Logger is a logging system for performance, large data generation, and post-processing. Logger was originally developed for large automated testing procedures against realtime hardware devices such as commercial satellites. Its goals were to log various types of events in human readable formats, but in an output that could easily be parsed and searched for later post-processing report generation.
During a run-for-record, large amounts of data could be generated (measured in gigabytes) so the logging facility needed to support auto-segmentation of files to avoid exceeding maximum file size limits.
Also an optional echoing feature is available for those wishing to see the output logged to a file but also a terminal for monitoring.
For additional speed and brevity, priority thresholds can be set at runtime to eliminate low priority messages from being logged.
Log Event entries were designed to be easily parsable so custom tools could easily be written to "grep" the data for specific queries and specific types of report generation. The format was originally designed as follows: (note tabs used in the first line to make regex simpler)
TimeStamp Keyword: SubKeyword: PRI=<num> Log Event message. Generally free form, including multiple lines, but avoid the end marker convention. END:
TimeStamps were written in a descending format: Year-Month-Day_HH:MM:SS.mmm The descending order and consistent spacing are the key attributes as it makes post-parsing very easy and also makes sorting dates a trivial operation as the descending order guarantees a simple string comparison or number comparison will always sort in the correct order. The END: marker always starts on the beginning of a newline and ends with a colon. Again, this is to make parsing faster disambigutate it from messages. Still, care should be taken to not introduce messages that will confuse post-processing tools. Logger itself doesn't really care and does no enforcement for performance.
Here is a sample timestamp:
2002-10-29_19:59:32.321 Error: CommunicationsSystem: PRI=5 CRC checksums failed. END:
Logger has been rewritten many times in many languages. Included in this package is my re-invention of Logger to C and C++ (with also an Objective-C macro interface that lives on top of the C version. I have found more mundane uses for Logger than commercial aerospace, but have still found it useful nonetheless. Some of the features like auto-segmentation might be overkill, but they can be easily disabled.
See the Files section in the Doxygen output for the specific documentation for the C or/and C++ versions. They are almost identical except that the C++ gets to implicitly hide the Logger object. The C++ version uses printf sementics for most operations instead of iostreams. This is somewhat because I never really cared to implement iostreams. It also wasn't obvious to me how to bypass stream processing when messages could be suppressed for performance, nor is it obvious how to deal with localization issues where parameters may need to be reordered.
Be aware the echo feature uses C99 va_copy. There is a fallback for compilers that don't support this (e.g. Visual Studio) but this may need to be dealt with for other compilers I haven't tested on.
Similar warning for threads. I currently only support pthreads and Windows. If you don't need thread safety in Logger, you can flip a compile switch to disable locking for additional performance.
Currently the C version might have a slight edge on features. The C version lets you specify a format string for file segmentation. This code has not been ported to the C++ version. (See comments inside the C++ implementation for why.) Lookup Logger.h under Files in the Doxygen documentation for the C-API. Lookup Logger under data structures in the Doxygen documentation for C++.
Sample Usage (C API):
Logger* a_logger = Logger_Create("myoutput.log"); Logger_LogEvent(a_logger, 5, "Error", "SDL_image::SDL_glLoadImage", "Error found: %s", SDL_GetError()); Logger_Free(a_logger);
Sample Usage (C++ API):
Logger a_logger; a_logger.Init("myoutput.log"); a_logger.LogEvent(5, "Error", "SDL_image::SDL_glLoadImage", "Error found: %s", SDL_GetError()); a_logger.Close(); // Not necessary to explicitly call, called by destructor
License: MIT
Home Page: http://playcontrol.net/opensource/Logger
1.7.2
