/* SPDX-License-Identifier: BSD-2-Clause */ /* * Copyright (C) 2019-2021, Raspberry Pi Ltd * * metadata.h - general metadata class */ #pragma once /* A simple class for carrying arbitrary metadata, for example about an image. */ #include <any> #include <map> #include <mutex> #include <string> namespace RPiController { class Metadata { public: Metadata() = default; Metadata(Metadata const &other) { std::scoped_lock otherLock(other.mutex_); data_ = other.data_; } Metadata(Metadata &&other) { std::scoped_lock otherLock(other.mutex_); data_ = std::move(other.data_); other.data_.clear(); } template<typename T> void set(std::string const &tag, T const &value) { std::scoped_lock lock(mutex_); data_[tag] = value; } template<typename T> int get(std::string const &tag, T &value) const { std::scoped_lock 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::scoped_lock lock(mutex_); data_.clear(); } Metadata &operator=(Metadata const &other) { std::scoped_lock lock(mutex_, other.mutex_); data_ = other.data_; return *this; } Metadata &operator=(Metadata &&other) { std::scoped_lock lock(mutex_, other.mutex_); data_ = std::move(other.data_); other.data_.clear(); return *this; } void merge(Metadata &other) { std::scoped_lock lock(mutex_, other.mutex_); data_.merge(other.data_); } 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<RPiController::Metadata> lock(metadata) */ void lock() { mutex_.lock(); } void unlock() { mutex_.unlock(); } private: mutable std::mutex mutex_; std::map<std::string, std::any> data_; }; } /* namespace RPiController */