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      1 // Copyright 2013 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 #ifndef BASE_TRACE_EVENT_TRACE_EVENT_SYSTEM_STATS_MONITOR_H_
      6 #define BASE_TRACE_EVENT_TRACE_EVENT_SYSTEM_STATS_MONITOR_H_
      7 
      8 #include "base/base_export.h"
      9 #include "base/gtest_prod_util.h"
     10 #include "base/macros.h"
     11 #include "base/memory/ref_counted.h"
     12 #include "base/memory/weak_ptr.h"
     13 #include "base/process/process_metrics.h"
     14 #include "base/timer/timer.h"
     15 #include "base/trace_event/trace_log.h"
     16 
     17 namespace base {
     18 
     19 class SingleThreadTaskRunner;
     20 
     21 namespace trace_event {
     22 
     23 // Watches for chrome://tracing to be enabled or disabled. When tracing is
     24 // enabled, also enables system events profiling. This class is the preferred
     25 // way to turn system tracing on and off.
     26 class BASE_EXPORT TraceEventSystemStatsMonitor
     27     : public TraceLog::EnabledStateObserver {
     28  public:
     29   // Length of time interval between stat profiles.
     30   static const int kSamplingIntervalMilliseconds = 2000;
     31 
     32   // |task_runner| must be the primary thread for the client
     33   // process, e.g. the UI thread in a browser.
     34   explicit TraceEventSystemStatsMonitor(
     35       scoped_refptr<SingleThreadTaskRunner> task_runner);
     36 
     37   ~TraceEventSystemStatsMonitor() override;
     38 
     39   // base::trace_event::TraceLog::EnabledStateChangedObserver overrides:
     40   void OnTraceLogEnabled() override;
     41   void OnTraceLogDisabled() override;
     42 
     43   // Retrieves system profiling at the current time.
     44   void DumpSystemStats();
     45 
     46  private:
     47   FRIEND_TEST_ALL_PREFIXES(TraceSystemStatsMonitorTest,
     48                            TraceEventSystemStatsMonitor);
     49 
     50   bool IsTimerRunningForTest() const;
     51 
     52   void StartProfiling();
     53 
     54   void StopProfiling();
     55 
     56   // Ensures the observer starts and stops tracing on the primary thread.
     57   scoped_refptr<SingleThreadTaskRunner> task_runner_;
     58 
     59   // Timer to schedule system profile dumps.
     60   RepeatingTimer dump_timer_;
     61 
     62   WeakPtrFactory<TraceEventSystemStatsMonitor> weak_factory_;
     63 
     64   DISALLOW_COPY_AND_ASSIGN(TraceEventSystemStatsMonitor);
     65 };
     66 
     67 // Converts system memory profiling stats in |input| to
     68 // trace event compatible JSON and appends to |output|. Visible for testing.
     69 BASE_EXPORT void AppendSystemProfileAsTraceFormat(const SystemMetrics&
     70                                                   system_stats,
     71                                                   std::string* output);
     72 
     73 }  // namespace trace_event
     74 }  // namespace base
     75 
     76 #endif  // BASE_TRACE_EVENT_TRACE_EVENT_SYSTEM_STATS_MONITOR_H_
     77