Add reference counter of DxgiDuplicatorController to unload DXGI components

webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.cc

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.h"
 
 #include <windows.h>
 
 #include <algorithm>
 #include <string>
 
 #include "webrtc/base/checks.h"
+#include "webrtc/base/logging.h"
 #include "webrtc/base/timeutils.h"
 #include "webrtc/modules/desktop_capture/desktop_capture_types.h"
 #include "webrtc/modules/desktop_capture/win/dxgi_frame.h"
 #include "webrtc/modules/desktop_capture/win/screen_capture_utils.h"
 #include "webrtc/system_wrappers/include/sleep.h"
 
 namespace webrtc {
 
 // static
+std::atomic_int DxgiDuplicatorController::refcount_(0);

[Sergey Ulanov, 2017/06/19 18:52:43]

Does this value need to be static?

[Hzj_jie, 2017/06/19 20:19:46]

Since we have only one DxgiDuplicatorController instance, using either member
variable or static variable does not make any differences I believe. But, yes,
using member variable can save several characters.

+
+// static
 DxgiDuplicatorController* DxgiDuplicatorController::Instance() {
   // The static instance won't be deleted to ensure it can be used by other
   // threads even during program exiting.
   static DxgiDuplicatorController* instance = new DxgiDuplicatorController();
   return instance;
 }
 
+// static
+DxgiDuplicatorController::Reference DxgiDuplicatorController::GetReference() {
+  return Reference(Instance());
+}
+
 DxgiDuplicatorController::DxgiDuplicatorController() = default;
 
-DxgiDuplicatorController::~DxgiDuplicatorController() {
-  rtc::CritScope lock(&lock_);
-  Deinitialize();
+void DxgiDuplicatorController::AddRef() const {
+  int refcount = (++refcount_);
+  RTC_DCHECK(refcount > 0);
+}
+
+void DxgiDuplicatorController::Release() {
+  int refcount = (--refcount_);
+  RTC_DCHECK(refcount >= 0);
+  if (refcount == 0) {
+    LOG(LS_WARNING) << "Count of references reaches zero, "
+                       "DxgiDuplicatorController will be unloaded.";
+    Unload();
+  }
 }
 
 bool DxgiDuplicatorController::IsSupported() {
   rtc::CritScope lock(&lock_);
   return Initialize();
 }
 
 bool DxgiDuplicatorController::RetrieveD3dInfo(D3dInfo* info) {
   rtc::CritScope lock(&lock_);
   if (!Initialize()) {
@@ skipping 72 matching lines @@
     // do not need to deinitialize.
     return Result::INVALID_MONITOR_ID;
   }
 
   // If the |monitor_id| is valid, but DoDuplicateUnlocked() failed, something
   // must be wrong from capturer APIs. We should Deinitialize().
   Deinitialize();
   return Result::DUPLICATION_FAILED;
 }
 
+void DxgiDuplicatorController::Unload() {
+  rtc::CritScope lock(&lock_);
+  Deinitialize();
+}
+
 void DxgiDuplicatorController::Unregister(const Context* const context) {
   rtc::CritScope lock(&lock_);
   if (ContextExpired(context)) {
     // The Context has not been setup after a recent initialization, so it
     // should not been registered in duplicators.
     return;
   }
   for (size_t i = 0; i < duplicators_.size(); i++) {
     duplicators_[i].Unregister(&context->contexts[i]);
   }
@@ skipping 230 matching lines @@
 void DxgiDuplicatorController::TranslateRect() {
   const DesktopVector position =
       DesktopVector().subtract(desktop_rect_.top_left());
   desktop_rect_.Translate(position);
   for (auto& duplicator : duplicators_) {
     duplicator.TranslateRect(position);
   }
 }
 
 }  // namespace webrtc