Java/Mode Selection Performance Test

1. if-else ¶

대강 다�� 드 ��것��다.

~cpp 
public class IfElse {
    public void printPerformance(String[] modeExecute) {
        long start;
        long end;
        start = System.currentTimeMillis();
        for (int i = 0; i < ModeChoicePerformanceTest.LOOPING_COUNT; i++) {
            executeIfElse(modeExecute);
        }
        end = System.currentTimeMillis();
        System.out.println("if - else elapsed time :" + (end - start) + "ms ");
    }

    private void executeIfElse(String[] modeExecute) {
        for (int i = 0; i < modeExecute.length; i++) {
            executeWithIfElse(modeExecute[i]);
        }
    }

    public void executeWithIfElse(String mode) {
        if (mode.equals("One")) {
            doOne(1);
        } else if (mode.equals("Two")) {
            doTwo(1);
        } else if (mode.equals("Three")) {
            doThree(1);
        } else if (mode.equals("Four")) {
            doFour(1);
        } else if (mode.equals("Five")) {
            doFive(1);
        } else {
            doDefault(1);
        }
    }


    public void doOne(int i) {
        i = 10;
    }

    public void doTwo(int i) {
        i = 10;
    }

    public void doThree(int i) {
        i = 10;
    }

    public void doFour(int i) {
        i = 10;
    }

    public void doFive(int i) {
        i = 10;
    }

    public void doDefault(int i) {
        i = 100;
    }
}

�� 방법�� 단 ��론 가�� 빠르다. ��만, ��로

WhySwitchStatementsAreBadSmell�� 리�� 까? 근데.. 그�� 대�� 반론��로 들��는것�� '�� mode ��기��므로 �� Switch-Statement �� 는 다른 �� 냐. �� 기 �� 그냥 ��당 부�� 되고 끝��다.' 라고 말��것��다. 글��. 모르겠다.
��로 느껴��는 것��로는, switch 로 ��기를 나�� mode string 과 �� parameter �� 복�� 것��라는 �� 보��다. 그리고 ��나�� mode 가 늘��날때��다 ��당 method 가 늘��나고, mode string �� 늘��나고, if-else 구문�� 길��다는 �� 다. �� 메��드로 �� 놓�� 만, 만�� 부�� 메��드로 �� 되��다면? 그�� 단 ��디 밖�� 말�� 다. (단, �� 논문�� 는 ��람�� ) GotoStatementConsideredHarmful.

두�� - Method reflection ¶

~cpp 

import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;

public class MethodFullReflection {
    public void printPerformance(String[] modeExecute) throws InvocationTargetException, IllegalAccessException {
        long start;
        long end;
        start = System.currentTimeMillis();
        for (int i = 0; i < ModeChoicePerformanceTest.LOOPING_COUNT; i++) {
            executeReflection(modeExecute);
        }
        end = System.currentTimeMillis();
        System.out.println("elapsed time :" + (end - start) + "ms ");

    }

    private void executeReflection(String[] modeExecute) throws InvocationTargetException, IllegalAccessException {
        for (int i = 0; i < modeExecute.length; i++) {
            Method method = null;
            try {
                method = this.getClass().getMethod("do" + modeExecute[i], new Class[]{int.class});
                method.invoke(this, new Object[]{new Integer(1)});
            } catch (NoSuchMethodException e) {
                this.doDefault(1);
            } catch (SecurityException e) {
                e.printStackTrace();  //To change body of catch statement use Options | File Templates.
            }
        }
    }

    private void doDefault(int i) {
        i = 100;
    }

    public void doOne(int i) {
        i = 10;
    }

    public void doTwo(int i) {
        i = 10;
    }

    public void doThree(int i) {
        i = 10;
    }

    public void doFour(int i) {
        i = 10;
    }

    public void doFive(int i) {
        i = 10;
    }

}

�� : MODE 가 ��가될때��다 doXXX ��로 �� 고 ��를 ��면 된다. �� 기 부�� 드가 ��가되�� 고, ��당 Mode 가 ��가될때��다 메��드 ��나만 ��가��면 된다.
단�� : ��바��는 Method Reflection & Invoke 가 �� 느리다.; ��는 밑��꺼 ��.

