Migrate from GLOG to Folly logging #409

We’re migrating Proxygen from using GLOG to Folly logging which is more flexible, natively supports async logging and has a number of other advantages.

General configuration instructions are here.

Notably, this means anything running Proxygen lib will need to use a different logging config, replacing -v and --vmodule with a matching config passed to --logging.

For example, if you wanted to print all logs up to V2, except in myprojectroot/proxygen/lib/transport/H3DatagramAsyncSocket.cpp and myprojectroot/proxygen/lib/transport/PersistentFizzPskCache.cpp, where you wanted to silence all the verbose logs entirely, then you might have run your binary with something like this:

-v=2 --vmodule=H3DatagramAsyncSocket*=0,PersistentFizzPskCache*=0

But now you would run it with:

--logging=DBG2,myprojectroot.proxygen.lib.transport.H3DatagramAsyncSocket:=INFO,myprojectroot.proxygen.lib.transport.PersistentFizzPskCache:=INFO

As another example, to exclude all verbose logging across the entire codebase and to exclude all logging (not just verbose) only from the files under proxygen/lib/transport/, you might run it with:

--logging=INFO,myprojectroot.proxygen.lib.transport:=MAX_LEVEL

If you use custom log sinks with GLOG, you will need to migrate them to Folly Log Handlers and if you use the GOOGLE_STRIP_LOG macro, you will need to use the corresponding value for FOLLY_XLOG_MIN_LEVEL.