Adding Baseframework of the ResourceManager (all hooks and observers) are being put in place with a…

athena/resource_manager/resource_manager.cc

Index: athena/resource_manager/resource_manager.cc
diff --git a/athena/resource_manager/resource_manager.cc b/athena/resource_manager/resource_manager.cc
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index 0000000000000000000000000000000000000000..4742132bc0a03a5e3fbb900982cb5212584c5743
--- /dev/null
+++ b/athena/resource_manager/resource_manager.cc
@@ -0,0 +1,249 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.

[Jun Mukai, 2014/08/27 01:21:19]

In athena, usually this file is named as resoure_manager_impl.cc because it's
for Impl subclass.

[Mr4D (OOO till 08-26), 2014/08/27 16:12:14]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "athena/resource_manager/public/resource_manager.h"
+
+#include <algorithm>
+#include <vector>
+
+#include "athena/activity/public/activity.h"
+#include "athena/activity/public/activity_manager.h"
+#include "athena/activity/public/activity_manager_observer.h"
+#include "athena/resource_manager/memory_pressure_notifier.h"
+#include "athena/resource_manager/public/resource_manager_delegate.h"
+#include "athena/wm/public/window_manager.h"
+#include "athena/wm/public/window_manager_observer.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "ui/aura/window.h"
+
+namespace athena {
+
+class ResourceManagerImpl : public ResourceManager,
+                            public WindowManagerObserver,
+                            public ActivityManagerObserver,
+                            public MemoryPressureObserver {
+ public:
+  ResourceManagerImpl(ResourceManagerDelegate* delegate);
+  virtual ~ResourceManagerImpl();
+
+  // ResourceManager:
+  virtual void SetMemoryPressureForTest(
+      MemoryPressureObserver::MemoryPressure pressure) OVERRIDE;
+
+  // ActivityManagerObserver:
+  virtual void OnActivityStarted(Activity* activity) OVERRIDE;
+  virtual void OnActivityEnding(Activity* activity) OVERRIDE;
+
+  // WindowManagerObserver:
+  virtual void OnOverviewModeEnter() OVERRIDE;
+  virtual void OnOverviewModeExit() OVERRIDE;
+  virtual void OnActivityOrderHasChanged() OVERRIDE;
+
+  // MemoryPressureObserver:
+  virtual void OnMemoryPressure(
+      MemoryPressureObserver::MemoryPressure pressure) OVERRIDE;
+  virtual ResourceManagerDelegate* GetDelegate() OVERRIDE;
+
+ private:
+  // Manage the resources for our activities.
+  void ManageResource();
+
+  // Order our activity list to the order of activities of the stream.
+  // TODO(skuhne): Once the ActivityManager is responsible to create this list
+  // for us, we can remove this code here.
+  void UpdateActivityOrder();
+
+  // The sorted (new(front) -> old(back)) activity list.
+  // TODO(skuhne): Once the ActivityManager is responsible to create this list
+  // for us, we can remove this code here.

[Jun Mukai, 2014/08/27 01:21:18]

Also, it's better to be unified with WindowListProvider in athena/wm...
They do very similar thing in different places.
Better to consult with oshima for that.

[Mr4D (OOO till 08-26), 2014/08/27 16:12:13]

I know. I have a CL queued (480293003) which adds more functionality to the
WindowListProvider. I have sent it to Oshima, but he was not yet looking at it.
To get this thing forward I have added it this way and will change once the
other thing lands. I therefore added the TODO.

[Jun Mukai, 2014/08/27 16:57:47]

Turns out I was still confused by the difference between window and activity.

+  std::vector<Activity*> activity_list_;
+
+  // The resource manager delegate.
+  scoped_ptr<ResourceManagerDelegate> delegate_;
+
+  // Keeping a reference to the current memory pressure.
+  MemoryPressureObserver::MemoryPressure current_memory_pressure_;
+
+  // The memory pressure notifier.
+  scoped_ptr<MemoryPressureNotifier> memory_pressure_notifier_;
+
+  DISALLOW_COPY_AND_ASSIGN(ResourceManagerImpl);
+};
+
+namespace {
+ResourceManagerImpl* instance = NULL;
+}  // namespace
+
+ResourceManagerImpl::ResourceManagerImpl(ResourceManagerDelegate* delegate)
+    : delegate_(delegate),
+      current_memory_pressure_(MemoryPressureObserver::MEMORY_PRESSURE_UNKNOWN),
+      memory_pressure_notifier_(new MemoryPressureNotifier(this)) {
+  WindowManager::GetInstance()->AddObserver(this);
+  ActivityManager::Get()->AddObserver(this);
+}
+
+ResourceManagerImpl::~ResourceManagerImpl() {
+  ActivityManager::Get()->RemoveObserver(this);
+  WindowManager::GetInstance()->RemoveObserver(this);
+}
+
+void ResourceManagerImpl::SetMemoryPressureForTest(

[Jun Mukai, 2014/08/27 01:21:19]

It might be great to cancel memory_pressure_notifier_ in testing environment?

