Provided by: erlang-manpages_24.3.4.1+dfsg-1_all 
NAME
logger_filters - Filters to use with Logger.
DESCRIPTION
All functions exported from this module can be used as primary or handler filters. See
logger:add_primary_filter/2 and logger:add_handler_filter/3 for more information about how
filters are added.
Filters are removed with logger:remove_primary_filter/1 and
logger:remove_handler_filter/2.
EXPORTS
domain(LogEvent, Extra) -> logger:filter_return()
Types:
LogEvent = logger:log_event()
Extra = {Action, Compare, MatchDomain}
Action = log | stop
Compare = super | sub | equal | not_equal | undefined
MatchDomain = [atom()]
This filter provides a way of filtering log events based on a domain field in
Metadata. This field is optional, and the purpose of using it is to group log
events from, for example, a specific functional area. This allows filtering or
other specialized treatment in a Logger handler.
A domain field must be a list of atoms, creating smaller and more specialized
domains as the list grows longer. The greatest domain is [], which comprises all
possible domains.
For example, consider the following domains:
D1 = [otp]
D2 = [otp, sasl]
D1 is the greatest of the two, and is said to be a super-domain of D2. D2 is a sub-
domain D1. Both D1 and D2 are sub-domains of [].
The above domains are used for logs originating from Erlang/OTP. D1 specifies that
the log event comes from Erlang/OTP in general, and D2 indicates that the log event
is a so called SASL report.
The Extra parameter to the domain/2 function is specified when adding the filter
via logger:add_primary_filter/2 or logger:add_handler_filter/3.
The filter compares the value of the domain field in the log event's metadata
(Domain) against MatchDomain. The filter matches if the value of Compare is:
sub:
and Domain is equal to or a sub-domain of MatchDomain, that is, if MatchDomain
is a prefix of Domain.
super:
and Domain is equal to or a super-domain of MatchDomain, that is, if Domain is
a prefix of MatchDomain.
equal:
and Domain is equal to MatchDomain.
not_equal:
and Domain differs from MatchDomain, or if there is no domain field in
metadata.
undefined:
and there is no domain field in metadata. In this case MatchDomain must be set
to [].
If the filter matches and Action is log, the log event is allowed. If the filter
matches and Action is stop, the log event is stopped.
If the filter does not match, it returns ignore, meaning that other filters, or the
value of the configuration parameter filter_default, decide if the event is allowed
or not.
Log events that do not contain any domain field, match only when Compare is equal
to undefined or not_equal.
Example: stop all events with domain [otp, sasl | _]
logger:set_handler_config(h1, filter_default, log). % this is the default
Filter = {fun logger_filters:domain/2, {stop, sub, [otp, sasl]}}.
logger:add_handler_filter(h1, no_sasl, Filter).
ok
level(LogEvent, Extra) -> logger:filter_return()
Types:
LogEvent = logger:log_event()
Extra = {Action, Operator, MatchLevel}
Action = log | stop
Operator = neq | eq | lt | gt | lteq | gteq
MatchLevel = logger:level()
This filter provides a way of filtering log events based on the log level. It
matches log events by comparing the log level with a specified MatchLevel
The Extra parameter is specified when adding the filter via
logger:add_primary_filter/2 or logger:add_handler_filter/3.
The filter compares the value of the event's log level (Level) to MatchLevel by
calling logger:compare_levels(Level, MatchLevel). The filter matches if the value
of Operator is:
neq:
and the compare function returns lt or gt.
eq:
and the compare function returns eq.
lt:
and the compare function returns lt.
gt:
and the compare function returns gt.
lteq:
and the compare function returns lt or eq.
gteq:
and the compare function returns gt or eq.
If the filter matches and Action is log, the log event is allowed. If the filter
matches and Action is stop, the log event is stopped.
If the filter does not match, it returns ignore, meaning that other filters, or the
value of the configuration parameter filter_default, will decide if the event is
allowed or not.
Example: only allow debug level log events
logger:set_handler_config(h1, filter_default, stop).
Filter = {fun logger_filters:level/2, {log, eq, debug}}.
logger:add_handler_filter(h1, debug_only, Filter).
ok
progress(LogEvent, Extra) -> logger:filter_return()
Types:
LogEvent = logger:log_event()
Extra = log | stop
This filter matches all progress reports from supervisor and
application_controller.
If Extra is log, the progress reports are allowed. If Extra is stop, the progress
reports are stopped.
The filter returns ignore for all other log events.
remote_gl(LogEvent, Extra) -> logger:filter_return()
Types:
LogEvent = logger:log_event()
Extra = log | stop
This filter matches all events originating from a process that has its group leader
on a remote node.
If Extra is log, the matching events are allowed. If Extra is stop, the matching
events are stopped.
The filter returns ignore for all other log events.
SEE ALSO
logger(3erl)