��. �� 방법�� 보�� 방법��다. 바로 �� Table Lookup. ¶

~cpp 

import java.util.HashMap;
import java.util.Map;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;

/**
 * User: Administrator Date: 2003. 7. 12. Time: ������ 12:48:38
 */
public class MethodTableLookupReflection {
    public void printPerformance(String[] modeExecute) throws InvocationTargetException, IllegalAccessException {
        long start;
        long end;
        start = System.currentTimeMillis();
        initReflectionMap(modeExecute);
        end = System.currentTimeMillis();
        System.out.println("reflection with method initialize table elapsed time :" + (end - start) + "ms ");

        start = System.currentTimeMillis();
        for (int i = 0; i < ModeChoicePerformanceTest.LOOPING_COUNT; i++) {
            executeReflectionWithMapping(modeExecute);
        }
        end = System.currentTimeMillis();
        System.out.println("reflection with method elapsed time :" + (end - start) + "ms ");

    }

    private static Map methodMap;


    private void executeReflectionWithMapping(String[] modeExecute) throws InvocationTargetException, IllegalAccessException {
        for (int i = 0; i < modeExecute.length; i++) {
            Method method = (Method) methodMap.get(modeExecute[i]);
            if (method != null)
                method.invoke(this, new Object[]{new Integer(1)});
            else
                doDefault(1);
        }
    }

    private void initReflectionMap(String[] methodNames) {
        methodMap = new HashMap();
        for (int i = 0; i < methodNames.length; i++) {
            try {
                methodMap.put(methodNames[i], this.getClass().getMethod("do" + methodNames[i], new Class[]{int.class}));
            } catch (NoSuchMethodException e) {
            } catch (SecurityException e) {
            }
        }

    }

    private void doDefault(int i) {
        i = 100;
    }

    public void doOne(int i) {
        i = 10;
    }

    public void doTwo(int i) {
        i = 10;
    }

    public void doThree(int i) {
        i = 10;
    }

    public void doFour(int i) {
        i = 10;
    }

    public void doFive(int i) {
        i = 10;
    }
}

�� 방법�� 방법과 같�� 면�� 먼��를 �� 10배가량 ��다.

��. Inner Class �� 대�� Command Pattern �� . ¶

~cpp 

import java.util.Map;
import java.util.HashMap;

/**
 * User: Administrator Date: 2003. 7. 12. Time: ������ 12:57:7
 */
public class InterfaceTableLookup {
    protected Map modeMap = new HashMap();

    public void printPerformance(String[] modeExecute) {
        long start;
        long end;
        start = System.currentTimeMillis();
        initModeMap();
        end = System.currentTimeMillis();
        System.out.println("interface table lookup init table elapsed time :" + (end - start) + "ms ");

        start = System.currentTimeMillis();
        for (int i = 0; i < ModeChoicePerformanceTest.LOOPING_COUNT; i++) {
            executeInnerclassMapping(modeExecute);
        }
        end = System.currentTimeMillis();
        System.out.println("interface table lookup elapsed time :" + (end - start) + "ms ");


    }

    private void executeInnerclassMapping(String[] modeExecute) {
        for (int i = 0; i < modeExecute.length; i++) {
            executeMode(modeExecute[i]);
         }
    }

    private void executeMode(String s) {
        IMode mode = (IMode) modeMap.get(s);
        if (mode == null) doDefault(1);
        else mode.execute(1);
    }

    public class ExOne implements IMode {
        public void execute(int i) {
            i = 10;
        }
    }

    public  class ExTwo implements IMode {
        public void execute(int i) {
            i = 10;
        }
    }

    public class ExThree implements IMode {
        public void execute(int i) {
            i = 10;
        }
    }

    public class ExFour implements IMode {
        public void execute(int i) {
            i = 10;
        }
    }

    public class ExFive implements IMode {
        public void execute(int i) {
            i = 10;
        }
    }

    private void initModeMap() {
        modeMap.put("One", new ExOne());
        modeMap.put("Two", new ExTwo());
        modeMap.put("Three", new ExThree());
        modeMap.put("Four", new ExFour());
        modeMap.put("Five", new ExFive());
    }
}

�� 방법�� initModeMap �� 매�� Mode�� 대�� 록�� 다. ��먼��는 Method Reflection 보다 �� 빠르다.

��막 방법 - interface & reflection ¶

�� 방법�� initModeMap �� reflection ��로 ��리�� 것��다.

