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
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
/*
* 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.RandomAccessFile;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.TreeMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadFactory;
public class CalculateAverage_gabrielfoo {
private static final String FILE = "./measurements.txt";
private static final int UTF8_MAX_LEN_100_BYTES = 400;
private static final int DOUBLE_DIGITS_MAX = 3;
private static final int UNIQUE_STATION_NAMES = 10000;
private static class ResultRow {
private double min = Double.POSITIVE_INFINITY;
private double sum = 0.0;
private double max = Double.NEGATIVE_INFINITY;
private int count = 0;
public String toString() {
return min + "/" + (Math.round(sum / count) / 10.0) + "/" + max;
}
public void updateMinMax(double incoming) {
min = Math.min(min, incoming);
max = Math.max(max, incoming);
sum += incoming * 10.0;
count += 1;
}
public void combine(ResultRow other) {
min = Math.min(min, other.min);
max = Math.max(max, other.max);
sum += other.sum;
count += other.count;
}
}
public static MappedByteBuffer[] mapFileToMemory(final RandomAccessFile file, final int chunkCount) throws Exception {
FileChannel channel = file.getChannel();
final long chunkSize = Math.ceilDiv(file.length(), chunkCount);
MappedByteBuffer buffers[] = new MappedByteBuffer[chunkCount];
long position = 0;
for (int i = 0; i < chunkCount - 1; ++i) {
file.seek(position + chunkSize);
long ptr = file.getFilePointer();
while (file.readByte() != '\n') {
file.seek(++ptr);
}
buffers[i] = channel.map(FileChannel.MapMode.READ_ONLY, position, ptr - position + 1);
position = ptr + 1;
}
buffers[buffers.length - 1] = channel.map(FileChannel.MapMode.READ_ONLY, position, file.length() - position);
return buffers;
}
public static void main(String[] args) throws Exception {
final RandomAccessFile file = new RandomAccessFile(FILE, "r");
final int coreCount = file.length() < 2147483647 ? 1 : Runtime.getRuntime().availableProcessors();
ArrayList<HashMap<String, ResultRow>> maps = new ArrayList<>();
final ThreadFactory threadFactory = new ThreadFactory() {
public Thread newThread(Runnable r) {
Thread t = new Thread(r);
t.setPriority(Thread.MAX_PRIORITY);
return t;
}
};
ExecutorService executor = Executors.newFixedThreadPool(coreCount, threadFactory);
Future<?> initFuture = executor.submit(() -> {
for (int i = 0; i < coreCount; ++i) {
maps.add(new HashMap<>(UNIQUE_STATION_NAMES, 0.9f));
}
});
MappedByteBuffer[] buffers = mapFileToMemory(file, coreCount);
initFuture.get();
Future<?>[] futures = new Future<?>[buffers.length];
for (int k = 0; k < buffers.length; ++k) {
final MappedByteBuffer buffer = buffers[k];
final var map = maps.get(k);
futures[k] = executor.submit(() -> {
int start = 0;
byte[] stationArr = new byte[UTF8_MAX_LEN_100_BYTES];
double[] floatArr = new double[DOUBLE_DIGITS_MAX];
byte currentByte;
while (buffer.hasRemaining()) {
currentByte = buffer.get();
stationArr[buffer.position() - start - 1] = currentByte;
if (currentByte == ';') {
final int stationEnd = buffer.position() - 1;
// convert to double now
currentByte = buffer.get();
boolean neg = currentByte == '-';
if (neg)
currentByte = buffer.get();
floatArr[0] = currentByte - '0';
currentByte = buffer.get();
if (currentByte == '.') {
floatArr[1] = (buffer.get() - '0') / 10.0;
floatArr[2] = 0.0;
}
else {
floatArr[0] *= 10.0;
floatArr[1] = (currentByte - '0');
buffer.get();
floatArr[2] = (buffer.get() - '0') / 10.0;
}
final double f = (neg ? -1 : 1) * (floatArr[0] + floatArr[1] + floatArr[2]);
buffer.get(); // discard \n
String station = new String(stationArr, 0, stationEnd - start);
map.compute(station, (key, existingRow) -> {
ResultRow row = (existingRow == null) ? new ResultRow() : existingRow;
row.updateMinMax(f);
return row;
});
start = buffer.position();
}
}
});
}
for (Future<?> future : futures) {
future.get();
}
HashMap<String, ResultRow> resultHashMap = maps.get(0);
maps.stream().skip(1).flatMap(map -> map.entrySet().stream()).forEach(entry -> {
resultHashMap.merge(entry.getKey(), entry.getValue(), (oldVal, newVal) -> {
oldVal.combine(newVal);
return oldVal;
});
});
TreeMap<String, ResultRow> res = new TreeMap<>(resultHashMap);
executor.shutdown();
System.out.println(res);
}
}
|
