shared_mutex (__shared_mutex_pthread, [...]): New helper types implementing the shared mutex requirements.

	* include/std/shared_mutex (__shared_mutex_pthread,
	__shared_mutex_cv): New helper types implementing the shared mutex
	requirements.
	(shared_mutex): New type for C++17.
	(shared_timed_mutex): Derive from one of the new helper types.
	* testsuite/30_threads/shared_mutex/cons/1.cc: New.
	* testsuite/30_threads/shared_mutex/cons/assign_neg.cc: New.
	* testsuite/30_threads/shared_mutex/cons/copy_neg.cc: New.
	* testsuite/30_threads/shared_mutex/requirements/standard_layout.cc:
	New.
	* testsuite/30_threads/shared_mutex/try_lock/1.cc: New.
	* testsuite/30_threads/shared_mutex/try_lock/2.cc: New.

From-SVN: r224158

1 files changed, 250 insertions, 170 deletions

diff --git a/libstdc++-v3/include/std/shared_mutex b/libstdc++-v3/include/std/shared_mutex
index b72a822..0a893ee 100644
--- a/libstdc++-v3/include/std/shared_mutex
+++ b/libstdc++-v3/include/std/shared_mutex
@@ -52,25 +52,31 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 #ifdef _GLIBCXX_USE_C99_STDINT_TR1
 #ifdef _GLIBCXX_HAS_GTHREADS
 
+#if __cplusplus > 201402L
+// TODO: #define __cpp_lib_shared_mutex 201505
+  class shared_mutex;
+#endif
+
 #define __cpp_lib_shared_timed_mutex 201402
+  class shared_timed_mutex;
 
-  /// shared_timed_mutex
-  class shared_timed_mutex
+#if _GLIBCXX_USE_PTHREAD_RWLOCK_T
+  /// A shared mutex type implemented using pthread_rwlock_t.
+  class __shared_mutex_pthread
   {
-#if _GLIBCXX_USE_PTHREAD_RWLOCK_T && _GTHREAD_USE_MUTEX_TIMEDLOCK
-    typedef chrono::system_clock	__clock_t;
+    friend class shared_timed_mutex;
 
 #ifdef PTHREAD_RWLOCK_INITIALIZER
     pthread_rwlock_t	_M_rwlock = PTHREAD_RWLOCK_INITIALIZER;
 
   public:
-    shared_timed_mutex() = default;
-    ~shared_timed_mutex() = default;
+    __shared_mutex_pthread() = default;
+    ~__shared_mutex_pthread() = default;
 #else
     pthread_rwlock_t	_M_rwlock;
 
   public:
-    shared_timed_mutex()
+    __shared_mutex_pthread()
     {
       int __ret = pthread_rwlock_init(&_M_rwlock, NULL);
       if (__ret == ENOMEM)
@@ -83,7 +89,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       _GLIBCXX_DEBUG_ASSERT(__ret == 0);
     }
 
-    ~shared_timed_mutex()
+    ~__shared_mutex_pthread()
     {
       int __ret __attribute((__unused__)) = pthread_rwlock_destroy(&_M_rwlock);
       // Errors not handled: EBUSY, EINVAL
@@ -91,10 +97,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     }
 #endif
 
-    shared_timed_mutex(const shared_timed_mutex&) = delete;
-    shared_timed_mutex& operator=(const shared_timed_mutex&) = delete;
-
-    // Exclusive ownership
+    __shared_mutex_pthread(const __shared_mutex_pthread&) = delete;
+    __shared_mutex_pthread& operator=(const __shared_mutex_pthread&) = delete;
 
     void
     lock()
@@ -116,48 +120,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       return true;
     }
 
-    template<typename _Rep, typename _Period>
-      bool
-      try_lock_for(const chrono::duration<_Rep, _Period>& __rel_time)
-      {
-	return try_lock_until(__clock_t::now() + __rel_time);
-      }
-
-    template<typename _Duration>
-      bool
-      try_lock_until(const chrono::time_point<__clock_t, _Duration>& __atime)
-      {
-	auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
-	auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
-
-	__gthread_time_t __ts =
-	  {
-	    static_cast<std::time_t>(__s.time_since_epoch().count()),
-	    static_cast<long>(__ns.count())
-	  };
-
-	int __ret = pthread_rwlock_timedwrlock(&_M_rwlock, &__ts);
-	// On self-deadlock, we just fail to acquire the lock.  Technically,
-	// the program violated the precondition.
-	if (__ret == ETIMEDOUT || __ret == EDEADLK)
-	  return false;
-	// Errors not handled: EINVAL
-	_GLIBCXX_DEBUG_ASSERT(__ret == 0);
-	return true;
-      }
-
-    template<typename _Clock, typename _Duration>
-      bool
-      try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time)
-      {
-	// 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 = __abs_time - __c_entry;
-	const auto __s_atime = __s_entry + __delta;
-	return try_lock_until(__s_atime);
-      }
-
     void
     unlock()
     {
@@ -198,74 +160,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       return true;
     }
 
