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Add option to increase the level of a logger #775

Merged
merged 5 commits into from Jan 30, 2020
Merged

Add option to increase the level of a logger #775

merged 5 commits into from Jan 30, 2020

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prashantv
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@prashantv prashantv commented Dec 23, 2019

We've had a few requests on how to change the level of a logger. With
the current APIs, it's not possible to reduce the log level (e.g., go
from Info to Debug), but it is possible to increase the level using
WrapCore with a custom filtering core.

Since it's a common request, I think we should add an option to make
this easy to use.

I want to make sure "increase" is part of the API to avoid confusion on
whether it can reduce the log level.

Fixes #774.

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@codecov codecov bot commented Dec 23, 2019

Codecov Report

Merging #775 into master will increase coverage by 0.01%.
The diff coverage is 100%.

Impacted file tree graph

@@            Coverage Diff             @@
##           master     #775      +/-   ##
==========================================
+ Coverage   98.19%   98.21%   +0.01%     
==========================================
  Files          42       43       +1     
  Lines        2275     2293      +18     
==========================================
+ Hits         2234     2252      +18     
  Misses         33       33              
  Partials        8        8
Impacted Files Coverage Δ
options.go 100% <100%> (ø) ⬆️
zapcore/increase_level.go 100% <100%> (ø)

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@weeco
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@weeco weeco commented Dec 23, 2019

I think this is related to #581 , but when I got the author correctly he wishes an option to change the loglevel on a per message basis rather than just having an easy way to create a new child logger which prints at a different log level.

I'll leave this note here and reference here, so that issue as it might help some of the users stumbling across #581

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@abhinav abhinav left a comment

Do we have any way to guard against attempts to lower the level?

I'm concerned that despite naming, this will be very easy to misuse.

// NewLevelCore creates a core that can be used to increase the level of an existing
// Core. It cannot be used to decrease the logging level, as it acts as a filter
// before calling the underlying core.
func NewLevelCore(core Core, level LevelEnabler) Core {
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@abhinav abhinav Dec 31, 2019

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I suspect this needs a similar name that implies increasing levels only.

@prashantv
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@prashantv prashantv commented Jan 7, 2020

Do we have any way to guard against attempts to lower the level?

I'm concerned that despite naming, this will be very easy to misuse.

We can't protect against it, but we can access the errorOutput for the logger, and write a message to it if we detect that someone tries to lower the log level. I don't think adding errors to the API will be very ergonomic. We could do a DPanic but that might be a little surprising. Any other ideas?

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@abhinav abhinav commented Jan 7, 2020

Logging to errorOutput seems reasonable. I agree that having this error out
would be less ergonomic.

prashantv added 2 commits Jan 24, 2020
We've had a few requests on how to change the level of a logger. With
the current APIs, it's not possible to reduce the log level (e.g., go
from Info to Debug), but it is possible to increase the level using
`WrapCore` with a custom filtering core.

Since it's a common request, I think we should add an option to make
this easy to use.

I want to make sure "increase" is part of the API to avoid confusion on
whether it can reduce the log level.

Fixes #774.
@prashantv prashantv changed the title [WIP] Add option to increase the level of a logger Add option to increase the level of a logger Jan 24, 2020
@prashantv
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@prashantv prashantv commented Jan 24, 2020

Updated with more explicit name + error if the level is decreased. Could definitely improve the message so looking for suggestions

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@abhinav abhinav left a comment

New APIs look fine. Minor comments.

zapcore/increase_level.go Show resolved Hide resolved
zapcore/increase_level_test.go Outdated Show resolved Hide resolved
logger_test.go Outdated Show resolved Hide resolved
increase_level_test.go Outdated Show resolved Hide resolved
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@abhinav abhinav left a comment

LGTM besides prior comments

prashantv and others added 3 commits Jan 30, 2020
Co-Authored-By: Abhinav Gupta <abg@uber.com>
Co-Authored-By: Abhinav Gupta <abg@uber.com>
@prashantv prashantv merged commit 127ea09 into master Jan 30, 2020
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@prashantv prashantv deleted the increase_level branch Jan 30, 2020
cgxxv pushed a commit to cgxxv/zap that referenced this issue Mar 25, 2022
We've had a few requests on how to change the level of a logger. With
the current APIs, it's not possible to reduce the log level (e.g., go
from Info to Debug), but it is possible to increase the level using
`WrapCore` with a custom filtering core.

Since it's a common request, I think we should add an option to make
this easy to use.

I want to make sure "increase" is part of the API to avoid confusion on
whether it can reduce the log level.

Fixes uber-go#774.
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3 participants