envoyproxy/envoy

Fine grained logging via FANCY_LOG always evaluates macro arguments

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#12,885 opened on Aug 29, 2020

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area/envoy_loghelp wanted

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Description

The ENVOY_LOG macro without fine grained logging doesn't evaluate variadic arguments when the log level squelches the message. When going through FANCY_LOG however, that no longer holds. Variadic arguments are always evaluated regardless of the log level involved. This could be problematic from a perf point of view.

Context: https://github.com/envoyproxy/envoy/pull/12830#issuecomment-681918730

Contributor guide

Research direction
Inspect the FANCY LOG macro definition and trace how variadic arguments are evaluated to find where eager evaluation occurs.
Tech stack
cpp
Domain
backendinfrastructure
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++Macros
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50