// $Id$
//
-// Copyright (C) 2007
-// Fraunhofer Institut fuer offene Kommunikationssysteme (FOKUS)
-// Kompetenzzentrum fuer Satelitenkommunikation (SatCom)
+// Copyright (C) 2007
+// Fraunhofer Institute for Open Communication Systems (FOKUS)
+// Competence Center NETwork research (NET), St. Augustin, GERMANY
// Stefan Bund <g0dil@berlios.de>
//
// This program is free software; you can redistribute it and/or modify
<em>Runtime</em> configuration on the other hand deals with routing all those messages, which
are enabled at compile time to the logging targets. If a message is not routed, it will be
discarded. This allows to additionally disable messages at run-time. Message routing is managed
- via the \ref Target interface.
+ via the ::Target interface.
+
+ \section config_compile Compile time configuration
+
+ Compile time configuration is set on the compiler command line:
+ <pre>
+ g++ ... -DSENF_LOG_CONF="(( (senf)(log)(Debug),(_),DISABLED ))
+ (( (senf)(log)(Debug),(foo)(SomeClass),VERBOSE ))
+ (( (foo)(Transactions),(_),NOTICE ))" ...
+ </pre>
+ The value is relatively complex; It's a Boost.Preprocessor style sequence of tuples, of which
+ the first and second elements are again sequences. What this boils down to, is that it allows to
+ configure compile time logging limits based on stream and optional area.
+
+ The above example disables all debug logging by setting the default log limit for all areas on
+ the \c senf::log::Debug stream to \c DISABLED. It then re-enables debug logging only within the
+ \c foo::SomeClass area, where it is set to \c VERBOSE. Furthermore, the limit on the \c
+ foo::Transactions stream is set to \c NOTICE.
+
+ There are two standard uses for this configuration: Either to disable most logging in final
+ builds by changing the compile time limit to something like senf::log::IMPORTANT or to enable
+ senf::log::VERBOSE messages for some area:
+ <pre>
+ # Disable debug logging below 'IMPORTANT' level
+ g++ ... -DSENF_LOG_CONF="(( (senf)(log)(Debug), (_), IMPORTANT ))"
+
+ # Or enable verbose messages for the 'some::Area' area
+ g++ ... -DSENF_LOG_CONF="(( (senf)(log)(Verbose), (some)(Area), VERBOSE ))"
+ </pre>
+
+
+ \see \ref SENF_LOG_CONF
+
+ \section config_runtime Runtime configuration
+
+ The runtime configuration is performed by routing messages to one or more logging targets:
+ \code
+ senf::log::ConsoleLog & consoleLog (senf::log::ConsoleLog::instance());
+ senf::log::FileLog fileLog ("my.log");
+
+ consoleLog.route<senf::log::Debug>();
+ consoleLog.route<foo::Transactions, foo::SomeClass>(senf::log::Target::REJECT);
+ consoleLog.route<foo::Transactions, senf::log::IMPORTANT>();
+
+ fileLog.route<foo::Transactions>();
+ \endcode
+ Here we see an already relatively complex setup: All debug messages (that is, those, which are
+ not disabled at compile time) are routed to the console. We also route important transactions to
+ the console \e except transactions from the \c foo::SomeClass area. The \c fileLog simply
+ receives all transaction log messages.
+
+ The routing statements are processed by the targets in order, the first matching rule will
+ decide a log messages fate for that target.
+
+ \section config_fallback Fallback routing
+
+ There are two cases, where this setup may lead to inadvertently lost log messages:
+ \li When using a library which does internally use the Logger but not initializing the logger in
+ your application.
+ \li When log messages are created during initialization of static objects.
+ Since no route is set up in these cases, the messages will be dropped.
+
+ To counter this problem, the logger is initially in <em>fallback routing</em> state. If any log
+ message arrives in this state, the message will be logged to the console if it is above the
+ default runtime limit of it's stream. The first routing statement on any target will take the
+ logger out of this state and normal routing will take place.
+
+ \see \ref senf::log::Target
+
+ \section config_timesource Log message timing
+
+ One auxiliary aspect of logging is message timing. Each message is stamped with a time-stamp
+ giving the exact time the message was created. How the current date/time value is created may be
+ changed by setting a \e TimeSource. A TimeSource is an instance derived from
+ senf::log::TimeSource which will return the current universal time (UTC) when called.
+
+ By default, the logging library will call gettimeofday() for each log message. To change the
+ time source, just pass the new class or instance to senf::log::timeSource:
+ \code
+ // Use senf::scheduler::eventTime() to time log messages
+ senf::log::timeSource<senf::scheduler::LogTimeSource>();
+ \endcode
*/
namespace senf {
/** \brief Compile time configuration
This define symbol sets the compile time logger configuration. This symbol should normally
- be set on the compiler command line:
- <pre>
- g++ ... -DSENF_LOG_CONF="(( (senf)(log)(Debug),(_),DISABLED ))
- (( (senf)(log)(Debug),(foo)(SomeClass),VERBOSE ))
- (( (foo)(Transactions),(_),NOTICE ))" ...
- </pre>
- (As this option can get quite long, you might want to use the '-imacros' option instead)
+ be set on the compiler command line.
The formal syntax of this option is:
<tr><td>stream</td> <td>::= \e scope_seq \n</td></tr>
<tr><td>optional_area</td><td>::= <tt>(_)</tt> | \e scope_seq \n</td></tr>
<tr><td>level</td> <td>::= \c VERBOSE | \c NOTICE | \c MESSAGE | \c IMPORTANT | \c CRITICAL | \c DISABLED \n</td></tr>
- <tr><td>scope_seq</td> <td>::= \e scope \e scope \e scope* \n</td></tr>
+ <tr><td>scope_seq</td> <td>::= \e scope \e scope* \n</td></tr>
<tr><td>scope</td> <td>::= <tt>(</tt> \e name <tt>)</tt> \n</td></tr>
<tr><td>name</td> <td>::= arbitrary C++ identifier</td></tr>
</table>
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