2016-08-18 11:05:53 -06:00

64 lines
1.6 KiB
Java

// understandingcollections/jmh/Sets.java
// (c)2016 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
// Demonstrates performance differences in Sets
package understandingcollections.jmh;
import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.infra.Blackhole;
import java.util.*;
import static java.util.concurrent.TimeUnit.*;
@State(Scope.Thread)
@Warmup(iterations = 5, time = 1, timeUnit = SECONDS)
@Measurement(iterations = 5, time = 1, timeUnit = SECONDS)
@Fork(1)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(MICROSECONDS)
public class Sets {
private Set<Integer> set;
@Param({"HashSet", "TreeSet", "LinkedHashSet"})
private String type;
private int begin;
private int end;
@Setup
public void setup() {
switch(type) {
case "HashSet":
set = new HashSet<>();
break;
case "TreeSet":
set = new TreeSet<>();
break;
case "LinkedHashSet":
set = new LinkedHashSet<>();
break;
default:
throw new IllegalStateException("Unknown " + type);
}
begin = 1;
end = 256;
for (int i = begin; i < end; i++)
set.add(i);
}
@Benchmark
public void add() {
for(int i = begin; i < end; i++)
set.add(i);
}
@Benchmark
public void contains(Blackhole bh) {
for(int i = begin; i < end; i++)
bh.consume(set.contains(i));
}
@Benchmark
public void iterate(Blackhole bh) {
Iterator<Integer> it = set.iterator();
while(it.hasNext())
bh.consume(it.next());
}
}