001 /*
002 * Java Genetic Algorithm Library (jenetics-8.0.0).
003 * Copyright (c) 2007-2024 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.util;
021
022 import static java.util.Objects.requireNonNull;
023
024 import java.io.Serial;
025 import java.io.Serializable;
026 import java.time.Clock;
027 import java.time.Instant;
028 import java.time.ZoneId;
029 import java.time.ZoneOffset;
030
031 /**
032 * Clock implementation with <i>nano</i> second precision.
033 *
034 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
035 * @since 3.1
036 * @version 3.1
037 */
038 public final class NanoClock extends Clock implements Serializable {
039
040 @Serial
041 private static final long serialVersionUID = 1L;
042
043 private static final long EPOCH_NANOS = System.currentTimeMillis()*1_000_000;
044 private static final long NANO_START = System.nanoTime();
045 private static final long OFFSET_NANOS = EPOCH_NANOS - NANO_START;
046
047 private static final NanoClock UTC_INSTANCE = new NanoClock(ZoneOffset.UTC);
048
049 private static final NanoClock DEFAULT_INSTANCE =
050 new NanoClock(ZoneId.systemDefault());
051
052 /**
053 * These constants hold the number of nanoseconds of one second.
054 */
055 public static final long NANOS_PER_SECOND = 1_000_000_000;
056
057 private final ZoneId _zone;
058
059 private NanoClock(final ZoneId zone) {
060 _zone = requireNonNull(zone, "zone");
061 }
062
063 @Override
064 public ZoneId getZone() {
065 return _zone;
066 }
067
068 @Override
069 public NanoClock withZone(final ZoneId zone) {
070 return zone.equals(_zone) ? this : new NanoClock(zone);
071 }
072
073 @Override
074 public long millis() {
075 return System.currentTimeMillis();
076 }
077
078 /**
079 * This returns the nanosecond-based instant, measured from
080 * 1970-01-01T00:00Z (UTC). This method will return valid values till the
081 * year 2262.
082 *
083 * @return the nanosecond-based instant, measured from 1970-01-01T00:00Z (UTC)
084 */
085 public long nanos() {
086 return System.nanoTime() + OFFSET_NANOS;
087 }
088
089 @Override
090 public Instant instant() {
091 final long now = nanos();
092 return Instant.ofEpochSecond(now/NANOS_PER_SECOND, now%NANOS_PER_SECOND);
093 }
094
095 @Override
096 public int hashCode() {
097 return _zone.hashCode() + 11;
098 }
099
100 @Override
101 public boolean equals(final Object obj) {
102 return obj == this ||
103 obj instanceof NanoClock other &&
104 other._zone.equals(_zone);
105 }
106
107 @Override
108 public String toString() {
109 return "NanoClock[" + _zone + "]";
110 }
111
112 /**
113 * This clock is based on the <i>nano</i> system clock. It uses
114 * {@link System#nanoTime()} resolution
115 * <p>
116 * Conversion from instant to date or time uses the specified time-zone.
117 * <p>
118 * The returned implementation is immutable, thread-safe and
119 * {@code Serializable}.
120 *
121 * @param zone the time-zone to use to convert the instant to date-time
122 * @return a clock that uses the best available system clock in the
123 * specified zone
124 * @throws java.lang.NullPointerException if the given {@code zone} is
125 * {@code null}
126 */
127 public static NanoClock system(final ZoneId zone) {
128 return new NanoClock(zone);
129 }
130
131 /**
132 * This clock is based on the <i>nano</i> system clock. It uses
133 * {@link System#nanoTime()} resolution
134 * <p>
135 * Conversion from instant to date or time uses the specified time-zone.
136 * <p>
137 * The returned implementation is immutable, thread-safe and
138 * {@code Serializable}.
139 *
140 * @return a clock that uses the best available system clock in the
141 * UTC zone
142 * @throws java.lang.NullPointerException if the given {@code zone} is
143 * {@code null}
144 */
145 public static NanoClock systemUTC() {
146 return UTC_INSTANCE;
147 }
148
149 /**
150 * This clock is based on the <i>nano</i> system clock. It uses
151 * {@link System#nanoTime()} resolution
152 * <p>
153 * Conversion from instant to date or time uses the specified time-zone.
154 * <p>
155 * The returned implementation is immutable, thread-safe and
156 * {@code Serializable}.
157 *
158 * @return a clock that uses the best available system clock in the
159 * default zone
160 * @throws java.lang.NullPointerException if the given {@code zone} is
161 * {@code null}
162 */
163 public static NanoClock systemDefaultZone() {
164 return DEFAULT_INSTANCE;
165 }
166
167 }
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