[memory-infra] Make MemoryDumpScheduler non-thread safe singleton

base/trace_event/memory_dump_scheduler.cc

 // Copyright 2017 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/trace_event/memory_dump_scheduler.h"
 
 #include "base/process/process_metrics.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/trace_event/memory_dump_manager.h"
 #include "build/build_config.h"
 
 namespace base {
 namespace trace_event {
 
 namespace {
 // Threshold on increase in memory from last dump beyond which a new dump must
 // be triggered.
 int64_t kDefaultMemoryIncreaseThreshold = 50 * 1024 * 1024;  // 50MiB
 const uint32_t kMemoryTotalsPollingInterval = 25;
 uint32_t g_polling_interval_ms_for_testing = 0;
 }  // namespace
 
-MemoryDumpScheduler::MemoryDumpScheduler(
+// static
+MemoryDumpScheduler* MemoryDumpScheduler::GetInstance() {
+  return Singleton<MemoryDumpScheduler,
+                   LeakySingletonTraits<MemoryDumpScheduler>>::get();
+}
+
+MemoryDumpScheduler::MemoryDumpScheduler() : mdm_(nullptr), is_setup_(false) {}
+MemoryDumpScheduler::~MemoryDumpScheduler() {}
+
+void MemoryDumpScheduler::Setup(
     MemoryDumpManager* mdm,
-    scoped_refptr<SingleThreadTaskRunner> polling_task_runner)
-    : mdm_(mdm), polling_state_(polling_task_runner) {}
-
-MemoryDumpScheduler::~MemoryDumpScheduler() {}
+    scoped_refptr<SingleThreadTaskRunner> polling_task_runner) {
+  mdm_ = mdm;
+  polling_task_runner_ = polling_task_runner;
+  periodic_state_.reset(new PeriodicTriggerState);
+  polling_state_.reset(new PollingTriggerState);
+  is_setup_ = true;
+}
 
 void MemoryDumpScheduler::AddTrigger(MemoryDumpType trigger_type,
                                      MemoryDumpLevelOfDetail level_of_detail,
                                      uint32_t min_time_between_dumps_ms) {
+  DCHECK(is_setup_);
   if (trigger_type == MemoryDumpType::PEAK_MEMORY_USAGE) {
-    DCHECK(!periodic_state_.is_configured);
-    DCHECK_EQ(PollingTriggerState::DISABLED, polling_state_.current_state);
+    DCHECK(!periodic_state_->is_configured);
+    DCHECK_EQ(PollingTriggerState::DISABLED, polling_state_->current_state);
     DCHECK_NE(0u, min_time_between_dumps_ms);
 
-    polling_state_.level_of_detail = level_of_detail;
-    polling_state_.min_polls_between_dumps =
-        (min_time_between_dumps_ms + polling_state_.polling_interval_ms - 1) /
-        polling_state_.polling_interval_ms;
-    polling_state_.current_state = PollingTriggerState::CONFIGURED;
+    polling_state_->level_of_detail = level_of_detail;
+    polling_state_->min_polls_between_dumps =
+        (min_time_between_dumps_ms + polling_state_->polling_interval_ms - 1) /
+        polling_state_->polling_interval_ms;
+    polling_state_->current_state = PollingTriggerState::CONFIGURED;
   } else if (trigger_type == MemoryDumpType::PERIODIC_INTERVAL) {
-    DCHECK_EQ(PollingTriggerState::DISABLED, polling_state_.current_state);
-    periodic_state_.is_configured = true;
+    DCHECK_EQ(PollingTriggerState::DISABLED, polling_state_->current_state);
+    periodic_state_->is_configured = true;
     DCHECK_NE(0u, min_time_between_dumps_ms);
     switch (level_of_detail) {
       case MemoryDumpLevelOfDetail::BACKGROUND:
         break;
       case MemoryDumpLevelOfDetail::LIGHT:
-        DCHECK_EQ(0u, periodic_state_.light_dump_period_ms);
-        periodic_state_.light_dump_period_ms = min_time_between_dumps_ms;
+        DCHECK_EQ(0u, periodic_state_->light_dump_period_ms);
+        periodic_state_->light_dump_period_ms = min_time_between_dumps_ms;
         break;
       case MemoryDumpLevelOfDetail::DETAILED:
-        DCHECK_EQ(0u, periodic_state_.heavy_dump_period_ms);
-        periodic_state_.heavy_dump_period_ms = min_time_between_dumps_ms;
+        DCHECK_EQ(0u, periodic_state_->heavy_dump_period_ms);
+        periodic_state_->heavy_dump_period_ms = min_time_between_dumps_ms;
         break;
     }
 
