Delivering the FIRST_NONEMPTY_PAINT phase changing event to base/

base/tracked_objects.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/tracked_objects.h"
 
 #include <limits.h>
 #include <stdlib.h>
 
 #include "base/atomicops.h"
 #include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/debug/leak_annotations.h"
 #include "base/logging.h"
 #include "base/process/process_handle.h"
 #include "base/profiler/alternate_timer.h"
+#include "base/stl_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/third_party/valgrind/memcheck.h"
 #include "base/tracking_info.h"
 
 using base::TimeDelta;
 
 namespace base {
 class TimeDelta;
 }
 
 namespace tracked_objects {
 
 namespace {
 // Flag to compile out almost all of the task tracking code.
 const bool kTrackAllTaskObjects = true;

[Ilya Sherman, 2015/04/07 01:15:30]

Is this flag still needed?  It might be helpful to remove it in a precursor CL,
so that the new code doesn't need to worry about it.

[vadimt, 2015/04/07 21:44:14]

Done; plase see (and LGTM) https://codereview.chromium.org/1068933003/

 
 // TODO(jar): Evaluate the perf impact of enabling this.  If the perf impact is
 // negligible, enable by default.
 // Flag to compile out parent-child link recording.
 const bool kTrackParentChildLinks = false;
 
 // When ThreadData is first initialized, should we start in an ACTIVE state to
 // record all of the startup-time tasks, or should we start up DEACTIVATED, so
 // that we only record after parsing the command line flag --enable-tracking.
 // Note that the flag may force either state, so this really controls only the
@@ skipping 46 matching lines @@
   }
   return current_timing_enabled == ENABLED_TIMING;
 }
 
 }  // namespace
 
 //------------------------------------------------------------------------------
 // DeathData tallies durations when a death takes place.
 
 DeathData::DeathData() {
-  Clear();
+  count_ = 0;
+  sample_probability_count_ = 0;
+  run_duration_sum_ = 0;
+  run_duration_max_ = 0;
+  run_duration_sample_ = 0;
+  queue_duration_sum_ = 0;
+  queue_duration_max_ = 0;
+  queue_duration_sample_ = 0;
+  last_phase_snapshot_ = nullptr;
 }
 
-DeathData::DeathData(int count) {
-  Clear();
+DeathData::DeathData(int count) : DeathData() {
   count_ = count;
 }
 
+DeathData::~DeathData() {
+  while (last_phase_snapshot_) {
+    DeathDataPhaseSnapshot* snapshot = last_phase_snapshot_;
+    last_phase_snapshot_ = snapshot->prev;
+    delete snapshot;
+  }
+}
+
 // TODO(jar): I need to see if this macro to optimize branching is worth using.
 //
 // This macro has no branching, so it is surely fast, and is equivalent to:
 //             if (assign_it)
 //               target = source;
 // We use a macro rather than a template to force this to inline.
 // Related code for calculating max is discussed on the web.
 #define CONDITIONAL_ASSIGN(assign_it, target, source) \
     ((target) ^= ((target) ^ (source)) & -static_cast<int32>(assign_it))
 
 void DeathData::RecordDeath(const int32 queue_duration,
                             const int32 run_duration,
                             const uint32 random_number) {
   // We'll just clamp at INT_MAX, but we should note this in the UI as such.
   if (count_ < INT_MAX)
     ++count_;
+  if (sample_probability_count_ < INT_MAX)
+    ++sample_probability_count_;
   queue_duration_sum_ += queue_duration;
   run_duration_sum_ += run_duration;
 
   if (queue_duration_max_ < queue_duration)
     queue_duration_max_ = queue_duration;
   if (run_duration_max_ < run_duration)
     run_duration_max_ = run_duration;
 
