boost log库使用二

最新推荐文章于 2024-12-27 09:31:04 发布

原创最新推荐文章于 2024-12-27 09:31:04 发布 · 213 阅读

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本文探讨了Boost日志库的动态过滤功能，演示了如何通过调整过滤级别实现在不重启程序的情况下控制日志输出，展示了从info到fatal不同级别的日志信息，并介绍了在实际应用中如何利用这一特性。

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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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