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

athena/resource_manager/resource_manager_impl.cc

Index: athena/resource_manager/resource_manager_impl.cc
diff --git a/athena/resource_manager/resource_manager_impl.cc b/athena/resource_manager/resource_manager_impl.cc
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+++ b/athena/resource_manager/resource_manager_impl.cc
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+// Copyright 2014 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 "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 SetMemoryPressureAndStopMonitoring(
+      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.
+  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::SetMemoryPressureAndStopMonitoring(
+    MemoryPressureObserver::MemoryPressure pressure) {
+  memory_pressure_notifier_->StopObserving();
+  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:
+      // If we do not know how much memory we have we assume that it must be a
+      // high consumption.
+      // Fallthrough.
+    case MEMORY_PRESSURE_HIGH:
+      max_running_activities = 5;
+      break;
+    case MEMORY_PRESSURE_CRITICAL:
+      max_running_activities = 0;
+      break;
+    case MEMORY_PRESSURE_MODERATE:
+      max_running_activities = 7;
+      break;
+    case MEMORY_PRESSURE_LOW:
+      // No need to do anything yet.
+      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);
+    return;
+  } else if (current_memory_pressure_ == MEMORY_PRESSURE_CRITICAL) {
+    if (oldest_media_activity) {
+      oldest_media_activity->SetCurrentState(Activity::ACTIVITY_UNLOADED);
+      return;
+    }
+    LOG(ERROR) << "[ResourceManager]: Single activity uses too much memory.";
+    return;
+  }
+  if (current_memory_pressure_ != MEMORY_PRESSURE_UNKNOWN) {
+    // Only show this warning when the memory pressure is actually known. This
+    // will suppress warnings in e.g. unit tests.
+    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_.empty())
+    return;
+  std::vector<Activity*> new_activity_list;
+  const aura::Window::Windows children =
+      activity_list_[0]->GetWindow()->parent()->children();
+  // 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