-    periodic_state_.min_timer_period_ms = std::min(
-        periodic_state_.min_timer_period_ms, min_time_between_dumps_ms);
-    DCHECK_EQ(0u, periodic_state_.light_dump_period_ms %
-                      periodic_state_.min_timer_period_ms);
-    DCHECK_EQ(0u, periodic_state_.heavy_dump_period_ms %
-                      periodic_state_.min_timer_period_ms);
+    periodic_state_->min_timer_period_ms = std::min(
+        periodic_state_->min_timer_period_ms, min_time_between_dumps_ms);
+    DCHECK_EQ(0u, periodic_state_->light_dump_period_ms %
+                      periodic_state_->min_timer_period_ms);
+    DCHECK_EQ(0u, periodic_state_->heavy_dump_period_ms %
+                      periodic_state_->min_timer_period_ms);
   }
 }
 
-void MemoryDumpScheduler::NotifyPeriodicTriggerSupported() {
-  if (!periodic_state_.is_configured || periodic_state_.timer.IsRunning())
+void MemoryDumpScheduler::EnablePeriodicTriggerIfNeeded() {
+  DCHECK(is_setup_);
+  if (!periodic_state_->is_configured || periodic_state_->timer.IsRunning())
     return;
-  periodic_state_.light_dumps_rate = periodic_state_.light_dump_period_ms /
-                                     periodic_state_.min_timer_period_ms;
-  periodic_state_.heavy_dumps_rate = periodic_state_.heavy_dump_period_ms /
-                                     periodic_state_.min_timer_period_ms;
+  periodic_state_->light_dumps_rate = periodic_state_->light_dump_period_ms /
+                                      periodic_state_->min_timer_period_ms;
+  periodic_state_->heavy_dumps_rate = periodic_state_->heavy_dump_period_ms /
+                                      periodic_state_->min_timer_period_ms;
 
-  periodic_state_.dump_count = 0;
-  periodic_state_.timer.Start(
+  periodic_state_->dump_count = 0;
+  periodic_state_->timer.Start(
       FROM_HERE,
-      TimeDelta::FromMilliseconds(periodic_state_.min_timer_period_ms),
+      TimeDelta::FromMilliseconds(periodic_state_->min_timer_period_ms),
       Bind(&MemoryDumpScheduler::RequestPeriodicGlobalDump, Unretained(this)));
 }
 
-void MemoryDumpScheduler::NotifyPollingSupported() {
-  if (polling_state_.current_state != PollingTriggerState::CONFIGURED)
+void MemoryDumpScheduler::EnablePollingIfNeeded() {
+  DCHECK(is_setup_);
+  if (polling_state_->current_state != PollingTriggerState::CONFIGURED)
     return;
 
-  polling_state_.current_state = PollingTriggerState::ENABLED;
-  polling_state_.ResetTotals();
+  polling_state_->current_state = PollingTriggerState::ENABLED;
+  polling_state_->ResetTotals();
 
-  polling_state_.polling_task_runner->PostTask(
+  polling_task_runner_->PostTask(
       FROM_HERE,
       Bind(&MemoryDumpScheduler::PollMemoryOnPollingThread, Unretained(this)));
 }
 
 void MemoryDumpScheduler::NotifyDumpTriggered() {
-  if (polling_state_.polling_task_runner &&
-      polling_state_.polling_task_runner->RunsTasksOnCurrentThread()) {
-    polling_state_.polling_task_runner->PostTask(
+  if (polling_task_runner_ &&
+      polling_task_runner_->RunsTasksOnCurrentThread()) {
+    polling_task_runner_->PostTask(
         FROM_HERE,
         Bind(&MemoryDumpScheduler::NotifyDumpTriggered, Unretained(this)));
     return;
   }
-  if (polling_state_.current_state != PollingTriggerState::ENABLED)
+
+  if (!polling_state_ ||
+      polling_state_->current_state != PollingTriggerState::ENABLED)
     return;
 
