third_party/WebKit/Source/platform/MemoryPurgeController.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MemoryPurgeController_h
   6 #define MemoryPurgeController_h
   7
   8 #include "platform/PlatformExport.h"
   9 #include "platform/heap/Handle.h"
  10 #include "wtf/MainThread.h"
  11
  12 namespace blink {
  13
  14 enum class MemoryPurgeMode {
  15     // The tab contains the webview went to background
  16     InactiveTab,
  17     // TODO(bashi): Add more modes as needed.
  18 };
  19
  20 enum class DeviceKind {
  21     NotSpecified,
  22     LowEnd,
  23 };
  24
  25 // Classes which have discardable/reducible memory can implement this
  26 // interface to be informed when they should reduce memory consumption.
  27 // MemoryPurgeController assumes that subclasses of MemoryPurgeClient are
  28 // WillBes.
  29 class MemoryPurgeClient : public WillBeGarbageCollectedMixin {
  30 public:
  31     virtual ~MemoryPurgeClient() { }
  32
  33     // MemoryPurgeController invokes this callback when a memory purge event
  34     // has occurred.
  35     virtual void purgeMemory(MemoryPurgeMode, DeviceKind) = 0;
  36
  37     DECLARE_TRACE();
  38 };
  39
  40 // MemoryPurgeController listens to some events which could be opportunities
  41 // for reducing memory consumption and notifies its clients.
  42 // Since we want to control memory per tab, MemoryPurgeController is owned by
  43 // Page.
  44 class PLATFORM_EXPORT MemoryPurgeController final : public NoBaseWillBeGarbageCollected<MemoryPurgeController> {
  45     DECLARE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(MemoryPurgeController);
  46 public:
  47     static PassOwnPtrWillBeRawPtr<MemoryPurgeController> create()
  48     {
  49         return adoptPtrWillBeNoop(new MemoryPurgeController);
  50     }
  51
  52     void registerClient(MemoryPurgeClient* client)
  53     {
  54         ASSERT(isMainThread());
  55         ASSERT(client);
  56         ASSERT(!m_clients.contains(client));
  57         m_clients.add(client);
  58     }
  59
  60     void unregisterClient(MemoryPurgeClient* client)
  61     {
  62         ASSERT(isMainThread());
  63         ASSERT(m_clients.contains(client));
  64         m_clients.remove(client);
  65     }
  66
  67     DECLARE_TRACE();
  68
  69 private:
  70     MemoryPurgeController();
  71
  72     void purgeMemory(MemoryPurgeMode);
  73
  74     WillBeHeapHashSet<RawPtrWillBeWeakMember<MemoryPurgeClient>> m_clients;
  75     DeviceKind m_deviceKind;
  76 };
  77
  78 } // namespace blink
  79
  80 #endif // MemoryPurgeController_h