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