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diff --git a/src/mongo/logv2/README.md b/src/mongo/logv2/README.md index 96f264028d3..ec28ee9e3a3 100644 --- a/src/mongo/logv2/README.md +++ b/src/mongo/logv2/README.md @@ -332,3 +332,39 @@ long | int64 (0x12) unsigned long | int64 (0x12) long long | int64 (0x12) unsigned long long | int64 (0x12) + +# Style guide + +### Message string + +* Prefer pithy noun phrases or short sentence describing what is being logged +* Avoid using replacement fields when not needed to describe meaning of log or attributes +* Avoid ending with punctuation (.) + +### Attribute names + +* Should be small number of camelCased words being understandable as description with just the message string as context for someone with reasonable understanding of mongod behavior +* Do not add unit suffix when logging duration type (it will be added by log system) +* Prefer naming attribute "duration" and use Milliseconds of unit when logging real-time durations as part of performance warnings. +* Prefer adding unit suffix if available when logging integral or floating point attributes + +##### Examples + +``` +LOGV2(1040, "Replica set state transition on this node", "oldState"_attr = getOldState(), "newState"_attr = getNewState()); + +{ ..., "id": 1040, "msg": "Replica set state transition on this node", "attr": { "oldState": "SECONARY", "newState": "PRIMARY" } } +``` + + ``` +LOGV2(1041, "Transition to PRIMARY complete"); + +{ ... , "id": 1041, "msg": "Transition to PRIMARY complete", "attr": {} } +``` + +``` +LOGV2(1042, "Slow query", "duration"_attr = getDurationMillis()); + +{ ..., "id": 1042, "msg": "Slow query", "attr": { "durationMillis": 1000 } } + +```
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