FM / bits

/usr/include/c++/8/bits

Name	Size	Mode	Actions
algorithmfwd.h	21736	0644	edit dl rm
allocated_ptr.h	3293	0644	edit dl rm
allocator.h	7569	0644	edit dl rm
alloc_traits.h	20066	0644	edit dl rm
atomic_base.h	23842	0644	edit dl rm
atomic_futex.h	9576	0644	edit dl rm
atomic_lockfree_defines.h	2253	0644	edit dl rm
basic_ios.h	16074	0644	edit dl rm
basic_ios.tcc	6083	0644	edit dl rm
basic_string.h	242697	0644	edit dl rm
basic_string.tcc	53755	0644	edit dl rm
boost_concept_check.h	27161	0644	edit dl rm
c++0x_warning.h	1474	0644	edit dl rm
char_traits.h	20915	0644	edit dl rm
codecvt.h	21289	0644	edit dl rm
concept_check.h	3423	0644	edit dl rm
cpp_type_traits.h	9789	0644	edit dl rm
cxxabi_forced.h	1811	0644	edit dl rm
cxxabi_init_exception.h	2220	0644	edit dl rm
deque.tcc	34122	0644	edit dl rm
enable_special_members.h	12387	0644	edit dl rm
exception.h	2280	0644	edit dl rm
exception_defines.h	1645	0644	edit dl rm
exception_ptr.h	5981	0644	edit dl rm
forward_list.h	48919	0644	edit dl rm
forward_list.tcc	13169	0644	edit dl rm
fstream.tcc	32799	0644	edit dl rm
fs_dir.h	14724	0644	edit dl rm
fs_fwd.h	10279	0644	edit dl rm
fs_ops.h	9730	0644	edit dl rm
fs_path.h	32894	0644	edit dl rm
functexcept.h	3254	0644	edit dl rm
functional_hash.h	8238	0644	edit dl rm
gslice.h	5518	0644	edit dl rm
gslice_array.h	7769	0644	edit dl rm
hashtable.h	73785	0644	edit dl rm
hashtable_policy.h	67971	0644	edit dl rm
hash_bytes.h	2146	0644	edit dl rm
indirect_array.h	7861	0644	edit dl rm
invoke.h	3657	0644	edit dl rm
ios_base.h	31023	0644	edit dl rm
istream.tcc	31093	0644	edit dl rm
list.tcc	15976	0644	edit dl rm
localefwd.h	5646	0644	edit dl rm
locale_classes.h	24897	0644	edit dl rm
locale_classes.tcc	8375	0644	edit dl rm
locale_conv.h	16097	0644	edit dl rm
locale_facets.h	92328	0644	edit dl rm
locale_facets.tcc	39548	0644	edit dl rm
locale_facets_nonio.h	68980	0644	edit dl rm
locale_facets_nonio.tcc	45280	0644	edit dl rm
mask_array.h	7595	0644	edit dl rm
memoryfwd.h	2453	0644	edit dl rm
move.h	6529	0644	edit dl rm
nested_exception.h	4802	0644	edit dl rm
node_handle.h	8216	0644	edit dl rm
ostream.tcc	12315	0644	edit dl rm
ostream_insert.h	4002	0644	edit dl rm
parse_numbers.h	7944	0644	edit dl rm
postypes.h	8208	0644	edit dl rm
predefined_ops.h	9083	0644	edit dl rm
ptr_traits.h	6626	0644	edit dl rm
quoted_string.h	5053	0644	edit dl rm
random.h	175250	0644	edit dl rm
random.tcc	105590	0644	edit dl rm
range_access.h	10030	0644	edit dl rm
refwrap.h	11884	0644	edit dl rm
regex.h	97402	0644	edit dl rm
regex.tcc	16565	0644	edit dl rm
regex_automaton.h	10722	0644	edit dl rm
regex_automaton.tcc	7838	0644	edit dl rm
regex_compiler.h	18050	0644	edit dl rm
regex_compiler.tcc	19288	0644	edit dl rm
regex_constants.h	14708	0644	edit dl rm
regex_error.h	4904	0644	edit dl rm
regex_executor.h	7488	0644	edit dl rm
regex_executor.tcc	18841	0644	edit dl rm
regex_scanner.h	7088	0644	edit dl rm
regex_scanner.tcc	15009	0644	edit dl rm
shared_ptr.h	23433	0644	edit dl rm
shared_ptr_atomic.h	9769	0644	edit dl rm
shared_ptr_base.h	54286	0644	edit dl rm
slice_array.h	9348	0644	edit dl rm
specfun.h	47051	0644	edit dl rm
sstream.tcc	10142	0644	edit dl rm
std_abs.h	3266	0644	edit dl rm
std_function.h	23260	0644	edit dl rm
