As part of the effort to improve logging in gecko we'd like to introduce a new
set of unified log levels.
Currently we use NSPR logging which defines the following log levels:
typedef enum PRLogModuleLevel {
PR_LOG_NONE = 0, /* nothing */
PR_LOG_ALWAYS = 1, /* always printed */ <---- lies, damned lies
PR_LOG_ERROR = 2, /* error messages */
PR_LOG_WARNING = 3, /* warning messages */
PR_LOG_DEBUG = 4, /* debug messages */
PR_LOG_NOTICE = PR_LOG_DEBUG, /* notice messages */
PR_LOG_WARN = PR_LOG_WARNING, /* warning messages */
PR_LOG_MIN = PR_LOG_DEBUG, /* minimal debugging messages */
PR_LOG_MAX = PR_LOG_DEBUG /* maximal debugging messages */
} PRLogModuleLevel;
After a rather thorough examination of usages of each I have come up with a set
that I believe would fit our needs:
enum class LogLevel {
Disabled = 0, // Logging is disabled for this module
Error,
Warning,
Info,
Debug,
};
This subset maps rather nicely to syslog and web console logging levels:
| Level | PR_LOG | Console | Syslog |
|---------|----------------|-------------------|---------|
| Error | PR_LOG_ERROR | console.error() | error |
| Warning | PR_LOG_WARNING | console.warn() | warning |
| Info | n/a | console.info() | info |
| Debug | PR_LOG_DEBUG | console.debug()* | debug |
This removes all of the various PR_LOG aliases as well as |PR_LOG_ALWAYS|. It
adds a generic |Info| level.
*PR_LOG_ALWAYS*
This really didn't mean what most uses thought it meant. Specifying
|PR_LOG_ALWAYS| did not in fact mean your message was always logged, it just
mean it was logged if at least log level 1 was specified. By default every
logger has output disabled.
For most instances it can be replaced with |Info|, a more generic log category
that is slightly more important than |Debug|, but not an error or warning.
*PR_LOG_DEBUG + 1 aka log level 5*
Various bits of code invented a log level that was less important than debug (I
would call this verbose). This was not specified in NSPR logging, but just kind
of worked. With the addition of |Info| we can transition code that was using
this pseudo log level to:
- map PR_LOG_DEBUG => Info
- map PR_LOG_DEBUG + 1 => Debug
In this case we could have added a |Verbose| log level, but with the addition
of |Info| and feeling that fewer is better we have decided against that.
*How will log levels be controlled?*
Similar to how it works now (if not terribly clear), turning on:
- LogLevel::Error => Error messages will be printed
- LogLevel::Warning => Error and Warning messages will be printed
- LogLevel::Info => Error, Warning, and Info messages will be printed
- LogLevel::Debug => Error, Warning, Info, and Debug messages will be
printed
As a future improvement we plan to add the ability to toggle this levels at
runtime.
Please let me know of any concerns or input you may have.
-e
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