~cpp 
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.HashMap;
import java.util.Map;

/**
 * User: Administrator Date: 2003. 7. 12. Time: ������ 1:2:16
 */
public class InterfaceTableLookupReflection {
    public void printPerformance(String[] modeExecute) throws NoSuchMethodException, InstantiationException, ClassNotFoundException, InvocationTargetException, IllegalAccessException {
        long start;
        long end;
        start = System.currentTimeMillis();
        initModeMapWithReflection(modeExecute);
        end = System.currentTimeMillis();
        System.out.println("interface reflection & table lookup init able elapsed time :" + (end - start) + "ms ");

        start = System.currentTimeMillis();
        for (int i = 0; i < ModeChoicePerformanceTest.LOOPING_COUNT; i++) {
            executeInnerclassMapping(modeExecute);
        }
        end = System.currentTimeMillis();
        System.out.println("interface reflection & table lookup elapsed time :" + (end - start) + "ms ");

    }

    private void executeInnerclassMapping(String[] modeExecute) {
        for (int i = 0; i < modeExecute.length; i++) {
            executeMode(modeExecute[i]);
         }
    }

    private void executeMode(String s) {
        IMode mode = (IMode) modeMap.get(s);
        if (mode == null) doDefault(1);
        else mode.execute(1);
    }

    protected Map modeMap = new HashMap();
    public final static String modeClassHeader = "Ex";
    String expectedClassNameHeader = this.getClass().getName() + "$" + modeClassHeader;

    private void initModeMapWithReflection(String[] modeExecute) throws InstantiationException, InvocationTargetException, IllegalAccessException, NoSuchMethodException {
        Class[] consParamClasses = new Class[]{this.getClass()};
        Object[] consParams = new Object[]{this};


        Class[] inners = this.getClass().getClasses();
        for (int i=0;i<inners.length;i++) {
            if (inners[i].getName().startsWith(expectedClassNameHeader)) {
                Constructor innerCons = inners[i].getDeclaredConstructor(consParamClasses);
                modeMap.put(modeExecute[i], innerCons.newInstance(consParams));
            }
        }
    }

    public void doDefault(int i) {
        i = 100;
    }

    public class ExOne implements IMode {
        public void execute(int i) {
            i = 10;
        }
    }

    public  class ExTwo implements IMode {
        public void execute(int i) {
            i = 10;
        }
    }

    public class ExThree implements IMode {
        public void execute(int i) {
            i = 10;
        }
    }

    public class ExFour implements IMode {
        public void execute(int i) {
            i = 10;
        }
    }

    public class ExFive implements IMode {
        public void execute(int i) {
            i = 10;
        }
    }
}

�� 방법�� Mode ��가�� 그냥 ExModeName ��로 ��가��면 된다. 그러면�� Mode �� 기 부�� 변�� 는다. Reflection��로 table lookup ��는 부��나 Mode �� 기 부�� 래��로 �� 다. ��먼��면��는 ��로 �� 동��로 map �� 는 방법과 같다. ��과 ��먼�� 두가��가 �� 는 방법��다.

�� 들�� 기 �� runner class.

~cpp 
import java.lang.reflect.InvocationTargetException;

/*
  ���가���려는 ������들 :
  1. ���당 method ��� naming ���로 reflection call.
  2. switch - case 로 mode 구��.
  3. interface & class - command pattern ��� 구���.

  ���가������들
  1. ���당 ���드 ������대�� 늘���나는 반복 ������들
  2. performance
  3. maintance
*/
public class ModeChoicePerformanceTest {
    public static final int LOOPING_COUNT = 1000000;

    public static void main(String[] args) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, ClassNotFoundException, InstantiationException {
        String[] modeExecute = new String[]{"One", "Two", "Three", "Four", "Five", "hugu"};

        new IfElse().printPerformance(modeExecute);
        new MethodFullReflection().printPerformance(modeExecute);
        new MethodTableLookupReflection().printPerformance(modeExecute);
        new InterfaceTableLookup().printPerformance(modeExecute);
        new InterfaceTableLookupReflection().printPerformance(modeExecute);
    }
}

결과 ¶

~cpp 
if - else elapsed time :611ms 
elapsed time :61889ms 
reflection with method initialize table elapsed time :0ms 
reflection with method elapsed time :6459ms 
interface table lookup init table elapsed time :10ms 
interface table lookup elapsed time :741ms 
interface reflection & table lookup init able elapsed time :10ms 
interface reflection & table lookup elapsed time :731ms

Java

Java/Mode Selection Performance Test

1. if-else ¶

두����� - Method reflection ¶

��������. ������ 방법��� 보������ 방법���다. 바로 ��������� Table Lookup. ¶

��������. Inner Class ��� 대��� Command Pattern ��� ������. ¶

�����막 방법 - interface & reflection ¶

결과 ¶

두�� - Method reflection ¶

��. �� 방법�� 보�� 방법��다. 바로 �� Table Lookup. ¶

��. Inner Class �� 대�� Command Pattern �� . ¶

��막 방법 - interface & reflection ¶