base/tracked_objects.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 "base/tracked_objects.h"
   6
   7 #include <limits.h>
   8 #include <stdlib.h>
   9
  10 #include "base/atomicops.h"
  11 #include "base/base_switches.h"
  12 #include "base/command_line.h"
  13 #include "base/compiler_specific.h"
  14 #include "base/debug/leak_annotations.h"
  15 #include "base/logging.h"
  16 #include "base/process/process_handle.h"
  17 #include "base/profiler/alternate_timer.h"
  18 #include "base/strings/stringprintf.h"
  19 #include "base/third_party/valgrind/memcheck.h"
  20 #include "base/tracking_info.h"
  21
  22 using base::TimeDelta;
  23
  24 namespace base {
  25 class TimeDelta;
  26 }
  27
  28 namespace tracked_objects {
  29
  30 namespace {
  31 // Flag to compile out almost all of the task tracking code.
  32 const bool kTrackAllTaskObjects = true;
  33
  34 // TODO(jar): Evaluate the perf impact of enabling this.  If the perf impact is
  35 // negligible, enable by default.
  36 // Flag to compile out parent-child link recording.
  37 const bool kTrackParentChildLinks = false;
  38
  39 // When ThreadData is first initialized, should we start in an ACTIVE state to
  40 // record all of the startup-time tasks, or should we start up DEACTIVATED, so
  41 // that we only record after parsing the command line flag --enable-tracking.
  42 // Note that the flag may force either state, so this really controls only the
  43 // period of time up until that flag is parsed. If there is no flag seen, then
  44 // this state may prevail for much or all of the process lifetime.
  45 const ThreadData::Status kInitialStartupState =
  46     ThreadData::PROFILING_CHILDREN_ACTIVE;
  47
  48 // Control whether an alternate time source (Now() function) is supported by
  49 // the ThreadData class.  This compile time flag should be set to true if we
  50 // want other modules (such as a memory allocator, or a thread-specific CPU time
  51 // clock) to be able to provide a thread-specific Now() function.  Without this
  52 // compile-time flag, the code will only support the wall-clock time.  This flag
  53 // can be flipped to efficiently disable this path (if there is a performance
  54 // problem with its presence).
  55 static const bool kAllowAlternateTimeSourceHandling = true;
  56
  57 // Possible states of the profiler timing enabledness.
  58 enum {
  59   UNDEFINED_TIMING,
  60   ENABLED_TIMING,
  61   DISABLED_TIMING,
  62 };
  63
  64 // State of the profiler timing enabledness.
  65 base::subtle::Atomic32 g_profiler_timing_enabled = UNDEFINED_TIMING;
  66
  67 // Returns whether profiler timing is enabled. The default is true, but this may
  68 // be overridden by a command-line flag. Some platforms may programmatically set
  69 // this command-line flag to the "off" value if it's not specified.
  70 // This in turn can be overridden by explicitly calling
  71 // ThreadData::EnableProfilerTiming, say, based on a field trial.
  72 inline bool IsProfilerTimingEnabled() {
  73   // Reading |g_profiler_timing_enabled| is done without barrier because
  74   // multiple initialization is not an issue while the barrier can be relatively
  75   // costly given that this method is sometimes called in a tight loop.
  76   base::subtle::Atomic32 current_timing_enabled =
  77       base::subtle::NoBarrier_Load(&g_profiler_timing_enabled);
  78   if (current_timing_enabled == UNDEFINED_TIMING) {
  79     if (!base::CommandLine::InitializedForCurrentProcess())
  80       return true;
  81     current_timing_enabled =
  82         (base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
  83              switches::kProfilerTiming) ==
  84          switches::kProfilerTimingDisabledValue)
  85             ? DISABLED_TIMING
  86             : ENABLED_TIMING;
  87     base::subtle::NoBarrier_Store(&g_profiler_timing_enabled,
  88                                   current_timing_enabled);
  89   }
  90   return current_timing_enabled == ENABLED_TIMING;
  91 }
  92
  93 }  // namespace
  94
  95 //------------------------------------------------------------------------------
  96 // DeathData tallies durations when a death takes place.
  97
  98 DeathData::DeathData() {
  99   Clear();
 100 }
 101
 102 DeathData::DeathData(int count) {
 103   Clear();
 104   count_ = count;
 105 }
 106
 107 // TODO(jar): I need to see if this macro to optimize branching is worth using.
 108 //
 109 // This macro has no branching, so it is surely fast, and is equivalent to:
 110 //             if (assign_it)
 111 //               target = source;
 112 // We use a macro rather than a template to force this to inline.
 113 // Related code for calculating max is discussed on the web.
 114 #define CONDITIONAL_ASSIGN(assign_it, target, source) \
 115     ((target) ^= ((target) ^ (source)) & -static_cast<int32>(assign_it))
 116
 117 void DeathData::RecordDeath(const int32 queue_duration,
 118                             const int32 run_duration,
 119                             const uint32 random_number) {
 120   // We'll just clamp at INT_MAX, but we should note this in the UI as such.
