Disabling INFO and WARN std::cerr

[springmeyer]

Ideally, for node-osrm, there could be a way to disable this OSRM output so that meaningful logging could be controlled by the application calling into node-osrm

[DennisOSRM]

Yes, makes sense.

[DennisOSRM]

I'll expose a parameter to the library constructor that allows you to mute the logging. Does that make sense to what you have in mind?

[springmeyer]

Yes. Was thinking silent by default and then verbose mode can be turned on. Plan to model this in node-osrm around how node-sqlite3 works.

[DennisOSRM]

k, cool. Will dig a bit into node-sqlite3 to get a better impression.

[springmeyer]

node-sqlite has db.on('trace'.. and db.on('profile'.. events you can hook into:

• https://github.com/developmentseed/node-sqlite3/blob/master/test/profile.test.js
• https://github.com/developmentseed/node-sqlite3/blob/master/test/trace.test.js

And node-blend has a third arg that is passed to callbacks (which were run in the thread pool) that provides an array of warnings:

• https://github.com/developmentseed/node-blend/blob/master/test/repeated.test.js#L24-L26

These are candidates for how to design ways to get more debugging info. But, on further thought I think this is overkill for now in terms of node-osrm. Just being able to mute things sounds just fine for now!

[DennisOSRM]

the current plan is to have a policy singleton that describes if logging is muted or not. And then a simple object that overrides std::ostringstreamoperator<< and which collects output. On destruction, it writes stuff to console. Usage will then be similar to Log().Get(logWarning) << "important message";

[springmeyer]

okay, sounds good. And familiar to the new boost log and the mapnik debug framework

[DennisOSRM]

Right, unfortunately the boost log library is not yet old enough to have trickled down into current linux distros.

[DennisOSRM]

This is now implement in Project-OSRM/osrm-backend@44eed92. The default is that logging is disabled. To enable, toggle the that of the LogPolicy singleton class:

LogPolicy::GetInstance().Unmute();

Likewise .Mute() silences any output. Logging messages is as easy as

SimpleLogger().Write() << "super informative message goes here";

whereas .Write() takes a parameter to indicate logging level:

• logINFO (default)
• logWARNING
• logDEBUG

[springmeyer]

fantastic, tests for node-osrm now run cleanly and without noise :)

The blue ones are pending, see #8 for details.