Global GPU memory manager for android webview

android_webview/browser/global_tile_manager.h

+// 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.
+
+#ifndef ANDROID_WEBVIEW_BROWSER_GLOBAL_TILE_MANAGER_H_
+#define ANDROID_WEBVIEW_BROWSER_GLOBAL_TILE_MANAGER_H_
+
+#include <list>
+#include "base/basictypes.h"
+#include "base/lazy_instance.h"
+#include "base/synchronization/lock.h"
+
+namespace android_webview {
+
+class HardwareRenderer;
+
+// A global tile manager to keep track of the number of tile resources. Each
+// tile needs file descriptors (typically 2) and there is a soft limit of 1024
+// file descriptors per Android process. The GlobalTileManager does not keep
+// track of how many tiles each individual view is actually using. The purpose
+// of GlobalTileManager is to behave gracefully (as in not crashing) when the
+// embedder of webview creates a lot of webviews and draw them at the same time.
+class GlobalTileManager {

[mkosiba (inactive), 2014/04/23 14:10:08]

*cough* unittests *cough* :)

+ private:
+  typedef std::list<HardwareRenderer*> ListType;
+ public:
+  typedef ListType::iterator Key;
+  static GlobalTileManager* GetInstance();
+
+  // Requests the |num_of_tiles| from the available global pool. Returns the
+  // actual number of tiles granted to the requester. If |is_starved| is true,
+  // the GlobalTileManager will evict tiles allocated to other
+  // requesters.
+  size_t RequestTiles(size_t old_num_of_tiles, size_t new_num_of_tiles,
+      bool is_starved, Key key);
+
+  // Continues evicting the least recently drawn views until freeing up at least
+  // amount of memory specified by |desired_policy| to draw a view specified
+  // by |key|.
+  // Returns the amount of memory that was actually evicted.
+  // This function is called when a requester is starved.
+  size_t EvictUntilSatisfied(size_t desired_num_tiles, Key key);
+
+  Key PushBack(HardwareRenderer* hardware_renderer);
+
+  // |key| must be already in manager. Move renderer corresponding to |key| to
+  // most recent.
+  void DidDrawGL(Key key);
+
+  void Remove(Key key);
+ private:
+  friend struct base::DefaultLazyInstanceTraits<GlobalTileManager>;
+  GlobalTileManager();
+  ~GlobalTileManager();
+  size_t allocated_tiles_;
+  ListType mru_list_;
+  // The list of inactive views is from inactive_views_ to mru_list_end().
+  Key inactive_views_;
+
+  DISALLOW_COPY_AND_ASSIGN(GlobalTileManager);
+};
+} // namespace android_webview
+
+#endif