libstdc++: Fix <stop_token> and improve tests

	* include/std/stop_token: Reduce header dependencies by including
	internal headers.
	(stop_token::swap(stop_token&), swap(stop_token&, stop_token&)):
	Define.
	(operator!=(const stop_token&, const stop_token&)): Fix return value.
	(stop_token::_Stop_cb::_Stop_cb(Cb&&)): Use std::forward instead of
	(stop_token::_Stop_state_t) [_GLIBCXX_HAS_GTHREADS]: Use lock_guard
	instead of unique_lock.
	[!_GLIBCXX_HAS_GTHREADS]: Do not use mutex.
	(stop_token::stop_token(_Stop_state)): Change parameter to lvalue
	reference.
	(stop_source): Remove unnecessary using-declarations for names only
	used once.
	(swap(stop_source&, stop_source&)): Define.
	(stop_callback(const stop_token&, _Cb&&))
	(stop_callback(stop_token&&, _Cb&&)): Replace lambdas with a named
	function. Use std::forward instead of std::move. Run callbacks if a
	stop request has already been made.
	(stop_source::_M_execute()): Remove.
	(stop_source::_S_execute(_Stop_cb*)): Define.
	* include/std/version (__cpp_lib_jthread): Define conditionally.
	* testsuite/30_threads/stop_token/stop_callback.cc: New test.
	* testsuite/30_threads/stop_token/stop_source.cc: New test.
	* testsuite/30_threads/stop_token/stop_token.cc: Enable test for
	immediate execution of callback.

From-SVN: r278325

libstdc++-v3/ChangeLog

+2019-11-15  Jonathan Wakely  <jwakely@redhat.com>
+
+	* include/std/stop_token: Reduce header dependencies by including
+	internal headers.
+	(stop_token::swap(stop_token&), swap(stop_token&, stop_token&)):
+	Define.
+	(operator!=(const stop_token&, const stop_token&)): Fix return value.
+	(stop_token::_Stop_cb::_Stop_cb(Cb&&)): Use std::forward instead of
+	(stop_token::_Stop_state_t) [_GLIBCXX_HAS_GTHREADS]: Use lock_guard
+	instead of unique_lock.
+	[!_GLIBCXX_HAS_GTHREADS]: Do not use mutex.
+	(stop_token::stop_token(_Stop_state)): Change parameter to lvalue
+	reference.
+	(stop_source): Remove unnecessary using-declarations for names only
+	used once.
+	(swap(stop_source&, stop_source&)): Define.
+	(stop_callback(const stop_token&, _Cb&&))
+	(stop_callback(stop_token&&, _Cb&&)): Replace lambdas with a named
+	function. Use std::forward instead of std::move. Run callbacks if a
+	stop request has already been made.
+	(stop_source::_M_execute()): Remove.
+	(stop_source::_S_execute(_Stop_cb*)): Define.
+	* include/std/version (__cpp_lib_jthread): Define conditionally.
+	* testsuite/30_threads/stop_token/stop_callback.cc: New test.
+	* testsuite/30_threads/stop_token/stop_source.cc: New test.
+	* testsuite/30_threads/stop_token/stop_token.cc: Enable test for
+	immediate execution of callback.
+
 2019-11-15  Edward Smith-Rowland  <3dw4rd@verizon.net>
 
 	Implement the default_searcher part of C++20 p1032 Misc constexpr bits.

libstdc++-v3/include/std/stop_token

@@ -31,24 +31,25 @@
 
 #if __cplusplus > 201703L
 
-#include <type_traits>
-#include <memory>
-#include <mutex>
 #include <atomic>
+#include <bits/std_mutex.h>
+#include <ext/concurrence.h>
+#include <bits/unique_ptr.h>
+#include <bits/shared_ptr.h>
 
-#define __cpp_lib_jthread 201907L
+#ifdef _GLIBCXX_HAS_GTHREADS
+# define __cpp_lib_jthread 201907L
+#endif
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
-  class stop_source;
-  template<typename _Callback>
-  class stop_callback;
-
+  /// Tag type indicating a stop_source should have no shared-stop-state.
   struct nostopstate_t { explicit nostopstate_t() = default; };
   inline constexpr nostopstate_t nostopstate{};
 
