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CharStreamsCopyBenchmark.java
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CharStreamsCopyBenchmark.java
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/*
* Copyright (C) 2017 The Guava 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 com.google.common.io;
import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;
import com.google.caliper.api.VmOptions;
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.nio.Buffer;
import java.nio.CharBuffer;
import java.util.Random;
/**
* Benchmarks for {@link CharStreams#copy}.
*
* <p>{@link CharStreams#copy} has type specific optimizations for various common Appendable and
* Reader implementations, this compares the performance of the different options.
*/
// These benchmarks allocate a lot of data so use a large heap
@VmOptions({"-Xms12g", "-Xmx12g", "-d64"})
public class CharStreamsCopyBenchmark {
enum CopyStrategy {
OLD {
@Override
long copy(Readable from, Appendable to) throws IOException {
CharBuffer buf = CharStreams.createBuffer();
long total = 0;
while (from.read(buf) != -1) {
((Buffer) buf).flip();
to.append(buf);
total += buf.remaining();
((Buffer) buf).clear();
}
return total;
}
},
NEW {
@Override
long copy(Readable from, Appendable to) throws IOException {
return CharStreams.copy(from, to);
}
};
abstract long copy(Readable from, Appendable to) throws IOException;
}
enum TargetSupplier {
STRING_WRITER {
@Override
Appendable get(int sz) {
return new StringWriter(sz);
}
},
STRING_BUILDER {
@Override
Appendable get(int sz) {
return new StringBuilder(sz);
}
};
abstract Appendable get(int sz);
}
@Param CopyStrategy strategy;
@Param TargetSupplier target;
@Param({"10", "1024", "1048576"})
int size;
String data;
@BeforeExperiment
public void setUp() {
// precalculate some random strings of ascii characters.
StringBuilder sb = new StringBuilder();
Random random = new Random(0xdeadbeef); // for unpredictable but reproducible behavior
sb.ensureCapacity(size);
for (int k = 0; k < size; k++) {
// [9-127) includes all ascii non-control characters
sb.append((char) (random.nextInt(127 - 9) + 9));
}
data = sb.toString();
}
@Benchmark
public long timeCopy(int reps) throws IOException {
long r = 0;
final String localData = data;
final TargetSupplier localTarget = target;
final CopyStrategy localStrategy = strategy;
for (int i = 0; i < reps; i++) {
Appendable appendable = localTarget.get(localData.length());
r += localStrategy.copy(new StringReader(localData), appendable);
}
return r;
}
}