110 lines
2.4 KiB
C++
110 lines
2.4 KiB
C++
/*
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* \brief LOG output functions
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* \author Norman Feske
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* \date 2016-05-03
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*/
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/*
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* Copyright (C) 2016 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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#ifndef _INCLUDE__BASE__LOG_H_
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#define _INCLUDE__BASE__LOG_H_
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#include <base/output.h>
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#include <base/lock.h>
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namespace Genode { class Log; }
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/**
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* Interface for writing output to the component's LOG session
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*
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* The LOG session is not used directly by the 'log', 'warning', and
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* 'error' functions. They access the LOG indirectly via this interface
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* instead, which ensures the proper synchronization of the output in the
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* presence of multiple threads and to apply distinguishable colors to the
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* different types of messages.
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*/
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class Genode::Log
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{
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public:
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/**
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* Type of message
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*/
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enum Type { LOG, WARNING, ERROR };
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private:
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Lock _lock;
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void _acquire(Type);
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void _release();
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Output &_output;
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/**
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* Helper for the sequential output of a variable list of arguments
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*/
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template <typename HEAD, typename... TAIL>
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void _output_args(Output &output, HEAD && head, TAIL &&... tail)
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{
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print(output, head);
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_output_args(output, tail...);
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}
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template <typename LAST>
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void _output_args(Output &output, LAST && last) { print(output, last); }
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public:
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Log(Output &output) : _output(output) { }
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template <typename... ARGS>
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void output(Type type, ARGS &&... args)
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{
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/*
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* This function is being inlined. Hence, we try to keep it as
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* small as possible. For this reason, the lock operations are
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* performed by the '_acquire' and '_release' functions instead of
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* using a lock guard.
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*/
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_acquire(type);
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_output_args(_output, args...);
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_release();
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}
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/**
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* Return component-global singleton instance of the 'Log'
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*/
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static Log &log();
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};
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namespace Genode {
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/**
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* Write 'args' as a regular message to the log
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*/
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template <typename... ARGS>
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void log(ARGS &&... args) { Log::log().output(Log::LOG, args...); }
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/**
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* Write 'args' as a warning message to the log
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*/
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template <typename... ARGS>
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void warning(ARGS &&... args) { Log::log().output(Log::WARNING, args...); }
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/**
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* Write 'args' as an error message to the log
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*/
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template <typename... ARGS>
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void error(ARGS &&... args) { Log::log().output(Log::ERROR, args...); }
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}
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#endif /* _INCLUDE__BASE__LOG_H_ */
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