Global GPU memory manager for android webview

android_webview/browser/gpu_memory_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_GPU_MEMORY_MANAGER_H_
+#define ANDROID_WEBVIEW_BROWSER_GPU_MEMORY_MANAGER_H_
+
+#include <list>
+#include "android_webview/browser/shared_renderer_state.h"
+#include "base/basictypes.h"
+#include "base/synchronization/lock.h"
+#include "content/public/browser/android/synchronous_compositor.h"
+
+namespace android_webview {
+
+namespace {
+  typedef content::SynchronousCompositorMemoryPolicy MemoryPolicy;
+  typedef GLViewRendererManager::Key Key;
+} // namespace
+
+// A global Gpu memory manager to keep track of gpu memory and 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 GpuMemoryManger does
+// not keep track of how much memory each individual view is using.
+class GpuMemoryManager {
+ public:
+  static GpuMemoryManager* GetInstance();
+
+  // Updates the memory allocation in GpuMemoryManager. Evicts other views if
+  // memory allocation is over limit. |key| is the GLViewRendererManager key of
+  // the view that requests the resources.
+  void UpdateResources(MemoryPolicy& old_policy,
+                       MemoryPolicy& new_policy,
+                       Key key);
+
+ private:
+  friend struct base::DefaultLazyInstanceTraits<GpuMemoryManager>;
+  GpuMemoryManager();
+  ~GpuMemoryManager();
+
+  // 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.
+  MemoryPolicy EvictUntilSatisfied(MemoryPolicy desired_policy, Key key);
+
+  MemoryPolicy allocated_;
+  // Gpu Memory in bytes
+  const static size_t kGpuMemoryLimit;
+  // On Android webview, One resource has a gralloc buffer backing it and one
+  // gralloc buffer has two file descriptors
+  const static size_t kNumResourcesLimit;
+  mutable base::Lock lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(GpuMemoryManager);
+};
+} // namespace android_webview
+
+#endif