New classes RefCounter and RefCountedBase.

Bug: webrtc:8270
Change-Id: Ibdab81b3fcbe6cba9ae24033f56c84b13c868b21
Reviewed-on: https://webrtc-review.googlesource.com/2684
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20386}

api/BUILD.gn

@@ -262,6 +262,15 @@ rtc_source_set("optional") {
   ]
 }
 
+rtc_source_set("refcountedbase") {
+  sources = [
+    "refcountedbase.h",
+  ]
+  deps = [
+    "../rtc_base:rtc_base_approved",
+  ]
+}
+
 rtc_source_set("libjingle_peerconnection_test_api") {
   testonly = true
   sources = [

api/refcountedbase.h

@@ -0,0 +1,43 @@
+/*
+ *  Copyright 2017 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.
+ */
+#ifndef API_REFCOUNTEDBASE_H_
+#define API_REFCOUNTEDBASE_H_
+
+#include "rtc_base/constructormagic.h"
+#include "rtc_base/refcount.h"
+#include "rtc_base/refcounter.h"
+
+namespace rtc {
+
+class RefCountedBase {
+ public:
+  RefCountedBase() = default;
+
+  void AddRef() const { ref_count_.IncRef(); }
+  RefCountReleaseStatus Release() const {
+    const auto status = ref_count_.DecRef();
+    if (status == RefCountReleaseStatus::kDroppedLastRef) {
+      delete this;
+    }
+    return status;
+  }
+
+ protected:
+  virtual ~RefCountedBase() = default;
+
+ private:
+  mutable webrtc::webrtc_impl::RefCounter ref_count_{0};
+
+  RTC_DISALLOW_COPY_AND_ASSIGN(RefCountedBase);
+};
+
+}  // namespace rtc
+
+#endif  // API_REFCOUNTEDBASE_H_

audio/audio_state.h

@@ -50,6 +50,7 @@ class AudioState final : public webrtc::AudioState {
   ScopedVoEInterface<VoEBase> voe_base_;
 
   // Reference count; implementation copied from rtc::RefCountedObject.
+  // TODO(nisse): Use RefCountedObject or RefCountedBase instead.
   mutable volatile int ref_count_ = 0;
 
   // Transports mixed audio from the mixer to the audio device and

modules/desktop_capture/BUILD.gn

@@ -337,6 +337,7 @@ rtc_static_library("desktop_capture_generic") {
   deps = [
     ":primitives",
     "../..:webrtc_common",
+    "../../api:refcountedbase",
     "../../rtc_base:rtc_base",  # TODO(kjellander): Cleanup in bugs.webrtc.org/3806.
     "../../system_wrappers",
     "//third_party/libyuv",

modules/desktop_capture/mac/desktop_configuration_monitor.cc

@@ -20,8 +20,7 @@ namespace webrtc {
 static const int64_t kDisplayConfigurationEventTimeoutMs = 10 * 1000;
 
 DesktopConfigurationMonitor::DesktopConfigurationMonitor()
-    : ref_count_(0),
-      display_configuration_capture_event_(EventWrapper::Create()) {
+    : display_configuration_capture_event_(EventWrapper::Create()) {
   CGError err = CGDisplayRegisterReconfigurationCallback(
       DesktopConfigurationMonitor::DisplaysReconfiguredCallback, this);
   if (err != kCGErrorSuccess) {

modules/desktop_capture/mac/desktop_configuration_monitor.h

@@ -16,9 +16,9 @@
 #include <memory>
 #include <set>
 
+#include "api/refcountedbase.h"
 #include "modules/desktop_capture/mac/desktop_configuration.h"
 #include "rtc_base/constructormagic.h"
-#include "system_wrappers/include/atomic32.h"
 
 namespace webrtc {
 
@@ -26,7 +26,7 @@ class EventWrapper;
 
 // The class provides functions to synchronize capturing and display
 // reconfiguring across threads, and the up-to-date MacDesktopConfiguration.
-class DesktopConfigurationMonitor {
+class DesktopConfigurationMonitor : public rtc::RefCountedBase {
  public:
   DesktopConfigurationMonitor();
   // Acquires a lock on the current configuration.
@@ -39,22 +39,16 @@ class DesktopConfigurationMonitor {
     return desktop_configuration_;
   }
 
