4 // Fraunhofer Institute for Open Communication Systems (FOKUS)
6 // The contents of this file are subject to the Fraunhofer FOKUS Public License
7 // Version 1.0 (the "License"); you may not use this file except in compliance
8 // with the License. You may obtain a copy of the License at
9 // http://senf.berlios.de/license.html
11 // The Fraunhofer FOKUS Public License Version 1.0 is based on,
12 // but modifies the Mozilla Public License Version 1.1.
13 // See the full license text for the amendments.
15 // Software distributed under the License is distributed on an "AS IS" basis,
16 // WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
17 // for the specific language governing rights and limitations under the License.
19 // The Original Code is Fraunhofer FOKUS code.
21 // The Initial Developer of the Original Code is Fraunhofer-Gesellschaft e.V.
22 // (registered association), Hansastraße 27 c, 80686 Munich, Germany.
23 // All Rights Reserved.
26 // Stefan Bund <g0dil@berlios.de>
29 \brief Config public header */
31 #ifndef HH_SENF_Utils_Logger_Config_
32 #define HH_SENF_Utils_Logger_Config_ 1
37 //#include "Config.mpp"
39 //-/////////////////////////////////////////////////////////////////////////////////////////////////
41 /** \defgroup config Configuration
43 The logger infrastructure provides for very fine-grained configuration of log messages. There
44 are two parts to this configuration: compile-time configuration and runtime configuration.
46 <em>Compile-time</em> configuration selects, which log statements will even be compiled. If
47 logging for a certain combination of stream, area and level is disabled at compile time, no code
48 will be generated for any such disabled log statement. This type of configuration is done using
51 <em>Runtime</em> configuration on the other hand deals with routing all those messages, which
52 are enabled at compile time to the logging targets. If a message is not routed, it will be
53 discarded. This allows to additionally disable messages at run-time. Message routing is managed
54 via the ::Target interface.
56 \section config_compile Compile time configuration
58 Compile time configuration is set on the compiler command line:
60 g++ ... -DSENF_LOG_CONF="(( (senf)(log)(Debug),(_),DISABLED ))
61 (( (senf)(log)(Debug),(foo)(SomeClass),VERBOSE ))
62 (( (_),(_),NOTICE ))" ...
64 The value is relatively complex; It's a Boost.Preprocessor style sequence of tuples, of which
65 the first and second elements are again sequences. What this boils down to, is that it allows to
66 configure compile time logging limits based on stream and optional area.
68 The above example disables all debug logging by setting the default log limit for all areas on
69 the \c senf::log::Debug stream to \c DISABLED. It enables debug logging only within the \c
70 foo::SomeClass area, where it is set to \c VERBOSE. Lastly, the global compile time limit is set
73 There are two standard uses for this configuration: Either to disable most logging in final
74 builds by changing the compile time limit to something like senf::log::IMPORTANT or to enable
75 senf::log::VERBOSE messages for some area:
77 # Disable debug logging below 'IMPORTANT' level
78 g++ ... -DSENF_LOG_CONF="(( (senf)(log)(Debug), (_), IMPORTANT ))"
80 # Or enable verbose messages for the 'some::Area' area
81 g++ ... -DSENF_LOG_CONF="(( (senf)(log)(Verbose), (some)(Area), VERBOSE ))"
84 All the entries specified via \c SENF_LOG_CONF are applied in a fixed order:
86 \li First the entries which have both a stream and an area specified are checked
87 \li next all entries with area but no stream given are checked
88 \li followed by all entries with a given stream but no area
89 \li and lastly if no match was found until now, a generic entry without stream and area is
91 \li if no matching entry is found, the default compile time limit of the stream is used
93 So an area specification has precedence over a stream specification.
95 \warning Enabling a message at compile time does \e not ensure, the message is shown. You
96 additionally need to \e route the message (see next chapter). This is especially true for \c
97 VERBOSE messages, which are default disabled at runtime.
99 \see \ref SENF_LOG_CONF
101 \section config_runtime Runtime configuration
103 The runtime configuration is performed by routing messages to one or more logging targets:
105 senf::log::ConsoleTarget & consoleLog (senf::log::ConsoleTarget::instance());
106 senf::log::FileTarget fileLog ("my.log");
108 consoleLog.route<senf::log::Debug>();
109 consoleLog.route<foo::Transactions, foo::SomeClass>(senf::log::Target::REJECT);
110 consoleLog.route<foo::Transactions, senf::log::IMPORTANT>();
112 fileLog.route<foo::Transactions>();
114 Here we see an already relatively complex setup: All debug messages (that is, those, which are
115 not disabled at compile time) are routed to the console. We also route important transactions to
116 the console \e except transactions from the \c foo::SomeClass area. The \c fileLog simply
117 receives all transaction log messages.
