src/chrome/browser/metrics/thread_watcher_unittest.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include <math.h>
   6
   7 #include "base/basictypes.h"
   8 #include "base/bind.h"
   9 #include "base/logging.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/message_loop/message_loop.h"
  12 #include "base/message_loop/message_loop_proxy.h"
  13 #include "base/strings/string_number_conversions.h"
  14 #include "base/strings/string_split.h"
  15 #include "base/strings/string_tokenizer.h"
  16 #include "base/synchronization/condition_variable.h"
  17 #include "base/synchronization/lock.h"
  18 #include "base/threading/platform_thread.h"
  19 #include "base/time/time.h"
  20 #include "build/build_config.h"
  21 #include "chrome/browser/metrics/thread_watcher.h"
  22 #include "chrome/common/chrome_switches.h"
  23 #include "content/public/test/test_browser_thread.h"
  24 #include "testing/gtest/include/gtest/gtest.h"
  25 #include "testing/platform_test.h"
  26
  27 using base::TimeDelta;
  28 using base::TimeTicks;
  29 using content::BrowserThread;
  30
  31 enum State {
  32   INITIALIZED,        // Created ThreadWatch object.
  33   ACTIVATED,          // Thread watching activated.
  34   SENT_PING,          // Sent ping message to watched thread.
  35   RECEIVED_PONG,      // Received Pong message.
  36   DEACTIVATED,        // Thread watching de-activated.
  37 };
  38
  39 enum WaitState {
  40   UNINITIALIZED,
  41   STARTED_WAITING,    // Start waiting for state_ to change to expected_state.
  42   STOPPED_WAITING,    // Done with the waiting.
  43   ALL_DONE,           // Done with waiting for STOPPED_WAITING.
  44 };
  45
  46 enum CheckResponseState {
  47   UNKNOWN,
  48   SUCCESSFUL,         // CheckResponse was successful.
  49   FAILED,             // CheckResponse has failed.
  50 };
  51
  52 // This class helps to track and manipulate thread state during tests. This
  53 // class also has utility method to simulate hanging of watched thread by making
  54 // the watched thread wait for a very long time by posting a task on watched
  55 // thread that keeps it busy. It also has an utility method to block running of
  56 // tests until ThreadWatcher object's post-condition state changes to an
  57 // expected state.
  58 class CustomThreadWatcher : public ThreadWatcher {
  59  public:
  60   base::Lock custom_lock_;
  61   base::ConditionVariable state_changed_;
  62   State thread_watcher_state_;
  63   WaitState wait_state_;
  64   CheckResponseState check_response_state_;
  65   uint64 ping_sent_;
  66   uint64 pong_received_;
  67   base::subtle::Atomic32 success_response_;
  68   base::subtle::Atomic32 failed_response_;
  69   base::TimeTicks saved_ping_time_;
  70   uint64 saved_ping_sequence_number_;
  71
  72   CustomThreadWatcher(const BrowserThread::ID thread_id,
  73                       const std::string thread_name,
  74                       const TimeDelta& sleep_time,
  75                       const TimeDelta& unresponsive_time)
  76       : ThreadWatcher(WatchingParams(thread_id, thread_name, sleep_time,
  77                       unresponsive_time, ThreadWatcherList::kUnresponsiveCount,
  78                       true, ThreadWatcherList::kLiveThreadsThreshold)),
  79         state_changed_(&custom_lock_),
  80         thread_watcher_state_(INITIALIZED),
  81         wait_state_(UNINITIALIZED),
  82         check_response_state_(UNKNOWN),
  83         ping_sent_(0),
  84         pong_received_(0),
  85         success_response_(0),
  86         failed_response_(0),
  87         saved_ping_time_(base::TimeTicks::Now()),
  88         saved_ping_sequence_number_(0) {
  89   }
  90
  91   State UpdateState(State new_state) {
  92     State old_state;