 121   if (count_ < INT_MAX)
 122     ++count_;
 123   queue_duration_sum_ += queue_duration;
 124   run_duration_sum_ += run_duration;
 125
 126   if (queue_duration_max_ < queue_duration)
 127     queue_duration_max_ = queue_duration;
 128   if (run_duration_max_ < run_duration)
 129     run_duration_max_ = run_duration;
 130
 131   // Take a uniformly distributed sample over all durations ever supplied.
 132   // The probability that we (instead) use this new sample is 1/count_.  This
 133   // results in a completely uniform selection of the sample (at least when we
 134   // don't clamp count_... but that should be inconsequentially likely).
 135   // We ignore the fact that we correlated our selection of a sample to the run
 136   // and queue times (i.e., we used them to generate random_number).
 137   CHECK_GT(count_, 0);
 138   if (0 == (random_number % count_)) {
 139     queue_duration_sample_ = queue_duration;
 140     run_duration_sample_ = run_duration;
 141   }
 142 }
 143
 144 int DeathData::count() const { return count_; }
 145
 146 int32 DeathData::run_duration_sum() const { return run_duration_sum_; }
 147
 148 int32 DeathData::run_duration_max() const { return run_duration_max_; }
 149
 150 int32 DeathData::run_duration_sample() const {
 151   return run_duration_sample_;
 152 }
 153
 154 int32 DeathData::queue_duration_sum() const {
 155   return queue_duration_sum_;
 156 }
 157
 158 int32 DeathData::queue_duration_max() const {
 159   return queue_duration_max_;
 160 }
 161
 162 int32 DeathData::queue_duration_sample() const {
 163   return queue_duration_sample_;
 164 }
 165
 166 void DeathData::ResetMax() {
 167   run_duration_max_ = 0;
 168   queue_duration_max_ = 0;
 169 }
 170
 171 void DeathData::Clear() {
 172   count_ = 0;
 173   run_duration_sum_ = 0;
 174   run_duration_max_ = 0;
 175   run_duration_sample_ = 0;
 176   queue_duration_sum_ = 0;
 177   queue_duration_max_ = 0;
 178   queue_duration_sample_ = 0;
 179 }
 180
 181 //------------------------------------------------------------------------------
 182 DeathDataSnapshot::DeathDataSnapshot()
 183     : count(-1),
 184       run_duration_sum(-1),
 185       run_duration_max(-1),
 186       run_duration_sample(-1),
 187       queue_duration_sum(-1),
 188       queue_duration_max(-1),
 189       queue_duration_sample(-1) {
 190 }
 191
 192 DeathDataSnapshot::DeathDataSnapshot(
 193     const tracked_objects::DeathData& death_data)
 194     : count(death_data.count()),
 195       run_duration_sum(death_data.run_duration_sum()),
 196       run_duration_max(death_data.run_duration_max()),
 197       run_duration_sample(death_data.run_duration_sample()),
 198       queue_duration_sum(death_data.queue_duration_sum()),
 199       queue_duration_max(death_data.queue_duration_max()),
 200       queue_duration_sample(death_data.queue_duration_sample()) {
 201 }
 202
 203 DeathDataSnapshot::~DeathDataSnapshot() {
 204 }
 205
 206 //------------------------------------------------------------------------------
 207 BirthOnThread::BirthOnThread(const Location& location,
 208                              const ThreadData& current)
 209     : location_(location),
 210       birth_thread_(&current) {
 211 }
 212
 213 //------------------------------------------------------------------------------
 214 BirthOnThreadSnapshot::BirthOnThreadSnapshot() {
 215 }
 216
 217 BirthOnThreadSnapshot::BirthOnThreadSnapshot(
 218     const tracked_objects::BirthOnThread& birth)
 219     : location(birth.location()),
 220       thread_name(birth.birth_thread()->thread_name()) {
 221 }
 222
 223 BirthOnThreadSnapshot::~BirthOnThreadSnapshot() {
 224 }
 225
 226 //------------------------------------------------------------------------------
 227 Births::Births(const Location& location, const ThreadData& current)
 228     : BirthOnThread(location, current),
 229       birth_count_(1) { }
 230
 231 int Births::birth_count() const { return birth_count_; }
 232
 233 void Births::RecordBirth() { ++birth_count_; }
 234
 235 void Births::ForgetBirth() { --birth_count_; }
 236
 237 void Births::Clear() { birth_count_ = 0; }
 238
 239 //------------------------------------------------------------------------------
 240 // ThreadData maintains the central data for all births and deaths on a single
 241 // thread.
 242
 243 // TODO(jar): We should pull all these static vars together, into a struct, and
 244 // optimize layout so that we benefit from locality of reference during accesses
 245 // to them.
 246
 247 // static
 248 NowFunction* ThreadData::now_function_ = NULL;
 249
 250 // static
 251 bool ThreadData::now_function_is_time_ = false;
 252
 253 // A TLS slot which points to the ThreadData instance for the current thread. We
 254 // do a fake initialization here (zeroing out data), and then the real in-place
 255 // construction happens when we call tls_index_.Initialize().
