mirror of https://github.com/CGAL/cgal
142 lines
3.3 KiB
C++
142 lines
3.3 KiB
C++
// Copyright (c) 1999
|
|
// Utrecht University (The Netherlands),
|
|
// ETH Zurich (Switzerland),
|
|
// INRIA Sophia-Antipolis (France),
|
|
// Max-Planck-Institute Saarbruecken (Germany),
|
|
// and Tel-Aviv University (Israel). All rights reserved.
|
|
//
|
|
// This file is part of CGAL (www.cgal.org)
|
|
//
|
|
// $URL$
|
|
// $Id$
|
|
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
|
|
//
|
|
//
|
|
// Author(s) : Sylvain Pion
|
|
|
|
#ifndef CGAL_HANDLE_H
|
|
#define CGAL_HANDLE_H
|
|
|
|
#include <cstddef>
|
|
#include <atomic>
|
|
#include <CGAL/Handle_for.h>
|
|
#include <CGAL/assertions.h>
|
|
|
|
namespace CGAL {
|
|
|
|
class Rep
|
|
{
|
|
friend class Handle;
|
|
protected:
|
|
Rep(int count = 1)
|
|
: count(count)
|
|
{}
|
|
virtual ~Rep() {}
|
|
|
|
std::atomic_int count;
|
|
};
|
|
|
|
|
|
class Handle
|
|
{
|
|
public:
|
|
|
|
typedef std::ptrdiff_t Id_type ;
|
|
|
|
Handle() noexcept
|
|
: PTR(static_cast<Rep*>(0)) {}
|
|
|
|
Handle(const Handle& x) noexcept(!(CGAL_PRECONDITIONS_ENABLED || CGAL_ASSERTIONS_ENABLED))
|
|
{
|
|
CGAL_precondition( x.PTR != static_cast<Rep*>(0) );
|
|
PTR = x.PTR;
|
|
//CGAL_assume (PTR->count > 0);
|
|
incref();
|
|
}
|
|
|
|
Handle(Handle&& x) noexcept : PTR(x.PTR) { x.PTR = 0; }
|
|
|
|
~Handle() { reset(); }
|
|
|
|
Handle&
|
|
operator=(const Handle& x) noexcept(!CGAL_PRECONDITIONS_ENABLED)
|
|
{
|
|
CGAL_precondition( x.PTR != static_cast<Rep*>(0) );
|
|
x.incref();
|
|
if(PTR) decref(); // not reset() in case this==&x
|
|
PTR = x.PTR;
|
|
return *this;
|
|
}
|
|
|
|
Handle&
|
|
operator=(Handle&& x) noexcept
|
|
{
|
|
swap(*this, x);
|
|
return *this;
|
|
}
|
|
|
|
friend void swap(Handle& a, Handle& b) noexcept { std::swap(a.PTR, b.PTR); }
|
|
|
|
private:
|
|
void incref() const noexcept
|
|
{
|
|
if (is_currently_single_threaded()) {
|
|
PTR->count.store(PTR->count.load(std::memory_order_relaxed) + 1, std::memory_order_relaxed);
|
|
} else {
|
|
PTR->count.fetch_add(1, std::memory_order_relaxed);
|
|
}
|
|
}
|
|
|
|
void decref()
|
|
{
|
|
if (is_currently_single_threaded()) {
|
|
auto c = PTR->count.load(std::memory_order_relaxed);
|
|
if (c == 1)
|
|
delete PTR;
|
|
else
|
|
PTR->count.store(c - 1, std::memory_order_relaxed);
|
|
} else {
|
|
// TSAN does not support fences :-(
|
|
#if !defined __SANITIZE_THREAD__ && !__has_feature(thread_sanitizer)
|
|
if (PTR->count.load(std::memory_order_relaxed) == 1
|
|
|| PTR->count.fetch_sub(1, std::memory_order_release) == 1) {
|
|
std::atomic_thread_fence(std::memory_order_acquire);
|
|
#else
|
|
if (PTR->count.fetch_sub(1, std::memory_order_acq_rel) == 1) {
|
|
#endif
|
|
delete PTR;
|
|
}
|
|
}
|
|
}
|
|
|
|
public:
|
|
void reset()
|
|
{
|
|
if (PTR)
|
|
{
|
|
decref();
|
|
PTR=0;
|
|
}
|
|
}
|
|
|
|
int
|
|
refs() const noexcept { return PTR->count.load(std::memory_order_relaxed); }
|
|
|
|
Id_type id() const noexcept { return std::distance(static_cast<Rep*>(0), PTR); }
|
|
|
|
bool identical(const Handle& h) const noexcept { return PTR == h.PTR; }
|
|
|
|
void * for_compact_container() const { return PTR; }
|
|
void for_compact_container(void* p) { PTR = static_cast<Rep*>(p); }
|
|
protected:
|
|
Rep* PTR;
|
|
};
|
|
|
|
//inline Handle::Id_type id(const Handle& x) { return x.id() ; }
|
|
|
|
inline bool identical(const Handle &h1, const Handle &h2) noexcept { return h1.identical(h2); }
|
|
|
|
} //namespace CGAL
|
|
|
|
#endif // CGAL_HANDLE_H
|