Server Logging Rules (obsolete)

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Louis Williams edited this page Jul 7, 2022 · 3 revisions

WARNING

This document is largely obsolete. Please refer to docs/logging.md for up-to-date guidance on logging.

Basic Rules

cout/cerr should never be used
Include mongo/util/log.h to use the LOG() helper macro
Declare a log component before the first #include statement in a .cpp file to assign a default log component to log messages.
```
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kStorage

#include ...
```

Normal Logging

Debugging with levels of verbosity. See the -v command line option (default level is 0). If the global log level is less than x, no functions in the stream are executed.
```
LOG( int x ) << ...
```
Informational
```
log() << ...
```
Warnings
- recoverable, e.g. replica set node down
```
warning() << ...
```
Errors
- unexpected system state (disk full)
- internal code errors
```
error() << ...
```