001 /*
002 * Java Genetic Algorithm Library (jenetics-7.1.0).
003 * Copyright (c) 2007-2022 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.lang.reflect.Array;
025 import java.util.Arrays;
026 import java.util.Collection;
027 import java.util.List;
028 import java.util.Objects;
029 import java.util.function.Function;
030 import java.util.stream.Stream;
031
032 import io.jenetics.ext.util.Tree;
033
034 import io.jenetics.prog.op.Op;
035
036 /**
037 * This class holds the actual sample values which are used for the symbolic
038 * regression example. This class is <em>thread-safe</em> and can be used in a
039 * <em>producer-consumer</em> setup. You can add single sample values
040 * ({@link #add(Sample)}) or a list ({@link #addAll(Collection)}) of new values.
041 * These values will be made available for evaluation after an explicit call of
042 * the {@link #publish()} method.
043 *
044 * @implNote
045 * This class is thread-safe.
046 *
047 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
048 * @version 6.0
049 * @since 6.0
050 */
051 public final class SampleBuffer<T> implements Sampling<T> {
052
053 private final RingBuffer _buffer;
054
055 private volatile SampleList<T> _snapshot = null;
056
057 public SampleBuffer(final int capacity) {
058 _buffer = new RingBuffer(capacity);
059 }
060
061 /**
062 * Adding a new sample point to the buffer. <em>You need to explicitly
063 * call {@link #publish()} to make it available for the {@link #eval(Tree)}
064 * method.</em>
065 *
066 * @param sample the sample point to add
067 * @throws NullPointerException if the given {@code sample} point is
068 * {@code null}
069 */
070 public void add(final Sample<T> sample) {
071 _buffer.add(requireNonNull(sample));
072 }
073
074 /**
075 * The the given sample points to the buffer. <em>You need to explicitly
076 * call {@link #publish()} to make it available for the {@link #eval(Tree)}
077 * method.</em>
078 *
079 * @param samples the samples to add to the buffer
080 * @throws NullPointerException if the given {@code samples} is {@code null}
081 */
082 public void addAll(final Collection<? extends Sample<T>> samples) {
083 samples.forEach(Objects::requireNonNull);
084 _buffer.addAll(samples);
085 }
086
087 /**
088 * Making the current sample points available for the {@link #eval(Tree)}
089 * function.
090 *
091 * @return the number of <em>published</em> sample points
092 */
093 @SuppressWarnings({"unchecked", "rawtypes"})
094 public int publish() {
095 final Object[] values = _buffer.snapshot();
096
097 SampleList<T> snapshot = null;
098 if (values != null && values.length > 0) {
099 final List samples = Arrays.asList(values);
100 snapshot = new SampleList(samples);
101 }
102
103 try {
104 return snapshot != null ? snapshot.size() : 0;
105 } finally {
106 _snapshot = snapshot;
107 }
108 }
109
110 /**
111 * Return the currently <em>published</em> sample points.
112 *
113 * @see #publish()
114 *
115 * @return the currently <em>published</em> sample points
116 */
117 List<Sample<T>> samples() {
118 final SampleList<T> snapshot = _snapshot;
119 return snapshot != null ? snapshot : List.of();
120 }
121
122 @Override
123 public Result<T> eval(final Tree<? extends Op<T>, ?> program) {
124 requireNonNull(program);
125
126 final SampleList<T> snapshot = _snapshot;
127 return snapshot != null && !snapshot.isEmpty()
128 ? snapshot.eval(program)
129 : null;
130 }
131
132 @Override
133 public Result<T> eval(final Function<? super T[], ? extends T> function) {
134 requireNonNull(function);
135
136 final SampleList<T> snapshot = _snapshot;
137 return snapshot != null && !snapshot.isEmpty()
138 ? snapshot.eval(function)
139 : null;
140 }
141
142 }
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