took over imrpvements

storagemanager/ConstStorageAccessor.h

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+#ifndef FRAMEWORK_STORAGEMANAGER_CONSTSTORAGEACCESSOR_H_
+#define FRAMEWORK_STORAGEMANAGER_CONSTSTORAGEACCESSOR_H_
+
+#include <framework/storagemanager/storeAddress.h>
+#include <framework/returnvalues/HasReturnvaluesIF.h>
+#include <cstddef>
+
+class StorageManagerIF;
+
+/**
+ * @brief 	Helper classes to facilitate safe access to storages which is also
+ * 			conforming to RAII principles
+ * @details
+ * Accessor class which can be returned by pool manager or passed and set by
+ * pool managers to have safe access to the pool resources.
+ *
+ * These helper can be used together with the StorageManager classes to manage
+ * access to a storage. It can take care of thread-safety while also providing
+ * mechanisms to automatically clear storage data.
+ */
+class ConstStorageAccessor {
+	//! StorageManager classes have exclusive access to private variables.
+	template<uint8_t NUMBER_OF_POOLS>
+	friend class PoolManager;
+	template<uint8_t NUMBER_OF_POOLS>
+	friend class LocalPool;
+public:
+	/**
+	 * @brief	Simple constructor which takes the store ID of the storage
+	 * 			entry to access.
+	 * @param storeId
+	 */
+	ConstStorageAccessor(store_address_t storeId);
+	ConstStorageAccessor(store_address_t storeId, StorageManagerIF* store);
+
+	/**
+	 * @brief 	The destructor in default configuration takes care of
+	 * 			deleting the accessed pool entry and unlocking the mutex
+	 */
+	virtual ~ConstStorageAccessor();
+
+	/**
+	 * @brief	Returns a pointer to the read-only data
+	 * @return
+	 */
+	const uint8_t* data() const;
+
+	/**
+	 * @brief	Copies the read-only data to the supplied pointer
+	 * @param pointer
+	 */
+	virtual ReturnValue_t getDataCopy(uint8_t *pointer, size_t maxSize);
+
+	/**
+	 * @brief   Calling this will prevent the Accessor from deleting the data
+	 *          when the destructor is called.
+	 */
+	void release();
+
+	/**
+	 * Get the size of the data
+	 * @return
+	 */
+	size_t size() const;
+
+	/**
+	 * Get the storage ID.
+	 * @return
+	 */
+	store_address_t getId() const;
+
+	void print() const;
+
+	/**
+	 * @brief	Move ctor and move assignment allow returning accessors as
+	 * 			a returnvalue. They prevent resource being free prematurely.
+	 * Refer to: https://github.com/MicrosoftDocs/cpp-docs/blob/master/docs/cpp/
+	 * move-constructors-and-move-assignment-operators-cpp.md
+	 * @param
+	 * @return
+	 */
+	ConstStorageAccessor& operator= (ConstStorageAccessor&&);
+	ConstStorageAccessor (ConstStorageAccessor&&);
+
+	//! The copy ctor and copy assignemnt should be deleted implicitely
+	//! according to https://foonathan.net/2019/02/special-member-functions/
+	//! but I still deleted them to make it more explicit. (remember rule of 5).
+	ConstStorageAccessor& operator= (ConstStorageAccessor&) = delete;
+	ConstStorageAccessor (ConstStorageAccessor&) = delete;
+protected:
+	const uint8_t* constDataPointer = nullptr;
+	store_address_t storeId;
+	size_t size_ = 0;
+	//! Managing pool, has to assign itself.
+	StorageManagerIF* store = nullptr;
+	bool deleteData = true;
+
+	enum class AccessState {
+		UNINIT,
+		ASSIGNED
+	};
+	//! Internal state for safety reasons.
+	AccessState internalState = AccessState::UNINIT;
+	/**
+	 * Used by the pool manager instances to assign themselves to the
+	 * accessor. This is necessary to delete the data when the acessor
+	 * exits the scope ! The internal state will be considered read
+	 * when this function is called, so take care all data is set properly as
+	 * well.
+	 * @param
+	 */
+	void assignStore(StorageManagerIF*);
+};
+
+
+#endif /* FRAMEWORK_STORAGEMANAGER_CONSTSTORAGEACCESSOR_H_ */