 256 // static
 257 base::ThreadLocalStorage::StaticSlot ThreadData::tls_index_ = TLS_INITIALIZER;
 258
 259 // static
 260 int ThreadData::worker_thread_data_creation_count_ = 0;
 261
 262 // static
 263 int ThreadData::cleanup_count_ = 0;
 264
 265 // static
 266 int ThreadData::incarnation_counter_ = 0;
 267
 268 // static
 269 ThreadData* ThreadData::all_thread_data_list_head_ = NULL;
 270
 271 // static
 272 ThreadData* ThreadData::first_retired_worker_ = NULL;
 273
 274 // static
 275 base::LazyInstance<base::Lock>::Leaky
 276     ThreadData::list_lock_ = LAZY_INSTANCE_INITIALIZER;
 277
 278 // static
 279 ThreadData::Status ThreadData::status_ = ThreadData::UNINITIALIZED;
 280
 281 ThreadData::ThreadData(const std::string& suggested_name)
 282     : next_(NULL),
 283       next_retired_worker_(NULL),
 284       worker_thread_number_(0),
 285       incarnation_count_for_pool_(-1),
 286       current_stopwatch_(NULL) {
 287   DCHECK_GE(suggested_name.size(), 0u);
 288   thread_name_ = suggested_name;
 289   PushToHeadOfList();  // Which sets real incarnation_count_for_pool_.
 290 }
 291
 292 ThreadData::ThreadData(int thread_number)
 293     : next_(NULL),
 294       next_retired_worker_(NULL),
 295       worker_thread_number_(thread_number),
 296       incarnation_count_for_pool_(-1),
 297       current_stopwatch_(NULL) {
 298   CHECK_GT(thread_number, 0);
 299   base::StringAppendF(&thread_name_, "WorkerThread-%d", thread_number);
 300   PushToHeadOfList();  // Which sets real incarnation_count_for_pool_.
 301 }
 302
 303 ThreadData::~ThreadData() {}
 304
 305 void ThreadData::PushToHeadOfList() {
 306   // Toss in a hint of randomness (atop the uniniitalized value).
 307   (void)VALGRIND_MAKE_MEM_DEFINED_IF_ADDRESSABLE(&random_number_,
 308                                                  sizeof(random_number_));
 309   MSAN_UNPOISON(&random_number_, sizeof(random_number_));
 310   random_number_ += static_cast<uint32>(this - static_cast<ThreadData*>(0));
 311   random_number_ ^= (Now() - TrackedTime()).InMilliseconds();
 312
 313   DCHECK(!next_);
 314   base::AutoLock lock(*list_lock_.Pointer());
 315   incarnation_count_for_pool_ = incarnation_counter_;
 316   next_ = all_thread_data_list_head_;
 317   all_thread_data_list_head_ = this;
 318 }
 319
 320 // static
 321 ThreadData* ThreadData::first() {
 322   base::AutoLock lock(*list_lock_.Pointer());
 323   return all_thread_data_list_head_;
 324 }
 325
 326 ThreadData* ThreadData::next() const { return next_; }
 327
 328 // static
 329 void ThreadData::InitializeThreadContext(const std::string& suggested_name) {
 330   if (!Initialize())  // Always initialize if needed.
 331     return;
 332   ThreadData* current_thread_data =
 333       reinterpret_cast<ThreadData*>(tls_index_.Get());
 334   if (current_thread_data)
 335     return;  // Browser tests instigate this.
 336   current_thread_data = new ThreadData(suggested_name);
 337   tls_index_.Set(current_thread_data);
 338 }
 339
 340 // static
 341 ThreadData* ThreadData::Get() {
 342   if (!tls_index_.initialized())
 343     return NULL;  // For unittests only.
 344   ThreadData* registered = reinterpret_cast<ThreadData*>(tls_index_.Get());
 345   if (registered)
 346     return registered;
 347
 348   // We must be a worker thread, since we didn't pre-register.
 349   ThreadData* worker_thread_data = NULL;
 350   int worker_thread_number = 0;
 351   {
 352     base::AutoLock lock(*list_lock_.Pointer());
 353     if (first_retired_worker_) {
 354       worker_thread_data = first_retired_worker_;
 355       first_retired_worker_ = first_retired_worker_->next_retired_worker_;
 356       worker_thread_data->next_retired_worker_ = NULL;
 357     } else {
 358       worker_thread_number = ++worker_thread_data_creation_count_;
 359     }
 360   }
 361
 362   // If we can't find a previously used instance, then we have to create one.
 363   if (!worker_thread_data) {
 364     DCHECK_GT(worker_thread_number, 0);
 365     worker_thread_data = new ThreadData(worker_thread_number);
 366   }
 367   DCHECK_GT(worker_thread_data->worker_thread_number_, 0);
 368
 369   tls_index_.Set(worker_thread_data);
 370   return worker_thread_data;
 371 }
 372
 373 // static
 374 void ThreadData::OnThreadTermination(void* thread_data) {
 375   DCHECK(thread_data);  // TLS should *never* call us with a NULL.
 376   // We must NOT do any allocations during this callback. There is a chance
 377   // that the allocator is no longer active on this thread.
 378   if (!kTrackAllTaskObjects)
 379     return;  // Not compiled in.