-  polling_state_.ResetTotals();
+  polling_state_->ResetTotals();
 }
 
 void MemoryDumpScheduler::DisableAllTriggers() {
-  if (periodic_state_.timer.IsRunning())
-    periodic_state_.timer.Stop();
-  DisablePolling();
+  if (periodic_state_) {
+    if (periodic_state_->timer.IsRunning())
+      periodic_state_->timer.Stop();
+    periodic_state_.reset();
+  }
+
+  if (polling_task_runner_) {
+    DCHECK(polling_state_);
+    polling_task_runner_->PostTask(
+        FROM_HERE, Bind(&MemoryDumpScheduler::DisablePollingOnPollingThread,
+                        Unretained(this)));
+    polling_task_runner_ = nullptr;

[Primiano Tucci (use gerrit), 2017/03/16 19:01:36]

.reset() might be slightly more readable, as it becomes clear that this is a
managed ptr (And also consistent with the reset() below)

[ssid, 2017/03/22 01:32:58]

scoped_refptr doesn't have a "reset()" method. The comment in the header says
use "= nullptr". So leaving it as it is.

+  }
+  is_setup_ = false;
 }
 
-void MemoryDumpScheduler::DisablePolling() {
-  if (polling_state_.polling_task_runner->RunsTasksOnCurrentThread()) {
-    if (polling_state_.polling_task_runner->PostTask(
-            FROM_HERE,
-            Bind(&MemoryDumpScheduler::DisablePolling, Unretained(this))))
-      return;
-  }
-  polling_state_.current_state = PollingTriggerState::DISABLED;
-  polling_state_.polling_task_runner = nullptr;
+void MemoryDumpScheduler::DisablePollingOnPollingThread() {
+  polling_state_->current_state = PollingTriggerState::DISABLED;
+  polling_state_.reset();
 }
 
 // static
 void MemoryDumpScheduler::SetPollingIntervalForTesting(uint32_t interval) {
   g_polling_interval_ms_for_testing = interval;
 }
 
 bool MemoryDumpScheduler::IsPeriodicTimerRunningForTesting() {
-  return periodic_state_.timer.IsRunning();
+  return periodic_state_->timer.IsRunning();
 }
 
 void MemoryDumpScheduler::RequestPeriodicGlobalDump() {
   MemoryDumpLevelOfDetail level_of_detail = MemoryDumpLevelOfDetail::BACKGROUND;
-  if (periodic_state_.light_dumps_rate > 0 &&
-      periodic_state_.dump_count % periodic_state_.light_dumps_rate == 0)
+  if (periodic_state_->light_dumps_rate > 0 &&
+      periodic_state_->dump_count % periodic_state_->light_dumps_rate == 0)
     level_of_detail = MemoryDumpLevelOfDetail::LIGHT;
-  if (periodic_state_.heavy_dumps_rate > 0 &&
-      periodic_state_.dump_count % periodic_state_.heavy_dumps_rate == 0)
+  if (periodic_state_->heavy_dumps_rate > 0 &&
+      periodic_state_->dump_count % periodic_state_->heavy_dumps_rate == 0)
     level_of_detail = MemoryDumpLevelOfDetail::DETAILED;
-  ++periodic_state_.dump_count;
+  ++periodic_state_->dump_count;
 
   mdm_->RequestGlobalDump(MemoryDumpType::PERIODIC_INTERVAL, level_of_detail);
 }
 
 void MemoryDumpScheduler::PollMemoryOnPollingThread() {
-  if (polling_state_.current_state != PollingTriggerState::ENABLED)
+  if (polling_state_->current_state != PollingTriggerState::ENABLED)
     return;
 