[Mr4D (OOO till 08-26), 2014/08/27 16:12:13]

The TestResourceManagerDelegate will never report any memory utilization and as
such it will never fire. Note furthermore that the timeout is quite high, so
that it would possibly never fire either.

I added some comments to make this clearer.

Nevertheless - I added the call to explicitly stop the timer as well (even
though a third insurance against firing seems over the top :) ).

[Jun Mukai, 2014/08/27 16:57:48]

Acknowledged.

+    MemoryPressureObserver::MemoryPressure pressure) {
+  OnMemoryPressure(pressure);
+}
+
+void ResourceManagerImpl::OnActivityStarted(Activity* activity) {
+  // As long as we have to manage the list of activities ourselves, we need to
+  // order it here.
+  activity_list_.push_back(activity);
+  UpdateActivityOrder();
+  // Update the activity states.
+  ManageResource();
+}
+
+void ResourceManagerImpl::OnActivityEnding(Activity* activity) {
+  // Remove the activity from the list again.
+  std::vector<Activity*>::iterator it =
+      std::find(activity_list_.begin(), activity_list_.end(), activity);
+  DCHECK(it != activity_list_.end());
+  activity_list_.erase(it);
+}
+
+void ResourceManagerImpl::OnOverviewModeEnter() {
+  // Nothing to do here.
+}
+
+void ResourceManagerImpl::OnOverviewModeExit() {
+  // Nothing to do here.
+}
+
+void ResourceManagerImpl::OnActivityOrderHasChanged() {
+  // As long as we have to manage the list of activities ourselves, we need to
+  // order it here.
+  UpdateActivityOrder();
+  // Manage the resources of each activity.
+  ManageResource();
+}
+
+void ResourceManagerImpl::OnMemoryPressure(
+      MemoryPressureObserver::MemoryPressure pressure) {
+  current_memory_pressure_ = pressure;
+  ManageResource();
+}
+
+ResourceManagerDelegate* ResourceManagerImpl::GetDelegate() {
+  return delegate_.get();
+}
+
+void ResourceManagerImpl::ManageResource() {
+  // If there is none or only one app running we cannot do anything.
+  if (activity_list_.size() <= 1U)
+    return;
+  // TODO(skuhne): This algorithm needs to take all kinds of predictive analysis
+  // and running applications into account. For this first patch we only do a
+  // very simple "floating window" algorithm which is surely not good enough.
+  size_t max_running_activities = 5;
+  switch (current_memory_pressure_) {
+    case MEMORY_PRESSURE_UNKNOWN:
+      max_running_activities = 5;
+      break;
+    case MEMORY_PRESSURE_CRITICAL:
+      max_running_activities = 0;
+      break;
+    case MEMORY_PRESSURE_HIGH:
+      max_running_activities = 5;
+      break;
+    case MEMORY_PRESSURE_MODERATE:
+      max_running_activities = 7;
+      break;
+    case MEMORY_PRESSURE_LOW:
+      // No need to do anything yet.

[Jun Mukai, 2014/08/27 01:21:19]

Not sure the difference between HIGH/UNKNOWN (setting to 5 explicitly) and LOW.
Do you expect the default value could be changed from 5?
Also, setting value in UNKNOWN doesn't look right. Is it intentional?

[Mr4D (OOO till 08-26), 2014/08/27 16:12:13]

I added another comment for unknown. You can find more comments about these
values in the header file which explains them, but since this is the part which
needs to be filled with more life, a bit more explanation:

1. This code will need to be changed with a smarter code (see TODO above). Smart
equals: looking at all kinds of input like how much memory is used by each
process, do incremental resource release instead of unload, look into usage
patterns, ...).
2. UNKNOWN means that the kernel does not tell us how much memory he has used /
available. As such we have to assume something bad. As such I have put in there
a HIGH. (let's discuss offline if you have questions about this point).
3. Could this value be changed? Obviously yes! This code is only a temporary
placeholder and will be replaced with more smarts. This is only the first stab
to see some management... :)

+      return;
+  }
+  Activity* oldest_media_activity = NULL;
+  std::vector<Activity*> unloadable_activities;
+  for (std::vector<Activity*>::iterator it = activity_list_.begin();
+       it != activity_list_.end(); ++it) {
+    // The activity should not be unloaded or visible.
+    if ((*it)->GetCurrentState() != Activity::ACTIVITY_UNLOADED &&
+        !(*it)->IsVisible()) {
+      if ((*it)->GetMediaState() == Activity::ACTIVITY_MEDIA_STATE_NONE) {
+        // Does not play media - so we can unload this immediately.
+        unloadable_activities.push_back(*it);
+      } else {
+        oldest_media_activity = *it;
+      }
+    }
+  }
+  if (unloadable_activities.size() > max_running_activities) {
+    unloadable_activities.back()->SetCurrentState(Activity::ACTIVITY_UNLOADED);

