FM / bits

/usr/include/c++/11/bits

Name	Size	Mode	Actions
algorithmfwd.h	24547	0644	edit dl rm
align.h	3711	0644	edit dl rm
allocated_ptr.h	3329	0644	edit dl rm
allocator.h	9737	0644	edit dl rm
alloc_traits.h	27632	0644	edit dl rm
atomic_base.h	57414	0644	edit dl rm
atomic_futex.h	12394	0644	edit dl rm
atomic_lockfree_defines.h	2353	0644	edit dl rm
atomic_timed_wait.h	13530	0644	edit dl rm
atomic_wait.h	12557	0644	edit dl rm
basic_ios.h	16080	0644	edit dl rm
basic_ios.tcc	6083	0644	edit dl rm
basic_string.h	251944	0644	edit dl rm
basic_string.tcc	54189	0644	edit dl rm
boost_concept_check.h	27182	0644	edit dl rm
c++0x_warning.h	1474	0644	edit dl rm
charconv.h	3435	0644	edit dl rm
char_traits.h	29350	0644	edit dl rm
codecvt.h	25500	0644	edit dl rm
concept_check.h	3423	0644	edit dl rm
cpp_type_traits.h	14003	0644	edit dl rm
cxxabi_forced.h	1811	0644	edit dl rm
cxxabi_init_exception.h	2220	0644	edit dl rm
deque.tcc	42361	0644	edit dl rm
enable_special_members.h	12452	0644	edit dl rm
erase_if.h	2066	0644	edit dl rm
exception.h	2504	0644	edit dl rm
exception_defines.h	1645	0644	edit dl rm
exception_ptr.h	7640	0644	edit dl rm
forward_list.h	50387	0644	edit dl rm
forward_list.tcc	14035	0644	edit dl rm
fstream.tcc	33672	0644	edit dl rm
fs_dir.h	16409	0644	edit dl rm
fs_fwd.h	10771	0644	edit dl rm
fs_ops.h	10739	0644	edit dl rm
fs_path.h	39745	0644	edit dl rm
functexcept.h	3509	0644	edit dl rm
functional_hash.h	8591	0644	edit dl rm
gslice.h	5519	0644	edit dl rm
gslice_array.h	7892	0644	edit dl rm
hashtable.h	84951	0644	edit dl rm
hashtable_policy.h	62156	0644	edit dl rm
hash_bytes.h	2146	0644	edit dl rm
indirect_array.h	7902	0644	edit dl rm
invoke.h	6059	0644	edit dl rm
ios_base.h	31934	0644	edit dl rm
istream.tcc	31595	0644	edit dl rm
iterator_concepts.h	33335	0644	edit dl rm
list.tcc	17201	0644	edit dl rm
localefwd.h	5943	0644	edit dl rm
locale_classes.h	25044	0644	edit dl rm
locale_classes.tcc	8375	0644	edit dl rm
locale_conv.h	18822	0644	edit dl rm
locale_facets.h	93655	0644	edit dl rm
locale_facets.tcc	40463	0644	edit dl rm
locale_facets_nonio.h	69704	0644	edit dl rm
locale_facets_nonio.tcc	47533	0644	edit dl rm
mask_array.h	7716	0644	edit dl rm
max_size_type.h	22715	0644	edit dl rm
memoryfwd.h	2504	0644	edit dl rm
move.h	6798	0644	edit dl rm
nested_exception.h	4887	0644	edit dl rm
node_handle.h	10920	0644	edit dl rm
ostream.tcc	12315	0644	edit dl rm
ostream_insert.h	4038	0644	edit dl rm
parse_numbers.h	7980	0644	edit dl rm
postypes.h	8465	0644	edit dl rm
predefined_ops.h	10177	0644	edit dl rm
ptr_traits.h	6708	0644	edit dl rm
quoted_string.h	5053	0644	edit dl rm
random.h	178359	0644	edit dl rm
random.tcc	105688	0644	edit dl rm
ranges_algo.h	116831	0644	edit dl rm
ranges_algobase.h	18871	0644	edit dl rm
