Fixed (ICE-6317) - Use std::atomic for C++11 builds

1 files changed, 15 insertions, 87 deletions

diff --git a/cpp/src/IceUtil/Shared.cpp b/cpp/src/IceUtil/Shared.cpp
index 1b84f7e5dc9..f242ee8d986 100644
--- a/cpp/src/IceUtil/Shared.cpp
+++ b/cpp/src/IceUtil/Shared.cpp
@@ -11,78 +11,6 @@
 
 using namespace IceUtil;
 
-#ifdef ICE_HAS_ATOMIC_FUNCTIONS
-
-namespace IceUtilInternal
-{
-
-//
-// Linux only. Unfortunately, asm/atomic.h builds non-SMP safe code
-// with non-SMP kernels. This means that executables compiled with a
-// non-SMP kernel would fail randomly due to concurrency errors with
-// reference counting on SMP hosts. Therefore the relevent pieces of
-// atomic.h are more-or-less duplicated.
-//
-
-/*
- * atomicInc - increment ice_atomic variable
- * @v: pointer of type AtomicCounter
- * 
- * Atomically increments @v by 1. Note that the guaranteed useful
- * range of an AtomicCounter is only 24 bits.
- *
- * Inlined because this operation is performance critical.
- */
-static inline void atomicInc(volatile int* counter)
-{
-    __asm__ __volatile__(
-        "lock ; incl %0"
-        :"=m" (*counter)
-        :"m" (*counter));
-}
-
-/**
- * atomicDecAndTest - decrement and test
- * @v: pointer of type AtomicCounter
- * 
- * Atomically decrements @v by 1 and returns true if the result is 0,
- * or false for all other cases. Note that the guaranteed useful
- * range of an AtomicCounter is only 24 bits.
- *
- * Inlined because this operation is performance critical.
- */
-static inline int atomicDecAndTest(volatile int* counter)
-{
-    unsigned char c;
-    __asm__ __volatile__(
-        "lock ; decl %0; sete %1"
-        :"=m" (*counter), "=qm" (c)
-        :"m" (*counter) : "memory");
-    return c != 0;
-}
-
-/**
- * atomicExchangeAdd - same as InterlockedExchangeAdd. This
- * didn't come from atomic.h (the code was derived from similar code
- * in /usr/include/asm/rwsem.h)
- *
- * Inlined because this operation is performance critical.
- */
-static inline int atomicExchangeAdd(volatile int* counter, int i)
-{
-    int tmp = i;
-    __asm__ __volatile__(
-        "lock ; xadd %0,(%2)"
-        :"+r"(tmp), "=m"(*counter)
-        :"r"(counter), "m"(*counter)
-        : "memory");
-    return tmp + i;
-}
-
-}
-
-#endif
-
 //
 // Flag constant used by the Shared class. Derived classes
 // such as GCObject define more flag constants.
@@ -116,7 +44,10 @@ IceUtil::Shared::Shared(const Shared&) :
 void 
 IceUtil::Shared::__incRef()
 {
-#if defined(_WIN32)
+#if defined(ICE_CPP11)
+    assert(_ref.fetch_add(0, std::memory_order_relaxed) >= 0);
+    ++_ref;
+#elif defined(_WIN32)
     assert(InterlockedExchangeAdd(&_ref, 0) >= 0);
     InterlockedIncrement(&_ref);
 #elif defined(ICE_HAS_GCC_BUILTINS)
@@ -126,9 +57,6 @@ IceUtil::Shared::__incRef()
 #   endif
         __sync_fetch_and_add(&_ref, 1);
     assert(c >= 0);
-#elif defined(ICE_HAS_ATOMIC_FUNCTIONS)
-    assert(IceUtilInternal::atomicExchangeAdd(&_ref, 0) >= 0);
-    IceUtilInternal::atomicInc(&_ref);
 #else
     _mutex.lock();
     assert(_ref >= 0);
@@ -140,7 +68,13 @@ IceUtil::Shared::__incRef()
 void 
 IceUtil::Shared::__decRef()
 {
-#if defined(_WIN32)
+#if defined(ICE_CPP11)
+    assert(_ref.fetch_add(0, std::memory_order_relaxed) > 0);
+    if(--_ref == 0 && !(_flags & NoDelete))
+    {
+        delete this;
+    }
+#elif defined(_WIN32)
     assert(InterlockedExchangeAdd(&_ref, 0) > 0);
     if(InterlockedDecrement(&_ref) == 0 && !(_flags & NoDelete))
     {
@@ -153,15 +87,9 @@ IceUtil::Shared::__decRef()
     {
         delete this;
     }
-#elif defined(ICE_HAS_ATOMIC_FUNCTIONS)
-    assert(IceUtilInternal::atomicExchangeAdd(&_ref, 0) > 0);
-    if(IceUtilInternal::atomicDecAndTest(&_ref) && !(_flags & NoDelete))
-    {
-        delete this;
-    }
 #else
-    _mutex.lock();
     bool doDelete = false;
+    _mutex.lock();
     assert(_ref > 0);
     if(--_ref == 0)
     {
@@ -179,12 +107,12 @@ IceUtil::Shared::__decRef()
 int
 IceUtil::Shared::__getRef() const
 {
-#if defined(_WIN32)
+#if defined(ICE_CPP11)
+    return _ref.load(std::memory_order_relaxed);
+#elif defined(_WIN32)
     return InterlockedExchangeAdd(const_cast<LONG*>(&_ref), 0);
 #elif defined(ICE_HAS_GCC_BUILTINS)
     return __sync_fetch_and_sub(const_cast<volatile int*>(&_ref), 0);
-#elif defined(ICE_HAS_ATOMIC_FUNCTIONS)
-    return IceUtilInternal::atomicExchangeAdd(const_cast<volatile int*>(&_ref), 0);
 #else
     _mutex.lock();
     int ref = _ref;