-    template<typename _Rep, typename _Period>
-      bool
-      try_lock_shared_for(const chrono::duration<_Rep, _Period>& __rel_time)
-      {
-	return try_lock_shared_until(__clock_t::now() + __rel_time);
-      }
-
-    template<typename _Duration>
-      bool
-      try_lock_shared_until(const chrono::time_point<__clock_t,
-			    _Duration>& __atime)
-      {
-	auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
-	auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
-
-	__gthread_time_t __ts =
-	  {
-	    static_cast<std::time_t>(__s.time_since_epoch().count()),
-	    static_cast<long>(__ns.count())
-	  };
-
-	int __ret;
-	// Unlike for lock(), we are not allowed to throw an exception so if
-	// the maximum number of read locks has been exceeded, or we would
-	// deadlock, we just try to acquire the lock again (and will time out
-	// eventually). 
-	// In cases where we would exceed the maximum number of read locks
-	// throughout the whole time until the timeout, we will fail to
-	// acquire the lock even if it would be logically free; however, this
-	// is allowed by the standard, and we made a "strong effort"
-	// (see C++14 30.4.1.4p26).
-	// For cases where the implementation detects a deadlock we
-	// intentionally block and timeout so that an early return isn't
-	// mistaken for a spurious failure, which might help users realise
-	// there is a deadlock.
-	do
-	  __ret = pthread_rwlock_timedrdlock(&_M_rwlock, &__ts);
-	while (__ret == EAGAIN || __ret == EDEADLK);
-	if (__ret == ETIMEDOUT)
-	  return false;
-	// Errors not handled: EINVAL
-	_GLIBCXX_DEBUG_ASSERT(__ret == 0);
-	return true;
-      }
-
-    template<typename _Clock, typename _Duration>
-      bool
-      try_lock_shared_until(const chrono::time_point<_Clock,
-			    _Duration>& __abs_time)
-      {
-	// 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 = __abs_time - __c_entry;
-	const auto __s_atime = __s_entry + __delta;
-	return try_lock_shared_until(__s_atime);
-      }
-
     void
     unlock_shared()
     {
       unlock();
     }
 
-#else // ! (_GLIBCXX_USE_PTHREAD_RWLOCK_T && _GTHREAD_USE_MUTEX_TIMEDLOCK)
+    void* native_handle() { return &_M_rwlock; }
+  };
+#endif
 
-    // Must use the same clock as condition_variable
-    typedef chrono::system_clock	__clock_t;
+#if ! (_GLIBCXX_USE_PTHREAD_RWLOCK_T && _GTHREAD_USE_MUTEX_TIMEDLOCK)
+  /// A shared mutex type implemented using std::condition_variable.
+  class __shared_mutex_cv
+  {
+    friend class shared_timed_mutex;
 
     // Based on Howard Hinnant's reference implementation from N2406.
 
@@ -312,15 +221,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     unsigned _M_readers() const { return _M_state & _S_max_readers; }
 
   public:
-    shared_timed_mutex() : _M_state(0) {}
+    __shared_mutex_cv() : _M_state(0) {}
 
-    ~shared_timed_mutex()
+    ~__shared_mutex_cv()
     {
       _GLIBCXX_DEBUG_ASSERT( _M_state == 0 );
     }
 
-    shared_timed_mutex(const shared_timed_mutex&) = delete;
-    shared_timed_mutex& operator=(const shared_timed_mutex&) = delete;
+    __shared_mutex_cv(const __shared_mutex_cv&) = delete;
+    __shared_mutex_cv& operator=(const __shared_mutex_cv&) = delete;
 
     // Exclusive ownership
 
@@ -347,35 +256,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       return false;
     }
 
