ceph/src/boost/libs/log/example/doc/sinks_async_bounded.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/sinks/bounded_fifo_queue.hpp>
  18 #include <boost/log/sinks/drop_on_overflow.hpp>
  19 #include <boost/log/sources/severity_channel_logger.hpp>
  20 #include <boost/log/sources/record_ostream.hpp>
  21
  22 namespace logging = boost::log;
  23 namespace src = boost::log::sources;
  24 namespace expr = boost::log::expressions;
  25 namespace sinks = boost::log::sinks;
  26 namespace keywords = boost::log::keywords;
  27
  28 enum severity_level
  29 {
  30     normal,
  31     warning,
  32     error
  33 };
  34
  35 //[ example_sinks_bounded_async_init
  36 // Complete sink type
  37 typedef sinks::asynchronous_sink<
  38     sinks::text_ostream_backend,
  39     sinks::bounded_fifo_queue<                                                   /*< log record queueing strategy >*/
  40         100,                                                                     /*< record queue capacity >*/
  41         sinks::drop_on_overflow                                                  /*< overflow handling policy >*/
  42     >
  43 > sink_t;
  44
  45 boost::shared_ptr< sink_t > init_logging()
  46 {
  47     boost::shared_ptr< logging::core > core = logging::core::get();
  48
  49     // Create a backend and initialize it with a stream
  50     boost::shared_ptr< sinks::text_ostream_backend > backend =
  51         boost::make_shared< sinks::text_ostream_backend >();
  52     backend->add_stream(
  53         boost::shared_ptr< std::ostream >(&std::clog, boost::null_deleter()));
  54
  55     // Wrap it into the frontend and register in the core
  56     boost::shared_ptr< sink_t > sink(new sink_t(backend));
  57     core->add_sink(sink);
  58
  59     // ...
  60     //<-
  61     // You can manage filtering and formatting through the sink interface
  62     sink->set_filter(expr::attr< severity_level >("Severity") >= warning);
  63     sink->set_formatter
  64     (
  65         expr::stream
  66             << "Level: " << expr::attr< severity_level >("Severity")
  67             << " Message: " << expr::message
  68     );
  69
  70     // You can also manage backend in a thread-safe manner
  71     {
  72         sink_t::locked_backend_ptr p = sink->locked_backend();
  73         p->add_stream(boost::make_shared< std::ofstream >("sample.log"));
  74     }
  75     //->
  76
  77     return sink;
  78 }
  79 //]
  80
  81 void stop_logging(boost::shared_ptr< sink_t >& sink)
  82 {
  83     boost::shared_ptr< logging::core > core = logging::core::get();
  84
  85     // Remove the sink from the core, so that no records are passed to it
  86     core->remove_sink(sink);
  87
  88     // Break the feeding loop
  89     sink->stop();
  90
  91     // Flush all log records that may have left buffered
  92     sink->flush();
  93
  94     sink.reset();
  95 }
  96
  97 int main(int, char*[])
  98 {
  99     boost::shared_ptr< sink_t > sink = init_logging();
 100
 101     src::severity_channel_logger< severity_level > lg(keywords::channel = "net");
 102     BOOST_LOG_SEV(lg, warning) << "Hello world!";
 103
 104     stop_logging(sink);
 105
 106     return 0;
 107 }