-  // Take a uniformly distributed sample over all durations ever supplied.
-  // The probability that we (instead) use this new sample is 1/count_.  This
-  // results in a completely uniform selection of the sample (at least when we
-  // don't clamp count_... but that should be inconsequentially likely).
-  // We ignore the fact that we correlated our selection of a sample to the run
-  // and queue times (i.e., we used them to generate random_number).
-  CHECK_GT(count_, 0);
-  if (0 == (random_number % count_)) {
+  // Take a uniformly distributed sample over all durations ever supplied during
+  // currrent profiling phase.
+  // The probability that we (instead) use this new sample is
+  // 1/sample_probability_count_. This results in a completely uniform selection
+  // of the sample (at least when we don't clamp sample_probability_count_...
+  // but that should be inconsequentially likely). We ignore the fact that we
+  // correlated our selection of a sample to the run and queue times (i.e., we
+  // used them to generate random_number).
+  CHECK_GT(sample_probability_count_, 0);
+  if (0 == (random_number % sample_probability_count_)) {
     queue_duration_sample_ = queue_duration;
     run_duration_sample_ = run_duration;
   }
 }
 
 int DeathData::count() const { return count_; }
 
 int32 DeathData::run_duration_sum() const { return run_duration_sum_; }
 
 int32 DeathData::run_duration_max() const { return run_duration_max_; }
 
 int32 DeathData::run_duration_sample() const {
   return run_duration_sample_;
 }
 
 int32 DeathData::queue_duration_sum() const {
   return queue_duration_sum_;
 }
 
 int32 DeathData::queue_duration_max() const {
   return queue_duration_max_;
 }
 
 int32 DeathData::queue_duration_sample() const {
   return queue_duration_sample_;
 }
 
-void DeathData::Clear() {
-  count_ = 0;
-  run_duration_sum_ = 0;
+DeathDataPhaseSnapshot* DeathData::last_phase_snapshot() const {
+  return last_phase_snapshot_;
+}
+
+void DeathData::OnProfilingPhaseCompletion(int profiling_phase) {
+  // Snapshotting and storing current state.
+  last_phase_snapshot_ = new DeathDataPhaseSnapshot(profiling_phase, *this);
+
+  // Not touching fields for which a delta can be computed by comparing with a
+  // snapshot from previos phase. Resetting other fields. Sample values will be
+  // reset upon next death recording because sample_probability_count_ is set to
+  // 0.
+  sample_probability_count_ = 0;
   run_duration_max_ = 0;
-  run_duration_sample_ = 0;
-  queue_duration_sum_ = 0;
   queue_duration_max_ = 0;
-  queue_duration_sample_ = 0;
 }
 
 //------------------------------------------------------------------------------
 DeathDataSnapshot::DeathDataSnapshot()
     : count(-1),
       run_duration_sum(-1),
       run_duration_max(-1),
       run_duration_sample(-1),
       queue_duration_sum(-1),
       queue_duration_max(-1),
       queue_duration_sample(-1) {
 }
 
 DeathDataSnapshot::DeathDataSnapshot(
     const tracked_objects::DeathData& death_data)
     : count(death_data.count()),
       run_duration_sum(death_data.run_duration_sum()),
       run_duration_max(death_data.run_duration_max()),
       run_duration_sample(death_data.run_duration_sample()),
       queue_duration_sum(death_data.queue_duration_sum()),
       queue_duration_max(death_data.queue_duration_max()),
       queue_duration_sample(death_data.queue_duration_sample()) {
 }
 
 DeathDataSnapshot::~DeathDataSnapshot() {
 }
 
+void DeathDataSnapshot::CalculateDelta(const DeathDataSnapshot& older) {
+  count -= older.count;
+  run_duration_sum -= older.run_duration_sum;
+  queue_duration_sum -= older.queue_duration_sum;
+}
+
 //------------------------------------------------------------------------------
 BirthOnThread::BirthOnThread(const Location& location,
                              const ThreadData& current)
     : location_(location),
       birth_thread_(&current) {
 }
 
 //------------------------------------------------------------------------------
 BirthOnThreadSnapshot::BirthOnThreadSnapshot() {
 }
@@ skipping 172 matching lines @@
     return;
   }
   // We must NOT do any allocations during this callback.
   // Using the simple linked lists avoids all allocations.
   DCHECK_EQ(this->next_retired_worker_, reinterpret_cast<ThreadData*>(NULL));
   this->next_retired_worker_ = first_retired_worker_;
   first_retired_worker_ = this;
 }
 