   uint64_t polled_memory = 0;
   bool res = mdm_->PollFastMemoryTotal(&polled_memory);
   DCHECK(res);
-  if (polling_state_.level_of_detail == MemoryDumpLevelOfDetail::DETAILED) {
+  if (polling_state_->level_of_detail == MemoryDumpLevelOfDetail::DETAILED) {
     TRACE_COUNTER1(MemoryDumpManager::kTraceCategory, "PolledMemoryMB",
                    polled_memory / 1024 / 1024);
   }
 
   if (ShouldTriggerDump(polled_memory)) {
     TRACE_EVENT_INSTANT1(MemoryDumpManager::kTraceCategory,
                          "Peak memory dump Triggered",
                          TRACE_EVENT_SCOPE_PROCESS, "total_usage_MB",
                          polled_memory / 1024 / 1024);
 
     mdm_->RequestGlobalDump(MemoryDumpType::PEAK_MEMORY_USAGE,
-                            polling_state_.level_of_detail);
+                            polling_state_->level_of_detail);
   }
 
   // TODO(ssid): Use RequestSchedulerCallback, crbug.com/607533.
   ThreadTaskRunnerHandle::Get()->PostDelayedTask(
       FROM_HERE,
       Bind(&MemoryDumpScheduler::PollMemoryOnPollingThread, Unretained(this)),
-      TimeDelta::FromMilliseconds(polling_state_.polling_interval_ms));
+      TimeDelta::FromMilliseconds(polling_state_->polling_interval_ms));
 }
 
 bool MemoryDumpScheduler::ShouldTriggerDump(uint64_t current_memory_total) {
   // This function tries to detect peak memory usage as discussed in
   // https://goo.gl/0kOU4A.
 
   if (current_memory_total == 0)
     return false;
 
   bool should_dump = false;
-  ++polling_state_.num_polls_from_last_dump;
-  if (polling_state_.last_dump_memory_total == 0) {
+  ++polling_state_->num_polls_from_last_dump;
+  if (polling_state_->last_dump_memory_total == 0) {
     // If it's first sample then trigger memory dump.
     should_dump = true;
-  } else if (polling_state_.min_polls_between_dumps >
-             polling_state_.num_polls_from_last_dump) {
+  } else if (polling_state_->min_polls_between_dumps >
+             polling_state_->num_polls_from_last_dump) {
     return false;
   }
 
   int64_t increase_from_last_dump =
-      current_memory_total - polling_state_.last_dump_memory_total;
+      current_memory_total - polling_state_->last_dump_memory_total;
   should_dump |=
-      increase_from_last_dump > polling_state_.memory_increase_threshold;
+      increase_from_last_dump > polling_state_->memory_increase_threshold;
   should_dump |= IsCurrentSamplePeak(current_memory_total);
   if (should_dump)
-    polling_state_.ResetTotals();
+    polling_state_->ResetTotals();
   return should_dump;
 }
 
 bool MemoryDumpScheduler::IsCurrentSamplePeak(
     uint64_t current_memory_total_bytes) {
   uint64_t current_memory_total_kb = current_memory_total_bytes / 1024;
-  polling_state_.last_memory_totals_kb_index =
-      (polling_state_.last_memory_totals_kb_index + 1) %
+  polling_state_->last_memory_totals_kb_index =
+      (polling_state_->last_memory_totals_kb_index + 1) %
       PollingTriggerState::kMaxNumMemorySamples;
   uint64_t mean = 0;
   for (uint32_t i = 0; i < PollingTriggerState::kMaxNumMemorySamples; ++i) {
-    if (polling_state_.last_memory_totals_kb[i] == 0) {
+    if (polling_state_->last_memory_totals_kb[i] == 0) {
       // Not enough samples to detect peaks.
       polling_state_
-          .last_memory_totals_kb[polling_state_.last_memory_totals_kb_index] =
+          ->last_memory_totals_kb[polling_state_->last_memory_totals_kb_index] =
           current_memory_total_kb;
       return false;
     }
-    mean += polling_state_.last_memory_totals_kb[i];
+    mean += polling_state_->last_memory_totals_kb[i];
   }
   mean = mean / PollingTriggerState::kMaxNumMemorySamples;
   uint64_t variance = 0;
   for (uint32_t i = 0; i < PollingTriggerState::kMaxNumMemorySamples; ++i) {
-    variance += (polling_state_.last_memory_totals_kb[i] - mean) *
-                (polling_state_.last_memory_totals_kb[i] - mean);
+    variance += (polling_state_->last_memory_totals_kb[i] - mean) *
+                (polling_state_->last_memory_totals_kb[i] - mean);
   }
   variance = variance / PollingTriggerState::kMaxNumMemorySamples;
 
