Task manager should support Idle Wakeups on Windows

chrome/browser/task_management/sampling/shared_sampler.h

+// Copyright 2016 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 CHROME_BROWSER_TASK_MANAGEMENT_SAMPLING_SHARED_SAMPLER_H_
+#define CHROME_BROWSER_TASK_MANAGEMENT_SAMPLING_SHARED_SAMPLER_H_
+
+#include <map>
+#include <memory>
+#include <utility>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/files/file_path.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/process/process_handle.h"
+#include "base/sequence_checker.h"
+#include "base/sequenced_task_runner.h"
+#include "build/build_config.h"
+
+namespace task_management {
+
+struct ProcessDataSnapshot;

[ncarter (slow), 2016/08/03 22:39:43]

Can ProcessDataSnapshot move into SharedSampler?

[stanisc, 2016/08/04 01:36:00]

If I move into SharedSampler I'll have to define it there and also define all
other structures it depends on. Some of those structures currently contain
windows specific types which would also require <windows.h> to be included here.
That all combined is the reason I wanted to avoid revealing all those
implementation details here.

+
+// Defines sampler that will calculate resources for all processes all at once,
+// on the worker thread. Created by TaskManagerImpl the UI thread, but used

[brucedawson, 2016/08/03 00:36:55]

Missing "on" before "the UI thread"

[stanisc, 2016/08/04 01:36:00]

Done.

+// mainly on a blocking pool thread.
+//
+// This exists because on Windows it is much faster to collect a group of
+// process metrics for all processes all at once using NtQuerySystemInformation
+// than to query the same data for for each process individually.

[brucedawson, 2016/08/03 00:36:55]

and because some types of data can only be collected this way.

??

[stanisc, 2016/08/04 01:36:00]

Thanks, this is a good suggestion. Done.

+class SharedSampler : public base::RefCountedThreadSafe<SharedSampler> {
+ public:
+  explicit SharedSampler(
+      const scoped_refptr<base::SequencedTaskRunner>& blocking_pool_runner);
+
+  // The below are the types of the callbacks to the UI thread upon their
+  // corresponding refresh are done on the worker thread.

[brucedawson, 2016/08/03 00:36:55]

I can't quite parse this sentence.

[stanisc, 2016/08/04 01:36:00]

Well, I copied this from TaskGroupSampler.h but apparently didn't read it.
Fixed.

+  using OnIdleWakeupsCallback = base::Callback<void(int)>;
+
+  // Returns a combination of refresh flags supported by the shared sampler.
+  int64_t SupportsFlags() const;

[ncarter (slow), 2016/08/03 22:28:55]

Rename this to GetSupportedFlags() or something similar, so that it starts with
a verb.

[stanisc, 2016/08/04 01:36:00]

Done.

+
+  // Registers task group specific callbacks.
+  void RegisterCallbacks(base::ProcessId process_id,
+                         const OnIdleWakeupsCallback& on_idle_wakeups);
+
+  // Unregisters task group specific callbacks.
+  void UnregisterCallbacks(base::ProcessId process_id);
+
+  // Refreshes the expensive process' stats (for now only idle wakeups per
+  // second) on the worker thread.
+  void Refresh(base::ProcessId process_id, int64_t refresh_flags);
+
+ private:
+  friend class base::RefCountedThreadSafe<SharedSampler>;
+  ~SharedSampler();
+
+#if defined(OS_WIN)
+  // The UI-thread callbacks in TaskGroup registered with RegisterCallbacks and
+  // to be called when refresh on the worker thread is done.
+  struct Callbacks {
+    Callbacks();
+    Callbacks(Callbacks&& other);
+    ~Callbacks();
+
+    OnIdleWakeupsCallback on_idle_wakeups;
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(Callbacks);
+  };
+
+  typedef std::map<base::ProcessId, Callbacks> CallbacksMap;
+
+  // Contains all results of refresh for a single process.
+  struct RefreshResult {
+    base::ProcessId process_id;
+    int idle_wakeups_per_second;
+  };
+
+  typedef std::vector<RefreshResult> RefreshResults;
+
+  // Posted on the worker thread to do the actual refresh.
+  std::unique_ptr<RefreshResults> RefreshOnWorkerThread();
+
+  // Called on UI thread when the refresh is done.
+  void OnRefreshDone(std::unique_ptr<RefreshResults> refresh_results);
+
+  // Clear cached data.
+  void ClearState();
+
+  // Used to filter process information.
+  static std::vector<base::FilePath> GetSupportedImageNames();
+  bool IsSupportedImageName(base::FilePath::StringPieceType image_name) const;
+
+  // Captures a snapshot of data for all chrome processes.
+  // Runs on the worker thread.
+  std::unique_ptr<ProcessDataSnapshot> CaptureSnapshot();
+
+  // Produce refresh results by diffing two snapshots.
+  static void MakeResultsFromTwoSnapshots(
+      const ProcessDataSnapshot& prev_snapshot,
+      const ProcessDataSnapshot& snapshot,
+      RefreshResults* results);
+
+  // Produce refresh results from one snapshot.
+  // This is used only the first time when only one snapshot is available.
+  static void MakeResultsFromSnapshot(
+      const ProcessDataSnapshot& snapshot,
+      RefreshResults* results);
+
+  // Accumulates callbacks passed from TaskGroup objects passed via
+  // RegisterCallbacks calls.
+  CallbacksMap callbacks_map_;
+
+  // Refresh flags passed via Refresh.
+  int64_t refresh_flags_;
+
+  // Snapshot of previously captured resources used to calculate the delta.
+  std::unique_ptr<ProcessDataSnapshot> previous_snapshot_;
+
+  // Size of the buffer previously used to query system information.
+  uint32_t previous_buffer_size_;
+
+  // Image names that CaptureSnapshot uses to filter processes.
+  const std::vector<base::FilePath> supported_image_names_;
+
+  // The specific blocking pool SequencedTaskRunner that will be used to post
+  // the refresh tasks onto serially.
+  scoped_refptr<base::SequencedTaskRunner> blocking_pool_runner_;
+
+  // To assert we're running on the correct thread.
+  base::SequenceChecker worker_pool_sequenced_checker_;
+#endif  // defined(OS_WIN)
+
+  DISALLOW_COPY_AND_ASSIGN(SharedSampler);
+};
+
+}  // namespace task_management
+
+#endif  // CHROME_BROWSER_TASK_MANAGEMENT_SAMPLING_SHARED_SAMPLER_H_