[PROTON-2131] Improved logging API

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: proton-c-0.30.0
• Component/s: proton-c
• Assignee: Andrew Stitcher
• Reporter: Andrew Stitcher
• Created: 07/Nov/19 06:45
• Updated: 12/Jul/20 11:11
• Resolved: 16/Dec/19 10:38

Description

Problems with current proton logging:

• There are multiple logging systems that are not connected

• pn_log_* is used for some things that are not connected to an AMQP
  connection (but not all things)
• pn_transport_t has its own logging system that is the major logging
  system in proton, with an pn_transport_logf() and friends API and an
  ability to sink the log its output log messages using
  pn_transport_set_tracer(). However not everything that might need to
  log messages is connected to a pn_transport_t so it makes a lot more
  sense for logging to be its own system that the pn_transport_t is
  connected to rather than the other way around.

• The logging only has a set of vague somewhat amorphous trace flags to
  decide which messages get logged. Currently the only coherent use for
  this subsystem is to set the environment variable PN_TRACE_FRM to get
  AMQP frame traces. There are other environment variable which produce
  output (and flags can be set programmatically by client programs) but
  which flags produce what output is not very systematic. There is no way
  to output only logging related to SSL/TLS for example.

• The callback function that an application can attach to receive the
  log messages only gets the message and maybe the pn_transport_t that is
  associated, but no indication of the severity or what pert of the
  library it came from.

Issue Links

• relates to: PROTON-343 Add a pluggable Proton logging layer
• links to: GitHub Pull Request #201