Merge branch 'develop' into bthomee/node_depth

include/xrpl/basics/Mutex.hpp

@@ -0,0 +1,155 @@
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2024, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+*/
+
+#pragma once
+
+#include <mutex>
+#include <type_traits>
+
+namespace xrpl {
+
+template <typename ProtectedDataType, typename MutexType>
+class Mutex;
+
+/**
+ * @brief A lock on a mutex that provides access to the protected data.
+ *
+ * @tparam ProtectedDataType data type to hold
+ * @tparam LockType type of lock
+ * @tparam MutexType type of mutex
+ */
+template <typename ProtectedDataType, template <typename...> typename LockType, typename MutexType>
+class Lock
+{
+    LockType<MutexType> lock_;
+    ProtectedDataType& data_;
+
+public:
+    /** @cond */
+    ProtectedDataType const&
+    operator*() const
+    {
+        return data_;
+    }
+
+    ProtectedDataType&
+    operator*()
+    {
+        return data_;
+    }
+
+    ProtectedDataType const&
+    get() const
+    {
+        return data_;
+    }
+
+    ProtectedDataType&
+    get()
+    {
+        return data_;
+    }
+
+    ProtectedDataType const*
+    operator->() const
+    {
+        return &data_;
+    }
+
+    ProtectedDataType*
+    operator->()
+    {
+        return &data_;
+    }
+
+    operator LockType<MutexType>&() &
+    {
+        return lock_;
+    }
+
+    operator LockType<MutexType> const&() const&
+    {
+        return lock_;
+    }
+    /** @endcond */
+
+private:
+    friend class Mutex<std::remove_const_t<ProtectedDataType>, MutexType>;
+
+    Lock(MutexType& mutex, ProtectedDataType& data) : lock_(mutex), data_(data)
+    {
+    }
+};
+
+/**
+ * @brief A container for data that is protected by a mutex. Inspired by Mutex in Rust.
+ *
+ * @tparam ProtectedDataType data type to hold
+ * @tparam MutexType type of mutex
+ */
+template <typename ProtectedDataType, typename MutexType = std::mutex>
+class Mutex
+{
+    mutable MutexType mutex_;
+    ProtectedDataType data_{};
+
+public:
+    Mutex() = default;
+
+    /**
+     * @brief Construct a new Mutex object with the given data
+     *
+     * @param data The data to protect
+     */
+    explicit Mutex(ProtectedDataType data) : data_(std::move(data))
+    {
+    }
+
+    /**
+     * @brief Make a new Mutex object with the given data
+     *
+     * @tparam Args The types of the arguments to forward to the constructor of the protected data
+     * @param args The arguments to forward to the constructor of the protected data
+     * @return The Mutex object that protects the given data
+     */
+    template <typename... Args>
+    static Mutex
+    make(Args&&... args)
+    {
+        return Mutex{ProtectedDataType{std::forward<Args>(args)...}};
+    }
+
+    /**
+     * @brief Lock the mutex and get a lock object allowing access to the protected data
+     *
+     * @tparam LockType The type of lock to use
+     * @return A lock on the mutex and a reference to the protected data
+     */
+    template <template <typename...> typename LockType = std::lock_guard>
+    Lock<ProtectedDataType const, LockType, MutexType>
+    lock() const
+    {
+        return {mutex_, data_};
+    }
+
+    /**
+     * @brief Lock the mutex and get a lock object allowing access to the protected data
+     *
+     * @tparam LockType The type of lock to use
+     * @return A lock on the mutex and a reference to the protected data
+     */
+    template <template <typename...> typename LockType = std::lock_guard>
+    Lock<ProtectedDataType, LockType, MutexType>
+    lock()
+    {
+        return {mutex_, data_};
+    }
+};
+
+}  // namespace xrpl