Optimised Code and Fixed Tests (#314)
Co-authored-by: Keshavram Kuduwa <keshavram.kuduwa@apptware.com>
This commit is contained in:
Keshavram Kuduwa
GitHub
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commit
1a82c77026
19
prepare_kuduwa-keshavram.sh
Executable file
19
prepare_kuduwa-keshavram.sh
Executable file
@ -0,0 +1,19 @@
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#!/bin/sh
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#
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# Copyright 2023 The original authors
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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source "$HOME/.sdkman/bin/sdkman-init.sh"
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sdk use java 21.0.1-graal 1>&2
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@ -25,113 +25,141 @@ import java.nio.channels.FileChannel.MapMode;
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import java.nio.file.Files;
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import java.nio.file.Path;
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import java.nio.file.StandardOpenOption;
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import java.util.DoubleSummaryStatistics;
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import java.util.Iterator;
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import java.util.Arrays;
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import java.util.List;
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import java.util.Map;
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import java.util.Spliterator;
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import java.util.Spliterators;
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import java.util.Objects;
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import java.util.TreeMap;
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import java.util.function.Function;
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import java.util.stream.Collectors;
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import java.util.stream.IntStream;
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import java.util.stream.StreamSupport;
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public class CalculateAverage_kuduwa_keshavram {
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private static final String FILE = "./measurements.txt";
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private static final long LEFT_SHIFT_EIGHT = Long.MAX_VALUE / (1L << 8);
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private static final long LEFT_SHIFT_FOUR = Long.MAX_VALUE / (1L << 4);
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private static final long LEFT_SHIFT_TWO = Long.MAX_VALUE / (1L << 2);
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private static final long LEFT_SHIFT_ONE = Long.MAX_VALUE / (1L << 1);
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public static void main(String[] args) throws IOException, InterruptedException {
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Map<String, DoubleSummaryStatistics> resultMap = getFileSegments(new File(FILE)).stream()
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TreeMap<String, Measurement> resultMap = getFileSegments(new File(FILE)).stream()
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.parallel()
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.flatMap(
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.map(
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segment -> {
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final Measurement[][] measurements = new Measurement[1024 * 128][3];
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try (FileChannel fileChannel = (FileChannel) Files.newByteChannel(Path.of(FILE), StandardOpenOption.READ)) {
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MappedByteBuffer byteBuffer = fileChannel.map(
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MapMode.READ_ONLY, segment.start, segment.end - segment.start);
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byteBuffer.order(ByteOrder.nativeOrder());
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Iterator<Measurement> iterator = getMeasurementIterator(byteBuffer);
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return StreamSupport.stream(
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Spliterators.spliteratorUnknownSize(iterator, Spliterator.NONNULL), true);
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while (byteBuffer.hasRemaining()) {
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byte[] city = new byte[100];
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byte b;
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int hash = 0;
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int i = 0;
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while ((b = byteBuffer.get()) != 59) {
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hash = 31 * hash + b;
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city[i++] = b;
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}
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byte[] newCity = new byte[i];
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System.arraycopy(city, 0, newCity, 0, i);
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int measurement = 0;
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boolean negative = false;
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while ((b = byteBuffer.get()) != 10) {
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if (b == 45) {
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negative = true;
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}
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else if (b == 46) {
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// skip
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}
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else {
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final int n = b - '0';
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measurement = measurement * 10 + n;
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}
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}
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putOrMerge(
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measurements,
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new Measurement(
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hash, newCity, negative ? measurement * -1 : measurement));
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}
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}
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catch (IOException e) {
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throw new RuntimeException(e);
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}
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return measurements;
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})
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.flatMap(measurements -> Arrays.stream(measurements).flatMap(Arrays::stream))
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.filter(Objects::nonNull)
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.collect(
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Collectors.groupingBy(
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Measurement::city, Collectors.summarizingDouble(Measurement::temp)));
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System.out.println(
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resultMap.entrySet().stream()
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.sorted(Map.Entry.comparingByKey())
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.map(
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entry -> String.format(
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"%s=%.1f/%.1f/%.1f",
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entry.getKey(),
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entry.getValue().getMin(),
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entry.getValue().getAverage(),
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entry.getValue().getMax()))
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.collect(Collectors.joining(", ", "{", "}")));
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Collectors.toMap(
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measurement -> new String(measurement.city),
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Function.identity(),
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(m1, m2) -> {
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m1.merge(m2);
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return m1;
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},
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TreeMap::new));
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System.out.println(resultMap);
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}
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private static Iterator<Measurement> getMeasurementIterator(MappedByteBuffer byteBuffer) {
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return new Iterator<>() {
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private int initialPosition;
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private int delimiterIndex;
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@Override
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public boolean hasNext() {
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boolean hasRemaining = byteBuffer.hasRemaining();
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if (hasRemaining) {
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initialPosition = byteBuffer.position();
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delimiterIndex = 0;
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while (true) {
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byte b = byteBuffer.get();
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if (b == 59) {
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break;
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private static void putOrMerge(Measurement[][] measurements, Measurement measurement) {
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int index = measurement.hash & (measurements.length - 1);
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Measurement[] existing = measurements[index];
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for (int i = 0; i < existing.length; i++) {
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Measurement existingMeasurement = existing[i];
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if (existingMeasurement == null) {
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measurements[index][i] = measurement;
