Add beast_basics module

modules/beast_basics/memory/beast_AtomicPointer.h

@@ -0,0 +1,146 @@
+/*============================================================================*/
+/*
+  VFLib: https://github.com/vinniefalco/VFLib
+
+  Copyright (C) 2008 by Vinnie Falco <vinnie.falco@gmail.com>
+
+  This library contains portions of other open source products covered by
+  separate licenses. Please see the corresponding source files for specific
+  terms.
+
+  VFLib is provided under the terms of The MIT License (MIT):
+
+  Permission is hereby granted, free of charge, to any person obtaining a copy
+  of this software and associated documentation files (the "Software"), to deal
+  in the Software without restriction, including without limitation the rights
+  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+  copies of the Software, and to permit persons to whom the Software is
+  furnished to do so, subject to the following conditions:
+
+  The above copyright notice and this permission notice shall be included in
+  all copies or substantial portions of the Software.
+
+  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+  IN THE SOFTWARE.
+*/
+/*============================================================================*/
+
+#ifndef BEAST_ATOMICPOINTER_BEASTHEADER
+#define BEAST_ATOMICPOINTER_BEASTHEADER
+
+/*============================================================================*/
+/**
+    A thread safe pointer.
+
+    This provides a simplified interface to an atomic pointer suitable
+    for building containers or composite classes. Operator overloads
+    allow access to the underlying pointer using natural C++ syntax.
+
+    @ingroup beast_core
+*/
+template <class P>
+class AtomicPointer
+{
+public:
+    /** Create a pointer.
+
+        @param initialValue An optional starting value (default is null).
+    */
+    explicit AtomicPointer (P* const initialValue = nullptr) noexcept
+:
+    m_value (initialValue)
+    {
+    }
+
+    /** Retrieve the pointer value */
+    inline P* get () const noexcept
+    {
+        return m_value.get ();
+    }
+
+    /** Obtain a pointer to P through type conversion.
+
+        The caller must synchronize access to P.
+
+        @return A pointer to P.
+    */
+    inline operator P* () const noexcept
+    {
+        return get ();
+    }
+
+    /** Dereference operator
+
+        The caller must synchronize access to P.
+
+        @return A reference to P.
+    */
+    inline P& operator* () const noexcept
+    {
+        return &get ();
+    }
+
+    /** Member selection
+
+        The caller must synchronize access to P.
+
+        @return A pointer to P.
+    */
+    inline P* operator-> () const noexcept
+    {
+        return get ();
+    }
+
+    inline void set (P* p)
+    {
+        m_value.set (p);
+    }
+
+    /** Atomically assign a new pointer
+
+        @param newValue The new value to assign.
+    */
+    inline void operator= (P* newValue) noexcept
+    {
+        set (newValue);
+    }
+
+    /** Atomically assign a new pointer and return the old value.
+
+        @param newValue The new value to assign.
+
+        @return         The previous value.
+    */
+    inline P* exchange (P* newValue)
+    {
+        return m_value.exchange (newValue);
+    }
+
+    /** Conditionally perform an atomic assignment.
+
+        The current value is compared with oldValue and atomically
+        set to newValue if the comparison is equal.
+
+        The caller is responsible for handling the ABA problem.
+
+        @param  newValue  The new value to assign.
+
+        @param  oldValue  The matching old value.
+
+        @return true if the assignment was performed.
+    */
+    inline bool compareAndSet (P* newValue, P* oldValue)
+    {
+        return m_value.compareAndSetBool (newValue, oldValue);
+    }
+
+private:
+    Atomic <P*> m_value;
+};
+
+#endif