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/*
* Copyright 2023 The original authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package dev.morling.onebrc;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.file.Files;
import java.nio.file.Path;
import java.time.Duration;
import java.time.Instant;
import java.util.TreeMap;
import java.util.stream.Collector;
import static java.util.stream.Collectors.groupingByConcurrent;
// gunnar morling - 2:10
// roy van rijn - 1:01
// 0:53
public class CalculateAverage_ddimtirov {
public record InputLine(String station, int value) {
public static InputLine fromLine(String line) {
int endOfText = line.indexOf(";");
String station = line.substring(0, endOfText);
int startOfWhole = endOfText + 1;
int sign;
if (line.charAt(startOfWhole) == '-') {
sign = -1;
startOfWhole++;
} else {
sign = 1;
}
int endOfWhole = line.lastIndexOf(".");
var whole = unsafeParsePositiveInt(line, startOfWhole, endOfWhole);
var decimal = unsafeParsePositiveInt(line,endOfWhole+1, line.length());
int fixpoint10 = (whole * 10 + decimal) * sign;
return new InputLine(station, fixpoint10);
}
static int unsafeParsePositiveInt(String s, int start, int end) {
int acc = 0;
for (int i = start; i<end; i++) {
if (acc != 0) acc *= 10;
char c = s.charAt(i);
var v = c - '0';
assert v>=0 && v<=9 : String.format("Character '%s', value %,d", c, v);
acc += v;
}
return acc;
}
}
private static class OutputMetrics {
private int min = Integer.MAX_VALUE;
private int max = Integer.MIN_VALUE;
private long sum;
private long count;
@SuppressWarnings("ManualMinMaxCalculation")
public OutputMetrics combine(OutputMetrics o) {
var r = new OutputMetrics();
r.min = min < o.min ? min : o.min;
r.max = max > o.max ? max : o.max;
r.sum = sum + o.sum;
r.count = count + o.count;
return r;
}
public void accumulate(InputLine m) {
if (m.value < min) min = m.value;
if (m.value > max) max = m.value;
sum += m.value;
count++;
}
@Override
public String toString() {
var min = this.min / 10.0;
var mean = Math.round(this.sum / (double) count) / 10.0;
var max = this.max / 10.0;
return min + "/" + mean + "/" + max;
}
}
public static void main(String[] args) throws IOException {
// var start = Instant.now();
Instant start = null;
var path = Path.of("./measurements.txt");
var buffer = 8192 * 20;
// Files.lines() is optimized for files that can be indexed by int
// For larger files it falls back to buffered reader, which we now
// use directly to be able to tweak the buffer size.
try (var reader = new BufferedReader(new InputStreamReader(Files.newInputStream(path)), buffer)) {
var stationsToMetrics = reader.lines()
.map(InputLine::fromLine)
.parallel()
.collect(groupingByConcurrent(InputLine::station, Collector.of(
OutputMetrics::new,
OutputMetrics::accumulate,
OutputMetrics::combine,
OutputMetrics::toString
)));
System.out.println(new TreeMap<>(stationsToMetrics));
assert Files.readAllLines(Path.of("expected_result.txt")).getFirst().equals(new TreeMap<>(stationsToMetrics).toString());
}
//noinspection ConstantValue
if (start!=null) System.err.println(Duration.between(start, Instant.now()));
}
}
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