+  /// Allow testing whether a stop request has been made on a `stop_source`.
   class stop_token
   {
   public:
@@ -63,7 +64,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     operator=(const stop_token& __rhs) noexcept = default;
 
     stop_token&
-    operator=(stop_token&& __rhs) noexcept;
+    operator=(stop_token&& __rhs) noexcept = default;
 
     [[nodiscard]]
     bool
@@ -79,6 +80,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       return stop_possible() && _M_state->_M_stop_requested();
     }
 
+    void
+    swap(stop_token& __rhs) noexcept
+    { _M_state.swap(__rhs._M_state); }
+
     [[nodiscard]]
     friend bool
     operator==(const stop_token& __a, const stop_token& __b)
@@ -90,26 +95,31 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     friend bool
     operator!=(const stop_token& __a, const stop_token& __b)
     {
-      return __a._M_state == __b._M_state;
+      return __a._M_state != __b._M_state;
     }
 
+    friend void
+    swap(stop_token& __lhs, stop_token& __rhs) noexcept
+    { __lhs.swap(__rhs); }
+
   private:
-    friend stop_source;
+    friend class stop_source;
     template<typename _Callback>
-    friend class stop_callback;
+      friend class stop_callback;
 
-    struct _Stop_cb {
+    struct _Stop_cb
+    {
       void(*_M_callback)(_Stop_cb*);
       _Stop_cb* _M_prev = nullptr;
       _Stop_cb* _M_next = nullptr;
 
       template<typename _Cb>
-      _Stop_cb(_Cb&& __cb)
-        : _M_callback(std::move(__cb))
-      { }
+	_Stop_cb(_Cb&& __cb)
+	: _M_callback(std::forward<_Cb>(__cb))
+	{ }
 
       bool
-      _M_linked() const
+      _M_linked() const noexcept
       {
         return (_M_prev != nullptr)
           || (_M_next != nullptr);
@@ -123,17 +133,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
     };
 
-    struct _Stop_state_t {
-      std::atomic<bool> _M_stopped;
-      std::mutex _M_mtx;
+    struct _Stop_state_t
+    {
+      std::atomic<bool> _M_stopped{false};
       _Stop_cb* _M_head = nullptr;
+#ifdef _GLIBCXX_HAS_GTHREADS
+      std::mutex _M_mtx;
+#endif
 
-      _Stop_state_t()
-        : _M_stopped{false}
-      { }
+      _Stop_state_t() = default;
 
       bool
-      _M_stop_requested()
+      _M_stop_requested() noexcept
       {
         return _M_stopped;
       }
@@ -144,7 +155,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
         bool __stopped = false;
         if (_M_stopped.compare_exchange_strong(__stopped, true))
           {
-            std::unique_lock<std::mutex> __lck{_M_mtx};
+#ifdef _GLIBCXX_HAS_GTHREADS
+            std::lock_guard<std::mutex> __lck{_M_mtx};
+#endif
             while (_M_head)
               {
                 auto __p = _M_head;
@@ -159,7 +172,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       bool
       _M_register_callback(_Stop_cb* __cb)
       {
-        std::unique_lock<std::mutex> __lck{_M_mtx};
+#ifdef _GLIBCXX_HAS_GTHREADS
+        std::lock_guard<std::mutex> __lck{_M_mtx};
+#endif
         if (_M_stopped)
           return false;
 
@@ -169,13 +184,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
             _M_head->_M_prev = __cb;
           }
         _M_head = __cb;
-         return true;
+        return true;
       }
 
       void
       _M_remove_callback(_Stop_cb* __cb)
       {
-        std::unique_lock<std::mutex> __lck{_M_mtx};
+#ifdef _GLIBCXX_HAS_GTHREADS
+        std::lock_guard<std::mutex> __lck{_M_mtx};
+#endif
         if (__cb == _M_head)
           {
             _M_head = _M_head->_M_next;
@@ -202,18 +219,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     using _Stop_state = std::shared_ptr<_Stop_state_t>;
     _Stop_state _M_state;
 
-    explicit stop_token(_Stop_state __state)
-      : _M_state{std::move(__state)}
+    explicit
+    stop_token(const _Stop_state& __state) noexcept
+    : _M_state{__state}
     { }
   };
 
