Class Cache

examples/https_server.cpp:19–78

#include <mutex>

class Cache : public CppCommon::Singleton<Cache>
{
   friend CppCommon::Singleton<Cache>;

public:
    std::string GetAllCache()
    {
        std::scoped_lock locker(_cache_lock);
        std::string result;
        result += "[\n";
        for (const auto& item : _cache)
        {
            result += "  {\n";
            result += "    \"key\": \"" + item.first + "\",\n";
            result += "    \"value\": \"" + item.second + "\",\n";
            result += "  },\n";
        }
        result += "]\n";
        return result;
    }

    bool GetCacheValue(std::string_view key, std::string& value)
    {
        std::scoped_lock locker(_cache_lock);
        auto it = _cache.find(key);
        if (it != _cache.end())
        {
            value = it->second;
            return true;
        }
        else
            return false;
    }

    void PutCacheValue(std::string_view key, std::string_view value)
    {
        std::scoped_lock locker(_cache_lock);
        auto it = _cache.emplace(key, value);
        if (!it.second)
            it.first->second = value;
    }

    bool DeleteCacheValue(std::string_view key, std::string& value)
    {
        std::scoped_lock locker(_cache_lock);
        auto it = _cache.find(key);
        if (it != _cache.end())
        {
            value = it->second;
            _cache.erase(it);
            return true;
        }
        else
            return false;
    }

private:
    std::mutex _cache_lock;