std_mutex.h	9298	0644	edit dl rm
stl_algo.h	214294	0644	edit dl rm
stl_algobase.h	50494	0644	edit dl rm
stl_bvector.h	33728	0644	edit dl rm
stl_construct.h	7397	0644	edit dl rm
stl_deque.h	78575	0644	edit dl rm
stl_function.h	41745	0644	edit dl rm
stl_heap.h	20206	0644	edit dl rm
stl_iterator.h	42291	0644	edit dl rm
stl_iterator_base_funcs.h	8178	0644	edit dl rm
stl_iterator_base_types.h	8680	0644	edit dl rm
stl_list.h	67558	0644	edit dl rm
stl_map.h	52791	0644	edit dl rm
stl_multimap.h	41557	0644	edit dl rm
stl_multiset.h	35809	0644	edit dl rm
stl_numeric.h	13832	0644	edit dl rm
stl_pair.h	18642	0644	edit dl rm
stl_queue.h	24073	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	36125	0644	edit dl rm
stl_stack.h	11938	0644	edit dl rm
stl_tempbuf.h	8344	0644	edit dl rm
stl_tree.h	74904	0644	edit dl rm
stl_uninitialized.h	27709	0644	edit dl rm
stl_vector.h	60534	0644	edit dl rm
streambuf.tcc	4929	0644	edit dl rm
streambuf_iterator.h	13758	0644	edit dl rm
stream_iterator.h	6654	0644	edit dl rm
stringfwd.h	2607	0644	edit dl rm
string_view.tcc	6698	0644	edit dl rm
uniform_int_dist.h	10081	0644	edit dl rm
unique_ptr.h	25984	0644	edit dl rm
unordered_map.h	75341	0644	edit dl rm
unordered_set.h	59148	0644	edit dl rm
uses_allocator.h	6525	0644	edit dl rm
valarray_after.h	22655	0644	edit dl rm
valarray_array.h	21807	0644	edit dl rm
valarray_array.tcc	7254	0644	edit dl rm
valarray_before.h	18513	0644	edit dl rm
vector.tcc	29644	0644	edit dl rm

Edit: /usr/include/c++/8/bits/atomic_futex.h (9576B)

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

// Copyright (C) 2015-2018 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

#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
#if defined(_GLIBCXX_HAVE_LINUX_FUTEX) && ATOMIC_INT_LOCK_FREE > 1
  struct __atomic_futex_unsigned_base
  {
    // Returns false iff a timeout occurred.
    bool
    _M_futex_wait_until(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::system_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.
    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
	}
    }

// 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, {}, {});
    }

// 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.
    template<typename _Dur>
    unsigned
    _M_load_and_test_until_impl(unsigned __assumed, unsigned __operand,
	bool __equal, memory_order __mo,
	const chrono::time_point<__clock_t, _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(__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)
      {
	return _M_load_when_equal_until(__val, __mo,
					__clock_t::now() + __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)
      {
	// DR 887 - Sync unknown clock to known clock.
	const typename _Clock::time_point __c_entry = _Clock::now();
	const __clock_t::time_point __s_entry = __clock_t::now();
	const auto __delta = __atime - __c_entry;
	const auto __s_atime = __s_entry + __delta;
	return _M_load_when_equal_until(__val, __mo, __s_atime);
      }

// 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<__clock_t, _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_USE_C99_STDINT_TR1

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif

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