068 public void add(final Sample<T> sample) {
069 _buffer.add(requireNonNull(sample));
070 }
071
072 /**
073 * The given sample points to the buffer. <em>You need to explicitly
074 * call {@link #publish()} to make it available for the {@link #eval(Tree)}
075 * method.</em>
076 *
077 * @param samples the samples to add to the buffer
078 * @throws NullPointerException if the given {@code samples} is {@code null}
079 */
080 public void addAll(final Collection<? extends Sample<? extends T>> samples) {
081 samples.forEach(Objects::requireNonNull);
082 _buffer.addAll(samples);
083 }
084
085 /**
086 * Making the current sample points available for the {@link #eval(Tree)}
087 * function.
088 *
089 * @return the number of <em>published</em> sample points
090 */
091 @SuppressWarnings({"unchecked", "rawtypes"})
092 public int publish() {
093 final Object[] values = _buffer.snapshot();
094
095 SampleList<T> snapshot = null;
096 if (values != null && values.length > 0) {
097 final List samples = Arrays.asList(values);
098 snapshot = new SampleList(samples);
099 }
100
101 try {
102 return snapshot != null ? snapshot.size() : 0;
103 } finally {
104 _snapshot = snapshot;
105 }
106 }
107
108 /**
109 * Return the currently <em>published</em> sample points.
110 *
111 * @see #publish()
112 *
113 * @return the currently <em>published</em> sample points
114 */
115 List<Sample<T>> samples() {
116 final SampleList<T> snapshot = _snapshot;
117 return snapshot != null ? snapshot : List.of();
118 }
119
120 @Override
121 public Result<T> eval(final Tree<? extends Op<T>, ?> program) {
122 requireNonNull(program);
123
124 final SampleList<T> snapshot = _snapshot;
125 return snapshot != null && !snapshot.isEmpty()
126 ? snapshot.eval(program)
127 : null;
128 }
129
130 @Override
131 public Result<T> eval(final Function<? super T[], ? extends T> function) {
132 requireNonNull(function);
133
134 final SampleList<T> snapshot = _snapshot;
135 return snapshot != null && !snapshot.isEmpty()
136 ? snapshot.eval(function)
137 : null;
138 }
139
140 }
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