  93     {
  94       base::AutoLock auto_lock(custom_lock_);
  95       old_state = thread_watcher_state_;
  96       if (old_state != DEACTIVATED)
  97         thread_watcher_state_ = new_state;
  98       if (new_state == SENT_PING)
  99         ++ping_sent_;
 100       if (new_state == RECEIVED_PONG)
 101         ++pong_received_;
 102       saved_ping_time_ = ping_time();
 103       saved_ping_sequence_number_ = ping_sequence_number();
 104     }
 105     state_changed_.Broadcast();
 106     return old_state;
 107   }
 108
 109   WaitState UpdateWaitState(WaitState new_state) {
 110     WaitState old_state;
 111     {
 112       base::AutoLock auto_lock(custom_lock_);
 113       old_state = wait_state_;
 114       wait_state_ = new_state;
 115     }
 116     state_changed_.Broadcast();
 117     return old_state;
 118   }
 119
 120   virtual void ActivateThreadWatching() OVERRIDE {
 121     State old_state = UpdateState(ACTIVATED);
 122     EXPECT_EQ(old_state, INITIALIZED);
 123     ThreadWatcher::ActivateThreadWatching();
 124   }
 125
 126   virtual void DeActivateThreadWatching() OVERRIDE {
 127     State old_state = UpdateState(DEACTIVATED);
 128     EXPECT_TRUE(old_state == ACTIVATED || old_state == SENT_PING ||
 129                 old_state == RECEIVED_PONG);
 130     ThreadWatcher::DeActivateThreadWatching();
 131   }
 132
 133   virtual void PostPingMessage() OVERRIDE {
 134     State old_state = UpdateState(SENT_PING);
 135     EXPECT_TRUE(old_state == ACTIVATED || old_state == RECEIVED_PONG);
 136     ThreadWatcher::PostPingMessage();
 137   }
 138
 139   virtual void OnPongMessage(uint64 ping_sequence_number) OVERRIDE {
 140     State old_state = UpdateState(RECEIVED_PONG);
 141     EXPECT_TRUE(old_state == SENT_PING || old_state == DEACTIVATED);
 142     ThreadWatcher::OnPongMessage(ping_sequence_number);
 143   }
 144
 145   virtual void OnCheckResponsiveness(uint64 ping_sequence_number) OVERRIDE {
 146     ThreadWatcher::OnCheckResponsiveness(ping_sequence_number);
 147     {
 148       base::AutoLock auto_lock(custom_lock_);
 149       if (responsive_) {
 150         base::subtle::Release_Store(&success_response_,
 151             base::subtle::Acquire_Load(&success_response_) + 1);
 152         check_response_state_ = SUCCESSFUL;
 153       } else {
 154         base::subtle::Release_Store(&failed_response_,
 155             base::subtle::Acquire_Load(&failed_response_) + 1);
 156         check_response_state_ = FAILED;
 157       }
 158     }
 159     // Broadcast to indicate we have checked responsiveness of the thread that
 160     // is watched.
 161     state_changed_.Broadcast();
 162   }
 163
 164   void WaitForWaitStateChange(TimeDelta wait_time, WaitState expected_state) {
 165     DCHECK(!WatchDogThread::CurrentlyOnWatchDogThread());
 166     TimeTicks end_time = TimeTicks::Now() + wait_time;
 167     {
 168       base::AutoLock auto_lock(custom_lock_);
 169       while (wait_state_ != expected_state && TimeTicks::Now() < end_time)
 170         state_changed_.TimedWait(end_time - TimeTicks::Now());
 171     }
 172   }
 173
 174   void VeryLongMethod(TimeDelta wait_time) {
 175     DCHECK(!WatchDogThread::CurrentlyOnWatchDogThread());
 176     WaitForWaitStateChange(wait_time, STOPPED_WAITING);
 177     UpdateWaitState(ALL_DONE);
 178   }
 179
 180   State WaitForStateChange(const TimeDelta& wait_time, State expected_state) {
 181     DCHECK(!WatchDogThread::CurrentlyOnWatchDogThread());
 182     UpdateWaitState(STARTED_WAITING);
 183
 184     State exit_state = INITIALIZED;
 185     // Keep the thread that is running the tests waiting until ThreadWatcher
 186     // object's state changes to the expected_state or until wait_time elapses.
