ringbuffer_sink.h

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// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)
 
#pragma once
 
#include "spdlog/sinks/base_sink.h"
#include "spdlog/details/circular_q.h"
#include "spdlog/details/log_msg_buffer.h"
#include "spdlog/details/null_mutex.h"
 
#include <mutex>
#include <string>
#include <vector>
 
namespace spdlog
{
    namespace sinks
    {
        /*
         * Ring buffer sink
         */
        template <typename Mutex>
        class ringbuffer_sink final : public base_sink<Mutex>
        {
        public:
            explicit ringbuffer_sink(size_t n_items)
                : q_{n_items}
            {
            }
 
            std::vector<details::log_msg_buffer> last_raw(size_t lim = 0)
            {
                std::lock_guard<Mutex>               lock(base_sink<Mutex>::mutex_);
                auto                                 items_available = q_.size();
                auto                                 n_items         = lim > 0 ? (std::min)(lim, items_available) : items_available;
                std::vector<details::log_msg_buffer> ret;
                ret.reserve(n_items);
                for (size_t i = (items_available - n_items); i < items_available; i++)
                {
                    ret.push_back(q_.at(i));
                }
                return ret;
            }
 
            std::vector<std::string> last_formatted(size_t lim = 0)
            {
                std::lock_guard<Mutex>   lock(base_sink<Mutex>::mutex_);
                auto                     items_available = q_.size();
                auto                     n_items         = lim > 0 ? (std::min)(lim, items_available) : items_available;
                std::vector<std::string> ret;
                ret.reserve(n_items);
                for (size_t i = (items_available - n_items); i < items_available; i++)
                {
                    memory_buf_t formatted;
                    base_sink<Mutex>::formatter_->format(q_.at(i), formatted);
                    ret.push_back(std::move(SPDLOG_BUF_TO_STRING(formatted)));
                }
                return ret;
            }
 
        protected:
            void sink_it_(const details::log_msg& msg) override
            {
                q_.push_back(details::log_msg_buffer{msg});
            }
            void flush_() override
            {
            }
 
        private:
            details::circular_q<details::log_msg_buffer> q_;
        };
 
        using ringbuffer_sink_mt = ringbuffer_sink<std::mutex>;
        using ringbuffer_sink_st = ringbuffer_sink<details::null_mutex>;
 
    } // namespace sinks
 
} // namespace spdlog