 // static
-void ThreadData::Snapshot(ProcessDataSnapshot* process_data_snapshot) {
-  ThreadData::SnapshotCurrentPhase(
-      &process_data_snapshot->phased_process_data_snapshots[0]);
+void ThreadData::Snapshot(int current_profiling_phase,
+                          ProcessDataSnapshot* process_data_snapshot) {
+  if (!kTrackAllTaskObjects)
+    return;  // Not compiled in.
+
+  BirthCountMap birth_counts;
+
+  // Get an unchanging copy of a ThreadData list.
+  ThreadData* my_list = ThreadData::first();
+
+  // Gather data serially.
+  // This hackish approach *can* get some slighly corrupt tallies, as we are
+  // grabbing values without the protection of a lock, but it has the advantage
+  // of working even with threads that don't have message loops.  If a user
+  // sees any strangeness, they can always just run their stats gathering a
+  // second time.
+  for (ThreadData* thread_data = my_list; thread_data;
+       thread_data = thread_data->next()) {
+    thread_data->SnapshotExecutedTasks(
+        current_profiling_phase,
+        &process_data_snapshot->phased_process_data_snapshots, &birth_counts);
+  }
+
+  // Add births that are still active -- i.e. objects that have tallied a birth,
+  // but have not yet tallied a matching death, and hence must be either
+  // running, queued up, or being held in limbo for future posting.
+  for (const auto& birth_count : birth_counts) {
+    if (birth_count.second > 0) {
+      process_data_snapshot
+          ->phased_process_data_snapshots[current_profiling_phase]
+          .tasks.push_back(TaskSnapshot(
+              BirthOnThreadSnapshot(*birth_count.first),
+              DeathDataSnapshot(DeathData(birth_count.second)), "Still_Alive"));
+    }
+  }
+}
+
+// static
+void ThreadData::OnProfilingPhaseCompletion(int profiling_phase) {
+  if (!kTrackAllTaskObjects)
+    return;  // Not compiled in.
+
+  // Get an unchanging copy of a ThreadData list.
+  ThreadData* my_list = ThreadData::first();
+
+  // Add snapshots for all death datas in all threads serially.
+  // This hackish approach *can* get some slighly corrupt tallies, as we are
+  // grabbing values without the protection of a lock, but it has the advantage
+  // of working even with threads that don't have message loops. Any corruption
+  // shouldn't cause "cascading damage" to anything else (in later phases).
+  for (ThreadData* thread_data = my_list; thread_data;
+       thread_data = thread_data->next()) {
+    thread_data->OnProfilingPhaseCompletionOnThread(profiling_phase);
+  }
 }
 
 Births* ThreadData::TallyABirth(const Location& location) {
   BirthMap::iterator it = birth_map_.find(location);
   Births* child;
   if (it != birth_map_.end()) {
     child =  it->second;
     child->RecordBirth();
   } else {
     child = new Births(location, *this);  // Leak this.
@@ skipping 11 matching lines @@
       // Lock since the map may get relocated now, and other threads sometimes
       // snapshot it (but they lock before copying it).
       base::AutoLock lock(map_lock_);
       parent_child_set_.insert(pair);
     }
   }
 
   return child;
 }
 
-void ThreadData::TallyADeath(const Births& birth,
+void ThreadData::TallyADeath(const Births& births,
                              int32 queue_duration,
                              const TaskStopwatch& stopwatch) {
   int32 run_duration = stopwatch.RunDurationMs();
 
   // Stir in some randomness, plus add constant in case durations are zero.
   const uint32 kSomePrimeNumber = 2147483647;
   random_number_ += queue_duration + run_duration + kSomePrimeNumber;
   // An address is going to have some randomness to it as well ;-).
-  random_number_ ^= static_cast<uint32>(&birth - reinterpret_cast<Births*>(0));
+  random_number_ ^= static_cast<uint32>(&births - reinterpret_cast<Births*>(0));
 