-  void AddRef() { ++ref_count_; }
-  void Release() {
-    if (--ref_count_ == 0)
-      delete this;
-  }
+ protected:
+  ~DesktopConfigurationMonitor() override;
 
  private:
   static void DisplaysReconfiguredCallback(CGDirectDisplayID display,
                                            CGDisplayChangeSummaryFlags flags,
                                            void *user_parameter);
-  ~DesktopConfigurationMonitor();
-
   void DisplaysReconfigured(CGDirectDisplayID display,
                             CGDisplayChangeSummaryFlags flags);
 
-  Atomic32 ref_count_;
   std::set<CGDirectDisplayID> reconfiguring_displays_;
   MacDesktopConfiguration desktop_configuration_;
   std::unique_ptr<EventWrapper> display_configuration_capture_event_;

modules/desktop_capture/mac/full_screen_chrome_window_detector.cc

@@ -141,7 +141,7 @@ bool IsChromeWindow(CGWindowID id) {
 }  // namespace
 
 FullScreenChromeWindowDetector::FullScreenChromeWindowDetector()
-    : ref_count_(0), last_update_time_ns_(0) {}
+    : last_update_time_ns_(0) {}
 
 FullScreenChromeWindowDetector::~FullScreenChromeWindowDetector() {}
 

modules/desktop_capture/mac/full_screen_chrome_window_detector.h

@@ -13,9 +13,9 @@
 
 #include <ApplicationServices/ApplicationServices.h>
 
+#include "api/refcountedbase.h"
 #include "modules/desktop_capture/desktop_capturer.h"
 #include "rtc_base/constructormagic.h"
-#include "system_wrappers/include/atomic32.h"
 
 namespace webrtc {
 
@@ -30,16 +30,10 @@ namespace webrtc {
 // 3. The new window is full-screen.
 // 4. The new window didn't exist at least 500 millisecond ago.
 
-class FullScreenChromeWindowDetector {
+class FullScreenChromeWindowDetector : public rtc::RefCountedBase {
  public:
   FullScreenChromeWindowDetector();
 
-  void AddRef() { ++ref_count_; }
-  void Release() {
-    if (--ref_count_ == 0)
-      delete this;
-  }
-
   // Returns the full-screen window in place of the original window if all the
   // criteria are met, or kCGNullWindowID if no such window found.
   CGWindowID FindFullScreenWindow(CGWindowID original_window);
@@ -48,11 +42,10 @@ class FullScreenChromeWindowDetector {
   // second.
   void UpdateWindowListIfNeeded(CGWindowID original_window);
 
+ protected:
+  ~FullScreenChromeWindowDetector() override;
+
  private:
-  ~FullScreenChromeWindowDetector();
-
-  Atomic32 ref_count_;
-
   // We cache the last two results of the window list, so
   // |previous_window_list_| is taken at least 500ms before the next Capture()
   // call. If we only save the last result, we may get false positive (i.e.

modules/desktop_capture/window_capturer_x11.cc

@@ -8,6 +8,8 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#include <string.h>
+
 #include <X11/extensions/Xcomposite.h>
 #include <X11/extensions/Xrender.h>
 #include <X11/Xutil.h>

modules/desktop_capture/x11/shared_x_display.h

@@ -16,9 +16,9 @@
 
 #include <string>
 
+#include "api/refcountedbase.h"
 #include "rtc_base/constructormagic.h"
 #include "rtc_base/scoped_ref_ptr.h"
-#include "system_wrappers/include/atomic32.h"
 
 // Including Xlib.h will involve evil defines (Bool, Status, True, False), which
 // easily conflict with other headers.
@@ -28,7 +28,7 @@ typedef union _XEvent XEvent;
 namespace webrtc {
 
 // A ref-counted object to store XDisplay connection.
-class SharedXDisplay {
+class SharedXDisplay : public rtc::RefCountedBase {
  public:
   class XEventHandler {
    public:
@@ -51,12 +51,6 @@ class SharedXDisplay {
   // DISPLAY). NULL is returned if X11 connection failed.
   static rtc::scoped_refptr<SharedXDisplay> CreateDefault();
 
-  void AddRef() { ++ref_count_; }
-  void Release() {
-    if (--ref_count_ == 0)
-      delete this;
-  }
-
   Display* display() { return display_; }
 
   // Adds a new event |handler| for XEvent's of |type|.
@@ -69,12 +63,12 @@ class SharedXDisplay {
   // Processes pending XEvents, calling corresponding event handlers.
   void ProcessPendingXEvents();
 
