/*
 * 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 com.google.common.truth.Truth.assertThat;

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++) {
      String unused = 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++) {
      MyObject unused = 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++) {
                  String unused = gson.toJson(myObj);
                }
              } catch (Throwable t) {
                failed.set(true);
              } finally {
                finishedLatch.countDown();
              }
            }
          });
    }
    startLatch.countDown();
    finishedLatch.await();
    assertThat(failed.get()).isFalse();
  }

  /**
   * 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++) {
                  MyObject unused =
                      gson.fromJson("{'a':'hello','b':'world','i':1}", MyObject.class);
                }
              } catch (Throwable t) {
                failed.set(true);
              } finally {
                finishedLatch.countDown();
              }
            }
          });
    }
    startLatch.countDown();
    finishedLatch.await();
    assertThat(failed.get()).isFalse();
  }

  @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;
    }
  }
}
