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
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
|
/*
* 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 static java.nio.charset.StandardCharsets.*;
import static java.util.stream.Collectors.*;
import java.io.File;
import java.io.RandomAccessFile;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.stream.IntStream;
public class CalculateAverage_phd3 {
private static final int NUM_THREADS = Runtime.getRuntime().availableProcessors() * 2;
private static final String FILE = "./measurements.txt";
private static final long FILE_SIZE = new File(FILE).length();
private static final int CHUNK_SIZE = 65536 * 1024;
private static final int PADDING = 512;
private static final double[] POWERS_OF_10 = IntStream.range(0, 6).mapToDouble(x -> Math.pow(10.0, x)).toArray();
private static final Map<String, AggregationInfo> globalMap = new ConcurrentHashMap<>();
private record ResultRow(double min, double mean, double max) {
public String toString() {
return round(min) + "/" + round(mean) + "/" + round(max);
}
private double round(double value) {
return Math.round(value * 10.0) / 10.0;
}
};
public static ResultRow resultRow(AggregationInfo aggregationInfo) {
return new ResultRow(aggregationInfo.min, aggregationInfo.sum / aggregationInfo.count, aggregationInfo.max);
}
public static void main(String[] args) throws Exception {
long fileLength = new File(FILE).length();
int numChunks = (int) Math.ceil(fileLength * 1.0 / CHUNK_SIZE);
ExecutorService executorService = Executors.newFixedThreadPool(NUM_THREADS);
BufferDataProvider provider = new RandomAccessBasedProvider(FILE, FILE_SIZE);
for (int chunkIndex = 0; chunkIndex < numChunks; chunkIndex++) {
executorService.submit(new Aggregator(chunkIndex, provider));
}
executorService.shutdown();
executorService.awaitTermination(10, TimeUnit.MINUTES);
Map<String, ResultRow> measurements = new TreeMap<>(globalMap.entrySet().stream()
.collect(toMap(Map.Entry::getKey, e -> resultRow(e.getValue()))));
System.out.println(measurements);
}
private static class AggregationInfo {
double min = Double.POSITIVE_INFINITY;
double max = Double.NEGATIVE_INFINITY;
double sum;
long count;
public AggregationInfo update(AggregationInfo update) {
this.count += update.count;
this.sum += update.sum;
if (this.max < update.max) {
this.max = update.max;
}
if (this.min > update.min) {
this.min = update.min;
}
return this;
}
public AggregationInfo update(double value) {
this.count++;
this.sum += value;
if (this.max < value) {
this.max = value;
}
if (this.min > value) {
this.min = value;
}
return this;
}
}
private interface BufferDataProvider {
int read(byte[] buffer, long offset) throws Exception;
}
private static class RandomAccessBasedProvider implements BufferDataProvider {
private final String filePath;
private final long fileSize;
RandomAccessBasedProvider(String filePath, long fileSize) {
this.filePath = filePath;
this.fileSize = fileSize;
}
@Override
public int read(byte[] buffer, long offset) throws Exception {
RandomAccessFile file = null;
try {
file = new RandomAccessFile(filePath, "r");
file.seek(offset);
return file.read(buffer);
}
finally {
if (file != null) {
file.close();
}
}
}
}
private static class Aggregator implements Runnable {
private final long startByte;
private final BufferDataProvider dataProvider;
public Aggregator(long chunkIndex, BufferDataProvider dataProvider) {
this.startByte = chunkIndex * CHUNK_SIZE;
this.dataProvider = dataProvider;
}
@Override
public void run() {
try {
// offset for the last byte to be processed (excluded)
long endByte = Math.min(startByte + CHUNK_SIZE, FILE_SIZE);
// read a little more than needed to cover next entry if needed
long bufferSize = endByte - startByte + ((endByte == FILE_SIZE) ? 0 : PADDING);
byte[] buffer = new byte[(int) bufferSize];
int bytes = dataProvider.read(buffer, startByte);
// Partial aggregation to avoid accessing global concurrent map for every entry
Map<String, AggregationInfo> updated = processBuffer(
buffer, startByte == 0, endByte - startByte);
// Full aggregation with global map
updated.entrySet().forEach(entry -> {
globalMap.compute(entry.getKey(), (k, v) -> {
if (v == null) {
return entry.getValue();
}
return v.update(entry.getValue());
});
});
}
catch (Throwable e) {
throw new RuntimeException(e);
}
}
private static Map<String, AggregationInfo> processBuffer(byte[] buffer, boolean isFileStart, long nextChunkStart) {
int start = 0;
// Move to the next entry after '\n'. Don't do this if we're at the start of
// the file to avoid missing first entry.
if (!isFileStart) {
while (buffer[start] != '\n') {
start++;
}
start += 1;
}
// local map for this thread, don't need thread safety
Map<String, AggregationInfo> chunkMap = new HashMap<>();
while (true) {
LineInfo lineInfo = getNextLine(buffer, start);
String key = new String(buffer, start, lineInfo.semicolonIndex - start);
double value = parseDouble(buffer, lineInfo.semicolonIndex + 1, lineInfo.nextStart - 1);
update(chunkMap, key, value);
if ((lineInfo.nextStart > nextChunkStart) || (lineInfo.nextStart >= buffer.length)) {
// we are already at a point where the next line will be processed in the next chunk,
// so the job is done here
break;
}
start = lineInfo.nextStart();
}
return chunkMap;
}
private static double parseDouble(byte[] bytes, int offset, int end) {
boolean negative = (bytes[offset] == '-');
int current = negative ? offset + 1 : offset;
int preFloat = 0;
while (current < end && bytes[current] != '.') {
preFloat = (preFloat * 10) + (bytes[current++] - '0');
}
current++;
int postFloatStart = current;
int postFloat = 0;
while (current < end) {
postFloat = (postFloat * 10) + (bytes[current++] - '0');
}
return (preFloat + ((postFloat) / POWERS_OF_10[end - postFloatStart])) * (negative ? -1 : 1);
}
private static void update(Map<String, AggregationInfo> state, String key, double value) {
AggregationInfo info = state.computeIfAbsent(key, k -> new AggregationInfo());
info.update(value);
}
// identifies indexes of the next ';' and '\n', which will be used to get entry key and value from line
private static LineInfo getNextLine(byte[] buffer, int start) {
// caller guarantees that the access is in bounds, so no index check
while (buffer[start] != ';') {
start++;
}
int semicolonIndex = start;
// caller guarantees that the access is in bounds, so no index check
while (buffer[start] != '\n') {
start++;
}
return new LineInfo(semicolonIndex, start + 1);
}
}
private record LineInfo(int semicolonIndex, int nextStart) {
}
}
|