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return;
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}
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delimiterIndex++;
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if (equals(existingMeasurement.city, measurement.city)) {
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existingMeasurement.merge(measurement);
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return;
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}
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return true;
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}
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}
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private static boolean equals(byte[] city1, byte[] city2) {
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for (int i = 0; i < city1.length; i++) {
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if (city1[i] != city2[i]) {
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return false;
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}
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@Override
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public Measurement next() {
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byteBuffer.position(initialPosition);
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byte[] city = new byte[delimiterIndex];
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for (int j = 0; j < delimiterIndex; j++) {
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city[j] = byteBuffer.get();
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}
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byteBuffer.get();
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String temp = "";
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while (true) {
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char c = (char) byteBuffer.get();
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if (c == '\n') {
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break;
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}
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temp += c;
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}
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return new Measurement(new String(city), toDouble(temp));
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}
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};
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return true;
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}
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private record FileSegment(long start, long end) {
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}
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private record Measurement(String city, double temp) {
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private static final class Measurement {
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private int hash;
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private byte[] city;
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int min;
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int max;
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int sum;
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int count;
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private Measurement(int hash, byte[] city, int temp) {
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this.hash = hash;
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this.city = city;
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this.min = this.max = this.sum = temp;
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this.count = 1;
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}
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private void merge(Measurement m2) {
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this.min = this.min < m2.min ? this.min : m2.min;
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this.max = this.max > m2.max ? this.max : m2.max;
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this.sum = this.sum + m2.sum;
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this.count = this.count + m2.count;
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}
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@Override
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public String toString() {
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return String.format(
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"%.1f/%.1f/%.1f", this.min / 10f, (this.sum / 10f) / this.count, this.max / 10f);
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}
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}
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private static List<FileSegment> getFileSegments(final File file) throws IOException {
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final int numberOfSegments = Runtime.getRuntime().availableProcessors();
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final int numberOfSegments = Runtime.getRuntime().availableProcessors() * 4;
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final long fileSize = file.length();
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final long segmentSize = fileSize / numberOfSegments;
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if (segmentSize < 1000) {
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@ -171,79 +199,4 @@ public class CalculateAverage_kuduwa_keshavram {
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}
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return location;
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}
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private static double toDouble(String num) {
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long value = 0;
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boolean negative = false;
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int decimalPlaces = Integer.MIN_VALUE;
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for (byte ch : num.getBytes()) {
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if (ch >= '0' && ch <= '9') {
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value = value * 10 + (ch - '0');
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decimalPlaces++;
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}
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else if (ch == '-') {
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negative = true;
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}
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else if (ch == '.') {
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decimalPlaces = 0;
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}
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else {
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break;
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}
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}
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return asDouble(value, negative, decimalPlaces);
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}
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private static double asDouble(long value, boolean negative, int decimalPlaces) {
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int exp = -48;
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value <<= 48;
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if (decimalPlaces > 0 && value < Long.MAX_VALUE / 2) {
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if (value < LEFT_SHIFT_EIGHT) {
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exp -= 8;
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value <<= 8;
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}
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if (value < LEFT_SHIFT_FOUR) {
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exp -= 4;
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value <<= 4;
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}
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if (value < LEFT_SHIFT_TWO) {
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exp -= 2;
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value <<= 2;
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}
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if (value < LEFT_SHIFT_ONE) {
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exp -= 1;
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value <<= 1;
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}
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}
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for (; decimalPlaces > 0; decimalPlaces--) {
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exp--;
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long mod = value % 5;
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value /= 5;
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int modDiv = 1;
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if (value < LEFT_SHIFT_FOUR) {
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exp -= 4;
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value <<= 4;
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modDiv <<= 4;
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}
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if (value < LEFT_SHIFT_TWO) {
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exp -= 2;
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value <<= 2;
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modDiv <<= 2;
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}
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if (value < LEFT_SHIFT_ONE) {
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exp -= 1;
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value <<= 1;
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modDiv <<= 1;
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}
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if (decimalPlaces > 1) {
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value += modDiv * mod / 5;
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}
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else {
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value += (modDiv * mod + 4) / 5;
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}
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}
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final double d = Math.scalb((double) value, exp);
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return negative ? -d : d;
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}
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}
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