c++ - BOOST_LOG_TRIVIAL 与 logrotate(重新打开日志)

Question

我有一个程序作为服务运行了很长时间。我用BOOST_LOG_TRIVIAL(info) << "Message"用于记录各种事件。我愿意与logrotate合作并在轮换后重新打开我的日志文件。理论上，剧本的工作原理如下:

• 我的程序启动，发生一些日志记录
• 日志由 something.log 重命名至something.log.1通过其他程序，如 logrotate或者由我手动操作。
• 我的程序继续登录到 something.log.1文件。
• 我向我的程序发送 SIGHUP (或其他东西)，以便我可以重新打开日志文件。但我不知道该怎么做。

到目前为止我准备的示例(可能没有必要):

#include <iostream>
#include <stdexcept>

#include <csignal>

#include <boost/thread.hpp>
#include <boost/chrono.hpp>
#include <boost/log/trivial.hpp>
#include <boost/log/expressions.hpp>
#include <boost/log/sources/severity_logger.hpp>
#include <boost/log/sources/record_ostream.hpp>
#include <boost/log/utility/setup/file.hpp>
#include <boost/log/utility/setup/console.hpp>
#include <boost/log/utility/setup/common_attributes.hpp>
#include <boost/log/support/date_time.hpp>

inline
void setupLogging(std::string const &logFileName)
{
  namespace logging = boost::log;
  namespace src = boost::log::sources;
  namespace expr = boost::log::expressions;
  namespace keywords = boost::log::keywords;
  logging::add_common_attributes();
  auto format = expr::stream
    << expr::format_date_time< boost::posix_time::ptime >("TimeStamp", "%Y-%m-%d %H:%M:%S.%f")
    << " progname " << logging::trivial::severity
    << ": " << expr::smessage;
  auto fileOutput = logging::add_file_log(
      keywords::file_name = logFileName, keywords::format = format
      , keywords::auto_flush = true, keywords::open_mode = std::ios::app
    );
  auto consoleOutput = logging::add_console_log(
    std::cerr, keywords::format = format, keywords::auto_flush = true
  );
  BOOST_LOG_TRIVIAL(debug) << "CHECKPOINT @ setupLogging() after log initialization.";
}

void my_signal_handler(int signal)
{
  BOOST_LOG_TRIVIAL(info) << "my_signal_handler BEGIN";
  /* REOPEN LOG HERE */
  BOOST_LOG_TRIVIAL(info) << "my_signal_handler END";
}

int main()
{
  setupLogging("logrotate.test.log");
  if(signal(SIGHUP, my_signal_handler) == SIG_ERR)
  {
    BOOST_LOG_TRIVIAL(error) << "Failed to register signal handler";
    return 1;
  } else
    BOOST_LOG_TRIVIAL(info) << "Signal handler registered.";
  BOOST_LOG_TRIVIAL(info) << "CHECKPOINT 0";
  for(size_t i=1; i<100; ++i)
  {
    boost::this_thread::sleep_for( boost::chrono::seconds(1) );
    BOOST_LOG_TRIVIAL(info) << "CHECKPOINT " << i;
  }
  return 0;
}

编译:

LINK="-lboost_system -lboost_date_time -lboost_log -lboost_log_setup -lboost_thread -lboost_chrono -lpthread"
g++ -std=c++11 -Wextra -DBOOST_LOG_DYN_LINK -pedantic -O3 logrotate_test.cpp -o logrotate_test $LINK

Adam 答案的源代码表示

namespace detail666777888
{
       using namespace boost;
       using namespace boost::log;
       typedef shared_ptr< sinks::synchronous_sink< sinks::text_file_backend > > T;
}
typedef detail666777888::T SPFileSink;
SPFileSink logFileSink;

void setupLogging(...){
... logFileSink = logging::add_file_log ...
}

void my_sighup_handler(int /*signal*/)
{
  BOOST_LOG_TRIVIAL(info) << "my_sighup_handler START";
  auto oldLFS = logFileSink;
  setupLogging("logrotate.test.log");
  boost::log::core::get()->remove_sink(oldLFS);
  BOOST_LOG_TRIVIAL(info) << "my_sighup_handler FINISH";
}

Answer 1

我遇到了同样的问题，并找到了一个非常简单的解决方案:只需使用单个文件名(没有任何模式)初始化 text_file_backend 并调用 text_file_backend::rotate_file() >。这将关闭当前文件并打开一个同名的新文件。

// create sink
auto backend = boost::make_shared< boost::log::sinks::text_file_backend >(
        boost::log::keywords::file_name = "my.log",
        boost::log::keywords::open_mode = std::ios_base::out | std::ios_base::app
);
auto sink = boost::make_shared<sinks::synchronous_sink<boost::log::sinks::text_file_backend>>(backend);
boost::log::core::get()->add_sink(sink);

// ... do some logging

// move log file and...
// reopen log file
sink->locked_backend()->rotate_file();

// ... do more logging

我使用 std::ios_base::app 打开日志文件，以防止日志文件在文件存在时被截断。

该方案的优点是无需复制文件，日志记录不会丢失，也不会重复。