 187     for (uint32 i = 0; i < unresponsive_threshold_; ++i) {
 188         TimeTicks end_time = TimeTicks::Now() + wait_time;
 189         {
 190           base::AutoLock auto_lock(custom_lock_);
 191           while (thread_watcher_state_ != expected_state &&
 192                  TimeTicks::Now() < end_time) {
 193             TimeDelta state_change_wait_time = end_time - TimeTicks::Now();
 194             state_changed_.TimedWait(state_change_wait_time);
 195           }
 196           // Capture the thread_watcher_state_ before it changes and return it
 197           // to the caller.
 198           exit_state = thread_watcher_state_;
 199           if (exit_state == expected_state)
 200             break;
 201         }
 202     }
 203     UpdateWaitState(STOPPED_WAITING);
 204     return exit_state;
 205   }
 206
 207   CheckResponseState WaitForCheckResponse(const TimeDelta& wait_time,
 208                                           CheckResponseState expected_state) {
 209     DCHECK(!WatchDogThread::CurrentlyOnWatchDogThread());
 210     UpdateWaitState(STARTED_WAITING);
 211
 212     CheckResponseState exit_state = UNKNOWN;
 213     // Keep the thread that is running the tests waiting until ThreadWatcher
 214     // object's check_response_state_ changes to the expected_state or until
 215     // wait_time elapses.
 216     for (uint32 i = 0; i < unresponsive_threshold_; ++i) {
 217         TimeTicks end_time = TimeTicks::Now() + wait_time;
 218         {
 219           base::AutoLock auto_lock(custom_lock_);
 220           while (check_response_state_ != expected_state &&
 221                  TimeTicks::Now() < end_time) {
 222             TimeDelta state_change_wait_time = end_time - TimeTicks::Now();
 223             state_changed_.TimedWait(state_change_wait_time);
 224           }
 225           // Capture the check_response_state_ before it changes and return it
 226           // to the caller.
 227           exit_state = check_response_state_;
 228           if (exit_state == expected_state)
 229             break;
 230         }
 231     }
 232     UpdateWaitState(STOPPED_WAITING);
 233     return exit_state;
 234   }
 235 };
 236
 237 class ThreadWatcherTest : public ::testing::Test {
 238  public:
 239   static const TimeDelta kSleepTime;
 240   static const TimeDelta kUnresponsiveTime;
 241   static const BrowserThread::ID io_thread_id;
 242   static const std::string io_thread_name;
 243   static const BrowserThread::ID db_thread_id;
 244   static const std::string db_thread_name;
 245   static const std::string crash_on_hang_seconds;
 246   static const std::string crash_on_hang_thread_names;
 247   static const std::string thread_names_and_live_threshold;
 248   static const std::string crash_on_hang_thread_data;
 249   CustomThreadWatcher* io_watcher_;
 250   CustomThreadWatcher* db_watcher_;
 251   ThreadWatcherList* thread_watcher_list_;
 252
 253   ThreadWatcherTest()
 254       : setup_complete_(&lock_),
 255         initialized_(false) {
 256     db_thread_.reset(new content::TestBrowserThread(BrowserThread::DB));
 257     io_thread_.reset(new content::TestBrowserThread(BrowserThread::IO));
 258     watchdog_thread_.reset(new WatchDogThread());
 259     db_thread_->Start();
 260     io_thread_->Start();
 261     watchdog_thread_->Start();
 262
 263     WatchDogThread::PostTask(
 264         FROM_HERE,
 265         base::Bind(&ThreadWatcherTest::SetUpObjects, base::Unretained(this)));
 266
 267     WaitForSetUp(TimeDelta::FromMinutes(1));
 268   }
 269
 270   void SetUpObjects() {
 271     DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
 272
 273     // Setup the registry for thread watchers.
