Drop the global memory state from memory coordinator

content/browser/memory/memory_coordinator_impl.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 CONTENT_BROWSER_MEMORY_MEMORY_COORDINATOR_IMPL_H_
 #define CONTENT_BROWSER_MEMORY_MEMORY_COORDINATOR_IMPL_H_
 
 #include "base/callback.h"
 #include "base/memory/memory_coordinator_client.h"
 #include "base/memory/memory_coordinator_proxy.h"
@@ skipping 13 matching lines @@
 
 // NOTE: Memory coordinator is under development and not fully working.
 
 class MemoryCoordinatorHandleImpl;
 class MemoryCoordinatorImplTest;
 class MemoryMonitor;
 class MemoryStateUpdater;
 class RenderProcessHost;
 struct MemoryCoordinatorSingletonTraits;
 
+// MemoryCondition is an internal state of memory coordinator which is used for
+// various things; calculating memory state for processes, requesting processes
+// to purge memory, and scheduling tab discarding.
+enum class MemoryCondition : int {
+  NORMAL = 0,
+  WARNING = 1,
+  CRITICAL = 2,
+};
+
 // MemoryCoordinatorImpl is an implementation of MemoryCoordinator.
 // The current implementation uses MemoryStateUpdater to update the global
 // memory state. See comments in MemoryStateUpdater for details.
 class CONTENT_EXPORT MemoryCoordinatorImpl : public base::MemoryCoordinator,
                                              public MemoryCoordinator,
                                              public NotificationObserver,
                                              public base::NonThreadSafe {
  public:
   using MemoryState = base::MemoryState;
 
@@ skipping 20 matching lines @@
 
   // Returns the memory state of the specified render process. Returns UNKNOWN
   // if the process is not tracked by this coordinator.
   MemoryState GetChildMemoryState(int render_process_id) const;
 
   // Records memory pressure notifications. Called by MemoryPressureMonitor.
   // TODO(bashi): Remove this when MemoryPressureMonitor is retired.
   void RecordMemoryPressure(
       base::MemoryPressureMonitor::MemoryPressureLevel level);
 
-  // Returns the global memory state.
-  virtual MemoryState GetGlobalMemoryState() const;
+  // Returns the current memory condition.
+  MemoryCondition GetMemoryCondtion() const { return memory_condition_; }
 
-  // Returns the browser's current memory state. Note that the current state
-  // could be different from the global memory state as the browser won't be
-  // suspended.
+  // Returns the browser's current memory state.
   MemoryState GetCurrentMemoryState() const override;
 
-  // Sets the global memory state for testing.
+  // Temporariy sets memory state of the browser process for testing.
   void SetCurrentMemoryStateForTesting(MemoryState memory_state) override;
 
-  // MemoryCoordinator implementation:
+  // content::MemoryCoordinator implementation:
   MemoryState GetStateForProcess(base::ProcessHandle handle) override;
 
   // NotificationObserver implementation:
   void Observe(int type,
                const NotificationSource& source,
                const NotificationDetails& details) override;
 
-  // Overrides the global state to |new_state|. State update tasks won't be
-  // scheduled until |duration| is passed. This means that the global state
-  // remains the same until |duration| is passed or another call of this method.
-  void ForceSetGlobalState(base::MemoryState new_state,
-                           base::TimeDelta duration);
+  // Overrides the current memory condition to |condition|. Memory condition
+  // update tasks won't be scheduled until |duration| is passed. This means that
+  // the memory condition remains the same until |duration| is passed or
+  // another call of this method.
+  void ForceSetMemoryCondition(MemoryCondition condition,
+                               base::TimeDelta duration);
 
-  // Changes the global state and notifies state changes to clients (lives in
-  // the browser) and child processes (renderers) if needed. Returns true when
-  // the state is actually changed.
-  bool ChangeStateIfNeeded(MemoryState prev_state, MemoryState next_state);
+  // Changes current memory condition if needed. This may trigger some actions
+  // like purging memory and memory state changes.
+  void UpdateConditionIfNeeded(MemoryCondition condition);
 
