boost::log::basic_core — Logging library core class.
// In header: <boost/log/core/core.hpp> template<typename CharT> class basic_core { public: // types typedef CharT char_type; // Character type. typedef basic_record< char_type > record_type; // Log record type. typedef record_type::string_type string_type; // String type to be used as a message text holder. typedef basic_attribute_set< char_type > attribute_set_type; // Attribute set type. typedef record_type::values_view_type values_view_type; // Attribute values view type. typedef sinks::sink< char_type > sink_type; // Sink interface type. typedef function1< bool, values_view_type const & > filter_type; // Filter function type. typedef function0< void > exception_handler_type; // Exception handler function type. // construct/copy/destruct ~basic_core(); // public member functions bool set_logging_enabled(bool = true); void set_filter(filter_type const &); void reset_filter(); void add_sink(shared_ptr< sink_type > const &); void remove_sink(shared_ptr< sink_type > const &); std::pair< typename attribute_set_type::iterator, bool > add_global_attribute(string_type const &, shared_ptr< attribute > const &); void remove_global_attribute(typename attribute_set_type::iterator); attribute_set_type get_global_attributes() const; void set_global_attributes(attribute_set_type const &); std::pair< typename attribute_set_type::iterator, bool > add_thread_attribute(string_type const &, shared_ptr< attribute > const &); void remove_thread_attribute(typename attribute_set_type::iterator); attribute_set_type get_thread_attributes() const; void set_thread_attributes(attribute_set_type const &); void set_exception_handler(exception_handler_type const &); record_type open_record(attribute_set_type const &); void push_record(record_type const &); // public static functions static shared_ptr< basic_core > get(); };
The logging core is used to interconnect log sources and sinks. It also provides a number of basic features, like global filtering and global and thread-specific attribute storage.
The logging core is a singleton. Users can acquire the core instance by calling the static method get
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basic_core
public member functionsbool set_logging_enabled(bool enabled = true);
The method enables or disables logging.
Setting this status to false
allows you to completely wipe out any logging activity, including filtering and generation of attribute values. It is useful if you want to completely disable logging in a running application. The state of logging does not alter any other properties of the logging library, such as filters or sinks, so you can enable logging with the very same settings that you had when the logging was disabled. This feature may also be useful if you want to perform major changes to logging configuration and don't want your application to block on opening or pushing a log record.
By default logging is enabled.
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Returns: | The previous value of enabled/disabled logging flag |
void set_filter(filter_type const & filter);
The method sets the global logging filter. The filter is applied to every log record that is processed.
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void reset_filter();
The method removes the global logging filter. All log records are passed to sinks without global filtering applied.
void add_sink(shared_ptr< sink_type > const & s);
The method adds a new sink. The sink is included into logging process immediately after being added and until being removed. No sink can be added more than once at the same time. If the sink is already registered, the call is ignored.
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void remove_sink(shared_ptr< sink_type > const & s);
The method removes the sink from the output. The sink will not receive any log records after removal. The call has no effect if the sink is not registered.
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std::pair< typename attribute_set_type::iterator, bool > add_global_attribute(string_type const & name, shared_ptr< attribute > const & attr);
The method adds an attribute to the global attribute set. The attribute will be implicitly added to every log record.
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Returns: | A pair of values. If the second member is |
void remove_global_attribute(typename attribute_set_type::iterator it);
The method removes an attribute from the global attribute set.
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Requires: | The attribute was added with the |
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Postconditions: | The attribute is no longer registered as a global attribute. The iterator is invalidated after removal. |
attribute_set_type get_global_attributes() const;
The method returns a copy of the complete set of currently registered global attributes.
void set_global_attributes(attribute_set_type const & attrs);
The method replaces the complete set of currently registered global attributes with the provided set.
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The method invalidates all iterators and references that may have been returned from the |
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std::pair< typename attribute_set_type::iterator, bool > add_thread_attribute(string_type const & name, shared_ptr< attribute > const & attr);
The method adds an attribute to the thread-specific attribute set. The attribute will be implicitly added to every log record made in the current thread.
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In single-threaded build the effect is the same as adding the attribute globally. This, however, does not imply that iterators to thread-specific and global attributes are interchangable. |
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Returns: | A pair of values. If the second member is |
void remove_thread_attribute(typename attribute_set_type::iterator it);
The method removes an attribute from the thread-specific attribute set.
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Requires: | The attribute was added with the |
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Postconditions: | The attribute is no longer registered as a thread-specific attribute. The iterator is invalidated after removal. |
attribute_set_type get_thread_attributes() const;
The method returns a copy of the complete set of currently registered thread-specific attributes.
void set_thread_attributes(attribute_set_type const & attrs);
The method replaces the complete set of currently registered thread-specific attributes with the provided set.
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The method invalidates all iterators and references that may have been returned from the |
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void set_exception_handler(exception_handler_type const & handler);
The method sets exception handler function. The function will be called with no arguments in case if an exception occurs during either open_record
or push_record
method execution. Since exception handler is called from a catch
statement, the exception can be rethrown in order to determine its type.
By default no handler is installed, thus any exception is propagated as usual.
See Also:
See also: utility/exception_handler.hpp
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The exception handler can be invoked in several threads concurrently. Thread interruptions are not affected by exception handlers. |
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record_type open_record(attribute_set_type const & source_attributes);
The method attempts to open a new record to be written. While attempting to open a log record all filtering is applied. A successfully opened record may be pushed further to sinks by calling the push_record
method or simply destroyed by destroying the returned handle.
More than one open records are allowed, such records exist independently. All attribute values are acquired during opening the record and do not interact between records.
The returned record handles may be copied, however, they must not be passed between different threads.
Throws: If an exception handler is installed, only throws if the handler throws. Otherwise may throw if one of the sinks throws, or some system resource limitation has been reached.
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Returns: | A valid log record if the record is opened, an invalid record object if not (e.g. because it didn't pass filtering). |
void push_record(record_type const & rec);
The method pushes the record to sinks.
Throws: If an exception handler is installed, only throws if the handler throws. Otherwise may throw if one of the sinks throws.
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basic_core
public static functionsstatic shared_ptr< basic_core > get();
Returns: | The method returns a pointer to the logging core singleton instance. |