-  class stop_source {
-    using _Stop_state_t = stop_token::_Stop_state_t;
-    using _Stop_state = stop_token::_Stop_state;
-
+  /// A type that allows a stop request to be made.
+  class stop_source
+  {
   public:
     stop_source()
-      : _M_state(std::make_shared<_Stop_state_t>())
+      : _M_state(std::make_shared<stop_token::_Stop_state_t>())
     { }
 
     explicit stop_source(std::nostopstate_t) noexcept
@@ -274,7 +291,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     void
     swap(stop_source& __other) noexcept
     {
-      std::swap(_M_state, __other._M_state);
+      _M_state.swap(__other._M_state);
     }
 
     [[nodiscard]]
@@ -291,59 +308,63 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       return __a._M_state != __b._M_state;
     }
 
+    friend void
+    swap(stop_source& __lhs, stop_source& __rhs) noexcept
+    {
+      __lhs.swap(__rhs);
+    }
+
   private:
-    _Stop_state _M_state;
+    stop_token::_Stop_state _M_state;
   };
 
+  /// A wrapper for callbacks to be run when a stop request is made.
   template<typename _Callback>
     class [[nodiscard]] stop_callback
       : private stop_token::_Stop_cb
     {
-      using _Stop_cb = stop_token::_Stop_cb;
-      using _Stop_state = stop_token::_Stop_state;
     public:
       using callback_type = _Callback;
 
       template<typename _Cb,
-               std::enable_if_t<std::is_constructible_v<_Callback, _Cb>, int> = 0>
-        explicit stop_callback(const stop_token& __token, _Cb&& __cb)
-        noexcept(std::is_nothrow_constructible_v<_Callback, _Cb>)
-        : _Stop_cb([](_Stop_cb* __that) noexcept
-                   {
-                     static_cast<stop_callback*>(__that)->_M_execute();
-                   }),
-        _M_cb(std::move(__cb))
+               enable_if_t<is_constructible_v<_Callback, _Cb>, int> = 0>
+        explicit
+	stop_callback(const stop_token& __token, _Cb&& __cb)
+        noexcept(is_nothrow_constructible_v<_Callback, _Cb>)
+        : _Stop_cb(&_S_execute), _M_cb(std::forward<_Cb>(__cb))
         {
-          auto res = __token._M_state->_M_register_callback(this);
-          if (__token._M_state && res)
-            {
-              _M_state = __token._M_state;
-            }
+	  if (auto __state = __token._M_state)
+	    {
+	      if (__state->_M_stop_requested())
+		_S_execute(this); // ensures std::terminate on throw
+	      else if (__state->_M_register_callback(this))
+		_M_state.swap(__state);
+	    }
         }
 
       template<typename _Cb,
-               std::enable_if_t<std::is_constructible_v<_Callback, _Cb>, int> = 0>
-        explicit stop_callback(stop_token&& __token, _Cb&& __cb)
-        noexcept(std::is_nothrow_constructible_v<_Callback, _Cb>)
-        : _Stop_cb([](_Stop_cb* __that) noexcept
-                   {
-                     static_cast<stop_callback*>(__that)->_M_execute();
-                   }),
-          _M_cb(std::move(__cb))
-          {
-            if (__token._M_state && __token._M_state->_M_register_callback(this))
-              {
-                std::swap(_M_state, __token._M_state);
-              }
-          }
+               enable_if_t<is_constructible_v<_Callback, _Cb>, int> = 0>
+        explicit
+	stop_callback(stop_token&& __token, _Cb&& __cb)
+        noexcept(is_nothrow_constructible_v<_Callback, _Cb>)
+        : _Stop_cb(&_S_execute), _M_cb(std::forward<_Cb>(__cb))
+	{
+	  if (auto& __state = __token._M_state)
+	    {
+	      if (__state->_M_stop_requested())
+		_S_execute(this); // ensures std::terminate on throw
+	      else if (__state->_M_register_callback(this))
+		_M_state.swap(__state);
+	    }
+	}
 
       ~stop_callback()
-        {
-          if (_M_state)
-            {
-              _M_state->_M_remove_callback(this);
-            }
-        }
+      {
+	if (_M_state)
+	  {
+	    _M_state->_M_remove_callback(this);
+	  }
+      }
 
       stop_callback(const stop_callback&) = delete;
       stop_callback& operator=(const stop_callback&) = delete;
@@ -352,12 +373,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     private:
       _Callback _M_cb;
-      _Stop_state _M_state = nullptr;
+      stop_token::_Stop_state _M_state = nullptr;
 
