4 // Fraunhofer Institute for Open Communication Systems (FOKUS)
5 // Competence Center NETwork research (NET), St. Augustin, GERMANY
6 // Stefan Bund <g0dil@berlios.de>
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 2 of the License, or
11 // (at your option) any later version.
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the
20 // Free Software Foundation, Inc.,
21 // 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
24 \brief Config public header */
32 //#include "Config.mpp"
34 ///////////////////////////////hh.p////////////////////////////////////////
36 /** \defgroup config Configuration
38 The logger infrastructure provides for very fine-grained configuration of log messages. There
39 are two parts to this configuration: compile-time configuration and runtime configuration.
41 <em>Compile-time</em> configuration selects, which log statements will even be compiled. If
42 logging for a certain combination of stream, area and level is disabled at compile time, no code
43 will be generated for any such disabled log statement. This type of configuration is done using
46 <em>Runtime</em> configuration on the other hand deals with routing all those messages, which
47 are enabled at compile time to the logging targets. If a message is not routed, it will be
48 discarded. This allows to additionally disable messages at run-time. Message routing is managed
49 via the \ref Target interface.
51 \section config_compile Compile time configuration
53 Compile time configuration is set on the compiler command line:
55 g++ ... -DSENF_LOG_CONF="(( (senf)(log)(Debug),(_),DISABLED ))
56 (( (senf)(log)(Debug),(foo)(SomeClass),VERBOSE ))
57 (( (foo)(Transactions),(_),NOTICE ))" ...
59 The value is relatively complex; It's a Boost.Preprocessor style sequence of tuples, of which
60 the first and second elements are again sequences. What this boils down to, is that it allows to
61 configure compile time logging limits based on stream and optional area.
63 The above example disables all debug logging by setting the default log limit for all areas on
64 the \c senf::log::Debug stream to \c DISABLED. It then re-enables debug logging only within the
65 \c foo::SomeClass area, where it is set to \c VERBOSE. Furthermore, the limit on the \c
66 foo::Transactions stream is set to \c NOTICE.
68 \see \ref SENF_LOG_CONF
70 \section config_runtime Runtime configuration
72 The runtime configuration is performed by routing messages to one or more logging targets:
74 senf::log::ConsoleLog & consoleLog (senf::log::ConsoleLog::instance());
75 senf::log::FileLog fileLog ("my.log");
77 consoleLog.route<senf::log::Debug>();
78 consoleLog.route<foo::Transactions, foo::SomeClass>(senf::log::Target::REJECT);
79 consoleLog.route<foo::Transactions, senf::log::IMPORTANT>();
81 fileLog.route<foo::Transactions>();
83 Here we see an already relatively complex setup: All debug messages (that is, those, which are
84 not disabled at compile time) are routed to the console. We also route important transactions to
85 the console \e except transactions from the \c foo::SomeClass area. The \c fileLog simply
86 receives all transaction log messages.
88 The routing statements are processed by the targets in order, the first matching rule will
89 decide a log messages fate for that target.
91 There are two cases, where this setup may lead to inadvertently lost log messages:
92 \li When using a library which does internally use the Logger but not initializing the logger in
94 \li When log messages are created during initialization of static objects.
95 Since no route is set up in these cases, the messages will be dropped.
97 To counter this problem, the logger is initially in <em>fallback routing</em> state. If any log
98 message arrives in this state, the message will be unconditionally logged to the console. The
99 first routing statement on any target will take the logger out of this state and normal routing
102 \see \ref senf::log::Target
104 \section config_timesource Log message timing
106 One auxiliary aspect of logging is message timing. Each message is stamped with a time-stamp
107 giving the exact time the message was created. How the current date/time value is created may be
108 changed by setting a \e TimeSource. A TimeSource is an instance derived from
109 senf::log::TimeSource which will return the current universal time (UTC) when called.
111 By default, the logging library will call gettimeofday() for each log message. To change the
112 time source, just pass the new class or instance to senf::log::timeSource:
114 // Use senf::Scheduler::instance().eventTime() to time log messages
115 senf::log::timeSource<senf::SchedulerLogTimeSource>();
127 /** \brief Compile time configuration
129 This define symbol sets the compile time logger configuration. This symbol should normally
130 be set on the compiler command line.
132 The formal syntax of this option is:
136 <tr><td>conf</td> <td>::= \e element \e element* \n</td></tr>
137 <tr><td>element</td> <td>::= <tt>((</tt> \e stream <tt>,</tt> \e optional_area <tt>,</tt> \e level <tt>))</tt> \n</td></tr>
138 <tr><td>stream</td> <td>::= \e scope_seq \n</td></tr>
139 <tr><td>optional_area</td><td>::= <tt>(_)</tt> | \e scope_seq \n</td></tr>
140 <tr><td>level</td> <td>::= \c VERBOSE | \c NOTICE | \c MESSAGE | \c IMPORTANT | \c CRITICAL | \c DISABLED \n</td></tr>
141 <tr><td>scope_seq</td> <td>::= \e scope \e scope \e scope* \n</td></tr>
142 <tr><td>scope</td> <td>::= <tt>(</tt> \e name <tt>)</tt> \n</td></tr>
143 <tr><td>name</td> <td>::= arbitrary C++ identifier</td></tr>
146 \ref SENF_LOG_CONF is a Boost.Preprocessor style sequence of 3-tuples. Each tuple applies to
147 a specific stream which is defined by the first tuple element \e stream.
149 The next tuple element, \e optional_area optionally restricts the entry to match only the
152 The last tuple element \e level defines the compile time log level. Messages with a level
153 below this are discarded at compile time.
155 Both \e stream and \e optional_area are given as a \e scope_seq. A scope sequence is a fully
156 qualified C++ identifier placed into a sequence: <tt>foo::bar::baz</tt> is represented by
157 <tt>(foo)(bar)(baz)</tt>.
159 # define SENF_LOG_CONF
163 /** \brief Check, if logging is enabled for stream/area/level tuple
165 This is a template meta-function which will check, whether logging to the given combination
166 of parameters \a Stream, \a Area and \a Level is compile-time enabled. The logging might
167 still be disabled at runtime.
169 if (senf::log::Enabled<senf::log::Debug,
170 senf::log::DefaultArea,
171 senf::log::VERBOSE>::value) {
176 Since the \e value member is a compile time constant, the compiler will completely optimize
177 away this block of code when logging is disabled.
179 template <class Stream, class Area, class Level>
182 static const bool value = (
183 (Level::value == NONE::value ? Stream::defaultLevel::value : Level::value)
184 >= detail::Config<Stream,Area>::compileLimit::value );
191 ///////////////////////////////hh.e////////////////////////////////////////
192 //#include "Config.cci"
193 //#include "Config.ct"
194 //#include "Config.cti"
201 // comment-column: 40
202 // c-file-style: "senf"
203 // indent-tabs-mode: nil
204 // ispell-local-dictionary: "american"
205 // compile-command: "scons -u test"