Alarmist (alarmist v0.2.1)
View SourceAlarm handler and more
Alarmist provides an :alarm_handler implementation that allows you to check
what alarms are currently active and subscribe to alarm status changes.
It also provides a DSL for defining alarms based on other alarms. See
Alarmist.Definition.
Summary
Functions
Add a rule-based alarm
Manually add a rule-based alarm
Return a list of all active alarm IDs
Return a list of all active alarms
Manually add a rule-based alarm
Subscribe to alarm status events
Unsubscribe the current process from the specified alarm :set and :clear events
Types
@type alarm() :: {alarm_id(), alarm_description()}
Alarm information
Calls to :alarm_handler.set_alarm/1 pass an alarm identifier and
description as a 2-tuple. Alarmist stores the description of the most recent
call.
:alarm_handler.set_alarm/1 doesn't enforce the use of 2-tuples. Alarmist
normalizes non-2-tuple alarms so that they have empty descriptions.
@type alarm_description() :: any()
Alarm description
This is optional supplemental information about the alarm. It could contain more information about why it was set. Don't use it to differentiate between alarms. Use the alarm ID for that.
@type alarm_id() :: atom()
Alarm identifier
Alarm identifiers are the unique identifiers of each alarm that can be set or cleared.
While SASL alarm identifiers can be anything, Alarmist imposes the restriction that they all be atoms. It is highly recommended to use module names to avoid naming collisions. Non-atom alarms are currently ignored by Alarmist.
@type alarm_state() :: :set | :clear
Alarm state
Alarms are in the :set state after a call to :alarm_handler.set_alarm/1
and in the :clear state after a call to :alarm_handler.clear_alarm/1.
Redundant calls to :alarm_handler.set_alarm/1 update the alarm description
and redundant calls to :alarm_handler.clear_alarm/1 are ignored.
@type compiled_rules() :: [Alarmist.Compiler.rule()]
Functions
@spec add_synthetic_alarm(module()) :: :ok
Add a rule-based alarm
After this call, Alarmist will watch for alarms to be set based on the supplied rules and set or clear the specified alarm ID. The alarm ID needs to be unique.
@spec add_synthetic_alarm(alarm_id(), compiled_rules()) :: :ok
Manually add a rule-based alarm
Use this when not using defalarm.
After this call, Alarmist will watch for alarms to be set based on the supplied rules and set or clear the specified alarm ID. The alarm ID needs to be unique.
@spec get_alarm_ids() :: [alarm_id()]
Return a list of all active alarm IDs
@spec get_alarms() :: [alarm()]
Return a list of all active alarms
This returns {id, description} tuples. Note that Alarmist normalizes
alarms that were not set as 2-tuples so this may not match calls to
:alarm_handler.set_alarm/1 exactly.
@spec remove_synthetic_alarm(alarm_id()) :: :ok
Manually add a rule-based alarm
Use this when not using defalarm.
After this call, Alarmist will watch for alarms to be set based on the supplied rules and set or clear the specified alarm ID. The alarm ID needs to be unique.
@spec subscribe(alarm_id()) :: :ok
Subscribe to alarm status events
Events will be delivered to the calling process as:
%Alarmist.Event{
id: TheAlarmId,
state: :set,
description: nil,
timestamp: -576460712978320952,
previous_state: :unknown,
previous_timestamp: -576460751417398083
}@spec unsubscribe(alarm_id()) :: :ok
Unsubscribe the current process from the specified alarm :set and :clear events