boost log库使用二
程序员文章站
2022-03-03 19:20:43
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这次,尝试filter,首先代码来自于官方文档。
#include <iostream>#include <boost/log/core.hpp>#include <boost/log/trivial.hpp>#include <boost/log/expressions.hpp>namespace logging = boost::log;using namespace std;void SetFilter() { logging::core::get()->set_filter(logging::trivial::severity >= logging::trivial::info);}int main () { cout << "hello, world" << endl; SetFilter(); BOOST_LOG_TRIVIAL(trace) << "A trace severity message"; BOOST_LOG_TRIVIAL(debug) << "A debug severity message"; BOOST_LOG_TRIVIAL(info) << "An informational severity message"; BOOST_LOG_TRIVIAL(warning) << "A warning severity message"; BOOST_LOG_TRIVIAL(error) << "An error severity message"; BOOST_LOG_TRIVIAL(fatal) << "A fatal severity message";}
当运行程序后,输出结果变了,trac和debug级别的信息被过滤掉了。
$ ./mainhello, world[2013-12-03 15:34:47.343223] [0x000007f680e76774] [info] An informational severity message[2013-12-03 15:34:47.343324] [0x000007f680e76774] [warning] A warning severity message[2013-12-03 15:34:47.343341] [0x000007f680e76774] [error] An error severity message[2013-12-03 15:34:47.343356] [0x000007f680e76774] [fatal] A fatal severity message
但是如果我们在运行时改变这个filter的设置,会怎样?现在试试看,修改一下代码:
#include <iostream>#include <boost/log/core.hpp>#include <boost/log/trivial.hpp>#include <boost/log/expressions.hpp>namespace logging = boost::log;using namespace std;void SetFilter1() { logging::core::get()->set_filter(logging::trivial::severity >= logging::trivial::info);}void SetFilter2() { logging::core::get()->set_filter(logging::trivial::severity >= logging::trivial::debug);}int main () { cout << "hello, world" << endl; SetFilter1(); BOOST_LOG_TRIVIAL(trace) << "A trace severity message"; BOOST_LOG_TRIVIAL(debug) << "A debug severity message"; BOOST_LOG_TRIVIAL(info) << "An informational severity message"; BOOST_LOG_TRIVIAL(warning) << "A warning severity message"; BOOST_LOG_TRIVIAL(error) << "An error severity message"; BOOST_LOG_TRIVIAL(fatal) << "A fatal severity message"; cout << "--------------------" << endl; SetFilter2(); BOOST_LOG_TRIVIAL(trace) << "A trace severity message"; BOOST_LOG_TRIVIAL(debug) << "A debug severity message"; BOOST_LOG_TRIVIAL(info) << "An informational severity message"; BOOST_LOG_TRIVIAL(warning) << "A warning severity message"; BOOST_LOG_TRIVIAL(error) << "An error severity message"; BOOST_LOG_TRIVIAL(fatal) << "A fatal severity message";}
好,现在观察结果。
$ ./mainhello, world[2013-12-03 15:37:54.399513] [0x000007fd7709a374] [info] An informational severity message[2013-12-03 15:37:54.399612] [0x000007fd7709a374] [warning] A warning severity message[2013-12-03 15:37:54.399630] [0x000007fd7709a374] [error] An error severity message[2013-12-03 15:37:54.399644] [0x000007fd7709a374] [fatal] A fatal severity message--------------------[2013-12-03 15:37:54.399666] [0x000007fd7709a374] [debug] A debug severity message[2013-12-03 15:37:54.399680] [0x000007fd7709a374] [info] An informational severity message[2013-12-03 15:37:54.399693] [0x000007fd7709a374] [warning] A warning severity message[2013-12-03 15:37:54.399706] [0x000007fd7709a374] [error] An error severity message[2013-12-03 15:37:54.399719] [0x000007fd7709a374] [fatal] A fatal severity message
起作用了。也就是说我们可以在不重新部署程序的情况下修改日志的过滤级别。在我的TCP服务中,可以监听一个管理端口,专门用来接受用于改变过滤级别的特殊消息。
非常好的特性,我喜欢这个功能。
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