119 The routing statements are processed by the targets in order, the first matching rule will
120 decide a log messages fate for that target.
122 \warning You can \e only route those messages at runtime which have been compile-time
123 enabled. By default, \c VERBOSE messages are \e disabled at compile time. They must be
124 enabled \e explicitly by setting \c SENF_LOG_CONF so they can be routed.
126 \section config_fallback Fallback routing
128 There are two cases, where this setup may lead to inadvertently lost log messages:
129 \li When using a library which does internally use the Logger but not initializing the logger in
131 \li When log messages are created during initialization of static objects.
132 Since no route is set up in these cases, the messages will be dropped.
134 To counter this problem, the logger is initially in <em>fallback routing</em> state. If any log
135 message arrives in this state, the message will be logged to the console if it is above the
136 default runtime limit of it's stream. The first routing statement on any target will take the
137 logger out of this state and normal routing will take place.
139 \see \ref senf::log::Target
141 \section config_timesource Log message timing
143 One auxiliary aspect of logging is message timing. Each message is stamped with a time-stamp
144 giving the exact time the message was created. How the current date/time value is created may be
145 changed by setting a \e TimeSource. A TimeSource is an instance derived from
146 senf::log::TimeSource which will return the current universal time (UTC) when called.
148 By default, the logging library will call gettimeofday() for each log message. To change the
149 time source, just pass the new class or instance to senf::log::timeSource:
151 // Use senf::scheduler::eventTime() to time log messages
152 senf::log::timeSource<senf::scheduler::LogTimeSource>();
164 /** \brief Compile time configuration
166 This define symbol sets the compile time logger configuration. This symbol should normally
167 be set on the compiler command line.
169 The formal syntax of this option is:
173 <tr><td>conf</td> <td>::= \e element \e element* \n</td></tr>
174 <tr><td>element</td> <td>::= <tt>((</tt> \e optional_stream <tt>,</tt> \e optional_area <tt>,</tt> \e level <tt>))</tt> \n</td></tr>
175 <tr><td>optional_stream</td> <td>::= <tt>(_)</tt> | \e scope_seq \n</td></tr>
176 <tr><td>optional_area</td> <td>::= <tt>(_)</tt> | \e scope_seq \n</td></tr>
177 <tr><td>level</td> <td>::= \c VERBOSE | \c NOTICE | \c MESSAGE | \c IMPORTANT | \c CRITICAL | \c DISABLED \n</td></tr>
178 <tr><td>scope_seq</td> <td>::= \e scope \e scope* \n</td></tr>
179 <tr><td>scope</td> <td>::= <tt>(</tt> \e name <tt>)</tt> \n</td></tr>
180 <tr><td>name</td> <td>::= arbitrary C++ identifier</td></tr>
183 \ref SENF_LOG_CONF is a Boost.Preprocessor style sequence of 3-tuples.
185 The first tuple element \e optional_stream specifies the stream to match. If this is
186 <tt>(_)</tt>, the entry will match any stream.
188 The next tuple element, \e optional_area optionally restricts the entry to match only the
189 given area. If set to <tt>(_)</tt>, the area is left unrestricted.
191 The last tuple element \e level defines the compile time log level. Messages with a level
192 below this are discarded at compile time.
194 Both \e optional_stream and \e optional_area are given as a \e scope_seq. A scope sequence
195 is a fully qualified C++ identifier placed into a sequence: <tt>foo::bar::baz</tt> is
196 represented by <tt>(foo)(bar)(baz)</tt>.
198 # define SENF_LOG_CONF
202 /** \brief Check, if logging is enabled for stream/area/level tuple
204 This is a template meta-function which will check, whether logging to the given combination
205 of parameters \a Stream, \a Area and \a Level is compile-time enabled. The logging might
206 still be disabled at runtime.
208 if (senf::log::Enabled<senf::log::Debug,
209 senf::log::DefaultArea,
210 senf::log::VERBOSE>::value) {
215 Since the \e value member is a compile time constant, the compiler will completely optimize
216 away this block of code when logging is disabled.
218 template <class Stream, class Area, class Level>
221 static const bool value = (
222 (Level::value == NONE::value ? Stream::defaultLevel::value : Level::value)
223 >= detail::Config<Stream,Area>::compileLimit::value );
230 //-/////////////////////////////////////////////////////////////////////////////////////////////////
231 //#include "Config.cci"
232 //#include "Config.ct"
233 //#include "Config.cti"
240 // comment-column: 40
241 // c-file-style: "senf"
242 // indent-tabs-mode: nil
243 // ispell-local-dictionary: "american"
244 // compile-command: "scons -u test"