 380   reinterpret_cast<ThreadData*>(thread_data)->OnThreadTerminationCleanup();
 381 }
 382
 383 void ThreadData::OnThreadTerminationCleanup() {
 384   // The list_lock_ was created when we registered the callback, so it won't be
 385   // allocated here despite the lazy reference.
 386   base::AutoLock lock(*list_lock_.Pointer());
 387   if (incarnation_counter_ != incarnation_count_for_pool_)
 388     return;  // ThreadData was constructed in an earlier unit test.
 389   ++cleanup_count_;
 390   // Only worker threads need to be retired and reused.
 391   if (!worker_thread_number_) {
 392     return;
 393   }
 394   // We must NOT do any allocations during this callback.
 395   // Using the simple linked lists avoids all allocations.
 396   DCHECK_EQ(this->next_retired_worker_, reinterpret_cast<ThreadData*>(NULL));
 397   this->next_retired_worker_ = first_retired_worker_;
 398   first_retired_worker_ = this;
 399 }
 400
 401 // static
 402 void ThreadData::Snapshot(bool reset_max, ProcessDataSnapshot* process_data) {
 403   // Add births that have run to completion to |collected_data|.
 404   // |birth_counts| tracks the total number of births recorded at each location
 405   // for which we have not seen a death count.
 406   BirthCountMap birth_counts;
 407   ThreadData::SnapshotAllExecutedTasks(reset_max, process_data, &birth_counts);
 408
 409   // Add births that are still active -- i.e. objects that have tallied a birth,
 410   // but have not yet tallied a matching death, and hence must be either
 411   // running, queued up, or being held in limbo for future posting.
 412   for (BirthCountMap::const_iterator it = birth_counts.begin();
 413        it != birth_counts.end(); ++it) {
 414     if (it->second > 0) {
 415       process_data->tasks.push_back(
 416           TaskSnapshot(*it->first, DeathData(it->second), "Still_Alive"));
 417     }
 418   }
 419 }
 420
 421 Births* ThreadData::TallyABirth(const Location& location) {
 422   BirthMap::iterator it = birth_map_.find(location);
 423   Births* child;
 424   if (it != birth_map_.end()) {
 425     child =  it->second;
 426     child->RecordBirth();
 427   } else {
 428     child = new Births(location, *this);  // Leak this.
 429     // Lock since the map may get relocated now, and other threads sometimes
 430     // snapshot it (but they lock before copying it).
 431     base::AutoLock lock(map_lock_);
 432     birth_map_[location] = child;
 433   }
 434
 435   if (kTrackParentChildLinks && status_ > PROFILING_ACTIVE &&
 436       !parent_stack_.empty()) {
 437     const Births* parent = parent_stack_.top();
 438     ParentChildPair pair(parent, child);
 439     if (parent_child_set_.find(pair) == parent_child_set_.end()) {
 440       // Lock since the map may get relocated now, and other threads sometimes
 441       // snapshot it (but they lock before copying it).
 442       base::AutoLock lock(map_lock_);
 443       parent_child_set_.insert(pair);
 444     }
 445   }
 446
 447   return child;
 448 }
 449
 450 void ThreadData::TallyADeath(const Births& birth,
 451                              int32 queue_duration,
 452                              const TaskStopwatch& stopwatch) {
 453   int32 run_duration = stopwatch.RunDurationMs();
 454
 455   // Stir in some randomness, plus add constant in case durations are zero.
 456   const uint32 kSomePrimeNumber = 2147483647;
 457   random_number_ += queue_duration + run_duration + kSomePrimeNumber;
 458   // An address is going to have some randomness to it as well ;-).
 459   random_number_ ^= static_cast<uint32>(&birth - reinterpret_cast<Births*>(0));
 460
 461   // We don't have queue durations without OS timer. OS timer is automatically
 462   // used for task-post-timing, so the use of an alternate timer implies all
 463   // queue times are invalid, unless it was explicitly said that we can trust
 464   // the alternate timer.
 465   if (kAllowAlternateTimeSourceHandling &&
 466       now_function_ &&
 467       !now_function_is_time_) {
 468     queue_duration = 0;
 469   }
 470
 471   DeathMap::iterator it = death_map_.find(&birth);
 472   DeathData* death_data;
 473   if (it != death_map_.end()) {
 474     death_data = &it->second;
 475   } else {
 476     base::AutoLock lock(map_lock_);  // Lock as the map may get relocated now.
 477     death_data = &death_map_[&birth];
 478   }  // Release lock ASAP.
 479   death_data->RecordDeath(queue_duration, run_duration, random_number_);
 480
 481   if (!kTrackParentChildLinks)
 482     return;
 483   if (!parent_stack_.empty()) {  // We might get turned off.
 484     DCHECK_EQ(parent_stack_.top(), &birth);
 485     parent_stack_.pop();
 486   }
 487 }
 488
 489 // static
 490 Births* ThreadData::TallyABirthIfActive(const Location& location) {
 491   if (!kTrackAllTaskObjects)
 492     return NULL;  // Not compiled in.