 274     thread_watcher_list_ = new ThreadWatcherList();
 275
 276     // Create thread watcher object for the IO thread.
 277     io_watcher_ = new CustomThreadWatcher(io_thread_id, io_thread_name,
 278                                           kSleepTime, kUnresponsiveTime);
 279     EXPECT_EQ(io_watcher_, thread_watcher_list_->Find(io_thread_id));
 280
 281     // Create thread watcher object for the DB thread.
 282     db_watcher_ = new CustomThreadWatcher(
 283         db_thread_id, db_thread_name, kSleepTime, kUnresponsiveTime);
 284     EXPECT_EQ(db_watcher_, thread_watcher_list_->Find(db_thread_id));
 285
 286     {
 287       base::AutoLock lock(lock_);
 288       initialized_ = true;
 289     }
 290     setup_complete_.Signal();
 291   }
 292
 293   void WaitForSetUp(TimeDelta wait_time) {
 294     DCHECK(!WatchDogThread::CurrentlyOnWatchDogThread());
 295     TimeTicks end_time = TimeTicks::Now() + wait_time;
 296     {
 297       base::AutoLock auto_lock(lock_);
 298       while (!initialized_ && TimeTicks::Now() < end_time)
 299         setup_complete_.TimedWait(end_time - TimeTicks::Now());
 300     }
 301   }
 302
 303   virtual ~ThreadWatcherTest() {
 304     ThreadWatcherList::DeleteAll();
 305     io_watcher_ = NULL;
 306     db_watcher_ = NULL;
 307     io_thread_.reset();
 308     db_thread_.reset();
 309     watchdog_thread_.reset();
 310     thread_watcher_list_ = NULL;
 311   }
 312
 313  private:
 314   base::Lock lock_;
 315   base::ConditionVariable setup_complete_;
 316   bool initialized_;
 317   scoped_ptr<content::TestBrowserThread> db_thread_;
 318   scoped_ptr<content::TestBrowserThread> io_thread_;
 319   scoped_ptr<WatchDogThread> watchdog_thread_;
 320 };
 321
 322 // Define static constants.
 323 const TimeDelta ThreadWatcherTest::kSleepTime =
 324     TimeDelta::FromMilliseconds(50);
 325 const TimeDelta ThreadWatcherTest::kUnresponsiveTime =
 326     TimeDelta::FromMilliseconds(500);
 327 const BrowserThread::ID ThreadWatcherTest::io_thread_id = BrowserThread::IO;
 328 const std::string ThreadWatcherTest::io_thread_name = "IO";
 329 const BrowserThread::ID ThreadWatcherTest::db_thread_id = BrowserThread::DB;
 330 const std::string ThreadWatcherTest::db_thread_name = "DB";
 331 const std::string ThreadWatcherTest::crash_on_hang_thread_names = "UI,IO";
 332 const std::string ThreadWatcherTest::thread_names_and_live_threshold =
 333     "UI:4,IO:4";
 334 const std::string ThreadWatcherTest::crash_on_hang_thread_data =
 335     "UI:5:12,IO:5:12,FILE:5:12";
 336
 337 TEST_F(ThreadWatcherTest, ThreadNamesOnlyArgs) {
 338   // Setup command_line arguments.
 339   CommandLine command_line(CommandLine::NO_PROGRAM);
 340   command_line.AppendSwitchASCII(switches::kCrashOnHangThreads,
 341                                  crash_on_hang_thread_names);
 342
 343   // Parse command_line arguments.
 344   ThreadWatcherList::CrashOnHangThreadMap crash_on_hang_threads;
 345   uint32 unresponsive_threshold;
 346   ThreadWatcherList::ParseCommandLine(command_line,
 347                                       &unresponsive_threshold,
 348                                       &crash_on_hang_threads);
 349
 350   // Verify the data.
