chromium/base/memory/ref_counted.cc

// Copyright 2011 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/memory/ref_counted.h"

#include <limits>
#include <ostream>
#include <type_traits>

#include "base/threading/thread_collision_warner.h"

namespace base {
namespace {

#if DCHECK_IS_ON()
std::atomic_int g_cross_thread_ref_count_access_allow_count(0);
#endif

}  // namespace

namespace subtle {

bool RefCountedThreadSafeBase::HasOneRef() const { … }

bool RefCountedThreadSafeBase::HasAtLeastOneRef() const { … }

#if DCHECK_IS_ON()
RefCountedThreadSafeBase::~RefCountedThreadSafeBase() { … }
#endif

// For security and correctness, we check the arithmetic on ref counts.
//
// In an attempt to avoid binary bloat (from inlining the `CHECK`), we define
// these functions out-of-line. However, compilers are wily. Further testing may
// show that `NOINLINE` helps or hurts.
//
#if defined(ARCH_CPU_64_BITS)
void RefCountedBase::AddRefImpl() const { … }

void RefCountedBase::ReleaseImpl() const { … }
#endif

#if !(defined(ARCH_CPU_X86_FAMILY) || defined(__ARM_FEATURE_ATOMICS))
bool RefCountedThreadSafeBase::Release() const {
  return ReleaseImpl();
}
void RefCountedThreadSafeBase::AddRef() const {
  AddRefImpl();
}
void RefCountedThreadSafeBase::AddRefWithCheck() const {
  AddRefWithCheckImpl();
}
#endif

#if DCHECK_IS_ON()
bool RefCountedBase::CalledOnValidSequence() const { … }
#endif

}  // namespace subtle

#if DCHECK_IS_ON()
ScopedAllowCrossThreadRefCountAccess::ScopedAllowCrossThreadRefCountAccess() { … }

ScopedAllowCrossThreadRefCountAccess::~ScopedAllowCrossThreadRefCountAccess() { … }
#endif

}  // namespace base