+ protected:
+  ~SharedXDisplay() override;
+
  private:
   typedef std::map<int, std::vector<XEventHandler*> > EventHandlersMap;
 
-  ~SharedXDisplay();
-
-  Atomic32 ref_count_;
   Display* display_;
 
   EventHandlersMap event_handlers_;

rtc_base/BUILD.gn

@@ -167,6 +167,7 @@ rtc_source_set("rtc_base_approved_generic") {
     "ratetracker.h",
     "refcount.h",
     "refcountedobject.h",
+    "refcounter.h",
     "safe_compare.h",
     "safe_conversions.h",
     "safe_conversions_impl.h",

rtc_base/refcountedobject.h

@@ -12,8 +12,9 @@
 
 #include <utility>
 
-#include "rtc_base/atomicops.h"
+#include "rtc_base/constructormagic.h"
 #include "rtc_base/refcount.h"
+#include "rtc_base/refcounter.h"
 
 namespace rtc {
 
@@ -31,14 +32,14 @@ class RefCountedObject : public T {
           std::forward<P1>(p1),
           std::forward<Args>(args)...) {}
 
-  virtual void AddRef() const { AtomicOps::Increment(&ref_count_); }
+  virtual void AddRef() const { ref_count_.IncRef(); }
 
   virtual RefCountReleaseStatus Release() const {
-    if (AtomicOps::Decrement(&ref_count_) == 0) {
+    const auto status = ref_count_.DecRef();
+    if (status == RefCountReleaseStatus::kDroppedLastRef) {
       delete this;
-      return RefCountReleaseStatus::kDroppedLastRef;
     }
-    return RefCountReleaseStatus::kOtherRefsRemained;
+    return status;
   }
 
   // Return whether the reference count is one. If the reference count is used
@@ -47,14 +48,14 @@ class RefCountedObject : public T {
   // performs the test for a reference count of one, and performs the memory
   // barrier needed for the owning thread to act on the object, knowing that it
   // has exclusive access to the object.
-  virtual bool HasOneRef() const {
-    return AtomicOps::AcquireLoad(&ref_count_) == 1;
-  }
+  virtual bool HasOneRef() const { return ref_count_.HasOneRef(); }
 
  protected:
   virtual ~RefCountedObject() {}
 
-  mutable volatile int ref_count_ = 0;
+  mutable webrtc::webrtc_impl::RefCounter ref_count_{0};
+
+  RTC_DISALLOW_COPY_AND_ASSIGN(RefCountedObject);
 };
 
 }  // namespace rtc

rtc_base/refcounter.h

@@ -0,0 +1,52 @@
+/*
+ *  Copyright 2017 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.
+ */
+#ifndef RTC_BASE_REFCOUNTER_H_
+#define RTC_BASE_REFCOUNTER_H_
+
+#include "rtc_base/atomicops.h"
+#include "rtc_base/refcount.h"
+
+namespace webrtc {
+namespace webrtc_impl {
+
+class RefCounter {
+ public:
+  explicit RefCounter(int ref_count) : ref_count_(ref_count) {}
+  RefCounter() = delete;
+
+  void IncRef() { rtc::AtomicOps::Increment(&ref_count_); }
+
+  // TODO(nisse): Switch return type to RefCountReleaseStatus?
+  // Returns true if this was the last reference, and the resource protected by
+  // the reference counter can be deleted.
+  rtc::RefCountReleaseStatus DecRef() {
+    return (rtc::AtomicOps::Decrement(&ref_count_) == 0)
+        ? rtc::RefCountReleaseStatus::kDroppedLastRef
+        : rtc::RefCountReleaseStatus::kOtherRefsRemained;
+  }
+
+  // Return whether the reference count is one. If the reference count is used
+  // in the conventional way, a reference count of 1 implies that the current
+  // thread owns the reference and no other thread shares it. This call performs
+  // the test for a reference count of one, and performs the memory barrier
+  // needed for the owning thread to act on the resource protected by the
+  // reference counter, knowing that it has exclusive access.
+  bool HasOneRef() const {
+    return rtc::AtomicOps::AcquireLoad(&ref_count_) == 1;
+  }
+
+ private:
+  volatile int ref_count_;
+};
+
+}  // namespace webrtc_impl
+}  // namespace webrtc
+
+#endif  // RTC_BASE_REFCOUNTER_H_