 493
 494   if (!TrackingStatus())
 495     return NULL;
 496   ThreadData* current_thread_data = Get();
 497   if (!current_thread_data)
 498     return NULL;
 499   return current_thread_data->TallyABirth(location);
 500 }
 501
 502 // static
 503 void ThreadData::TallyRunOnNamedThreadIfTracking(
 504     const base::TrackingInfo& completed_task,
 505     const TaskStopwatch& stopwatch) {
 506   if (!kTrackAllTaskObjects)
 507     return;  // Not compiled in.
 508
 509   // Even if we have been DEACTIVATED, we will process any pending births so
 510   // that our data structures (which counted the outstanding births) remain
 511   // consistent.
 512   const Births* birth = completed_task.birth_tally;
 513   if (!birth)
 514     return;
 515   ThreadData* current_thread_data = stopwatch.GetThreadData();
 516   if (!current_thread_data)
 517     return;
 518
 519   // Watch out for a race where status_ is changing, and hence one or both
 520   // of start_of_run or end_of_run is zero.  In that case, we didn't bother to
 521   // get a time value since we "weren't tracking" and we were trying to be
 522   // efficient by not calling for a genuine time value. For simplicity, we'll
 523   // use a default zero duration when we can't calculate a true value.
 524   TrackedTime start_of_run = stopwatch.StartTime();
 525   int32 queue_duration = 0;
 526   if (!start_of_run.is_null()) {
 527     queue_duration = (start_of_run - completed_task.EffectiveTimePosted())
 528         .InMilliseconds();
 529   }
 530   current_thread_data->TallyADeath(*birth, queue_duration, stopwatch);
 531 }
 532
 533 // static
 534 void ThreadData::TallyRunOnWorkerThreadIfTracking(
 535     const Births* birth,
 536     const TrackedTime& time_posted,
 537     const TaskStopwatch& stopwatch) {
 538   if (!kTrackAllTaskObjects)
 539     return;  // Not compiled in.
 540
 541   // Even if we have been DEACTIVATED, we will process any pending births so
 542   // that our data structures (which counted the outstanding births) remain
 543   // consistent.
 544   if (!birth)
 545     return;
 546
 547   // TODO(jar): Support the option to coalesce all worker-thread activity under
 548   // one ThreadData instance that uses locks to protect *all* access.  This will
 549   // reduce memory (making it provably bounded), but run incrementally slower
 550   // (since we'll use locks on TallyABirth and TallyADeath).  The good news is
 551   // that the locks on TallyADeath will be *after* the worker thread has run,
 552   // and hence nothing will be waiting for the completion (... besides some
 553   // other thread that might like to run).  Also, the worker threads tasks are
 554   // generally longer, and hence the cost of the lock may perchance be amortized
 555   // over the long task's lifetime.
 556   ThreadData* current_thread_data = stopwatch.GetThreadData();
 557   if (!current_thread_data)
 558     return;
 559
 560   TrackedTime start_of_run = stopwatch.StartTime();
 561   int32 queue_duration = 0;
 562   if (!start_of_run.is_null()) {
 563     queue_duration = (start_of_run - time_posted).InMilliseconds();
 564   }
 565   current_thread_data->TallyADeath(*birth, queue_duration, stopwatch);
 566 }
 567
 568 // static
 569 void ThreadData::TallyRunInAScopedRegionIfTracking(
 570     const Births* birth,
 571     const TaskStopwatch& stopwatch) {
 572   if (!kTrackAllTaskObjects)
 573     return;  // Not compiled in.
 574
 575   // Even if we have been DEACTIVATED, we will process any pending births so
 576   // that our data structures (which counted the outstanding births) remain
 577   // consistent.
 578   if (!birth)
 579     return;
 580
 581   ThreadData* current_thread_data = stopwatch.GetThreadData();
 582   if (!current_thread_data)
 583     return;
 584
 585   int32 queue_duration = 0;
 586   current_thread_data->TallyADeath(*birth, queue_duration, stopwatch);
 587 }
 588
 589 // static
 590 void ThreadData::SnapshotAllExecutedTasks(bool reset_max,
 591                                           ProcessDataSnapshot* process_data,
 592                                           BirthCountMap* birth_counts) {
 593   if (!kTrackAllTaskObjects)
 594     return;  // Not compiled in.
 595
 596   // Get an unchanging copy of a ThreadData list.
 597   ThreadData* my_list = ThreadData::first();
 598
 599   // Gather data serially.
 600   // This hackish approach *can* get some slighly corrupt tallies, as we are
 601   // grabbing values without the protection of a lock, but it has the advantage
 602   // of working even with threads that don't have message loops.  If a user
 603   // sees any strangeness, they can always just run their stats gathering a
 604   // second time.
 605   for (ThreadData* thread_data = my_list;
 606        thread_data;
 607        thread_data = thread_data->next()) {
 608     thread_data->SnapshotExecutedTasks(reset_max, process_data, birth_counts);
 609   }
 610 }
 611
 612 void ThreadData::SnapshotExecutedTasks(bool reset_max,
 613                                        ProcessDataSnapshot* process_data,
 614                                        BirthCountMap* birth_counts) {
 615   // Get copy of data, so that the data will not change during the iterations
 616   // and processing.
