ceph/src/boost/libs/log/example/doc/expressions_has_attr_stat_accum.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 <cstddef>
   9 #include <string>
  10 #include <map>
  11 #include <iostream>
  12 #include <fstream>
  13 #include <boost/smart_ptr/shared_ptr.hpp>
  14 #include <boost/smart_ptr/make_shared_object.hpp>
  15 #include <boost/log/sinks.hpp>
  16 #include <boost/log/expressions.hpp>
  17 #include <boost/log/attributes/scoped_attribute.hpp>
  18 #include <boost/log/sources/logger.hpp>
  19 #include <boost/log/sources/record_ostream.hpp>
  20 #include <boost/log/utility/value_ref.hpp>
  21 #include <boost/log/utility/manipulators/add_value.hpp>
  22
  23 namespace logging = boost::log;
  24 namespace src = boost::log::sources;
  25 namespace expr = boost::log::expressions;
  26 namespace sinks = boost::log::sinks;
  27 namespace keywords = boost::log::keywords;
  28
  29 //[ example_expressions_has_attr_stat_accumulator
  30 // Declare attribute keywords
  31 BOOST_LOG_ATTRIBUTE_KEYWORD(stat_stream, "StatisticStream", std::string)
  32 BOOST_LOG_ATTRIBUTE_KEYWORD(change, "Change", int)
  33
  34 // A simple sink backend to accumulate statistic information
  35 class my_stat_accumulator :
  36     public sinks::basic_sink_backend< sinks::synchronized_feeding >
  37 {
  38     // A map of accumulated statistic values,
  39     // ordered by the statistic information stream name
  40     typedef std::map< std::string, int > stat_info_map;
  41     stat_info_map m_stat_info;
  42
  43 public:
  44     // Destructor
  45     ~my_stat_accumulator()
  46     {
  47         // Display the accumulated data
  48         stat_info_map::const_iterator it = m_stat_info.begin(), end = m_stat_info.end();
  49         for (; it != end; ++it)
  50         {
  51             std::cout << "Statistic stream: " << it->first
  52                 << ", accumulated value: " << it->second << "\n";
  53         }
  54         std::cout.flush();
  55     }
  56
  57     // The method is called for every log record being put into the sink backend
  58     void consume(logging::record_view const& rec)
  59     {
  60         // First, acquire statistic information stream name
  61         logging::value_ref< std::string, tag::stat_stream > name = rec[stat_stream];
  62         if (name)
  63         {
  64             // Next, get the statistic value change
  65             logging::value_ref< int, tag::change > change_amount = rec[change];
  66             if (change_amount)
  67             {
  68                 // Accumulate the statistic data
  69                 m_stat_info[name.get()] += change_amount.get();
  70             }
  71         }
  72     }
  73 };
  74
  75 // The function registers two sinks - one for statistic information,
  76 // and another one for other records
  77 void init()
  78 {
  79     boost::shared_ptr< logging::core > core = logging::core::get();
  80
  81     // Create a backend and attach a stream to it
  82     boost::shared_ptr< sinks::text_ostream_backend > backend =
  83         boost::make_shared< sinks::text_ostream_backend >();
  84     backend->add_stream(
  85         boost::shared_ptr< std::ostream >(new std::ofstream("test.log")));
  86
  87     // Create a frontend and setup filtering
  88     typedef sinks::synchronous_sink< sinks::text_ostream_backend > log_sink_type;
  89     boost::shared_ptr< log_sink_type > log_sink(new log_sink_type(backend));
  90     // All records that don't have a "StatisticStream" attribute attached
  91     // will go to the "test.log" file
  92     log_sink->set_filter(!expr::has_attr(stat_stream));
  93
  94     core->add_sink(log_sink);
  95
  96     // Create another sink that will receive all statistic data
  97     typedef sinks::synchronous_sink< my_stat_accumulator > stat_sink_type;
  98     boost::shared_ptr< stat_sink_type > stat_sink(new stat_sink_type());
  99     // All records with a "StatisticStream" string attribute attached
 100     // will go to the my_stat_accumulator sink
 101     stat_sink->set_filter(expr::has_attr(stat_stream));
 102
 103     core->add_sink(stat_sink);
 104 }
 105
 106 // This simple macro will simplify putting statistic data into a logger
 107 #define PUT_STAT(lg, stat_stream_name, change)\
 108     if (true) {\
 109         BOOST_LOG_SCOPED_LOGGER_TAG(lg, "StatisticStream", stat_stream_name);\
 110         BOOST_LOG(lg) << logging::add_value("Change", (int)(change));\
 111     } else ((void)0)
 112
 113 void logging_function()
 114 {
 115     src::logger lg;
 116
 117     // Put a regular log record, it will go to the "test.log" file
 118     BOOST_LOG(lg) << "A regular log record";
 119
 120     // Put some statistic data
 121     PUT_STAT(lg, "StreamOne", 10);
 122     PUT_STAT(lg, "StreamTwo", 20);
 123     PUT_STAT(lg, "StreamOne", -5);
 124 }
 125 //]
 126
 127 int main(int, char*[])
 128 {
 129     init();
 130     logging_function();
 131
 132     return 0;
 133 }