-      void
-        _M_execute() noexcept
+      static void
+      _S_execute(_Stop_cb* __that) noexcept
       {
-        _M_cb();
+	static_cast<stop_callback*>(__that)->_M_cb();
       }
     };
 
@@ -366,5 +387,5 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
-#endif // __cplusplus >= 201703L
+#endif // __cplusplus > 201703L
 #endif // _GLIBCXX_STOP_TOKEN

libstdc++-v3/include/std/version

@@ -184,10 +184,12 @@
 #define __cpp_lib_constexpr_invoke 201907L
 #define __cpp_lib_erase_if 201900L
 #define __cpp_lib_interpolate 201902L
+#ifdef _GLIBCXX_HAS_GTHREADS
+# define __cpp_lib_jthread 201907L
+#endif
 #define __cpp_lib_list_remove_return_type 201806L
 #define __cpp_lib_math_constants 201907L
 #define __cpp_lib_span 201902L
-#define __cpp_lib_jthread 201907L
 #if __cpp_impl_three_way_comparison >= 201907L
 # define __cpp_lib_three_way_comparison 201711L
 #endif

libstdc++-v3/testsuite/30_threads/stop_token/stop_callback.cc

+// Copyright (C) 2019 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.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do run { target c++2a } }
+
+#include <stop_token>
+#include <functional>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  bool called = false;
+  std::function<void()> f = [&called]{ called = true; };
+  std::stop_source ssrc;
+  ssrc.request_stop();
+  std::stop_token tok = ssrc.get_token();
+  std::stop_callback cb1(tok, f);
+  VERIFY( tok.stop_possible() );
+  VERIFY( f != nullptr );
+  VERIFY( called == true );
+
+  called = false;
+  std::stop_callback cb2(std::move(tok), f);
+  // when callback is executed immediately, no change in ownership:
+  VERIFY( tok.stop_possible() );
+  VERIFY( f != nullptr );
+  VERIFY( called == true );
+
+  std::stop_token sink(std::move(tok)); // leave tok empty
+
+  called = false;
+  std::stop_callback cb3(tok, f);
+  VERIFY( f != nullptr );
+  VERIFY( called == false );
+
+  called = false;
+  std::stop_callback cb4(std::move(tok), f);
+  VERIFY( f != nullptr );
+  VERIFY( called == false );
+}
+
+void
+test02()
+{
+  bool called = false;
+  std::function<void()> f0 = [&called]{ called = true; };
+  std::function<void()> f = f0;
+  std::stop_source ssrc;
+  ssrc.request_stop();
+  std::stop_token tok = ssrc.get_token();
+
+  std::stop_callback cb1(tok, std::move(f));
+  VERIFY( tok.stop_possible() );
+  VERIFY( f == nullptr );
+  VERIFY( called == true );
+
+  called = false;
+  f = f0;
+  std::stop_callback cb2(std::move(tok), std::move(f));
+  // when callback is executed immediately, no change in ownership:
+  VERIFY( tok.stop_possible() );
+  VERIFY( f == nullptr );
+  VERIFY( called == true );
+
+  std::stop_token sink(std::move(tok)); // leave tok empty
+
+  called = false;
+  f = f0;
+  std::stop_callback cb3(tok, std::move(f));
+  VERIFY( f == nullptr );
+  VERIFY( called == false );
+
+  called = false;
+  f = f0;
+  std::stop_callback cb4(std::move(tok), std::move(f));
+  VERIFY( f == nullptr );
+  VERIFY( called == false );
+}
+
+void
+test03()
+{
+  bool called[4] = { };
+  std::stop_source ssrc;
+  std::stop_token tok = ssrc.get_token();
+  std::stop_callback cb1(tok, [&]{ called[0] = true; });
+  VERIFY( tok.stop_possible() );
+  VERIFY( called[0] == false );
+
+  std::stop_callback cb2(std::move(tok), [&]{ called[1] = true; });
+  VERIFY( !tok.stop_possible() );
+  VERIFY( called[1] == false );
+
+  std::stop_callback cb3(tok, [&]{ called[2] = true; });
+  VERIFY( called[2] == false );
+
+  std::stop_callback cb4(std::move(tok), [&]{ called[3] = true; });
+  VERIFY( called[3] == false );
+
+  ssrc.request_stop();
+  VERIFY( called[0] == true );
+  VERIFY( called[1] == true );
+  VERIFY( called[2] == false );
+  VERIFY( called[3] == false );
+}
+
+int main()
+{
+  test01();
+  test02();
+  test03();
+}

