[tracing] Implement polling in MemoryDumpManager

base/trace_event/memory_dump_scheduler.h

Index: base/trace_event/memory_dump_scheduler.h
diff --git a/base/trace_event/memory_dump_scheduler.h b/base/trace_event/memory_dump_scheduler.h
new file mode 100644
index 0000000000000000000000000000000000000000..dcb2e6f7ab8ded0776a918d75e0061cecd26a694
--- /dev/null
+++ b/base/trace_event/memory_dump_scheduler.h
@@ -0,0 +1,156 @@
+// 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.
+
+#ifndef BASE_TRACE_EVENT_MEMORY_DUMP_SCHEDULER_H
+#define BASE_TRACE_EVENT_MEMORY_DUMP_SCHEDULER_H
+
+#include "base/base_export.h"
+#include "base/gtest_prod_util.h"
+#include "base/memory/ref_counted.h"
+#include "base/timer/timer.h"
+#include "base/trace_event/memory_dump_request_args.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+
+namespace trace_event {
+
+class MemoryDumpManager;
+
+// Schedules global dump requests based on the triggers added.
+class BASE_EXPORT MemoryDumpScheduler {
+ public:
+  MemoryDumpScheduler(
+      MemoryDumpManager* mdm_,
+      scoped_refptr<SingleThreadTaskRunner> polling_task_runner);
+  ~MemoryDumpScheduler();
+
+  // Adds triggers for scheduling global dumps. Both periodic and peak triggers
+  // cannot be added together. At the moment the periodic support is limited to
+  // at most one periodic trigger per dump mode and peak triggers are limited to
+  // at most one. All intervals should be an integeral multiple of the smallest
+  // interval specified.
+  void AddTrigger(MemoryDumpType trigger_type,
+                  MemoryDumpLevelOfDetail level_of_detail,
+                  uint32_t min_time_between_dumps_ms);
+
+  // Starts periodic dumps.
+  void NotifyPeriodicTriggerSupported();

[Primiano Tucci (use gerrit), 2017/01/26 02:52:23]

thinking more, should these methods just be called:
EnablePeriodicTriggers() and EnablePollingTriggers() ?

[ssid, 2017/01/26 21:48:57]

Yes I was thinking the same. But felt enable is a stronger command to be given
here. By that I mean, EnablePeriodicTriggers() would enable the timer only if
periodic triggers were added. Else it would just do nothing. Now, in MDM we
cannot keep track of whether periodic triggers were added (need to read trace
config again). So, notify is a better option.

+
+  // Starts polling memory total.
+  void NotifyPollingSupported();
+
+  // Disables all triggers.
+  void DisableAllTriggers();
+
+ private:
+  friend class MemoryDumpManagerTest;
+  FRIEND_TEST_ALL_PREFIXES(MemoryDumpManagerTest, TestPollingOnDumpThread);
+
+  // Helper class to schdule periodic memory dumps.
+  class PeriodicDumpScheduler {

[Primiano Tucci (use gerrit), 2017/01/26 02:52:23]

aren't these sub-classes a bit too much overkill?

[ssid, 2017/01/26 21:48:57]

The main reason for having them is because I wanted to keep the members
separate. Otherwise there are too many members in this class and we could easily
miss access some state of periodic dumps in a peak detection function.
The other reason is the names of all members were getting too long.
periodic_heavy_dumps_rate and periodic_heavy_dump_period_ms. Instead it's better
to have it in one class and use shorter names. Especially when we have better
peak detection logic we will have more states with long names.
Also avoids communication between the two schedulers.

+   public:
+    explicit PeriodicDumpScheduler(MemoryDumpManager* mdm);
+    ~PeriodicDumpScheduler();
+
+    // Adds periodic dump time periods.
+    void AddTrigger(MemoryDumpLevelOfDetail level_of_detail,
+                    uint32_t min_time_between_dumps_ms);
+
+    // Starts periodic timer on notification.
+    void NotifySupported();

[Primiano Tucci (use gerrit), 2017/01/26 02:52:23]

just Enable()

[ssid, 2017/01/26 21:48:57]

Same reply as above. Enable() does not enable unless triggers were added. No
reason to keep track of periodic triggers or peak triggers in current session in
the scheduler class.

+
+    // Disables periodic timer.
+    void Disable();
+
+    bool IsTimerRunning() { return timer_.IsRunning(); }
+
+    // Periodically called by the timer.
+    void RequestPeriodicGlobalDump();
+
+    // True if periodic scheduler is enabled in this session.
+    bool is_setup() const { return is_setup_; }
+
+   private:
+    MemoryDumpManager* mdm_;
+
+    bool is_setup_;
+
+    // Timer for periodic dumps.
+    RepeatingTimer timer_;
+    uint32_t dump_count_;
+    uint32_t min_timer_period_ms_;
+    uint32_t light_dumps_rate_;
+    uint32_t heavy_dumps_rate_;
+
+    uint32_t light_dump_period_ms = 0;
+    uint32_t heavy_dump_period_ms = 0;
+
+    DISALLOW_COPY_AND_ASSIGN(PeriodicDumpScheduler);
+  };
+
+  class PeakDumpScheduler {
+   public:
+    PeakDumpScheduler(
+        MemoryDumpManager* mdm,
+        scoped_refptr<SingleThreadTaskRunner> polling_task_runner);
+    ~PeakDumpScheduler();
+
+    // Sets up peak dump triggers for global memory dumps according to
+    // the trigger.
+    void AddTrigger(MemoryDumpLevelOfDetail level_of_detail,
+                    uint32_t min_time_between_dumps_ms);
+
+    // Called for polling memory usage and trigger dumps if peak is detected.
+    void PollMemoryOnPollingThread();
+
+    // Starts polling for peak detection.
+    void NotifySupported();

[Primiano Tucci (use gerrit), 2017/01/26 02:52:23]

ditto

+
+    // Disables polling for peak detection.
+    void Disable();
+
+    // True if peak dumps scheduler is enabled in this session.
+    bool is_setup() const { return is_setup_; }
+
+   private:
+    // Returns true if peak memory value is detected.
+    bool ShouldTriggerDump(uint64_t current_memory_total);
+
+    MemoryDumpManager* mdm_;
+
+    bool is_setup_;
+    MemoryDumpLevelOfDetail dump_mode_;
+
+    scoped_refptr<SingleThreadTaskRunner> polling_task_runner_;
+    uint32_t polling_interval_ = 0;
+
+    int min_polls_between_dumps_ = 0;
+    int num_polls_from_last_dump_ = 0;
+
+    // Threshold on increase in memory from last dump beyond which a new dump
+    // must be triggered.
+    int64_t memory_increase_threshold_ = 50 * 1024 * 1024;  // 50MiB
+    uint64_t last_dump_memory_total_ = 0;
+
+    DISALLOW_COPY_AND_ASSIGN(PeakDumpScheduler);
+  };
+
+  // Must be set before enabling tracing.
+  static void SetPollingIntervalForTesting(uint32_t interval);
+
+  bool IsPeriodicTimerRunningForTesting();
+
+  MemoryDumpManager* mdm_;
+
+  PeriodicDumpScheduler periodic_dump_scheduler_;
+  PeakDumpScheduler peak_dump_scheduler_;
+
+  DISALLOW_COPY_AND_ASSIGN(MemoryDumpScheduler);
+};
+
+}  // namespace trace_event
+}  // namespace base
+
+#endif  // BASE_TRACE_EVENT_MEMORY_DUMP_SCHEDULER_H