-    template<typename _Rep, typename _Period>
-      bool
-      try_lock_for(const chrono::duration<_Rep, _Period>& __rel_time)
-      {
-	return try_lock_until(__clock_t::now() + __rel_time);
-      }
-
-    template<typename _Clock, typename _Duration>
-      bool
-      try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time)
-      {
-	unique_lock<mutex> __lk(_M_mut);
-	if (!_M_gate1.wait_until(__lk, __abs_time,
-				 [=]{ return !_M_write_entered(); }))
-	  {
-	    return false;
-	  }
-	_M_state |= _S_write_entered;
-	if (!_M_gate2.wait_until(__lk, __abs_time,
-				 [=]{ return _M_readers() == 0; }))
-	  {
-	    _M_state ^= _S_write_entered;
-	    // Wake all threads blocked while the write-entered flag was set.
-	    _M_gate1.notify_all();
-	    return false;
-	  }
-	return true;
-      }
-
     void
     unlock()
     {
@@ -411,28 +291,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       return false;
     }
 
-    template<typename _Rep, typename _Period>
-      bool
-      try_lock_shared_for(const chrono::duration<_Rep, _Period>& __rel_time)
-      {
-	return try_lock_shared_until(__clock_t::now() + __rel_time);
-      }
-
-    template <typename _Clock, typename _Duration>
-      bool
-      try_lock_shared_until(const chrono::time_point<_Clock,
-						     _Duration>& __abs_time)
-      {
-	unique_lock<mutex> __lk(_M_mut);
-	if (!_M_gate1.wait_until(__lk, __abs_time,
-				 [=]{ return _M_state < _S_max_readers; }))
-	  {
-	    return false;
-	  }
-	++_M_state;
-	return true;
-      }
-
     void
     unlock_shared()
     {
@@ -455,6 +313,228 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	    _M_gate1.notify_one();
 	}
     }
+  };
+#endif
+
+#if __cplusplus > 201402L
+  /// The standard shared mutex type.
+  class shared_mutex
+  {
+  public:
+    shared_mutex() = default;
+    ~shared_mutex() = default;
+
+    shared_mutex(const shared_mutex&) = delete;
+    shared_mutex& operator=(const shared_mutex&) = delete;
+
+    // Exclusive ownership
+
+    void lock() { _M_impl.lock(); }
+    bool try_lock() { return _M_impl.try_lock(); }
+    void unlock() { _M_impl.try_lock(); }
+
+    // Shared ownership
+
+    void lock_shared() { _M_impl.lock_shared(); }
+    bool try_lock_shared() { return _M_impl.try_lock_shared(); }
+    void unlock_shared() { _M_impl.unlock_shared(); }
+
+#if _GLIBCXX_USE_PTHREAD_RWLOCK_T
+    typedef void* native_handle_type;
+    native_handle_type native_handle() { return _M_impl.native_handle(); }
+
+  private:
+    __shared_mutex_pthread _M_impl;
+#else
+  private:
+    __shared_mutex_cv _M_impl;
+#endif
+  };
+#endif // C++17
+
+#if _GLIBCXX_USE_PTHREAD_RWLOCK_T && _GTHREAD_USE_MUTEX_TIMEDLOCK
+  using __shared_timed_mutex_base = __shared_mutex_pthread;
+#else
+  using __shared_timed_mutex_base = __shared_mutex_cv;
+#endif
+
+  /// The standard shared timed mutex type.
+  class shared_timed_mutex
+  : private __shared_timed_mutex_base
+  {
+    using _Base = __shared_timed_mutex_base;
+
+    // Must use the same clock as condition_variable for __shared_mutex_cv.
+    typedef chrono::system_clock	__clock_t;
+
+  public:
+    shared_timed_mutex() = default;
+    ~shared_timed_mutex() = default;
+
+    shared_timed_mutex(const shared_timed_mutex&) = delete;
+    shared_timed_mutex& operator=(const shared_timed_mutex&) = delete;
+
+    // Exclusive ownership
+
+    void lock() { _Base::lock(); }
+    bool try_lock() { return _Base::try_lock(); }
+    void unlock() { _Base::unlock(); }
+
+    template<typename _Rep, typename _Period>
+      bool
+      try_lock_for(const chrono::duration<_Rep, _Period>& __rel_time)
+      {
+	return try_lock_until(__clock_t::now() + __rel_time);
+      }
+
+    // Shared ownership
+
+    void lock_shared() { _Base::lock_shared(); }
+    bool try_lock_shared() { return _Base::try_lock_shared(); }
+    void unlock_shared() { _Base::unlock_shared(); }
+
+    template<typename _Rep, typename _Period>
+      bool
+      try_lock_shared_for(const chrono::duration<_Rep, _Period>& __rel_time)
+      {
+	return try_lock_shared_until(__clock_t::now() + __rel_time);
+      }
+