 617   ThreadData::BirthMap birth_map;
 618   ThreadData::DeathMap death_map;
 619   ThreadData::ParentChildSet parent_child_set;
 620   SnapshotMaps(reset_max, &birth_map, &death_map, &parent_child_set);
 621
 622   for (ThreadData::DeathMap::const_iterator it = death_map.begin();
 623        it != death_map.end(); ++it) {
 624     process_data->tasks.push_back(
 625         TaskSnapshot(*it->first, it->second, thread_name()));
 626     (*birth_counts)[it->first] -= it->first->birth_count();
 627   }
 628
 629   for (ThreadData::BirthMap::const_iterator it = birth_map.begin();
 630        it != birth_map.end(); ++it) {
 631     (*birth_counts)[it->second] += it->second->birth_count();
 632   }
 633
 634   if (!kTrackParentChildLinks)
 635     return;
 636
 637   for (ThreadData::ParentChildSet::const_iterator it = parent_child_set.begin();
 638        it != parent_child_set.end(); ++it) {
 639     process_data->descendants.push_back(ParentChildPairSnapshot(*it));
 640   }
 641 }
 642
 643 // This may be called from another thread.
 644 void ThreadData::SnapshotMaps(bool reset_max,
 645                               BirthMap* birth_map,
 646                               DeathMap* death_map,
 647                               ParentChildSet* parent_child_set) {
 648   base::AutoLock lock(map_lock_);
 649   for (BirthMap::const_iterator it = birth_map_.begin();
 650        it != birth_map_.end(); ++it)
 651     (*birth_map)[it->first] = it->second;
 652   for (DeathMap::iterator it = death_map_.begin();
 653        it != death_map_.end(); ++it) {
 654     (*death_map)[it->first] = it->second;
 655     if (reset_max)
 656       it->second.ResetMax();
 657   }
 658
 659   if (!kTrackParentChildLinks)
 660     return;
 661
 662   for (ParentChildSet::iterator it = parent_child_set_.begin();
 663        it != parent_child_set_.end(); ++it)
 664     parent_child_set->insert(*it);
 665 }
 666
 667 // static
 668 void ThreadData::ResetAllThreadData() {
 669   ThreadData* my_list = first();
 670
 671   for (ThreadData* thread_data = my_list;
 672        thread_data;
 673        thread_data = thread_data->next())
 674     thread_data->Reset();
 675 }
 676
 677 void ThreadData::Reset() {
 678   base::AutoLock lock(map_lock_);
 679   for (DeathMap::iterator it = death_map_.begin();
 680        it != death_map_.end(); ++it)
 681     it->second.Clear();
 682   for (BirthMap::iterator it = birth_map_.begin();
 683        it != birth_map_.end(); ++it)
 684     it->second->Clear();
 685 }
 686
 687 static void OptionallyInitializeAlternateTimer() {
 688   NowFunction* alternate_time_source = GetAlternateTimeSource();
 689   if (alternate_time_source)
 690     ThreadData::SetAlternateTimeSource(alternate_time_source);
 691 }
 692
 693 bool ThreadData::Initialize() {
 694   if (!kTrackAllTaskObjects)
 695     return false;  // Not compiled in.
 696   if (status_ >= DEACTIVATED)
 697     return true;  // Someone else did the initialization.
 698   // Due to racy lazy initialization in tests, we'll need to recheck status_
 699   // after we acquire the lock.
 700
 701   // Ensure that we don't double initialize tls.  We are called when single
 702   // threaded in the product, but some tests may be racy and lazy about our
 703   // initialization.
 704   base::AutoLock lock(*list_lock_.Pointer());
 705   if (status_ >= DEACTIVATED)
 706     return true;  // Someone raced in here and beat us.
 707
 708   // Put an alternate timer in place if the environment calls for it, such as
 709   // for tracking TCMalloc allocations.  This insertion is idempotent, so we
 710   // don't mind if there is a race, and we'd prefer not to be in a lock while
 711   // doing this work.
 712   if (kAllowAlternateTimeSourceHandling)
 713     OptionallyInitializeAlternateTimer();
 714
 715   // Perform the "real" TLS initialization now, and leave it intact through
 716   // process termination.
 717   if (!tls_index_.initialized()) {  // Testing may have initialized this.
 718     DCHECK_EQ(status_, UNINITIALIZED);
 719     tls_index_.Initialize(&ThreadData::OnThreadTermination);
 720     if (!tls_index_.initialized())
 721       return false;
 722   } else {
 723     // TLS was initialzed for us earlier.
 724     DCHECK_EQ(status_, DORMANT_DURING_TESTS);
 725   }
 726
 727   // Incarnation counter is only significant to testing, as it otherwise will
 728   // never again change in this process.
 729   ++incarnation_counter_;
 730
 731   // The lock is not critical for setting status_, but it doesn't hurt. It also
 732   // ensures that if we have a racy initialization, that we'll bail as soon as
 733   // we get the lock earlier in this method.
