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// **********************************************************************
//
// Copyright (c) 2003-2012 ZeroC, Inc. All rights reserved.
//
// This copy of Ice is licensed to you under the terms described in the
// ICE_LICENSE file included in this distribution.
//
// **********************************************************************
#include <IceUtil/Shared.h>
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
IceUtil::SimpleShared::SimpleShared() :
_ref(0),
_noDelete(false)
{
}
IceUtil::SimpleShared::SimpleShared(const SimpleShared&) :
_ref(0),
_noDelete(false)
{
}
IceUtil::Shared::Shared() :
_ref(0),
_noDelete(false)
{
}
IceUtil::Shared::Shared(const Shared&) :
_ref(0),
_noDelete(false)
{
}
void
IceUtil::Shared::__incRef()
{
#if defined(_WIN32)
assert(InterlockedExchangeAdd(&_ref, 0) >= 0);
InterlockedIncrement(&_ref);
#elif defined(ICE_HAS_GCC_BUILTINS)
int c = __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);
++_ref;
_mutex.unlock();
#endif
}
void
IceUtil::Shared::__decRef()
{
#if defined(_WIN32)
assert(InterlockedExchangeAdd(&_ref, 0) > 0);
if(InterlockedDecrement(&_ref) == 0 && !_noDelete)
{
_noDelete = true;
delete this;
}
#elif defined(ICE_HAS_GCC_BUILTINS)
int c = __sync_fetch_and_sub(&_ref, 1);
assert(c > 0);
if(c == 1 && !_noDelete)
{
_noDelete = true;
delete this;
}
#elif defined(ICE_HAS_ATOMIC_FUNCTIONS)
assert(IceUtilInternal::atomicExchangeAdd(&_ref, 0) > 0);
if(IceUtilInternal::atomicDecAndTest(&_ref) && !_noDelete)
{
_noDelete = true;
delete this;
}
#else
_mutex.lock();
bool doDelete = false;
assert(_ref > 0);
if(--_ref == 0)
{
doDelete = !_noDelete;
_noDelete = true;
}
_mutex.unlock();
if(doDelete)
{
delete this;
}
#endif
}
int
IceUtil::Shared::__getRef() const
{
#if 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;
_mutex.unlock();
return ref;
#endif
}
void
IceUtil::Shared::__setNoDelete(bool b)
{
_noDelete = b;
}
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