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
|
/*
* 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.ByteArrayOutputStream;
import java.io.IOException;
import java.lang.foreign.Arena;
import java.lang.foreign.MemorySegment;
import java.lang.foreign.ValueLayout;
import java.nio.channels.FileChannel;
import java.nio.charset.StandardCharsets;
import java.nio.file.Path;
import java.nio.file.StandardOpenOption;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.stream.Collectors;
public class CalculateAverage_faridtmammadov {
private static final String FILE = "./measurements.txt";
public static void main(String[] args) throws IOException {
int availableProcessors = Runtime.getRuntime().availableProcessors();
var map = getSegments(availableProcessors).stream()
.map(CalculateAverage_faridtmammadov::aggregate).parallel()
.flatMap(f -> f.entrySet().stream())
.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, Aggregate::update, TreeMap::new));
printFormatted(map);
}
private static List<MemorySegment> getSegments(int numberOfChunks) throws IOException {
try (var fileChannel = FileChannel.open(Path.of(FILE), StandardOpenOption.READ)) {
var fileSize = fileChannel.size();
var segmentSize = fileSize / numberOfChunks;
var segment = fileChannel.map(FileChannel.MapMode.READ_ONLY, 0, fileSize, Arena.global());
var baseAddress = segment.address();
var endAddress = baseAddress + fileSize;
var segments = new ArrayList<MemorySegment>();
var startAddress = baseAddress;
for (var i = 0; i < numberOfChunks; i++) {
var pointer = startAddress + segmentSize;
while (pointer < endAddress) {
long offset = pointer - baseAddress;
byte b = segment.get(ValueLayout.JAVA_BYTE, offset);
if (b == '\n') {
break;
}
pointer++;
}
if (pointer >= endAddress) {
var offsetStart = startAddress - baseAddress;
var offsetEnd = endAddress - baseAddress - offsetStart;
segments.add(segment.asSlice(offsetStart, offsetEnd));
break;
}
var offsetStart = startAddress - baseAddress;
var offsetEnd = pointer - baseAddress - offsetStart;
segments.add(segment.asSlice(offsetStart, offsetEnd));
startAddress = pointer + 1;
}
return segments;
}
}
private static Map<String, Aggregate> aggregate(MemorySegment segment) {
var map = new HashMap<String, Aggregate>();
var iterator = new MemorySegmentIterator(segment);
while (iterator.hasNext()) {
String city = parseCity(iterator);
long temperature = parseTemperature(iterator);
map.compute(city, (key, value) -> {
if (value == null) {
return new Aggregate(temperature);
}
else {
return value.update(temperature);
}
});
}
return map;
}
private static String parseCity(MemorySegmentIterator iterator) {
var byteStream = new ByteArrayOutputStream();
while (iterator.hasNext()) {
var b = iterator.getNextByte();
if (b == ';') {
return byteStream.toString(StandardCharsets.UTF_8);
}
byteStream.write(b);
}
return null;
}
public static long parseTemperature(MemorySegmentIterator iterator) {
long value = 0L;
int sign = 1;
while (iterator.hasNext()) {
byte b = iterator.getNextByte();
if (b >= '0' && b <= '9') {
value = value * 10 + b - '0';
}
else if (b == '\n') {
return value * sign;
}
else if (b == '-') {
sign = -1;
}
}
return value * sign;
}
private static void printFormatted(Map<String, Aggregate> map) {
var iterator = map.entrySet().iterator();
var length = map.entrySet().size();
System.out.print("{");
for (int i = 0; i < length - 1; i++) {
var entry = iterator.next();
System.out.printf("%s=%s, ", entry.getKey(), entry.getValue().toString());
}
var lastEntry = iterator.next();
System.out.printf("%s=%s}\n", lastEntry.getKey(), lastEntry.getValue().toString());
}
static class Aggregate {
long min;
long max;
long sum;
int count;
public Aggregate(long temperature) {
min = temperature;
max = temperature;
sum = temperature;
count = 1;
}
public Aggregate update(long temp) {
min = Math.min(min, temp);
max = Math.max(max, temp);
sum += temp;
count++;
return this;
}
public Aggregate update(Aggregate agg) {
min = Math.min(min, agg.min);
max = Math.max(max, agg.max);
sum += agg.sum;
count += agg.count;
return this;
}
public String toString() {
return String.format("%s/%s/%s", min / 10.0f, Math.round(sum * 1.0f / count) / 10.0f, max / 10.0f);
}
}
static class MemorySegmentIterator {
private long offset;
private final MemorySegment segment;
private final long segmentSize;
public MemorySegmentIterator(MemorySegment segment) {
this.segment = segment;
this.segmentSize = segment.byteSize();
}
public boolean hasNext() {
return offset < segmentSize;
}
public byte getNextByte() {
var b = segment.get(ValueLayout.JAVA_BYTE, offset);
offset++;
return b;
}
}
}
|