ranges_base.h	24392	0644	edit dl rm
ranges_cmp.h	6017	0644	edit dl rm
ranges_uninitialized.h	18130	0644	edit dl rm
ranges_util.h	20591	0644	edit dl rm
range_access.h	10707	0644	edit dl rm
refwrap.h	13208	0644	edit dl rm
regex.h	103969	0644	edit dl rm
regex.tcc	16492	0644	edit dl rm
regex_automaton.h	10788	0644	edit dl rm
regex_automaton.tcc	7722	0644	edit dl rm
regex_compiler.h	16219	0644	edit dl rm
regex_compiler.tcc	19158	0644	edit dl rm
regex_constants.h	15549	0644	edit dl rm
regex_error.h	5015	0644	edit dl rm
regex_executor.h	8852	0644	edit dl rm
regex_executor.tcc	18837	0644	edit dl rm
regex_scanner.h	7047	0644	edit dl rm
regex_scanner.tcc	15249	0644	edit dl rm
semaphore_base.h	7936	0644	edit dl rm
shared_ptr.h	30981	0644	edit dl rm
shared_ptr_atomic.h	9874	0644	edit dl rm
shared_ptr_base.h	54907	0644	edit dl rm
slice_array.h	9619	0644	edit dl rm
specfun.h	47240	0644	edit dl rm
sstream.tcc	10148	0644	edit dl rm
std_abs.h	3384	0644	edit dl rm
std_function.h	22863	0644	edit dl rm
std_mutex.h	6443	0644	edit dl rm
std_thread.h	8589	0644	edit dl rm
stl_algo.h	214703	0644	edit dl rm
stl_algobase.h	76254	0644	edit dl rm
stl_bvector.h	35574	0644	edit dl rm
stl_construct.h	8800	0644	edit dl rm
stl_deque.h	76970	0644	edit dl rm
stl_function.h	43897	0644	edit dl rm
stl_heap.h	20756	0644	edit dl rm
stl_iterator.h	78851	0644	edit dl rm
stl_iterator_base_funcs.h	8178	0644	edit dl rm
stl_iterator_base_types.h	9662	0644	edit dl rm
stl_list.h	69779	0644	edit dl rm
stl_map.h	54693	0644	edit dl rm
stl_multimap.h	43534	0644	edit dl rm
stl_multiset.h	37675	0644	edit dl rm
stl_numeric.h	14601	0644	edit dl rm
stl_pair.h	20135	0644	edit dl rm
stl_queue.h	25036	0644	edit dl rm
stl_raw_storage_iter.h	3830	0644	edit dl rm
stl_relops.h	4594	0644	edit dl rm
stl_set.h	37939	0644	edit dl rm
stl_stack.h	12684	0644	edit dl rm
stl_tempbuf.h	8655	0644	edit dl rm
stl_tree.h	73922	0644	edit dl rm
stl_uninitialized.h	34013	0644	edit dl rm
stl_vector.h	65919	0644	edit dl rm
streambuf.tcc	4929	0644	edit dl rm
streambuf_iterator.h	15532	0644	edit dl rm
stream_iterator.h	7697	0644	edit dl rm
stringfwd.h	2690	0644	edit dl rm
string_view.tcc	7167	0644	edit dl rm
this_thread_sleep.h	3307	0644	edit dl rm
uniform_int_dist.h	13052	0644	edit dl rm
unique_lock.h	6143	0644	edit dl rm
unique_ptr.h	32537	0644	edit dl rm
unordered_map.h	76669	0644	edit dl rm
unordered_set.h	62934	0644	edit dl rm
uses_allocator.h	6906	0644	edit dl rm
uses_allocator_args.h	7562	0644	edit dl rm
valarray_after.h	23283	0644	edit dl rm
valarray_array.h	21295	0644	edit dl rm
valarray_array.tcc	7254	0644	edit dl rm
valarray_before.h	19142	0644	edit dl rm
vector.tcc	30985	0644	edit dl rm

Edit: /usr/include/c++/11/bits/atomic_futex.h (12394B)

// -*- C++ -*- header.