libstdc++-v3/testsuite/30_threads/stop_token/stop_source.cc

@@ -68,8 +68,27 @@ test02()
   VERIFY( !ssrc.stop_requested() );
 }
 
+void
+test03()
+{
+  std::stop_source s1;
+  s1.request_stop();
+  std::stop_source s2(std::nostopstate);
+  s1.swap(s2);
+  VERIFY( !s1.stop_possible() );
+  VERIFY( !s1.stop_requested() );
+  VERIFY( s2.stop_possible() );
+  VERIFY( s2.stop_requested() );
+  swap(s1, s2);
+  VERIFY( s1.stop_possible() );
+  VERIFY( s1.stop_requested() );
+  VERIFY( !s2.stop_possible() );
+  VERIFY( !s2.stop_requested() );
+}
+
 int main()
 {
   test01();
   test02();
+  test03();
 }

libstdc++-v3/testsuite/30_threads/stop_token/stop_token.cc

@@ -21,7 +21,76 @@
 #include <stop_token>
 #include <testsuite_hooks.h>
 
-int main()
+void
+test01()
+{
+  std::stop_source ssrc;
+  std::stop_token tok = ssrc.get_token();
+  VERIFY(tok.stop_possible());
+  VERIFY(!tok.stop_requested());
+
+  std::stop_token copy(tok);
+  VERIFY(copy == tok);
+  VERIFY(copy.stop_possible());
+  VERIFY(!copy.stop_requested());
+  VERIFY(tok.stop_possible());
+  VERIFY(!tok.stop_requested());
+
+  std::stop_token move(std::move(tok));
+  VERIFY(move != tok);
+  VERIFY(move == copy);
+  VERIFY(move.stop_possible());
+  VERIFY(!move.stop_requested());
+  VERIFY(!tok.stop_possible());
+  VERIFY(!tok.stop_requested());
+  VERIFY(copy.stop_possible());
+  VERIFY(!copy.stop_requested());
+
+  ssrc.request_stop();
+  VERIFY(move.stop_possible());
+  VERIFY(move.stop_requested());
+  VERIFY(!tok.stop_possible());
+  VERIFY(!tok.stop_requested());
+  VERIFY(copy.stop_possible());
+  VERIFY(copy.stop_requested());
+
+  tok.swap(move);
+  VERIFY(tok == copy);
+  VERIFY(!move.stop_possible());
+  VERIFY(!move.stop_requested());
+  VERIFY(tok.stop_possible());
+  VERIFY(tok.stop_requested());
+  VERIFY(copy.stop_possible());
+  VERIFY(copy.stop_requested());
+
+  swap(move, copy);
+  VERIFY(tok == move);
+  VERIFY(move.stop_possible());
+  VERIFY(move.stop_requested());
+  VERIFY(tok.stop_possible());
+  VERIFY(tok.stop_requested());
+  VERIFY(!copy.stop_possible());
+  VERIFY(!copy.stop_requested());
+}
+
+void
+test02()
+{
+  std::stop_source src1, src2;
+  std::stop_token tok = src1.get_token();
+  VERIFY(tok.stop_possible());
+  VERIFY(!tok.stop_requested());
+
+  std::stop_token copy = src2.get_token();
+  VERIFY(copy != tok);
+  copy = tok;
+  VERIFY(copy == tok);
+  copy = src2.get_token();
+  VERIFY(copy != tok);
+}
+
+void
+test03()
 {
   // create stop_source
   std::stop_source ssrc;
@@ -77,8 +146,6 @@ int main()
   b = ssrc.request_stop();
   VERIFY(!b);
 
-  // TODO verify the standard requires this
-#if 0
   // register another callback
   bool cb3called{false};
   std::stop_callback scb3{stok, [&]
@@ -92,5 +159,11 @@ int main()
   VERIFY(!cb1called);
   VERIFY(cb2called);
   VERIFY(cb3called);
-#endif
+}
+
+int main()
+{
+  test01();
+  test02();
+  test03();
 }