 734   status_ = kInitialStartupState;
 735   if (!kTrackParentChildLinks &&
 736       kInitialStartupState == PROFILING_CHILDREN_ACTIVE)
 737     status_ = PROFILING_ACTIVE;
 738   DCHECK(status_ != UNINITIALIZED);
 739   return true;
 740 }
 741
 742 // static
 743 bool ThreadData::InitializeAndSetTrackingStatus(Status status) {
 744   DCHECK_GE(status, DEACTIVATED);
 745   DCHECK_LE(status, PROFILING_CHILDREN_ACTIVE);
 746
 747   if (!Initialize())  // No-op if already initialized.
 748     return false;  // Not compiled in.
 749
 750   if (!kTrackParentChildLinks && status > DEACTIVATED)
 751     status = PROFILING_ACTIVE;
 752   status_ = status;
 753   return true;
 754 }
 755
 756 // static
 757 ThreadData::Status ThreadData::status() {
 758   return status_;
 759 }
 760
 761 // static
 762 bool ThreadData::TrackingStatus() {
 763   return status_ > DEACTIVATED;
 764 }
 765
 766 // static
 767 bool ThreadData::TrackingParentChildStatus() {
 768   return status_ >= PROFILING_CHILDREN_ACTIVE;
 769 }
 770
 771 // static
 772 void ThreadData::PrepareForStartOfRun(const Births* parent) {
 773   if (kTrackParentChildLinks && parent && status_ > PROFILING_ACTIVE) {
 774     ThreadData* current_thread_data = Get();
 775     if (current_thread_data)
 776       current_thread_data->parent_stack_.push(parent);
 777   }
 778 }
 779
 780 // static
 781 void ThreadData::SetAlternateTimeSource(NowFunction* now_function) {
 782   DCHECK(now_function);
 783   if (kAllowAlternateTimeSourceHandling)
 784     now_function_ = now_function;
 785 }
 786
 787 // static
 788 void ThreadData::EnableProfilerTiming() {
 789   base::subtle::NoBarrier_Store(&g_profiler_timing_enabled, ENABLED_TIMING);
 790 }
 791
 792 // static
 793 TrackedTime ThreadData::Now() {
 794   if (kAllowAlternateTimeSourceHandling && now_function_)
 795     return TrackedTime::FromMilliseconds((*now_function_)());
 796   if (kTrackAllTaskObjects && IsProfilerTimingEnabled() && TrackingStatus())
 797     return TrackedTime::Now();
 798   return TrackedTime();  // Super fast when disabled, or not compiled.
 799 }
 800
 801 // static
 802 void ThreadData::EnsureCleanupWasCalled(int major_threads_shutdown_count) {
 803   base::AutoLock lock(*list_lock_.Pointer());
 804   if (worker_thread_data_creation_count_ == 0)
 805     return;  // We haven't really run much, and couldn't have leaked.
 806
 807   // TODO(jar): until this is working on XP, don't run the real test.
 808 #if 0
 809   // Verify that we've at least shutdown/cleanup the major namesd threads.  The
 810   // caller should tell us how many thread shutdowns should have taken place by
 811   // now.
 812   CHECK_GT(cleanup_count_, major_threads_shutdown_count);
 813 #endif
 814 }
 815
 816 // static
 817 void ThreadData::ShutdownSingleThreadedCleanup(bool leak) {
 818   // This is only called from test code, where we need to cleanup so that
 819   // additional tests can be run.
 820   // We must be single threaded... but be careful anyway.
 821   if (!InitializeAndSetTrackingStatus(DEACTIVATED))
 822     return;
 823   ThreadData* thread_data_list;
 824   {
 825     base::AutoLock lock(*list_lock_.Pointer());
 826     thread_data_list = all_thread_data_list_head_;
 827     all_thread_data_list_head_ = NULL;
 828     ++incarnation_counter_;
 829     // To be clean, break apart the retired worker list (though we leak them).
 830     while (first_retired_worker_) {
 831       ThreadData* worker = first_retired_worker_;
 832       CHECK_GT(worker->worker_thread_number_, 0);
 833       first_retired_worker_ = worker->next_retired_worker_;
 834       worker->next_retired_worker_ = NULL;
 835     }
 836   }
 837
 838   // Put most global static back in pristine shape.
 839   worker_thread_data_creation_count_ = 0;
 840   cleanup_count_ = 0;
 841   tls_index_.Set(NULL);
 842   status_ = DORMANT_DURING_TESTS;  // Almost UNINITIALIZED.
 843
 844   // To avoid any chance of racing in unit tests, which is the only place we
 845   // call this function, we may sometimes leak all the data structures we
 846   // recovered, as they may still be in use on threads from prior tests!
 847   if (leak) {
 848     ThreadData* thread_data = thread_data_list;
 849     while (thread_data) {
 850       ANNOTATE_LEAKING_OBJECT_PTR(thread_data);
 851       thread_data = thread_data->next();
 852     }
 853     return;
 854   }
 855
 856   // When we want to cleanup (on a single thread), here is what we do.
 857
 858   // Do actual recursive delete in all ThreadData instances.