   polling_state_
-      .last_memory_totals_kb[polling_state_.last_memory_totals_kb_index] =
+      ->last_memory_totals_kb[polling_state_->last_memory_totals_kb_index] =
       current_memory_total_kb;
 
   // If stddev is less than 0.2% then we consider that the process is inactive.
   bool is_stddev_low = variance < mean / 500 * mean / 500;
   if (is_stddev_low)
     return false;
 
   // (mean + 3.69 * stddev) corresponds to a value that is higher than current
   // sample with 99.99% probability.
   return (current_memory_total_kb - mean) * (current_memory_total_kb - mean) >
          (3.69 * 3.69 * variance);
 }
 
 MemoryDumpScheduler::PeriodicTriggerState::PeriodicTriggerState()
     : is_configured(false),
       dump_count(0),
       min_timer_period_ms(std::numeric_limits<uint32_t>::max()),
       light_dumps_rate(0),
       heavy_dumps_rate(0),
       light_dump_period_ms(0),
       heavy_dump_period_ms(0) {}
 
 MemoryDumpScheduler::PeriodicTriggerState::~PeriodicTriggerState() {
   DCHECK(!timer.IsRunning());
 }
 
-MemoryDumpScheduler::PollingTriggerState::PollingTriggerState(
-    scoped_refptr<SingleThreadTaskRunner> polling_task_runner)
+MemoryDumpScheduler::PollingTriggerState::PollingTriggerState()
     : current_state(DISABLED),
       level_of_detail(MemoryDumpLevelOfDetail::FIRST),
-      polling_task_runner(polling_task_runner),
       polling_interval_ms(g_polling_interval_ms_for_testing
                               ? g_polling_interval_ms_for_testing
                               : kMemoryTotalsPollingInterval),
       min_polls_between_dumps(0),
       num_polls_from_last_dump(-1),
       last_dump_memory_total(0),
       memory_increase_threshold(0),
       last_memory_totals_kb_index(0) {}
 
-MemoryDumpScheduler::PollingTriggerState::~PollingTriggerState() {
-  DCHECK(!polling_task_runner);
-}
+MemoryDumpScheduler::PollingTriggerState::~PollingTriggerState() {}
 
 void MemoryDumpScheduler::PollingTriggerState::ResetTotals() {
   if (!memory_increase_threshold) {
     memory_increase_threshold = kDefaultMemoryIncreaseThreshold;
 #if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX) || \
     defined(OS_ANDROID)
     // Set threshold to 1% of total system memory.
     SystemMemoryInfoKB meminfo;
     bool res = GetSystemMemoryInfo(&meminfo);
     if (res)
       memory_increase_threshold = (meminfo.total / 100) * 1024;
 #endif
   }
 
   // Update the |last_dump_memory_total|'s value from the totals if it's not
   // first poll.
   if (num_polls_from_last_dump >= 0 &&
       last_memory_totals_kb[last_memory_totals_kb_index]) {
     last_dump_memory_total =
         last_memory_totals_kb[last_memory_totals_kb_index] * 1024;
   }
   num_polls_from_last_dump = 0;
   for (uint32_t i = 0; i < kMaxNumMemorySamples; ++i)
     last_memory_totals_kb[i] = 0;
   last_memory_totals_kb_index = 0;
 }
 
 }  // namespace trace_event
 }  // namespace base