   // We don't have queue durations without OS timer. OS timer is automatically
   // used for task-post-timing, so the use of an alternate timer implies all
   // queue times are invalid, unless it was explicitly said that we can trust
   // the alternate timer.
   if (kAllowAlternateTimeSourceHandling &&
       now_function_ &&
       !now_function_is_time_) {
     queue_duration = 0;
   }
 
-  DeathMap::iterator it = death_map_.find(&birth);
+  DeathMap::iterator it = death_map_.find(&births);
   DeathData* death_data;
   if (it != death_map_.end()) {
     death_data = &it->second;
   } else {
     base::AutoLock lock(map_lock_);  // Lock as the map may get relocated now.
-    death_data = &death_map_[&birth];
+    death_data = &death_map_[&births];
   }  // Release lock ASAP.
   death_data->RecordDeath(queue_duration, run_duration, random_number_);
 
   if (!kTrackParentChildLinks)
     return;
   if (!parent_stack_.empty()) {  // We might get turned off.
-    DCHECK_EQ(parent_stack_.top(), &birth);
+    DCHECK_EQ(parent_stack_.top(), &births);
     parent_stack_.pop();
   }
 }
 
 // static
 Births* ThreadData::TallyABirthIfActive(const Location& location) {
   if (!kTrackAllTaskObjects)
     return NULL;  // Not compiled in.
 
   if (!TrackingStatus())
     return NULL;
   ThreadData* current_thread_data = Get();
   if (!current_thread_data)
     return NULL;
   return current_thread_data->TallyABirth(location);
 }
 
 // static
 void ThreadData::TallyRunOnNamedThreadIfTracking(
     const base::TrackingInfo& completed_task,
     const TaskStopwatch& stopwatch) {
   if (!kTrackAllTaskObjects)
     return;  // Not compiled in.
 
   // Even if we have been DEACTIVATED, we will process any pending births so
   // that our data structures (which counted the outstanding births) remain
   // consistent.
-  const Births* birth = completed_task.birth_tally;
-  if (!birth)
+  const Births* births = completed_task.birth_tally;
+  if (!births)
     return;
   ThreadData* current_thread_data = stopwatch.GetThreadData();
   if (!current_thread_data)
     return;
 
   // Watch out for a race where status_ is changing, and hence one or both
   // of start_of_run or end_of_run is zero.  In that case, we didn't bother to
   // get a time value since we "weren't tracking" and we were trying to be
   // efficient by not calling for a genuine time value. For simplicity, we'll
   // use a default zero duration when we can't calculate a true value.
   TrackedTime start_of_run = stopwatch.StartTime();
   int32 queue_duration = 0;
   if (!start_of_run.is_null()) {
     queue_duration = (start_of_run - completed_task.EffectiveTimePosted())
         .InMilliseconds();
   }
-  current_thread_data->TallyADeath(*birth, queue_duration, stopwatch);
+  current_thread_data->TallyADeath(*births, queue_duration, stopwatch);
 }
 
 // static
 void ThreadData::TallyRunOnWorkerThreadIfTracking(
-    const Births* birth,
+    const Births* births,
     const TrackedTime& time_posted,
     const TaskStopwatch& stopwatch) {
   if (!kTrackAllTaskObjects)
     return;  // Not compiled in.
 
   // Even if we have been DEACTIVATED, we will process any pending births so
   // that our data structures (which counted the outstanding births) remain
   // consistent.
-  if (!birth)
+  if (!births)
     return;
 
   // TODO(jar): Support the option to coalesce all worker-thread activity under
   // one ThreadData instance that uses locks to protect *all* access.  This will
   // reduce memory (making it provably bounded), but run incrementally slower
   // (since we'll use locks on TallyABirth and TallyADeath).  The good news is
   // that the locks on TallyADeath will be *after* the worker thread has run,
   // and hence nothing will be waiting for the completion (... besides some
   // other thread that might like to run).  Also, the worker threads tasks are
   // generally longer, and hence the cost of the lock may perchance be amortized
   // over the long task's lifetime.
   ThreadData* current_thread_data = stopwatch.GetThreadData();
   if (!current_thread_data)
     return;
 