 351   base::StringTokenizer tokens(crash_on_hang_thread_names, ",");
 352   std::vector<std::string> values;
 353   while (tokens.GetNext()) {
 354     const std::string& token = tokens.token();
 355     base::SplitString(token, ':', &values);
 356     std::string thread_name = values[0];
 357
 358     ThreadWatcherList::CrashOnHangThreadMap::iterator it =
 359         crash_on_hang_threads.find(thread_name);
 360     bool crash_on_hang = (it != crash_on_hang_threads.end());
 361     EXPECT_TRUE(crash_on_hang);
 362     EXPECT_LT(0u, it->second.live_threads_threshold);
 363     EXPECT_LT(0u, it->second.unresponsive_threshold);
 364   }
 365 }
 366
 367 TEST_F(ThreadWatcherTest, ThreadNamesAndLiveThresholdArgs) {
 368   // Setup command_line arguments.
 369   CommandLine command_line(CommandLine::NO_PROGRAM);
 370   command_line.AppendSwitchASCII(switches::kCrashOnHangThreads,
 371                                  thread_names_and_live_threshold);
 372
 373   // Parse command_line arguments.
 374   ThreadWatcherList::CrashOnHangThreadMap crash_on_hang_threads;
 375   uint32 unresponsive_threshold;
 376   ThreadWatcherList::ParseCommandLine(command_line,
 377                                       &unresponsive_threshold,
 378                                       &crash_on_hang_threads);
 379
 380   // Verify the data.
 381   base::StringTokenizer tokens(thread_names_and_live_threshold, ",");
 382   std::vector<std::string> values;
 383   while (tokens.GetNext()) {
 384     const std::string& token = tokens.token();
 385     base::SplitString(token, ':', &values);
 386     std::string thread_name = values[0];
 387
 388     ThreadWatcherList::CrashOnHangThreadMap::iterator it =
 389         crash_on_hang_threads.find(thread_name);
 390     bool crash_on_hang = (it != crash_on_hang_threads.end());
 391     EXPECT_TRUE(crash_on_hang);
 392     EXPECT_EQ(4u, it->second.live_threads_threshold);
 393     EXPECT_LT(0u, it->second.unresponsive_threshold);
 394   }
 395 }
 396
 397 TEST_F(ThreadWatcherTest, CrashOnHangThreadsAllArgs) {
 398   // Setup command_line arguments.
 399   CommandLine command_line(CommandLine::NO_PROGRAM);
 400   command_line.AppendSwitchASCII(switches::kCrashOnHangThreads,
 401                                  crash_on_hang_thread_data);
 402
 403   // Parse command_line arguments.
 404   ThreadWatcherList::CrashOnHangThreadMap crash_on_hang_threads;
 405   uint32 unresponsive_threshold;
 406   ThreadWatcherList::ParseCommandLine(command_line,
 407                                       &unresponsive_threshold,
 408                                       &crash_on_hang_threads);
 409
 410   // Verify the data.
 411   base::StringTokenizer tokens(crash_on_hang_thread_data, ",");
 412   std::vector<std::string> values;
 413   while (tokens.GetNext()) {
 414     const std::string& token = tokens.token();
 415     base::SplitString(token, ':', &values);
 416     std::string thread_name = values[0];
 417
 418     ThreadWatcherList::CrashOnHangThreadMap::iterator it =
 419         crash_on_hang_threads.find(thread_name);
 420
 421     bool crash_on_hang = (it != crash_on_hang_threads.end());
 422     EXPECT_TRUE(crash_on_hang);
 423
 424     uint32 crash_live_threads_threshold = it->second.live_threads_threshold;
 425     EXPECT_EQ(5u, crash_live_threads_threshold);
 426
 427     uint32 crash_unresponsive_threshold = it->second.unresponsive_threshold;
 428     uint32 crash_on_unresponsive_seconds =
 429         ThreadWatcherList::kUnresponsiveSeconds * crash_unresponsive_threshold;
 430     EXPECT_EQ(12u, crash_on_unresponsive_seconds);
 431   }
 432 }
 433
 434 // Test registration. When thread_watcher_list_ goes out of scope after
 435 // TearDown, all thread watcher objects will be deleted.