[Jun Mukai, 2014/08/27 01:21:18]

Is it enough to set the state on only the oldest unloadable activity?
I would expect that:
for (size_t i = max_running_activities; i < unloadable_activities.size(); ++i) {
  unloadable_activities[i]->SetCurrentState(UNLOADED);
}

[Mr4D (OOO till 08-26), 2014/08/27 16:12:13]

The crux here is that any resource change takes time to trickle through the
system and it is unclear of how much memory is released. As such, the logic in
ash does unload one tab, wait for ~1s and then checks again if it helped.

A more sophisticated logic might then use the ProcessInfo utilities to estimate
the release, but that will be part of another CL. Also note that this CL does
not yet use the sleeping modes which will also add additional saving methods.

On the other hand - looking at applications, a single app might have multiple
activities and the app only gets unloaded when all activities are marked for
unloading. So in the worst case, several iterations would not turn up any
release. But using the sleep states and other logic will ballance that out (in
most cases).

Again - this is a "dumb" implementation to get started.

[Jun Mukai, 2014/08/27 16:57:47]

Ah, I see.

+    return;
+  } else if (current_memory_pressure_ == MEMORY_PRESSURE_CRITICAL) {

[Jun Mukai, 2014/08/27 01:21:18]

Think that there are multiple media activities and pressure is CRITICAL.
This logic unloads the oldest one but keeps other media activities. Is that
okay?

[Mr4D (OOO till 08-26), 2014/08/27 16:12:13]

That was the intent. If there is no memory left and we have to do something we
will give the oldest one the boots. We could however wait until the kernel
forecfully kills one... 

But - we have to release memory and since all are "Active" we need to kill one
which is not visible and plays media.

[Jun Mukai, 2014/08/27 16:57:47]

Acknowledged.

+    if (oldest_media_activity) {
+      oldest_media_activity->SetCurrentState(Activity::ACTIVITY_UNLOADED);
+      return;
+    }
+    LOG(ERROR) << "[ResourceManager]: Single activity uses too much memory.";
+    return;
+  }
+  LOG(WARNING) << "[ResourceManager]: No way to release memory pressure (" <<
+      current_memory_pressure_ <<
+      "), Activities (running, allowed, unloadable)=(" <<
+      activity_list_.size() << ", " <<
+      max_running_activities << ", " <<
+      unloadable_activities.size() << ")";
+}
+
+void ResourceManagerImpl::UpdateActivityOrder() {
+  if (!activity_list_.size())

[Jun Mukai, 2014/08/27 01:21:18]

activity_list_.empty() is clearer to me

[Mr4D (OOO till 08-26), 2014/08/27 16:12:13]

Done.

+    return;
+  std::vector<Activity*> new_activity_list;
+  const aura::Window::Windows children =
+      activity_list_[0]->GetWindow()->parent()->children();;

[Jun Mukai, 2014/08/27 01:21:18]

double semicolon at end

[Mr4D (OOO till 08-26), 2014/08/27 16:12:14]

Done.

+  // Find the first window in the container which is part of the application.
+  for (aura::Window::Windows::const_iterator child_iterator = children.begin();
+      child_iterator != children.end(); ++child_iterator) {
+    for (std::vector<Activity*>::iterator activity_iterator =
+             activity_list_.begin();
+        activity_iterator != activity_list_.end(); ++activity_iterator) {
+      if (*child_iterator == (*activity_iterator)->GetWindow()) {
+        new_activity_list.push_back(*activity_iterator);
+        activity_list_.erase(activity_iterator);
+        break;
+      }
+    }
+  }
+  // At this point the old list should be empty and we can swap the lists.
+  DCHECK(!activity_list_.size());
+  activity_list_ = new_activity_list;
+}
+
+// static
+void ResourceManager::Create() {
+  DCHECK(!instance);
+  instance = new ResourceManagerImpl(
+      ResourceManagerDelegate::CreateResourceManagerDelegate());
+}
+
+// static
+ResourceManager* ResourceManager::Get() {
+  return instance;
+}
+
+// static
+void ResourceManager::Shutdown() {
+  DCHECK(instance);
+  delete instance;
+  instance = NULL;
+}
+
+ResourceManager::ResourceManager() {}
+
+ResourceManager::~ResourceManager() {
+  DCHECK(instance);
+  instance = NULL;
+}
+
+}  // namespace athena