// Copyright (C) 2015-2021 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file bits/atomic_futex.h
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly.
 */

#ifndef _GLIBCXX_ATOMIC_FUTEX_H
#define _GLIBCXX_ATOMIC_FUTEX_H 1

#pragma GCC system_header

#include <bits/c++config.h>
#include <atomic>
#include <chrono>
#if ! (defined(_GLIBCXX_HAVE_LINUX_FUTEX) && ATOMIC_INT_LOCK_FREE > 1)
#include <mutex>
#include <condition_variable>
#endif

#ifndef _GLIBCXX_ALWAYS_INLINE
#define _GLIBCXX_ALWAYS_INLINE inline __attribute__((__always_inline__))
#endif

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

#ifdef _GLIBCXX_HAS_GTHREADS
#if defined(_GLIBCXX_HAVE_LINUX_FUTEX) && ATOMIC_INT_LOCK_FREE > 1
  struct __atomic_futex_unsigned_base
  {
    // __s and __ns are measured against CLOCK_REALTIME. Returns false
    // iff a timeout occurred.
    bool
    _M_futex_wait_until(unsigned *__addr, unsigned __val, bool __has_timeout,
	chrono::seconds __s, chrono::nanoseconds __ns);

// __s and __ns are measured against CLOCK_MONOTONIC. Returns
    // false iff a timeout occurred.
    bool
    _M_futex_wait_until_steady(unsigned *__addr, unsigned __val,
	bool __has_timeout, chrono::seconds __s, chrono::nanoseconds __ns);

// This can be executed after the object has been destroyed.
    static void _M_futex_notify_all(unsigned* __addr);
  };

template <unsigned _Waiter_bit = 0x80000000>
  class __atomic_futex_unsigned : __atomic_futex_unsigned_base
  {
    typedef chrono::steady_clock __clock_t;

// This must be lock-free and at offset 0.
    atomic<unsigned> _M_data;

public:
    explicit
    __atomic_futex_unsigned(unsigned __data) : _M_data(__data)
    { }

_GLIBCXX_ALWAYS_INLINE unsigned
    _M_load(memory_order __mo)
    {
      return _M_data.load(__mo) & ~_Waiter_bit;
    }

private:
    // If a timeout occurs, returns a current value after the timeout;
    // otherwise, returns the operand's value if equal is true or a different
    // value if equal is false.
    // The assumed value is the caller's assumption about the current value
    // when making the call.
    // __s and __ns are measured against CLOCK_REALTIME.
    unsigned
    _M_load_and_test_until(unsigned __assumed, unsigned __operand,
	bool __equal, memory_order __mo, bool __has_timeout,
	chrono::seconds __s, chrono::nanoseconds __ns)
    {
      for (;;)
	{
	  // Don't bother checking the value again because we expect the caller
	  // to have done it recently.
	  // memory_order_relaxed is sufficient because we can rely on just the
	  // modification order (store_notify uses an atomic RMW operation too),
	  // and the futex syscalls synchronize between themselves.
	  _M_data.fetch_or(_Waiter_bit, memory_order_relaxed);
	  bool __ret = _M_futex_wait_until((unsigned*)(void*)&_M_data,
					   __assumed | _Waiter_bit,
					   __has_timeout, __s, __ns);
	  // Fetch the current value after waiting (clears _Waiter_bit).
	  __assumed = _M_load(__mo);
	  if (!__ret || ((__operand == __assumed) == __equal))
	    return __assumed;
	  // TODO adapt wait time
	}
    }