 436 TEST_F(ThreadWatcherTest, Registration) {
 437   // Check ThreadWatcher object has all correct parameters.
 438   EXPECT_EQ(io_thread_id, io_watcher_->thread_id());
 439   EXPECT_EQ(io_thread_name, io_watcher_->thread_name());
 440   EXPECT_EQ(kSleepTime, io_watcher_->sleep_time());
 441   EXPECT_EQ(kUnresponsiveTime, io_watcher_->unresponsive_time());
 442   EXPECT_FALSE(io_watcher_->active());
 443
 444   // Check ThreadWatcher object of watched DB thread has correct data.
 445   EXPECT_EQ(db_thread_id, db_watcher_->thread_id());
 446   EXPECT_EQ(db_thread_name, db_watcher_->thread_name());
 447   EXPECT_EQ(kSleepTime, db_watcher_->sleep_time());
 448   EXPECT_EQ(kUnresponsiveTime, db_watcher_->unresponsive_time());
 449   EXPECT_FALSE(db_watcher_->active());
 450 }
 451
 452 // Test ActivateThreadWatching and DeActivateThreadWatching of IO thread. This
 453 // method also checks that pong message was sent by the watched thread and pong
 454 // message was received by the WatchDogThread. It also checks that
 455 // OnCheckResponsiveness has verified the ping-pong mechanism and the watched
 456 // thread is not hung.
 457 TEST_F(ThreadWatcherTest, ThreadResponding) {
 458   TimeTicks time_before_ping = TimeTicks::Now();
 459   // Activate watching IO thread.
 460   WatchDogThread::PostTask(
 461       FROM_HERE,
 462       base::Bind(&ThreadWatcher::ActivateThreadWatching,
 463                  base::Unretained(io_watcher_)));
 464
 465   // Activate would have started ping/pong messaging. Expect atleast one
 466   // ping/pong messaging sequence to happen.
 467   io_watcher_->WaitForStateChange(kSleepTime + TimeDelta::FromMinutes(1),
 468                                   RECEIVED_PONG);
 469   EXPECT_GT(io_watcher_->ping_sent_, static_cast<uint64>(0));
 470   EXPECT_GT(io_watcher_->pong_received_, static_cast<uint64>(0));
 471   EXPECT_TRUE(io_watcher_->active());
 472   EXPECT_GE(io_watcher_->saved_ping_time_, time_before_ping);
 473   EXPECT_GE(io_watcher_->saved_ping_sequence_number_, static_cast<uint64>(0));
 474
 475   // Verify watched thread is responding with ping/pong messaging.
 476   io_watcher_->WaitForCheckResponse(
 477       kUnresponsiveTime + TimeDelta::FromMinutes(1), SUCCESSFUL);
 478   EXPECT_GT(base::subtle::NoBarrier_Load(&(io_watcher_->success_response_)),
 479       static_cast<base::subtle::Atomic32>(0));
 480   EXPECT_EQ(base::subtle::NoBarrier_Load(&(io_watcher_->failed_response_)),
 481       static_cast<base::subtle::Atomic32>(0));
 482
 483   // DeActivate thread watching for shutdown.
 484   WatchDogThread::PostTask(
 485       FROM_HERE,
 486       base::Bind(&ThreadWatcher::DeActivateThreadWatching,
 487       base::Unretained(io_watcher_)));
 488 }
 489
 490 // This test posts a task on watched thread that takes very long time (this is
 491 // to simulate hanging of watched thread). It then checks for
 492 // OnCheckResponsiveness raising an alert (OnCheckResponsiveness returns false
 493 // if the watched thread is not responding).
