1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
|
/*
* 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.FileDescriptor;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.io.RandomAccessFile;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;
import java.util.Map;
import java.util.StringTokenizer;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
public class CalculateAverage_mahadev_k {
private static final String FILE = "./measurements.txt";
private static Map<String, MeasurementAggregator> stationMap = new ConcurrentSkipListMap<>();
private static double round(double value) {
return Math.round(value * 10.0) / 10.0;
}
private static class MeasurementAggregator {
double minima = Double.POSITIVE_INFINITY, maxima = Double.NEGATIVE_INFINITY, total = 0, count = 0;
public synchronized void accept(double value) {
if (minima > value)
minima = value;
if (maxima < value)
maxima = value;
total += value;
count++;
}
public double min() {
return round(minima);
}
public double max() {
return round(maxima);
}
public double avg() {
return round((Math.round(total * 10.0) / 10.0) / count);
}
}
public static void main(String[] args) throws IOException {
int chunkSize = args.length == 1 ? Integer.parseInt(args[0]) : 1_000_000;
readAndProcess(chunkSize);
print();
}
public static void readAndProcess(int chunkSize) {
final ThreadFactory factory = Thread.ofVirtual().name("routine-", 0).factory();
try (RandomAccessFile file = new RandomAccessFile(FILE, "r")) {
try (var executor = Executors.newThreadPerTaskExecutor(factory)) {
var channel = file.getChannel();
var size = channel.size();
long start = 0;
while (start <= size) {
long end = start + chunkSize;
String letter = "";
do {
end--;
ByteBuffer buffer = ByteBuffer.allocate(1);
channel.read(buffer, end);
buffer.flip();
letter = StandardCharsets.UTF_8.decode(buffer).toString();
} while (!letter.equals("\n"));
if (end < start)
end = start + chunkSize;
final long currentStart = start;
final long currentEnd = end;
executor.submit(() -> {
ByteBuffer buffer = ByteBuffer.allocate((int) (currentEnd - currentStart + 1));
try {
channel.read(buffer, currentStart);
}
catch (IOException e) {
e.printStackTrace();
}
buffer.flip();
String data = StandardCharsets.UTF_8.decode(buffer).toString();
processData(data);
});
start = end + 1;
}
}
}
catch (IOException e) {
e.printStackTrace();
}
}
public static void processData(String dataBlock) {
StringTokenizer tokenizer = new StringTokenizer(dataBlock, "\n");
while (tokenizer.hasMoreElements()) {
StringTokenizer tokens = new StringTokenizer(tokenizer.nextToken(), ";");
String station = tokens.nextToken();
double value = Double.parseDouble(tokens.nextToken());
processMinMaxMean(station, value);
}
}
private static void processMinMaxMean(String station, double temp) {
var values = stationMap.get(station);
if (values == null) {
values = new MeasurementAggregator();
stationMap.putIfAbsent(station, values);
}
values = stationMap.get(station);
values.accept(temp);
}
public static void print() throws UnsupportedEncodingException {
System.setOut(new PrintStream(new FileOutputStream(FileDescriptor.out), true, StandardCharsets.UTF_8));
System.out.print("{");
int i = stationMap.size();
for (var kv : stationMap.entrySet()) {
System.out.printf("%s=%s/%s/%s", kv.getKey(), kv.getValue().min(), kv.getValue().avg(), kv.getValue().max());
if (i > 1)
System.out.print(", ");
i--;
}
System.out.println("}");
}
}
|