   TrackedTime start_of_run = stopwatch.StartTime();
   int32 queue_duration = 0;
   if (!start_of_run.is_null()) {
     queue_duration = (start_of_run - time_posted).InMilliseconds();
   }
-  current_thread_data->TallyADeath(*birth, queue_duration, stopwatch);
+  current_thread_data->TallyADeath(*births, queue_duration, stopwatch);
 }
 
 // static
 void ThreadData::TallyRunInAScopedRegionIfTracking(
-    const Births* birth,
+    const Births* births,
     const TaskStopwatch& stopwatch) {
   if (!kTrackAllTaskObjects)
     return;  // Not compiled in.
 
   // Even if we have been DEACTIVATED, we will process any pending births so
   // that our data structures (which counted the outstanding births) remain
   // consistent.
-  if (!birth)
+  if (!births)
     return;
 
   ThreadData* current_thread_data = stopwatch.GetThreadData();
   if (!current_thread_data)
     return;
 
   int32 queue_duration = 0;
-  current_thread_data->TallyADeath(*birth, queue_duration, stopwatch);
-}
-
-// static
-void ThreadData::SnapshotAllExecutedTasks(
-    ProcessDataPhaseSnapshot* process_data_phase,
-    BirthCountMap* birth_counts) {
-  if (!kTrackAllTaskObjects)
-    return;  // Not compiled in.
-
-  // Get an unchanging copy of a ThreadData list.
-  ThreadData* my_list = ThreadData::first();
-
-  // Gather data serially.
-  // This hackish approach *can* get some slighly corrupt tallies, as we are
-  // grabbing values without the protection of a lock, but it has the advantage
-  // of working even with threads that don't have message loops.  If a user
-  // sees any strangeness, they can always just run their stats gathering a
-  // second time.
-  for (ThreadData* thread_data = my_list;
-       thread_data;
-       thread_data = thread_data->next()) {
-    thread_data->SnapshotExecutedTasks(process_data_phase, birth_counts);
-  }
-}
-
-// static
-void ThreadData::SnapshotCurrentPhase(
-    ProcessDataPhaseSnapshot* process_data_phase) {
-  // Add births that have run to completion to |collected_data|.
-  // |birth_counts| tracks the total number of births recorded at each location
-  // for which we have not seen a death count.
-  BirthCountMap birth_counts;
-  ThreadData::SnapshotAllExecutedTasks(process_data_phase, &birth_counts);
-
-  // Add births that are still active -- i.e. objects that have tallied a birth,
-  // but have not yet tallied a matching death, and hence must be either
-  // running, queued up, or being held in limbo for future posting.
-  for (const auto& birth_count : birth_counts) {
-    if (birth_count.second > 0) {
-      process_data_phase->tasks.push_back(TaskSnapshot(
-          *birth_count.first, DeathData(birth_count.second), "Still_Alive"));
-    }
-  }
+  current_thread_data->TallyADeath(*births, queue_duration, stopwatch);
 }
 
 void ThreadData::SnapshotExecutedTasks(
-    ProcessDataPhaseSnapshot* process_data_phase,
+    int current_profiling_phase,
+    PhasedProcessDataSnapshotMap* phased_process_data_snapshots,
     BirthCountMap* birth_counts) {
   // Get copy of data, so that the data will not change during the iterations
   // and processing.
-  ThreadData::BirthMap birth_map;
-  ThreadData::DeathMap death_map;
-  ThreadData::ParentChildSet parent_child_set;
-  SnapshotMaps(&birth_map, &death_map, &parent_child_set);
-
-  for (const auto& death : death_map) {
-    process_data_phase->tasks.push_back(
-        TaskSnapshot(*death.first, death.second, thread_name()));
-    (*birth_counts)[death.first] -= death.first->birth_count();
-  }
+  BirthMap birth_map;
+  DeathsSnapshot deaths;
+  ParentChildSet parent_child_set;
+  SnapshotMaps(current_profiling_phase, &birth_map, &deaths, &parent_child_set);
 
   for (const auto& birth : birth_map) {
     (*birth_counts)[birth.second] += birth.second->birth_count();
   }
 