   // Asks the delegate to discard a tab.
   void DiscardTab();
 
  protected:
   // Returns the RenderProcessHost which is correspond to the given id.
   // Returns nullptr if there is no corresponding RenderProcessHost.
   // This is a virtual method so that we can write tests without having
   // actual RenderProcessHost.
   virtual RenderProcessHost* GetRenderProcessHost(int render_process_id);
@@ skipping 16 matching lines @@
   bool CanSuspendRenderer(int render_process_id);
 
   // Stores information about any known child processes.
   struct ChildInfo {
     // This object must be compatible with STL containers.
     ChildInfo();
     ChildInfo(const ChildInfo& rhs);
     ~ChildInfo();
 
     MemoryState memory_state;
+    base::TimeTicks last_state_change;
     bool is_visible = false;
     std::unique_ptr<MemoryCoordinatorHandleImpl> handle;
   };
 
   // A map from process ID (RenderProcessHost::GetID()) to child process info.
   using ChildInfoMap = std::map<int, ChildInfo>;
 
   ChildInfoMap& children() { return children_; }
 
  private:
 #if !defined(OS_MACOSX)
   FRIEND_TEST_ALL_PREFIXES(MemoryCoordinatorImplBrowserTest, HandleAdded);
   FRIEND_TEST_ALL_PREFIXES(MemoryCoordinatorImplBrowserTest,
                            CanSuspendRenderer);
   FRIEND_TEST_ALL_PREFIXES(MemoryCoordinatorWithServiceWorkerTest,
                            CannotSuspendRendererWithServiceWorker);
 #endif
   FRIEND_TEST_ALL_PREFIXES(MemoryCoordinatorImplTest, CalculateNextState);
   FRIEND_TEST_ALL_PREFIXES(MemoryCoordinatorImplTest, UpdateState);
   FRIEND_TEST_ALL_PREFIXES(MemoryCoordinatorImplTest, SetMemoryStateForTesting);
   FRIEND_TEST_ALL_PREFIXES(MemoryCoordinatorImplTest, ForceSetGlobalState);
 
   friend struct MemoryCoordinatorSingletonTraits;
   friend class MemoryCoordinatorHandleImpl;
 
+  // Updates the browser's memory state if needed.
+  void UpdateCurrentMemoryState(MemoryState state);
+
   // Called when ChildMemoryCoordinator calls AddChild().
   void OnChildAdded(int render_process_id);
 
   // Called by SetChildMemoryState() to determine a child memory state based on
   // the current status of the child process.
-  MemoryState OverrideGlobalState(MemoryState memroy_state,
-                                  const ChildInfo& child);
+  MemoryState OverrideState(MemoryState memroy_state, const ChildInfo& child);
 
   // Helper function of CreateHandle and AddChildForTesting.
   void CreateChildInfoMapEntry(
       int render_process_id,
       std::unique_ptr<MemoryCoordinatorHandleImpl> handle);
 
   // Notifies a state change to in-process clients.
-  void NotifyStateToClients();
+  void NotifyStateToClients(MemoryState state);
 
   // Notifies a state change to child processes.
-  void NotifyStateToChildren();
+  void NotifyStateToChildren(MemoryState state);
 
   // Records metrics. This is called when the global state is changed.
   void RecordStateChange(MemoryState prev_state,
                          MemoryState next_state,
                          base::TimeDelta duration);
 
   std::unique_ptr<MemoryCoordinatorDelegate> delegate_;
   std::unique_ptr<MemoryMonitor> memory_monitor_;
   std::unique_ptr<MemoryStateUpdater> state_updater_;
   NotificationRegistrar notification_registrar_;
-  // The global memory state.
+
+  // The current memory condition.
+  MemoryCondition memory_condition_ = MemoryCondition::NORMAL;
+
+  // The memory state of the browser process.
   MemoryState current_state_ = MemoryState::NORMAL;
-  // The time tick of last global state change.
+
+  // The time tick of last state change of the browser process.
   base::TimeTicks last_state_change_;
+
+  // Memory state for a process will remain unchanged until this period of time
+  // passes.
+  base::TimeDelta minimum_state_transition_period_;
+
   // Tracks child processes. An entry is added when a renderer connects to
   // MemoryCoordinator and removed automatically when an underlying binding is
   // disconnected.
   ChildInfoMap children_;
 
   DISALLOW_COPY_AND_ASSIGN(MemoryCoordinatorImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEMORY_MEMORY_COORDINATOR_IMPL_H_