Log messages, usually for analysing the program's internal flow for debugging purposes. More...

#include </home/werner/origo/vish/ocean/plankton/VLogger.hpp>

Classes

struct Context
Set logging context with auto-cleanup. More...
class Indent
A class for setting a temporary increment of the indentation of logging text; it allows to indent logged text automatically during the lifetime of the Indent object. More...
class State
Describes a thread-local state of the logging process. More...

Public Member Functions

bool activate ()
Activate this VLogger object.
virtual void printmsg (const string &text, int verbosity, int indent_spaces, const string &srcfilename, unsigned linenumber, const WeakPtr< VTask > &ThreadID, const string &funcname)
Message output function.
VLogger ()
Constructs and adds a logging object.
~VLogger ()
Destructor.

Static Public Member Functions

static State & CurrentState ()
static void enter (const char *context)
static void increment_indent (int i)
static void leave ()
static void print (const string &text, int verbosity, int indent_spaces, const string &srcfilename, unsigned linenumber, const WeakPtr< VTask > &ThreadID, const string &funcname)
Verbose print function.
static void print (int verbosity, const string &s)
Simplified print function.
static void print_internals ()
static void printf (int verbosity, const char *format,...)
Print formatted function with parameters.
static void setSrcLine (const char *srcfilename, unsigned linenumber)

Detailed Description

Log messages, usually for analysing the program's internal flow for debugging purposes.

While using of debuggers is helpful to trace down fatal program errors leading to segmentation faults and core dumps, debugging tools are not too effective to analyse and verify the execution flow of a program. Logical errors - in contrast to simple programming errors - are hardly determinable using runtime debuggers since they only show a certain state of a program, but not the execution history. The ability to log the program's execution flow is the more effective approach for tracing higher-level errors, especcially in a multithreaded context.

This class only provides an abstraction interface to various output facilities. Multiple clients may connect to the logging instance.

The API is intentionally as simple as possible, such that application code just needs to be instrumented with print() or printf() calls. Only required addition is the specification of a verbosity level. The higher the verbosity level, the more detailed the information is, and it is the duty of the implementation of a VLogger to display logging information only up to a certain verbosity level.

The VLogger class implements a function call stack for each thread and keep track of a context when issuing print statements. This context contains the current function name, source file name, line number and indentation level. The context may be setup automatically by some external source code instrumentation tool which inserts certain code lines. However, manual instrumentation might be more effective since there doesn't need to be a 1:1 correspondence. For instance, one specific line in a source code might emit multiple logging lines, or a function should not show up explicitely since the calling function is the one providing the relevant context.

Class Derivation Example:

class   MyLogger : public VLogger
{
        override void printmsg(const string&text,               
                               int verbosity,                   
                               int indent_spaces,               
                               const string&srcfilename,        
                               unsigned linenumber,             
                               const WeakPtr<VTask>&ThreadID,    
                               const string&funcname            
                        );


};

main()
{
RefPtr<MyLogger> MainLogger = new MyLogger();
        MainLogger->activate();
}

bool activate();

Todo:: Provide a std::ostream interface . But should be in a separate header file.

Member Function Documentation

bool Wizt::VLogger::activate ( )

Activate this VLogger object.

It must be referenced via a strongptr from some application code.

void Wizt::VLogger::print	(	const string &	text,
		int	verbosity,
		int	indent_spaces,
		const string &	srcfilename,
		unsigned	linenumber,
		const WeakPtr< VTask > &	ThreadID,
		const string &	funcname
	)		`[static]`

Verbose print function.

All arguments are broadcasted to all activated instances of VLogger objects.

Parameters:

text	the actual text to be printed
verbosity	the verbosity level
indent_spaces	how many spaces to indent at the beginning of the line?
srcfilename	the file name of the source that issues this command, usually __FILE__
linenumber	the line number of the source file, usually __LINE__
ThreadID	an identifier for the thread issuing the message
funcname	the function context for which this function was called.

void Wizt::VLogger::printmsg	(	const string &	text,
		int	verbosity,
		int	indent_spaces,
		const string &	srcfilename,
		unsigned	linenumber,
		const WeakPtr< VTask > &	ThreadID,
		const string &	funcname
	)		`[virtual]`

Message output function.

By default, prints message on standard output.

Parameters:

text	the actual text to be printed
verbosity	the verbosity level
indent_spaces	how many spaces to indent at the beginning of the line?
srcfilename	the file name of the source that issues this command, usually __FILE__
linenumber	the line number of the source file, usually __LINE__
ThreadID	an identifier for the thread issuing the message
funcname	current function (last registered for debugging)

Reimplemented in Wizt::VStreamLogger::Logger.

The documentation for this class was generated from the following files:

ocean/plankton/VLogger.hpp
ocean/plankton/VLogger.cpp