package info.xiancloud.yy;

import org.apache.logging.log4j.util.StackLocatorUtil;

/**
 * Test the speed of various methods for getting the caller class name
 */
public class TestGetCallerClassName {

    /**
     * Abstract class for testing different methods of getting the caller class name
     */
    private static abstract class GetCallerClassNameMethod {
        public abstract String getCallerClassName(int callStackDepth);

        public abstract String getMethodName();
    }

    /**
     * Uses the internal Reflection class
     */
    private static class ReflectionMethod extends GetCallerClassNameMethod {
        public String getCallerClassName(int callStackDepth) {
            return sun.reflect.Reflection.getCallerClass(callStackDepth).getName();
        }

        public String getMethodName() {
            return "Reflection";
        }
    }

    /**
     * Get a stack trace from the current thread
     */
    private static class ThreadStackTraceMethod extends GetCallerClassNameMethod {
        public String getCallerClassName(int callStackDepth) {
            return Thread.currentThread().getStackTrace()[callStackDepth].getClassName();
        }

        public String getMethodName() {
            return "Current Thread StackTrace";
        }
    }

    /**
     * Get a stack trace from a new Throwable
     */
    private static class ThrowableStackTraceMethod extends GetCallerClassNameMethod {

        public String getCallerClassName(int callStackDepth) {
            return new Throwable().getStackTrace()[callStackDepth].getClassName();
        }

        public String getMethodName() {
            return "Throwable StackTrace";
        }
    }

    /**
     * Use the SecurityManager.getClassContext()
     */
    private static class SecurityManagerMethod extends GetCallerClassNameMethod {
        public String getCallerClassName(int callStackDepth) {
            return mySecurityManager.getCallerClassName(callStackDepth);
        }

        public String getMethodName() {
            return "SecurityManager";
        }

        /**
         * A custom security manager that exposes the getClassContext() information
         */
        static class MySecurityManager extends SecurityManager {
            public String getCallerClassName(int callStackDepth) {
                return getClassContext()[callStackDepth].getName();
            }
        }

        private final static MySecurityManager mySecurityManager =
                new MySecurityManager();
    }

    private static class Log4j2StackLocatorUtilMethod extends GetCallerClassNameMethod {

        @Override
        public String getCallerClassName(int callStackDepth) {
            return StackLocatorUtil.getCallerClass(callStackDepth).getName();
        }

        @Override
        public String getMethodName() {
            return "Log4j2StackLocatorUtil";
        }
    }

    /**
     * Test all four methods
     */
    public static void main(String[] args) {
        testMethod(new Log4j2StackLocatorUtilMethod());
        testMethod(new ReflectionMethod());
        testMethod(new ThreadStackTraceMethod());
        testMethod(new ThrowableStackTraceMethod());
        testMethod(new SecurityManagerMethod());
    }

    private static void testMethod(GetCallerClassNameMethod method) {
        long startTime = System.nanoTime();
        String className = null;
        for (int i = 0; i < 1000000; i++) {
            className = method.getCallerClassName(2);
        }
        printElapsedTime(method.getMethodName(), startTime);
    }

    private static void printElapsedTime(String title, long startTime) {
        System.out.println(title + ": " + ((double) (System.nanoTime() - startTime)) / 1000000 + " ms.");
    }
}