/* SPDX-License-Identifier: BSD-2-Clause */ /* * Copyright (C) 2019, Raspberry Pi (Trading) Limited * * metadata.hpp - general metadata class */ #pragma once // A simple class for carrying arbitrary metadata, for example about an image. #include <any> #include <string> #include <mutex> #include <map> #include <memory> namespace RPiController { class Metadata { public: template<typename T> void Set(std::string const &tag, T const &value) { std::lock_guard<std::mutex> lock(mutex_); data_[tag] = value; } template<typename T> int Get(std::string const &tag, T &value) const { std::lock_guard<std::mutex> lock(mutex_); auto it = data_.find(tag); if (it == data_.end()) return -1; value = std::any_cast<T>(it->second); return 0; } void Clear() { std::lock_guard<std::mutex> lock(mutex_); data_.clear(); } Metadata &operator=(Metadata const &other) { std::lock_guard<std::mutex> lock(mutex_); std::lock_guard<std::mutex> other_lock(other.mutex_); data_ = other.data_; return *this; } template<typename T> T *GetLocked(std::string const &tag) { // This allows in-place access to the Metadata contents, // for which you should be holding the lock. auto it = data_.find(tag); if (it == data_.end()) return nullptr; return std::any_cast<T>(&it->second); } template<typename T> void SetLocked(std::string const &tag, T const &value) { // Use this only if you're holding the lock yourself. data_[tag] = value; } // Note: use of (lowercase) lock and unlock means you can create scoped // locks with the standard lock classes. // e.g. std::lock_guard<PisP::Metadata> lock(metadata) void lock() { mutex_.lock(); } void unlock() { mutex_.unlock(); } private: mutable std::mutex mutex_; std::map<std::string, std::any> data_; }; typedef std::shared_ptr<Metadata> MetadataPtr; } // namespace RPiController