logger.hpp

Go to the documentation of this file.

 
#pragma once
 
#include <mutex>
#include <sstream>
#include <unistd.h>
 
namespace fix40 {
 
class Logger {
public:
    static Logger& instance() {
        static Logger logger;
        return logger;
    }
 
    void setEnabled(bool enabled) {
        enabled_ = enabled;
    }
 
    bool isEnabled() const {
        return enabled_;
    }
 
    class LogStream {
    public:
        LogStream(std::mutex& mtx, bool enabled) : mtx_(mtx), enabled_(enabled) {}
        
        ~LogStream() {
            if (!enabled_) return;
            buffer_ << '\n';
            std::string str = buffer_.str();
            std::lock_guard<std::mutex> lock(mtx_);
            // 使用 write() 系统调用，单次调用是原子的
            ::write(STDOUT_FILENO, str.c_str(), str.size());
        }
 
        LogStream(const LogStream&) = delete;
        LogStream& operator=(const LogStream&) = delete;
        
        LogStream(LogStream&& other) noexcept 
            : mtx_(other.mtx_), enabled_(other.enabled_), buffer_(std::move(other.buffer_)) {}
 
        template<typename T>
        LogStream& operator<<(const T& value) {
            if (enabled_) {
                buffer_ << value;
            }
            return *this;
        }
 
    private:
        std::mutex& mtx_;           
        bool enabled_;              
        std::ostringstream buffer_; 
    };
 
    LogStream log() {
        return LogStream(mutex_, enabled_);
    }
 
private:
    Logger() = default;
    std::mutex mutex_;          
    bool enabled_ = true;       
};
 
#define LOG() fix40::Logger::instance().log()
 
} // namespace fix40