// If a timeout occurs, returns a current value after the timeout;
    // otherwise, returns the operand's value if equal is true or a different
    // value if equal is false.
    // The assumed value is the caller's assumption about the current value
    // when making the call.
    // __s and __ns are measured against CLOCK_MONOTONIC.
    unsigned
    _M_load_and_test_until_steady(unsigned __assumed, unsigned __operand,
	bool __equal, memory_order __mo, bool __has_timeout,
	chrono::seconds __s, chrono::nanoseconds __ns)
    {
      for (;;)
	{
	  // Don't bother checking the value again because we expect the caller
	  // to have done it recently.
	  // memory_order_relaxed is sufficient because we can rely on just the
	  // modification order (store_notify uses an atomic RMW operation too),
	  // and the futex syscalls synchronize between themselves.
	  _M_data.fetch_or(_Waiter_bit, memory_order_relaxed);
	  bool __ret = _M_futex_wait_until_steady((unsigned*)(void*)&_M_data,
					   __assumed | _Waiter_bit,
					   __has_timeout, __s, __ns);
	  // Fetch the current value after waiting (clears _Waiter_bit).
	  __assumed = _M_load(__mo);
	  if (!__ret || ((__operand == __assumed) == __equal))
	    return __assumed;
	  // TODO adapt wait time
	}
    }

// Returns the operand's value if equal is true or a different value if
    // equal is false.
    // The assumed value is the caller's assumption about the current value
    // when making the call.
    unsigned
    _M_load_and_test(unsigned __assumed, unsigned __operand,
	bool __equal, memory_order __mo)
    {
      return _M_load_and_test_until(__assumed, __operand, __equal, __mo,
				    false, {}, {});
    }

template<typename _Dur>
    unsigned
    _M_load_and_test_until_impl(unsigned __assumed, unsigned __operand,
	bool __equal, memory_order __mo,
	const chrono::time_point<std::chrono::steady_clock, _Dur>& __atime)
    {
      auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
      auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
      // XXX correct?
      return _M_load_and_test_until_steady(__assumed, __operand, __equal, __mo,
	  true, __s.time_since_epoch(), __ns);
    }

public:

_GLIBCXX_ALWAYS_INLINE unsigned
    _M_load_when_not_equal(unsigned __val, memory_order __mo)
    {
      unsigned __i = _M_load(__mo);
      if ((__i & ~_Waiter_bit) != __val)
	return (__i & ~_Waiter_bit);
      // TODO Spin-wait first.
      return _M_load_and_test(__i, __val, false, __mo);
    }

_GLIBCXX_ALWAYS_INLINE void
    _M_load_when_equal(unsigned __val, memory_order __mo)
    {
      unsigned __i = _M_load(__mo);
      if ((__i & ~_Waiter_bit) == __val)
	return;
      // TODO Spin-wait first.
      _M_load_and_test(__i, __val, true, __mo);
    }

// Returns false iff a timeout occurred.
    template<typename _Rep, typename _Period>
      _GLIBCXX_ALWAYS_INLINE bool
      _M_load_when_equal_for(unsigned __val, memory_order __mo,
	  const chrono::duration<_Rep, _Period>& __rtime)
      {
	using __dur = typename __clock_t::duration;
	return _M_load_when_equal_until(__val, __mo,
		    __clock_t::now() + chrono::__detail::ceil<__dur>(__rtime));
      }

// Returns false iff a timeout occurred.
    template<typename _Clock, typename _Duration>
      _GLIBCXX_ALWAYS_INLINE bool
      _M_load_when_equal_until(unsigned __val, memory_order __mo,
	  const chrono::time_point<_Clock, _Duration>& __atime)
      {
	typename _Clock::time_point __c_entry = _Clock::now();
	do {
	  const __clock_t::time_point __s_entry = __clock_t::now();
	  const auto __delta = __atime - __c_entry;
	  const auto __s_atime = __s_entry +
	      chrono::__detail::ceil<__clock_t::duration>(__delta);
	  if (_M_load_when_equal_until(__val, __mo, __s_atime))
	    return true;
	  __c_entry = _Clock::now();
	} while (__c_entry < __atime);
	return false;
      }

