Create rtc::AtomicInt POD struct.

webrtc/base/atomicops.h

Index: webrtc/base/atomicops.h
diff --git a/webrtc/base/atomicops.h b/webrtc/base/atomicops.h
index a863566a670aad0b3d4904f0040c3c20ad845461..573db7f9ddc74f21c34f9fadc185ac837901d0f5 100644
--- a/webrtc/base/atomicops.h
+++ b/webrtc/base/atomicops.h
@@ -11,6 +11,8 @@
 #ifndef WEBRTC_BASE_ATOMICOPS_H_
 #define WEBRTC_BASE_ATOMICOPS_H_
 
+#include "webrtc/base/constructormagic.h"
+
 #if defined(WEBRTC_WIN)
 // Include winsock2.h before including <windows.h> to maintain consistency with
 // win32.h.  We can't include win32.h directly here since it pulls in
@@ -21,6 +23,7 @@
 #endif  // defined(WEBRTC_WIN)
 
 namespace rtc {
+
 class AtomicOps {
  public:
 #if defined(WEBRTC_WIN)
@@ -61,8 +64,34 @@ class AtomicOps {
 #endif
 };
 
+// POD struct version of AtomicOps, prevents accidental non-atomic usage (such
+// as ++, =, reads or writes). Operations are still explicit to not hide that
+// the operations are atomic.

[kwiberg-webrtc, 2015/11/02 12:41:49]

Maybe "Functions are static, so that the AtomicInt:: prefix must be present in
the code, clearly labeling the operations as being atomic." for the last
sentence?

Also, do you plan to migrate all current users of AtomicOps?

[pbos-webrtc, 2015/11/02 15:21:15]

Done, yep that's the plan. I'm not sure if that should entail removing AtomicOps
though.

+struct AtomicInt {
+  AtomicInt() = delete;
 
+  // value_ is public to permit brace initialization. Should not be accessed
+  // directly.
+  volatile int value_;
 
+  static int Increment(AtomicInt* i) {
+    return AtomicOps::Increment(&i->value_);
+  }
+  static int Decrement(AtomicInt* i) {
+    return AtomicOps::Decrement(&i->value_);
+  }
+  static int AcquireLoad(const AtomicInt* i) {
+    return AtomicOps::AcquireLoad(&i->value_);
+  }
+  static void ReleaseStore(AtomicInt* i, int value) {
+    AtomicOps::ReleaseStore(&i->value_, value);
+  }
+  static int CompareAndSwap(AtomicInt* i, int old_value, int new_value) {
+    return AtomicOps::CompareAndSwap(&i->value_, old_value, new_value);
+  }

[kwiberg-webrtc, 2015/11/02 12:41:50]

I'd like a short comment on each of these, explaining what it does and what it
returns.

[pbos-webrtc, 2015/11/02 15:21:15]

Done.

+
+  RTC_DISALLOW_COPY_AND_ASSIGN(AtomicInt);
+};
 }
 
 #endif  // WEBRTC_BASE_ATOMICOPS_H_