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/*! @page verbose_messaging Verbose messaging
As part of normal operation, WiredTiger will produce verbose messages
around various events, actions and possible issues/errors. Verbose
messages are spread across various categories, representing different sub-systems
throughout WiredTiger. Verbose messages can be usefully leveraged to monitor,
debug and diagnose events across WiredTiger's runtime.
@section verbosity_levels Verbosity Levels
WiredTiger associates a verbosity level with each message. The verbosity
level denotes the severity of a given message, ranging from high
severity error messages (\c ERROR) to low severity debug informational
messages (\c DEBUG). The full range of verbosity levels and their associated
meanings are:
<table>
@hrow{Level, Value, Description}
@row{\c ERROR, -3, Critical error conditions triggered in WiredTiger. Usually requiring a DB restart. }
@row{\c WARNING, -2, Warning conditions potentially signaling non-imminent errors and behaviors. Important to be aware of and useful for diagnosing potential error states. }
@row{\c NOTICE, -1, Messages for significant events in WiredTiger\, usually worth noting. Notice messages are associated with normal runtime operations i.e not produced from any state considered harmful or error-prone.}
@row{\c INFO, 0, Informational style messages\, usually describing statuses and actions performed by WiredTiger. }
@row{\c DEBUG, 1, Low severity messages\, useful for debugging purposes. }
</table>
@section verbosity_categories Verbosity Categories
Each verbose message is associated with a category. Verbose categories represent a range of different
sub-systems in WiredTiger, where messages will denote a specific operation or event under a given sub-system.
To see the complete exhaustive list of available verbose categories, refer to the \c 'verbose' configuration option
under ::wiredtiger_open.
Each verbosity category can be individually configured with a verbosity level (as described in @ref verbosity_levels).
This allowing the end user to fine tune and tailor the verbosity of each category to fit their use case
e.g configuring WiredTiger's runtime for debugging/monitoring a specific sub-system.
When a category is assigned a verbosity level, any associated message less than or equal to (\c <=) that level will be displayed.
As an example, configuring the \c checkpoint category with the \c DEBUG verbosity level would display \c checkpoint related messages
less than or equal to the \c DEBUG level.
Any category that is not explicitly configured with a verbosity level will default to the \c NOTICE (\c -1) level, effectively masking
\c INFO and \c DEBUG informational messages.
@subsection verbosity_configuration Configuring Verbose Categories
Configuration of the verbose messaging system is achieved via the \c verbose configuration option when either
opening a wiredtiger connection (::wiredtiger_open) or re-configuring a wiredtiger connection (WT_CONNECTION::reconfigure).
The \c verbose configuration takes in a list of categories, where each category can be optionally associated with a verbosity level.
An example configuring a WiredTiger connection with verbosity enabled:
@snippet ex_verbose.c Configure verbose_messaging
In the above example:
- \c api is configured to the \c DEBUG verbosity level.
- \c version is configured to the \c DEBUG verbosity level. If a category is passed without a verbosity
level (.e.g \c <code>:0</code>), the category will default to the \c DEBUG level (i.e <code>verbose=[version]</code> is equivalent to <code>verbose=[version:1]</code>).
- \c write is configured to the \c INFO verbosity level.
When configuring verbosity levels, the lowest value the user can associate with a category is \c 0 (\c INFO). This ensuring
the lower verbosity levels, \c NOTICE (\c -1) and below, are unmasked. Messages with levels less than or equal to \c NOTICE are considered
to have important diagnostic information and thus should not be hidden.
*/
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