listcomparisons.java

thinking in java 书中源码 第四版

//: concurrency/ListComparisons.java
// {Args: 1 10 10} (Fast verification check during build)
// Rough comparison of thread-safe List performance.
import java.util.concurrent.*;
import java.util.*;
import net.mindview.util.*;

abstract class ListTest extends Tester<List<Integer>> {
  ListTest(String testId, int nReaders, int nWriters) {
    super(testId, nReaders, nWriters);
  }
  class Reader extends TestTask {
    long result = 0;
    void test() {
      for(long i = 0; i < testCycles; i++)
        for(int index = 0; index < containerSize; index++)
          result += testContainer.get(index);
    }
    void putResults() {
      readResult += result;
      readTime += duration;
    }
  }
  class Writer extends TestTask {
    void test() {
      for(long i = 0; i < testCycles; i++)
        for(int index = 0; index < containerSize; index++)
          testContainer.set(index, writeData[index]);
    }
    void putResults() {
      writeTime += duration;
    }
  }
  void startReadersAndWriters() {
    for(int i = 0; i < nReaders; i++)
      exec.execute(new Reader());
    for(int i = 0; i < nWriters; i++)
      exec.execute(new Writer());
  }
}

class SynchronizedArrayListTest extends ListTest {
  List<Integer> containerInitializer() {
    return Collections.synchronizedList(
      new ArrayList<Integer>(
        new CountingIntegerList(containerSize)));
  }
  SynchronizedArrayListTest(int nReaders, int nWriters) {
    super("Synched ArrayList", nReaders, nWriters);
  }
}

class CopyOnWriteArrayListTest extends ListTest {
  List<Integer> containerInitializer() {
    return new CopyOnWriteArrayList<Integer>(
      new CountingIntegerList(containerSize));
  }
  CopyOnWriteArrayListTest(int nReaders, int nWriters) {
    super("CopyOnWriteArrayList", nReaders, nWriters);
  }
}

public class ListComparisons {
  public static void main(String[] args) {
    Tester.initMain(args);
    new SynchronizedArrayListTest(10, 0);
    new SynchronizedArrayListTest(9, 1);
    new SynchronizedArrayListTest(5, 5);
    new CopyOnWriteArrayListTest(10, 0);
    new CopyOnWriteArrayListTest(9, 1);
    new CopyOnWriteArrayListTest(5, 5);
    Tester.exec.shutdown();
  }
} /* Output: (Sample)
Type                             Read time     Write time
Synched ArrayList 10r 0w      232158294700              0
Synched ArrayList 9r 1w       198947618203    24918613399
readTime + writeTime =        223866231602
Synched ArrayList 5r 5w       117367305062   132176613508
readTime + writeTime =        249543918570
CopyOnWriteArrayList 10r 0w      758386889              0
CopyOnWriteArrayList 9r 1w       741305671      136145237
readTime + writeTime =           877450908
CopyOnWriteArrayList 5r 5w       212763075    67967464300
readTime + writeTime =         68180227375
*///:~