ThreadLocalCacheTest.java

package com.alibaba.json.bvt.util;

import java.lang.reflect.Field;
import java.lang.reflect.Method;

import org.junit.Assert;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializeWriter;
import com.alibaba.fastjson.util.IOUtils;

import junit.framework.TestCase;

public class ThreadLocalCacheTest extends TestCase {

    public void test() throws Exception {

        clearChars();
        Assert.assertEquals(allocateChars(0).length, 1024 * 64);
        Assert.assertEquals(allocateChars(1024).length, 1024 * 64);
        Assert.assertEquals(allocateChars(2048).length, 1024 * 64);
        Assert.assertEquals(allocateChars(0).length, 1024 * 64);
        Assert.assertEquals(allocateChars(1024 * 128).length, 1024 * 128);
        Assert.assertEquals(allocateChars(0).length, 1024 * 64);

        clearChars();
        Assert.assertEquals(allocateChars(2048).length, 1024 * 64);

        clearChars();
        Assert.assertEquals(allocateChars(1024 * 256).length, 1024 * 256);
        Assert.assertEquals(allocateChars(0).length, 1024 * 64);
        clearChars();

    }
    
    static char[] allocateChars(int length) throws Exception {
        Method method = JSON.class.getDeclaredMethod("allocateChars", int.class);
        method.setAccessible(true);
        return (char[]) method.invoke(null, length);
    }
    
    public static void clearChars() throws Exception {
        Field field = JSON.class.getDeclaredField("charsLocal");
        field.setAccessible(true);
        
        ThreadLocal<char[]> charsLocal = (ThreadLocal<char[]>) field.get(null);
        charsLocal.set(null);
    }

    public void testBytes() throws Exception {

        clearBytes();
        Assert.assertEquals(getBytes(0).length, 8192);
        Assert.assertEquals(getBytes(1024).length, 8192);
        Assert.assertEquals(getBytes(8192 * 2).length, 8192 * 2);
        Assert.assertEquals(getBytes(0).length, 8192);
        Assert.assertSame(getBytes(0), getBytes(1204));
        Assert.assertNotSame(getBytes(9000), getBytes(9000));

        clearBytes();
        Assert.assertEquals(getBytes(2048).length, 8192);

        clearBytes();
        Assert.assertEquals(getBytes(1024 * 256).length, 1024 * 256);
        Assert.assertEquals(getBytes(0).length, 8192);
        clearBytes();

    }
    
    public static byte[] getBytes(int length) throws Exception {
        Field field = SerializeWriter.class.getDeclaredField("bytesBufLocal");
        field.setAccessible(true);
        ThreadLocal<byte[]> bytesBufLocal = (ThreadLocal<byte[]>) field.get(null);
        
        byte[] bytes = bytesBufLocal.get();

        if (bytes == null) {
            bytes = new byte[1024 * 8];
            bytesBufLocal.set(bytes);
        }
        
        return bytes.length < length //
            ? new byte[length] //
            : bytes;
    }
    
    public static void clearBytes() throws Exception {
        Field field = SerializeWriter.class.getDeclaredField("bytesBufLocal");
        field.setAccessible(true);
        ThreadLocal<byte[]> bytesBufLocal = (ThreadLocal<byte[]>) field.get(null);
        bytesBufLocal.set(null);
    }
}