 494 TEST_F(ThreadWatcherTest, ThreadNotResponding) {
 495   // Simulate hanging of watched thread by making the watched thread wait for a
 496   // very long time by posting a task on watched thread that keeps it busy.
 497   // It is safe to use base::Unretained because test is waiting for the method
 498   // to finish.
 499   BrowserThread::PostTask(
 500       io_thread_id,
 501       FROM_HERE,
 502       base::Bind(&CustomThreadWatcher::VeryLongMethod,
 503                  base::Unretained(io_watcher_),
 504                  kUnresponsiveTime * 10));
 505
 506   // Activate thread watching.
 507   WatchDogThread::PostTask(
 508       FROM_HERE,
 509       base::Bind(&ThreadWatcher::ActivateThreadWatching,
 510                  base::Unretained(io_watcher_)));
 511
 512   // Verify watched thread is not responding for ping messages.
 513   io_watcher_->WaitForCheckResponse(
 514       kUnresponsiveTime + TimeDelta::FromMinutes(1), FAILED);
 515   EXPECT_EQ(base::subtle::NoBarrier_Load(&(io_watcher_->success_response_)),
 516       static_cast<base::subtle::Atomic32>(0));
 517   EXPECT_GT(base::subtle::NoBarrier_Load(&(io_watcher_->failed_response_)),
 518       static_cast<base::subtle::Atomic32>(0));
 519
 520   // DeActivate thread watching for shutdown.
 521   WatchDogThread::PostTask(
 522       FROM_HERE,
 523       base::Bind(&ThreadWatcher::DeActivateThreadWatching,
 524                  base::Unretained(io_watcher_)));
 525
 526   // Wait for the io_watcher_'s VeryLongMethod to finish.
 527   io_watcher_->WaitForWaitStateChange(kUnresponsiveTime * 10, ALL_DONE);
 528 }
 529
 530 // Test watching of multiple threads with all threads not responding.
 531 TEST_F(ThreadWatcherTest, MultipleThreadsResponding) {
 532   // Check for DB thread to perform ping/pong messaging.
 533   WatchDogThread::PostTask(
 534       FROM_HERE,
 535       base::Bind(&ThreadWatcher::ActivateThreadWatching,
 536                  base::Unretained(db_watcher_)));
 537
 538   // Check for IO thread to perform ping/pong messaging.
 539   WatchDogThread::PostTask(
 540       FROM_HERE,
 541       base::Bind(&ThreadWatcher::ActivateThreadWatching,
 542                  base::Unretained(io_watcher_)));
 543
 544   // Verify DB thread is responding with ping/pong messaging.
 545   db_watcher_->WaitForCheckResponse(
 546       kUnresponsiveTime + TimeDelta::FromMinutes(1), SUCCESSFUL);
 547   EXPECT_GT(db_watcher_->ping_sent_, static_cast<uint64>(0));
 548   EXPECT_GT(db_watcher_->pong_received_, static_cast<uint64>(0));
 549   EXPECT_GE(db_watcher_->ping_sequence_number_, static_cast<uint64>(0));
 550   EXPECT_GT(base::subtle::NoBarrier_Load(&(db_watcher_->success_response_)),
 551       static_cast<base::subtle::Atomic32>(0));
 552   EXPECT_EQ(base::subtle::NoBarrier_Load(&(db_watcher_->failed_response_)),
 553       static_cast<base::subtle::Atomic32>(0));
 554
 555   // Verify IO thread is responding with ping/pong messaging.
