ulsp: add a logger class

[Jafaral]

This adds a general logging class that I hope to move to the library. For now keeping it and using it in ulsp.

example run

./ulsp --socket 12345 --logfile ulsp.log 

[Don-Ward]

There are probably as many ways to write a logger class as there are authors of such classes. Many choices are a matter of style (and here is not really the place to debate them). We can probably take the experience we get from using this class and feed it into the creatiion of a library logging class. The two changes I would ask for is that the more important/critical messages are immediately flushed, to avoid any danger of them being lost. The second change is to make the class thread safe so logging messages that are the result of a single use of the class come out together rather than being interspersed with other concurrent logging usage: there are already comments in the ulsp source about using threads, so we might as well get this right to start with.

[Jafaral]

@Don-Ward I agree. Those are good suggestions, but I'm trying to get something going in the short term. I updated the PR to allow defining debug classes/filters. I added a c command line option just as an example, with a couple of debug message use case for demonstration purposes. A log message will be printed if the log level is high enough for it to be printed, or it matches a calls/filter. Filter supports sub-classes too. Ex:

jafar@jtr:ulsp$ ./ulsp --socket 12345 -s --debugfilter "db:path"
[debug:db:path]  /home/jafar/unicon/ipl/lib
[debug:db:path]  /home/jafar/unicon/uni/lib
[debug:db:path]  /home/jafar/unicon/uni/gui
[debug:db:path]  /home/jafar/unicon/uni/xml
[debug:db:path]  /home/jafar/unicon/uni/3d
[debug:db:path]  /home/jafar/unicon/plugins/lib
[debug:db:path]  /home/jafar/unicon/ipl/procs
[debug:db:path]  /home/jafar/unicon/uni/unidoc
^C
shutdown signal received! Server Shutting down...
jafar@jtr:ulsp$ ./ulsp --socket 12345 -s --debugfilter "db"
[debug:db]Looking in 1
[debug:db:path]  /home/jafar/unicon/ipl/lib
[debug:db:path]  /home/jafar/unicon/uni/lib
[debug:db:path]  /home/jafar/unicon/uni/gui
[debug:db:path]  /home/jafar/unicon/uni/xml
[debug:db:path]  /home/jafar/unicon/uni/3d
[debug:db:path]  /home/jafar/unicon/plugins/lib
[debug:db:path]  /home/jafar/unicon/ipl/procs
[debug:db:path]  /home/jafar/unicon/uni/unidoc
^C
shutdown signal received! Server Shutting down...
jafar@jtr:ulsp$ ./ulsp --socket 12345 -s --debugfilter "db" --loglevel 10
[info]Loading Database...
[debug:db]Looking in 1
[debug:db:path]  /home/jafar/unicon/ipl/lib
[debug:db:path]  /home/jafar/unicon/uni/lib
[debug:db:path]  /home/jafar/unicon/uni/gui
[debug:db:path]  /home/jafar/unicon/uni/xml
[debug:db:path]  /home/jafar/unicon/uni/3d
[debug:db:path]  /home/jafar/unicon/plugins/lib
[debug:db:path]  /home/jafar/unicon/ipl/procs
[debug:db:path]  /home/jafar/unicon/uni/unidoc
[info]Starting Unicon LSP in server mode at :12345

[Jafaral]

I made further updates, changing the filtering logic based on testing I did. I also changed "filter" to "class". Log level now much be 8+ for filters to work, I.e, debugging must be enabled. I added flush, but chose to ignore threads for now. The class is a bit thread "friendly" already, but it is good to add support so that each log is written out to all log destinations from one thread before processing a new log request.

jafar@mac16 ulsp % ./ulsp --socket 12345 --loglevel 8 --debug-class "db:path:package"
[info] Loading Database...
[debug3:db:path:package] Processing (main)
[debug3:db:path:package] Processing doptions
[debug3:db:path:package] Processing exception
[debug3:db:path:package] Processing lang

[Jafaral]

example log file

./ulsp --socket 12345 --loglevel 8 --debug-class "db:path" --logfile /tmp/ulsp.log

jafar@mac16 ulsp % cat /tmp/ulsp.log 
[2024/09/17 00:36:21][info] Loading Database...
[2024/09/17 00:36:21][debug2:db:path] Processing /Users/jafar/proj/unicon/ipl/lib
[2024/09/17 00:36:21][debug2:db:path] Processing /Users/jafar/proj/unicon/uni/lib
[2024/09/17 00:36:23][debug2:db:path] Processing /Users/jafar/proj/unicon/uni/gui
[2024/09/17 00:36:23][debug2:db:path] Processing /Users/jafar/proj/unicon/uni/xml
[2024/09/17 00:36:24][debug2:db:path] Processing /Users/jafar/proj/unicon/uni/3d
[2024/09/17 00:36:24][debug2:db:path] Processing /Users/jafar/proj/unicon/plugins/lib
[2024/09/17 00:36:24][debug2:db:path] Processing /Users/jafar/proj/unicon/ipl/procs
[2024/09/17 00:36:26][debug2:db:path] Processing /Users/jafar/proj/unicon/uni/unidoc
[2024/09/17 00:36:26][info] Starting Unicon LSP in server mode at 127.0.0.1:12345
[2024/09/17 00:36:31][notice] 
shutdown signal received! Server Shutting down...