Lesson 35 - Get Compute Auth Token Working

Plugins/GameLiftPlugin/Source/AWSSDK/Include/aws/crt/RefCounted.h

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+#pragma once
+/**
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0.
+ */
+
+#include <aws/common/assert.h>
+#include <memory>
+#include <mutex>
+
+namespace Aws
+{
+    namespace Crt
+    {
+        /**
+         * Inherit from RefCounted to allow reference-counting from C code,
+         * which will keep your C++ object alive as long as the count is non-zero.
+         *
+         * A class must inherit from RefCounted and std::enable_shared_from_this.
+         * Your class must always be placed inside a shared_ptr (do not create on
+         * the stack, or keep on the heap as a raw pointer).
+         *
+         * Whenever the reference count goes from 0 to 1 a shared_ptr is created
+         * internally to keep this object alive. Whenever the reference count
+         * goes from 1 to 0 the internal shared_ptr is reset, allowing this object
+         * to be destroyed.
+         */
+        template <class T> class RefCounted
+        {
+          protected:
+            RefCounted() {}
+            ~RefCounted() {}
+
+            void AcquireRef()
+            {
+                m_mutex.lock();
+                if (m_count++ == 0)
+                {
+                    m_strongPtr = static_cast<T *>(this)->shared_from_this();
+                }
+                m_mutex.unlock();
+            }
+
+            void ReleaseRef()
+            {
+                // Move contents of m_strongPtr to a temp so that this
+                // object can't be destroyed until the function exits.
+                std::shared_ptr<T> tmpStrongPtr;
+
+                m_mutex.lock();
+                AWS_ASSERT(m_count > 0 && "refcount has gone negative");
+                if (m_count-- == 1)
+                {
+                    std::swap(m_strongPtr, tmpStrongPtr);
+                }
+                m_mutex.unlock();
+            }
+
+          private:
+            RefCounted(const RefCounted &) = delete;
+            RefCounted &operator=(const RefCounted &) = delete;
+
+            size_t m_count = 0;
+            std::shared_ptr<T> m_strongPtr;
+            std::mutex m_mutex;
+        };
+    } // namespace Crt
+} // namespace Aws