 556   io_watcher_->WaitForCheckResponse(
 557       kUnresponsiveTime + TimeDelta::FromMinutes(1), SUCCESSFUL);
 558   EXPECT_GT(io_watcher_->ping_sent_, static_cast<uint64>(0));
 559   EXPECT_GT(io_watcher_->pong_received_, static_cast<uint64>(0));
 560   EXPECT_GE(io_watcher_->ping_sequence_number_, static_cast<uint64>(0));
 561   EXPECT_GT(base::subtle::NoBarrier_Load(&(io_watcher_->success_response_)),
 562       static_cast<base::subtle::Atomic32>(0));
 563   EXPECT_EQ(base::subtle::NoBarrier_Load(&(io_watcher_->failed_response_)),
 564       static_cast<base::subtle::Atomic32>(0));
 565
 566   // DeActivate thread watching for shutdown.
 567   WatchDogThread::PostTask(
 568       FROM_HERE,
 569       base::Bind(&ThreadWatcher::DeActivateThreadWatching,
 570                  base::Unretained(io_watcher_)));
 571
 572   WatchDogThread::PostTask(
 573       FROM_HERE,
 574       base::Bind(&ThreadWatcher::DeActivateThreadWatching,
 575                  base::Unretained(db_watcher_)));
 576 }
 577
 578 // Test watching of multiple threads with one of the threads not responding.
 579 TEST_F(ThreadWatcherTest, MultipleThreadsNotResponding) {
 580   // Simulate hanging of watched thread by making the watched thread wait for a
 581   // very long time by posting a task on watched thread that keeps it busy.
 582   // It is safe ot use base::Unretained because test is waiting for the method
 583   // to finish.
 584   BrowserThread::PostTask(
 585       io_thread_id,
 586       FROM_HERE,
 587       base::Bind(&CustomThreadWatcher::VeryLongMethod,
 588                  base::Unretained(io_watcher_),
 589                  kUnresponsiveTime * 10));
 590
 591   // Activate watching of DB thread.
 592   WatchDogThread::PostTask(
 593       FROM_HERE,
 594       base::Bind(&ThreadWatcher::ActivateThreadWatching,
 595                  base::Unretained(db_watcher_)));
 596
 597   // Activate watching of IO thread.
 598   WatchDogThread::PostTask(
 599       FROM_HERE,
 600       base::Bind(&ThreadWatcher::ActivateThreadWatching,
 601                  base::Unretained(io_watcher_)));
 602
 603   // Verify DB thread is responding with ping/pong messaging.
 604   db_watcher_->WaitForCheckResponse(
 605       kUnresponsiveTime + TimeDelta::FromMinutes(1), SUCCESSFUL);
 606   EXPECT_GT(base::subtle::NoBarrier_Load(&(db_watcher_->success_response_)),
 607       static_cast<base::subtle::Atomic32>(0));
 608   EXPECT_EQ(base::subtle::NoBarrier_Load(&(db_watcher_->failed_response_)),
 609       static_cast<base::subtle::Atomic32>(0));
 610
 611   // Verify IO thread is not responding for ping messages.
 612   io_watcher_->WaitForCheckResponse(
 613       kUnresponsiveTime + TimeDelta::FromMinutes(1), FAILED);
 614   EXPECT_EQ(base::subtle::NoBarrier_Load(&(io_watcher_->success_response_)),
 615       static_cast<base::subtle::Atomic32>(0));
 616   EXPECT_GT(base::subtle::NoBarrier_Load(&(io_watcher_->failed_response_)),
 617       static_cast<base::subtle::Atomic32>(0));
 618
 619   // DeActivate thread watching for shutdown.
 620   WatchDogThread::PostTask(
 621       FROM_HERE,
 622       base::Bind(&ThreadWatcher::DeActivateThreadWatching,
 623                  base::Unretained(io_watcher_)));
 624   WatchDogThread::PostTask(
 625       FROM_HERE,
 626       base::Bind(&ThreadWatcher::DeActivateThreadWatching,
 627                  base::Unretained(db_watcher_)));
 628
 629   // Wait for the io_watcher_'s VeryLongMethod to finish.
 630   io_watcher_->WaitForWaitStateChange(kUnresponsiveTime * 10, ALL_DONE);
 631 }