logcontext 0.1.1

A simple logging system for (async) contexts

This module helps to solve the following problem:

You have an async program. It does lots of things in parallel. You don't really know what's happening. Then you get a deadlock, or a cancellation whose initial trigger is masked by another error or an unprotected async call within a finally: block.

You now have no idea what's happening, and low-level instrumentation of your code causes the error to get lost in the noise.

Here's how logcontext can help.

First, wrap your main code::

from logcontext import main_context
def main():
	with main_context():
		... # whatever your program does

Then you wrap each possibly-interesting block, nursery, async context, … with

from logcontext import context_of
...
async def code_of_interest(arg):
	with context_of("interesting: %s", arg) as ctx:
	    ... # start some subtask

		# display what my subcontexts are doing, if anything
		ctx.log_tree()  

Text and positional arguments will be passed to logging.log.

Reporting on the current state of your code is then as easy as::

from logcontext import log_backtrace, log_tree

...
log_tree()  # reports the whole program's context tree
log_backtrace()  # reports the contexts leading to the current code

Both context_of and log_tree accept a log level. This way you can selectively attach higher log levels to possibly-interesting code. "Uninteresting" subtrees are skipped.

"""

from ._main import main_context, context_of, log_backtrace, log_tree