 859   while (thread_data_list) {
 860     ThreadData* next_thread_data = thread_data_list;
 861     thread_data_list = thread_data_list->next();
 862
 863     for (BirthMap::iterator it = next_thread_data->birth_map_.begin();
 864          next_thread_data->birth_map_.end() != it; ++it)
 865       delete it->second;  // Delete the Birth Records.
 866     delete next_thread_data;  // Includes all Death Records.
 867   }
 868 }
 869
 870 //------------------------------------------------------------------------------
 871 TaskStopwatch::TaskStopwatch()
 872     : wallclock_duration_ms_(0),
 873       current_thread_data_(NULL),
 874       excluded_duration_ms_(0),
 875       parent_(NULL) {
 876 #if DCHECK_IS_ON()
 877   state_ = CREATED;
 878   child_ = NULL;
 879 #endif
 880 }
 881
 882 TaskStopwatch::~TaskStopwatch() {
 883 #if DCHECK_IS_ON()
 884   DCHECK(state_ != RUNNING);
 885   DCHECK(child_ == NULL);
 886 #endif
 887 }
 888
 889 void TaskStopwatch::Start() {
 890 #if DCHECK_IS_ON()
 891   DCHECK(state_ == CREATED);
 892   state_ = RUNNING;
 893 #endif
 894
 895   start_time_ = ThreadData::Now();
 896
 897   current_thread_data_ = ThreadData::Get();
 898   if (!current_thread_data_)
 899     return;
 900
 901   parent_ = current_thread_data_->current_stopwatch_;
 902 #if DCHECK_IS_ON()
 903   if (parent_) {
 904     DCHECK(parent_->state_ == RUNNING);
 905     DCHECK(parent_->child_ == NULL);
 906     parent_->child_ = this;
 907   }
 908 #endif
 909   current_thread_data_->current_stopwatch_ = this;
 910 }
 911
 912 void TaskStopwatch::Stop() {
 913   const TrackedTime end_time = ThreadData::Now();
 914 #if DCHECK_IS_ON()
 915   DCHECK(state_ == RUNNING);
 916   state_ = STOPPED;
 917   DCHECK(child_ == NULL);
 918 #endif
 919
 920   if (!start_time_.is_null() && !end_time.is_null()) {
 921     wallclock_duration_ms_ = (end_time - start_time_).InMilliseconds();
 922   }
 923
 924   if (!current_thread_data_)
 925     return;
 926
 927   DCHECK(current_thread_data_->current_stopwatch_ == this);
 928   current_thread_data_->current_stopwatch_ = parent_;
 929   if (!parent_)
 930     return;
 931
 932 #if DCHECK_IS_ON()
 933   DCHECK(parent_->state_ == RUNNING);
 934   DCHECK(parent_->child_ == this);
 935   parent_->child_ = NULL;
 936 #endif
 937   parent_->excluded_duration_ms_ += wallclock_duration_ms_;
 938   parent_ = NULL;
 939 }
 940
 941 TrackedTime TaskStopwatch::StartTime() const {
 942 #if DCHECK_IS_ON()
 943   DCHECK(state_ != CREATED);
 944 #endif
 945
 946   return start_time_;
 947 }
 948
 949 int32 TaskStopwatch::RunDurationMs() const {
 950 #if DCHECK_IS_ON()
 951   DCHECK(state_ == STOPPED);
 952 #endif
 953
 954   return wallclock_duration_ms_ - excluded_duration_ms_;
 955 }
 956
 957 ThreadData* TaskStopwatch::GetThreadData() const {
 958 #if DCHECK_IS_ON()
 959   DCHECK(state_ != CREATED);
 960 #endif
 961
 962   return current_thread_data_;
 963 }
 964
 965 //------------------------------------------------------------------------------
 966 TaskSnapshot::TaskSnapshot() {
 967 }
 968
 969 TaskSnapshot::TaskSnapshot(const BirthOnThread& birth,
 970                            const DeathData& death_data,
 971                            const std::string& death_thread_name)
 972     : birth(birth),
 973       death_data(death_data),
 974       death_thread_name(death_thread_name) {
 975 }
 976
 977 TaskSnapshot::~TaskSnapshot() {
 978 }
 979
 980 //------------------------------------------------------------------------------
 981 // ParentChildPairSnapshot
 982
 983 ParentChildPairSnapshot::ParentChildPairSnapshot() {
 984 }
 985
 986 ParentChildPairSnapshot::ParentChildPairSnapshot(
 987     const ThreadData::ParentChildPair& parent_child)
 988     : parent(*parent_child.first),
 989       child(*parent_child.second) {
 990 }
 991
 992 ParentChildPairSnapshot::~ParentChildPairSnapshot() {
 993 }
 994
 995 //------------------------------------------------------------------------------
 996 // ProcessDataSnapshot
 997
 998 ProcessDataSnapshot::ProcessDataSnapshot()
 999 #if !defined(OS_NACL)
1000     : process_id(base::GetCurrentProcId()) {
1001 #else
1002     : process_id(0) {
1003 #endif
1004 }
1005
1006 ProcessDataSnapshot::~ProcessDataSnapshot() {
1007 }
1008
1009 }  // namespace tracked_objects