// Returns false iff a timeout occurred.
    template<typename _Duration>
    _GLIBCXX_ALWAYS_INLINE bool
    _M_load_when_equal_until(unsigned __val, memory_order __mo,
	const chrono::time_point<std::chrono::system_clock, _Duration>& __atime)
    {
      unsigned __i = _M_load(__mo);
      if ((__i & ~_Waiter_bit) == __val)
	return true;
      // TODO Spin-wait first.  Ignore effect on timeout.
      __i = _M_load_and_test_until_impl(__i, __val, true, __mo, __atime);
      return (__i & ~_Waiter_bit) == __val;
    }

// Returns false iff a timeout occurred.
    template<typename _Duration>
    _GLIBCXX_ALWAYS_INLINE bool
    _M_load_when_equal_until(unsigned __val, memory_order __mo,
	const chrono::time_point<std::chrono::steady_clock, _Duration>& __atime)
    {
      unsigned __i = _M_load(__mo);
      if ((__i & ~_Waiter_bit) == __val)
	return true;
      // TODO Spin-wait first.  Ignore effect on timeout.
      __i = _M_load_and_test_until_impl(__i, __val, true, __mo, __atime);
      return (__i & ~_Waiter_bit) == __val;
    }

_GLIBCXX_ALWAYS_INLINE void
    _M_store_notify_all(unsigned __val, memory_order __mo)
    {
      unsigned* __futex = (unsigned *)(void *)&_M_data;
      if (_M_data.exchange(__val, __mo) & _Waiter_bit)
	_M_futex_notify_all(__futex);
    }
  };

#else // ! (_GLIBCXX_HAVE_LINUX_FUTEX && ATOMIC_INT_LOCK_FREE > 1)

// If futexes are not available, use a mutex and a condvar to wait.
  // Because we access the data only within critical sections, all accesses
  // are sequentially consistent; thus, we satisfy any provided memory_order.
  template <unsigned _Waiter_bit = 0x80000000>
  class __atomic_futex_unsigned
  {
    typedef chrono::system_clock __clock_t;

unsigned _M_data;
    mutex _M_mutex;
    condition_variable _M_condvar;

public:
    explicit
    __atomic_futex_unsigned(unsigned __data) : _M_data(__data)
    { }

_GLIBCXX_ALWAYS_INLINE unsigned
    _M_load(memory_order __mo)
    {
      unique_lock<mutex> __lock(_M_mutex);
      return _M_data;
    }

_GLIBCXX_ALWAYS_INLINE unsigned
    _M_load_when_not_equal(unsigned __val, memory_order __mo)
    {
      unique_lock<mutex> __lock(_M_mutex);
      while (_M_data == __val)
	_M_condvar.wait(__lock);
      return _M_data;
    }

_GLIBCXX_ALWAYS_INLINE void
    _M_load_when_equal(unsigned __val, memory_order __mo)
    {
      unique_lock<mutex> __lock(_M_mutex);
      while (_M_data != __val)
	_M_condvar.wait(__lock);
    }

template<typename _Rep, typename _Period>
      _GLIBCXX_ALWAYS_INLINE bool
      _M_load_when_equal_for(unsigned __val, memory_order __mo,
	  const chrono::duration<_Rep, _Period>& __rtime)
      {
	unique_lock<mutex> __lock(_M_mutex);
	return _M_condvar.wait_for(__lock, __rtime,
				   [&] { return _M_data == __val;});
      }

template<typename _Clock, typename _Duration>
      _GLIBCXX_ALWAYS_INLINE bool
      _M_load_when_equal_until(unsigned __val, memory_order __mo,
	  const chrono::time_point<_Clock, _Duration>& __atime)
      {
	unique_lock<mutex> __lock(_M_mutex);
	return _M_condvar.wait_until(__lock, __atime,
				     [&] { return _M_data == __val;});
      }

_GLIBCXX_ALWAYS_INLINE void
    _M_store_notify_all(unsigned __val, memory_order __mo)
    {
      unique_lock<mutex> __lock(_M_mutex);
      _M_data = __val;
      _M_condvar.notify_all();
    }
  };

#endif // _GLIBCXX_HAVE_LINUX_FUTEX && ATOMIC_INT_LOCK_FREE > 1
#endif // _GLIBCXX_HAS_GTHREADS

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif

cmd: