Android: Free GLHelper context ashmem when it makes sense

content/browser/renderer_host/render_widget_host_view_android.cc

 // Copyright (c) 2012 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 "content/browser/renderer_host/render_widget_host_view_android.h"
 
 #include <android/bitmap.h>
 
 #include <utility>
 
+#include "base/android/application_status_listener.h"
 #include "base/android/build_info.h"
 #include "base/android/context_utils.h"
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/macros.h"
+#include "base/memory/memory_pressure_listener.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/sys_info.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/threading/worker_pool.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/surface_layer.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/copy_output_request.h"
@@ skipping 63 matching lines @@
 #include "ui/touch_selection/touch_selection_controller.h"
 
 namespace content {
 
 namespace {
 
 const int kUndefinedOutputSurfaceId = -1;
 
 static const char kAsyncReadBackString[] = "Compositing.CopyFromSurfaceTime";
 
+using base::android::ApplicationState;
+using base::android::ApplicationStatusListener;
+using base::MemoryPressureListener;
+
 class GLHelperHolder {
  public:
   static GLHelperHolder* Create();
 
   display_compositor::GLHelper* gl_helper() { return gl_helper_.get(); }
   bool IsLost() {
     if (!gl_helper_)
       return true;
     return provider_->ContextGL()->GetGraphicsResetStatusKHR() != GL_NO_ERROR;
   }
 
+  void FreeUnusedSharedMemoryIfNeeded();
+
  private:
-  GLHelperHolder() = default;
+  GLHelperHolder();
   void Initialize();
   void OnContextLost();
+  void OnApplicationStatusChanged(ApplicationState new_state);
+  void OnMemoryPressure(MemoryPressureListener::MemoryPressureLevel level);
 
   scoped_refptr<ContextProviderCommandBuffer> provider_;
   std::unique_ptr<display_compositor::GLHelper> gl_helper_;
 
+  bool has_running_activities_;
+  bool should_aggressively_free_memory_;
+
+  std::unique_ptr<ApplicationStatusListener> app_status_listener_;
+  std::unique_ptr<MemoryPressureListener> mem_pressure_listener_;
+
   DISALLOW_COPY_AND_ASSIGN(GLHelperHolder);
 };
 
+GLHelperHolder::GLHelperHolder()
+    : has_running_activities_(
+          ApplicationStatusListener::GetState() ==
+          base::android::APPLICATION_STATE_HAS_RUNNING_ACTIVITIES),
+      should_aggressively_free_memory_(!has_running_activities_) {}
+
 GLHelperHolder* GLHelperHolder::Create() {
   GLHelperHolder* holder = new GLHelperHolder;
   holder->Initialize();
   return holder;
 }
 
 void GLHelperHolder::Initialize() {
   auto* factory = BrowserGpuChannelHostFactory::instance();
   scoped_refptr<gpu::GpuChannelHost> gpu_channel_host(factory->GetGpuChannel());
 
@@ skipping 42 matching lines @@
   if (!provider_->BindToCurrentThread())
     return;
   provider_->ContextGL()->TraceBeginCHROMIUM(
       "gpu_toplevel",
       base::StringPrintf("CmdBufferImageTransportFactory-%p", provider_.get())
           .c_str());
   provider_->SetLostContextCallback(
       base::Bind(&GLHelperHolder::OnContextLost, base::Unretained(this)));
   gl_helper_.reset(new display_compositor::GLHelper(
       provider_->ContextGL(), provider_->ContextSupport()));
+
+  app_status_listener_.reset(new ApplicationStatusListener(base::Bind(
+      &GLHelperHolder::OnApplicationStatusChanged, base::Unretained(this))));

[danakj, 2016/09/13 22:44:58]

Please leave a comment explaining why unretained this is safe

[no sievers, 2016/09/26 22:19:28]

Done.

+  mem_pressure_listener_.reset(new MemoryPressureListener(base::Bind(
+      &GLHelperHolder::OnMemoryPressure, base::Unretained(this))));

[danakj, 2016/09/13 22:44:58]

ditto

[no sievers, 2016/09/26 22:19:28]

Done.

+}
+
+void GLHelperHolder::FreeUnusedSharedMemoryIfNeeded() {
+  if (should_aggressively_free_memory_)
+    provider_->FreeUnusedSharedMemory();
 }
 
 void GLHelperHolder::OnContextLost() {
+  app_status_listener_.reset();
+  mem_pressure_listener_.reset();
+  provider_->FreeUnusedSharedMemory();

[danakj, 2016/09/13 22:44:58]

What if we just delete the helper instead?

[no sievers, 2016/09/26 22:19:28]

Yes, good idea and it works because IsLost() above will handle |gl_helper_ ==
null| and we'd recreate it lazily from the getter below.

   // Need to post a task because the command buffer client cannot be deleted
   // from within this callback.
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::Bind(&RenderWidgetHostViewAndroid::OnContextLost));
 }
 
-// This can only be used for readback postprocessing. It may return null if the
-// channel was lost and not reestablished yet.
-display_compositor::GLHelper* GetPostReadbackGLHelper() {
+void GLHelperHolder::OnApplicationStatusChanged(ApplicationState new_state) {
+  bool new_has_running_activities =
+      new_state == base::android::APPLICATION_STATE_HAS_RUNNING_ACTIVITIES;
+
+  if (!has_running_activities_ && new_has_running_activities) {
+    // Intentionally allow reset at this time even if we previously had a
+    // low memory signal.
+    should_aggressively_free_memory_ = false;
+  } else if (!new_has_running_activities) {
+    should_aggressively_free_memory_ = true;
+    provider_->FreeUnusedSharedMemory();
+  }
+
+  has_running_activities_ = new_has_running_activities;
+}
+
+void GLHelperHolder::OnMemoryPressure(
+    MemoryPressureListener::MemoryPressureLevel level) {
+  if (level == MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE ||
+      level == MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL) {
+    should_aggressively_free_memory_ = true;

[danakj, 2016/09/13 22:44:58]

I feel weird about 2 functions setting this independently, will this lead to
some weird behaviour where one sets it and the other changes it and we get not
what we hoped for?

[no sievers, 2016/09/26 22:19:28]

Done.

+    provider_->FreeUnusedSharedMemory();
+  }
+}
+
+GLHelperHolder* GetPostReadbackGLHelperHolder(bool create_if_necessary) {
   static GLHelperHolder* g_readback_helper_holder = nullptr;
 
+  if (!create_if_necessary && !g_readback_helper_holder)
+    return nullptr;
+
   if (g_readback_helper_holder && g_readback_helper_holder->IsLost()) {
     delete g_readback_helper_holder;
     g_readback_helper_holder = nullptr;
   }
 
   if (!g_readback_helper_holder)
     g_readback_helper_holder = GLHelperHolder::Create();
 
-  return g_readback_helper_holder->gl_helper();
+  return g_readback_helper_holder;
+}
+
+display_compositor::GLHelper* GetPostReadbackGLHelper() {
+  return GetPostReadbackGLHelperHolder(true)->gl_helper();

[danakj, 2016/09/13 22:44:58]

can you put the true into a temp var to give it a name

[no sievers, 2016/09/26 22:19:29]

Done.

+}
+
+void FreeUnusedGLHelperMemory() {
+  GLHelperHolder* holder = GetPostReadbackGLHelperHolder(false);

[danakj, 2016/09/13 22:44:58]

ditto for false

[no sievers, 2016/09/26 22:19:28]

Done.

+
+  if (holder) {
+    holder->FreeUnusedSharedMemoryIfNeeded();
+  }
 }
 
 void CopyFromCompositingSurfaceFinished(
     const ReadbackRequestCallback& callback,
     std::unique_ptr<cc::SingleReleaseCallback> release_callback,
     std::unique_ptr<SkBitmap> bitmap,
     const base::TimeTicks& start_time,
     std::unique_ptr<SkAutoLockPixels> bitmap_pixels_lock,
     bool result) {
   TRACE_EVENT0(
       "cc", "RenderWidgetHostViewAndroid::CopyFromCompositingSurfaceFinished");
   bitmap_pixels_lock.reset();
   gpu::SyncToken sync_token;
   if (result) {
     display_compositor::GLHelper* gl_helper = GetPostReadbackGLHelper();
     if (gl_helper)
       gl_helper->GenerateSyncToken(&sync_token);
   }
+
+  FreeUnusedGLHelperMemory();

[danakj, 2016/09/13 22:44:58]

What if there was more than one copy going?

[no sievers, 2016/09/26 22:19:28]

I think that's fine because it would only free *unused* memory until the last
readback completes and we'd free the remainder.

+
   const bool lost_resource = !sync_token.HasData();
   release_callback->Run(sync_token, lost_resource);
   UMA_HISTOGRAM_TIMES(kAsyncReadBackString,
                       base::TimeTicks::Now() - start_time);
   ReadbackResponse response = result ? READBACK_SUCCESS : READBACK_FAILED;
   callback.Run(*bitmap, response);
 }
 
 std::unique_ptr<ui::TouchSelectionController> CreateSelectionController(
     ui::TouchSelectionControllerClient* client,
@@ skipping 1643 matching lines @@
     case ui::MotionEvent::ACTION_UP:
     case ui::MotionEvent::ACTION_POINTER_UP:
       UMA_HISTOGRAM_CUSTOM_COUNTS("Event.Latency.OS.TOUCH_RELEASED",
                                   delta.InMicroseconds(), 1, 1000000, 50);
     default:
       return;
   }
 }
 
 }  // namespace content