ceph/src/boost/libs/log/example/doc/sinks_async.cpp

   1 /*
   2  *          Copyright Andrey Semashev 2007 - 2015.
   3  * Distributed under the Boost Software License, Version 1.0.
   4  *    (See accompanying file LICENSE_1_0.txt or copy at
   5  *          http://www.boost.org/LICENSE_1_0.txt)
   6  */
   7
   8 #include <string>
   9 #include <fstream>
  10 #include <iostream>
  11 #include <boost/smart_ptr/shared_ptr.hpp>
  12 #include <boost/core/null_deleter.hpp>
  13 #include <boost/log/core.hpp>
  14 #include <boost/log/expressions.hpp>
  15 #include <boost/log/sinks/async_frontend.hpp>
  16 #include <boost/log/sinks/text_ostream_backend.hpp>
  17 #include <boost/log/sources/severity_channel_logger.hpp>
  18 #include <boost/log/sources/record_ostream.hpp>
  19
  20 namespace logging = boost::log;
  21 namespace src = boost::log::sources;
  22 namespace expr = boost::log::expressions;
  23 namespace sinks = boost::log::sinks;
  24 namespace keywords = boost::log::keywords;
  25
  26 //[ example_sinks_async_init
  27 enum severity_level
  28 {
  29     normal,
  30     warning,
  31     error
  32 };
  33
  34 // Complete sink type
  35 typedef sinks::asynchronous_sink< sinks::text_ostream_backend > sink_t;
  36
  37 boost::shared_ptr< sink_t > init_logging()
  38 {
  39     boost::shared_ptr< logging::core > core = logging::core::get();
  40
  41     // Create a backend and initialize it with a stream
  42     boost::shared_ptr< sinks::text_ostream_backend > backend =
  43         boost::make_shared< sinks::text_ostream_backend >();
  44     backend->add_stream(
  45         boost::shared_ptr< std::ostream >(&std::clog, boost::null_deleter()));
  46
  47     // Wrap it into the frontend and register in the core
  48     boost::shared_ptr< sink_t > sink(new sink_t(backend));
  49     core->add_sink(sink);
  50
  51     // You can manage filtering and formatting through the sink interface
  52     sink->set_filter(expr::attr< severity_level >("Severity") >= warning);
  53     sink->set_formatter
  54     (
  55         expr::stream
  56             << "Level: " << expr::attr< severity_level >("Severity")
  57             << " Message: " << expr::message
  58     );
  59
  60     // You can also manage backend in a thread-safe manner
  61     {
  62         sink_t::locked_backend_ptr p = sink->locked_backend();
  63         p->add_stream(boost::make_shared< std::ofstream >("sample.log"));
  64     } // the backend gets released here
  65
  66     return sink;
  67 }
  68 //]
  69
  70 //[ example_sinks_async_stop
  71 void stop_logging(boost::shared_ptr< sink_t >& sink)
  72 {
  73     boost::shared_ptr< logging::core > core = logging::core::get();
  74
  75     // Remove the sink from the core, so that no records are passed to it
  76     core->remove_sink(sink);
  77
  78     // Break the feeding loop
  79     sink->stop();
  80
  81     // Flush all log records that may have left buffered
  82     sink->flush();
  83
  84     sink.reset();
  85 }
  86 //]
  87
  88 int main(int, char*[])
  89 {
  90     boost::shared_ptr< sink_t > sink = init_logging();
  91
  92     src::severity_channel_logger< severity_level > lg(keywords::channel = "net");
  93     BOOST_LOG_SEV(lg, warning) << "Hello world!";
  94
  95     stop_logging(sink);
  96
  97     return 0;
  98 }