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74 lines
2.4 KiB
74 lines
2.4 KiB
// The contents of this file are in the public domain. See LICENSE_FOR_EXAMPLE_PROGRAMS.txt
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/*
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This is an example showing how to control where the dlib::logger sends its messages.
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This is done by creating a "hook" class that is called whenever any of the loggers want
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to log a message. The hook class then outputs the messages using any method you like.
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Prior to reading this example, you should understand the basics of the dlib::logger.
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So you should have already read the logger_ex.cpp and logger_ex_2.cpp example programs.
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*/
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#include <dlib/logger.h>
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using namespace dlib;
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using namespace std;
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class my_hook
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{
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public:
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my_hook(
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)
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{
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fout.open("my_log_file.txt");
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}
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void log (
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const string& logger_name,
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const log_level& ll,
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const uint64 thread_id,
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const char* message_to_log
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)
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{
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// Log all messages from any logger to our log file.
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fout << ll << " ["<<thread_id<<"] " << logger_name << ": " << message_to_log << endl;
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// But only log messages that are of LINFO priority or higher to the console.
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if (ll >= LINFO)
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cout << ll << " ["<<thread_id<<"] " << logger_name << ": " << message_to_log << endl;
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}
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private:
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ofstream fout;
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};
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int main()
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{
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my_hook hook;
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// This tells all dlib loggers to send their logging events to the hook object. That
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// is, any time a logger generates a message it will call hook.log() with the message
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// contents. Additionally, hook.log() will also only be called from one thread at a
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// time so it is safe to use this kind of hook in a multi-threaded program with many
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// loggers in many threads.
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set_all_logging_output_hooks(hook);
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// It should also be noted that the hook object must not be destructed while the
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// loggers are still in use. So it is a good idea to declare the hook object
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// somewhere where it will live the entire lifetime of the program, as we do here.
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logger dlog("main");
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// Tell the dlog logger to emit a message for all logging events rather than its
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// default behavior of only logging LERROR or above.
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dlog.set_level(LALL);
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// All these message go to my_log_file.txt, but only the last two go to the console.
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dlog << LDEBUG << "This is a debugging message.";
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dlog << LINFO << "This is an informational message.";
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dlog << LERROR << "An error message!";
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}
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