/*
 * Copyright (C) 2008 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.gson.functional;

import static org.junit.Assert.assertFalse;

import com.google.gson.Gson;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicBoolean;
import org.junit.Before;
import org.junit.Test;

/**
 * Tests for ensuring Gson thread-safety.
 * 
 * @author Inderjeet Singh
 * @author Joel Leitch
 */
public class ConcurrencyTest {
  private Gson gson;

  @Before
  public void setUp() throws Exception {
    gson = new Gson();
  }

  /**
   * Source-code based on
   * http://groups.google.com/group/google-gson/browse_thread/thread/563bb51ee2495081
   */
  @Test
  public void testSingleThreadSerialization() { 
    MyObject myObj = new MyObject(); 
    for (int i = 0; i < 10; i++) { 
      gson.toJson(myObj); 
    } 
  } 

  /**
   * Source-code based on
   * http://groups.google.com/group/google-gson/browse_thread/thread/563bb51ee2495081
   */
  @Test
  public void testSingleThreadDeserialization() { 
    for (int i = 0; i < 10; i++) { 
      gson.fromJson("{'a':'hello','b':'world','i':1}", MyObject.class); 
    } 
  } 

  /**
   * Source-code based on
   * http://groups.google.com/group/google-gson/browse_thread/thread/563bb51ee2495081
   */
  @Test
  public void testMultiThreadSerialization() throws InterruptedException {
    final CountDownLatch startLatch = new CountDownLatch(1);
    final CountDownLatch finishedLatch = new CountDownLatch(10);
    final AtomicBoolean failed = new AtomicBoolean(false);
    ExecutorService executor = Executors.newFixedThreadPool(10);
    for (int taskCount = 0; taskCount < 10; taskCount++) {
      executor.execute(new Runnable() {
        @Override public void run() {
          MyObject myObj = new MyObject();
          try {
            startLatch.await();
            for (int i = 0; i < 10; i++) {
              gson.toJson(myObj);
            }
          } catch (Throwable t) {
            failed.set(true);
          } finally {
            finishedLatch.countDown();
          }
        }
      });
    }
    startLatch.countDown();
    finishedLatch.await();
    assertFalse(failed.get());
  }

  /**
   * Source-code based on
   * http://groups.google.com/group/google-gson/browse_thread/thread/563bb51ee2495081
   */
  @Test
  public void testMultiThreadDeserialization() throws InterruptedException {
    final CountDownLatch startLatch = new CountDownLatch(1);
    final CountDownLatch finishedLatch = new CountDownLatch(10);
    final AtomicBoolean failed = new AtomicBoolean(false);
    ExecutorService executor = Executors.newFixedThreadPool(10);
    for (int taskCount = 0; taskCount < 10; taskCount++) {
      executor.execute(new Runnable() {
        @Override public void run() {
          try {
            startLatch.await();
            for (int i = 0; i < 10; i++) {
              gson.fromJson("{'a':'hello','b':'world','i':1}", MyObject.class); 
            }
          } catch (Throwable t) {
            failed.set(true);
          } finally {
            finishedLatch.countDown();
          }
        }
      });
    }
    startLatch.countDown();
    finishedLatch.await();
    assertFalse(failed.get());
  }
  
  @SuppressWarnings("unused")
  private static class MyObject {
    String a;
    String b;
    int i;

    MyObject() {
      this("hello", "world", 42);
    }

    public MyObject(String a, String b, int i) {
      this.a = a;
      this.b = b;
      this.i = i;
    }
  }
}
