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3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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9  * This code is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
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23 package org.openjdk.bench.java.io;
24 
25 import java.io.File;
26 import java.io.IOException;
27 import java.nio.ByteBuffer;
28 import java.nio.channels.FileChannel;
29 import java.nio.file.StandardOpenOption;
30 import java.util.concurrent.TimeUnit;
31 
32 import org.openjdk.jmh.annotations.*;
33 
34 /**
35  * Tests the overheads of I/O API.
36  * This test is known to depend heavily on disk subsystem performance.
37  */
38 @BenchmarkMode(Mode.Throughput)
39 @OutputTimeUnit(TimeUnit.MILLISECONDS)
40 @State(Scope.Thread)
41 public class FileChannelWrite {
42 
43     @Param("1000000")
44     private int fileSize;
45 
46     private File f;
47     private FileChannel fc;
48     private ByteBuffer bb;
49     private int count;
50 
51     @Setup(Level.Trial)
beforeRun()52     public void beforeRun() throws IOException {
53         f = File.createTempFile("FileChannelWriteBench", ".bin");
54         bb = ByteBuffer.allocate(1);
55         bb.put((byte) 47);
56         bb.flip();
57     }
58 
59     @TearDown(Level.Trial)
afterRun()60     public void afterRun() throws IOException {
61         f.delete();
62     }
63 
64     @Setup(Level.Iteration)
beforeIteration()65     public void beforeIteration() throws IOException {
66         fc = FileChannel.open(f.toPath(), StandardOpenOption.WRITE);
67         count = 0;
68     }
69 
70     @TearDown(Level.Iteration)
afterIteration()71     public void afterIteration() throws IOException {
72         fc.close();
73     }
74 
75     @Benchmark
test()76     public void test() throws IOException {
77         fc.write(bb);
78         bb.flip();
79         count++;
80         if (count >= fileSize) {
81             // start over
82             fc.position(0);
83             count = 0;
84         }
85     }
86 
87 }
88