-  if (!kTrackParentChildLinks)
-    return;
+  for (const auto& death : deaths) {
+    (*birth_counts)[death.first] -= death.first->birth_count();
 
-  for (const auto& parent_child : parent_child_set) {
-    process_data_phase->descendants.push_back(
-        ParentChildPairSnapshot(parent_child));
+    for (const DeathDataPhaseSnapshot* phase = &death.second; phase;
+         phase = phase->prev) {
+      DeathDataSnapshot death_data = phase->death_data;
+
+      if (phase->prev)
+        death_data.CalculateDelta(phase->prev->death_data);
+
+      if (death_data.count > 0)
+        (*phased_process_data_snapshots)[phase->profiling_phase]
+            .tasks.push_back(TaskSnapshot(BirthOnThreadSnapshot(*death.first),
+                                          death_data, thread_name()));
+    }
   }
 }
 
 // This may be called from another thread.
-void ThreadData::SnapshotMaps(BirthMap* birth_map,
-                              DeathMap* death_map,
+void ThreadData::SnapshotMaps(int profiling_phase,
+                              BirthMap* birth_map,
+                              DeathsSnapshot* deaths,
                               ParentChildSet* parent_child_set) {
   base::AutoLock lock(map_lock_);
+
   for (const auto& birth : birth_map_)
     (*birth_map)[birth.first] = birth.second;
-  for (const auto& death : death_map_)
-    (*death_map)[death.first] = death.second;
+
+  for (const auto& death : death_map_) {
+    deaths->push_back(DeathsSnapshot::value_type(
+        death.first, DeathDataPhaseSnapshot(profiling_phase, death.second)));
+  }
 
   if (!kTrackParentChildLinks)
     return;
 
   for (const auto& parent_child : parent_child_set_)
     parent_child_set->insert(parent_child);
 }
 
+void ThreadData::OnProfilingPhaseCompletionOnThread(int profiling_phase) {
+  base::AutoLock lock(map_lock_);
+
+  for (auto& death : death_map_) {
+    death.second.OnProfilingPhaseCompletion(profiling_phase);
+  }
+}
+
 static void OptionallyInitializeAlternateTimer() {
   NowFunction* alternate_time_source = GetAlternateTimeSource();
   if (alternate_time_source)
     ThreadData::SetAlternateTimeSource(alternate_time_source);
 }
 
 bool ThreadData::Initialize() {
   if (!kTrackAllTaskObjects)
     return false;  // Not compiled in.
   if (status_ >= DEACTIVATED)
@@ skipping 259 matching lines @@
 
 ThreadData* TaskStopwatch::GetThreadData() const {
 #if DCHECK_IS_ON()
   DCHECK(state_ != CREATED);
 #endif
 
   return current_thread_data_;
 }
 
 //------------------------------------------------------------------------------
+// DeathDataPhaseSnapshot
+
+DeathDataPhaseSnapshot::DeathDataPhaseSnapshot(int profiling_phase,
+                                               const DeathData& death_data)
+    : profiling_phase(profiling_phase),
+      death_data(death_data),
+      prev(death_data.last_phase_snapshot()) {
+}
+
+//------------------------------------------------------------------------------
+// TaskSnapshot
+
 TaskSnapshot::TaskSnapshot() {
 }
 
-TaskSnapshot::TaskSnapshot(const BirthOnThread& birth,
-                           const DeathData& death_data,
+TaskSnapshot::TaskSnapshot(const BirthOnThreadSnapshot& birth,
+                           const DeathDataSnapshot& death_data,
                            const std::string& death_thread_name)
     : birth(birth),
       death_data(death_data),
       death_thread_name(death_thread_name) {
 }
 
 TaskSnapshot::~TaskSnapshot() {
 }
 
 //------------------------------------------------------------------------------
@@ skipping 28 matching lines @@
     : process_id(base::GetCurrentProcId()) {
 #else
     : process_id(base::kNullProcessId) {
 #endif
 }
 
 ProcessDataSnapshot::~ProcessDataSnapshot() {
 }
 
 }  // namespace tracked_objects