+#if _GLIBCXX_USE_PTHREAD_RWLOCK_T && _GTHREAD_USE_MUTEX_TIMEDLOCK
+
+    // Exclusive ownership
+
+    template<typename _Duration>
+      bool
+      try_lock_until(const chrono::time_point<__clock_t, _Duration>& __atime)
+      {
+	auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
+	auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
+
+	__gthread_time_t __ts =
+	  {
+	    static_cast<std::time_t>(__s.time_since_epoch().count()),
+	    static_cast<long>(__ns.count())
+	  };
+
+	int __ret = pthread_rwlock_timedwrlock(&_M_rwlock, &__ts);
+	// On self-deadlock, we just fail to acquire the lock.  Technically,
+	// the program violated the precondition.
+	if (__ret == ETIMEDOUT || __ret == EDEADLK)
+	  return false;
+	// Errors not handled: EINVAL
+	_GLIBCXX_DEBUG_ASSERT(__ret == 0);
+	return true;
+      }
+
+    template<typename _Clock, typename _Duration>
+      bool
+      try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time)
+      {
+	// 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 = __abs_time - __c_entry;
+	const auto __s_atime = __s_entry + __delta;
+	return try_lock_until(__s_atime);
+      }
+
+    // Shared ownership
+
+    template<typename _Duration>
+      bool
+      try_lock_shared_until(const chrono::time_point<__clock_t,
+			    _Duration>& __atime)
+      {
+	auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
+	auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
+
+	__gthread_time_t __ts =
+	  {
+	    static_cast<std::time_t>(__s.time_since_epoch().count()),
+	    static_cast<long>(__ns.count())
+	  };
+
+	int __ret;
+	// Unlike for lock(), we are not allowed to throw an exception so if
+	// the maximum number of read locks has been exceeded, or we would
+	// deadlock, we just try to acquire the lock again (and will time out
+	// eventually).
+	// In cases where we would exceed the maximum number of read locks
+	// throughout the whole time until the timeout, we will fail to
+	// acquire the lock even if it would be logically free; however, this
+	// is allowed by the standard, and we made a "strong effort"
+	// (see C++14 30.4.1.4p26).
+	// For cases where the implementation detects a deadlock we
+	// intentionally block and timeout so that an early return isn't
+	// mistaken for a spurious failure, which might help users realise
+	// there is a deadlock.
+	do
+	  __ret = pthread_rwlock_timedrdlock(&_M_rwlock, &__ts);
+	while (__ret == EAGAIN || __ret == EDEADLK);
+	if (__ret == ETIMEDOUT)
+	  return false;
+	// Errors not handled: EINVAL
+	_GLIBCXX_DEBUG_ASSERT(__ret == 0);
+	return true;
+      }
+
+    template<typename _Clock, typename _Duration>
+      bool
+      try_lock_shared_until(const chrono::time_point<_Clock,
+						     _Duration>& __abs_time)
+      {
+	// 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 = __abs_time - __c_entry;
+	const auto __s_atime = __s_entry + __delta;
+	return try_lock_shared_until(__s_atime);
+      }
+
+#else // ! (_GLIBCXX_USE_PTHREAD_RWLOCK_T && _GTHREAD_USE_MUTEX_TIMEDLOCK)
+
+    // Exclusive ownership
+
+    template<typename _Clock, typename _Duration>
+      bool
+      try_lock_until(const chrono::time_point<_Clock, _Duration>& __abs_time)
+      {
+	unique_lock<mutex> __lk(_M_mut);
+	if (!_M_gate1.wait_until(__lk, __abs_time,
+				 [=]{ return !_M_write_entered(); }))
+	  {
+	    return false;
+	  }
+	_M_state |= _S_write_entered;
+	if (!_M_gate2.wait_until(__lk, __abs_time,
+				 [=]{ return _M_readers() == 0; }))
+	  {
+	    _M_state ^= _S_write_entered;
+	    // Wake all threads blocked while the write-entered flag was set.
+	    _M_gate1.notify_all();
+	    return false;
+	  }
+	return true;
+      }
+
+    // Shared ownership
+
+    template <typename _Clock, typename _Duration>
+      bool
+      try_lock_shared_until(const chrono::time_point<_Clock,
+						     _Duration>& __abs_time)
+      {
+	unique_lock<mutex> __lk(_M_mut);
+	if (!_M_gate1.wait_until(__lk, __abs_time,
+				 [=]{ return _M_state < _S_max_readers; }))
+	  {
+	    return false;
+	  }
+	++_M_state;
+	return true;
+      }
+
 #endif // _GLIBCXX_USE_PTHREAD_RWLOCK_T && _GTHREAD_USE_MUTEX_TIMEDLOCK
   };
 #endif // _GLIBCXX_HAS_GTHREADS