PollingRule¶

class lsst.ts.watcher.PollingRule(config, name, remote_info_list, log=None)¶

Bases: BaseRule

Base class for watcher rules that poll for data.

Regularly call update_alarm_severity with no arguments, at the interval specified by config.poll_interval.

Parameters:

configtypes.SimpleNamespace: Rule configuration, as validated by the schema. Must include a float field named “poll_interval” set to the polling interval in seconds.
namestr: Name of alarm. This must be unique among all alarms and should be of the form system.[subsystem….]_name so that groups of related alarms can be acknowledged.
remote_info_listlist [RemoteInfo]: Information about the remotes used by this rule.
loglogging.Logger, optional: Parent logger.

Attributes:

BaseRule attributes: All attributes from BaseRule, plus:
poll_start_taifloat: The time (TAI, unix seconds) at which polling began.
poll_loop_taskasyncio.Future: Task that runs the polling loop.

Attributes Summary

name

Get the rule name.

Methods Summary

`compute_alarm_severity`(**kwargs)	Compute and set alarm severity and reason.
`get_schema`()	Return a jsonschema as a `dict`, to validate configuration.
`is_usable`(disabled_sal_components)	Return True if rule can be used, despite disabled SAL components.
`make_config`(**kwargs)	Make a config from keyword arguments, after applying defaults.
`poll_loop`()
`setup`(model)	Perform post-constructor setup.
`start`()	Start any background tasks, such as a polling loop.
`stop`()	Stop all background tasks.
`update_alarm_severity`(**kwargs)	Compute and set alarm severity and reason.

Attributes Documentation

name¶: Get the rule name.

Methods Documentation

abstract compute_alarm_severity(**kwargs: Any) → tuple[lsst.ts.xml.enums.Watcher.AlarmSeverity, str] | None¶

Compute and set alarm severity and reason.

Parameters:

**kwargsdict [str, typing.Any]

Keyword arguments. If triggered by TopicCallback calling update_alarm_severity, the arguments will be as follows:

data : salobj.BaseMsgType Message from the topic described by topic_callback.
topic_callback : TopicCallback Topic callback wrapper.

Returns:

None, if no change or unknown, or a tuple of two values:
severity: lsst.ts.xml.enums.Watcher.AlarmSeverity: The new alarm severity.
reasonstr: Detailed reason for the severity, e.g. a string describing what value is out of range, and what the range is. If severity is NONE then this value is ignored (but still required) and the old reason is retained until the alarm is reset to nominal state.

Notes

You may return NoneNoReason if the alarm state is NONE.

abstract classmethod get_schema() → dict[str, Any]¶

Return a jsonschema as a dict, to validate configuration.

Notes

Please provide default values for all fields for which defaults make sense. This makes watcher configuration files easier to write.

If your rule has no configuration then return None.

We recommend that you write the schema as yaml, for compactness, then use yaml.safe_load to convert it to a dict. For example:

schema_yaml = """
    $schema: http://json-schema.org/draft-07/schema#
    description: Configuration for MyRule
    type: object
    properties:
    ...
    required: [...]
    additionalProperties: false
"""
return yaml.safe_load(schema_yaml)

is_usable(disabled_sal_components: set[tuple[str, int]]) → bool¶

Return True if rule can be used, despite disabled SAL components.

The default implementation returns true if all remotes used by this rule are enabled. Override if you need something more complicated. The attributes config, name and remote_info_list are all available when this method is called.

Parameters:

disabled_sal_componentsset [tuple [str, int]]

Set of disabled SAL components. Each element is a tuple of:

SAL component name (e.g. “ATPtg”)
SAL index

classmethod make_config(**kwargs: str) → SimpleNamespace¶

Make a config from keyword arguments, after applying defaults.

Parameters:

kwargs: The configuration, as a dict of property: name. The allowed properties and values are specified by the rule’s config schema.

Returns:

configtypes.SimpleNamespace: The rule configuration, with defaults applied as needed.

Raises:

jsonschema.ValidationError: If the provided kwargs are incorrect (missing keys, misspelled keys, incorrect data types…).

async poll_loop()¶

setup(model: Model) → None¶

Perform post-constructor setup.

Called after the remotes are constructed and populated with topics, but before the remotes have started.

Parameters:

modelModel: The watcher model.

Notes

Possible uses:

Rules in which topics and/or fields are specified in configuration should check that the topics and/or fields exist. They may also set variables pointing to the appropriate topics.
Rules that start a background process may start the process here rather than in the constructor; this is especially helpful if the process needs access to topics or fields.

Few rules require setup, so the default implemention is a no-op.

start()¶

Start any background tasks, such as a polling loop.

This is called when the watcher goes into the enabled state.

Notes

Do not assume that start is called before stop; the order depends on the initial state of the Watcher.

Immediate subclasses need not call super().start()

stop()¶

Stop all background tasks.

This is called when the watcher goes out of the enabled state, and must stop any tasks that might trigger an alarm state change.

Notes

Do not assume that start is called before stop; the order depends on the initial state of the Watcher.

This base implementation does nothing, so immediate subclasses need not call super().stop().

async update_alarm_severity(**kwargs: Any) → None¶

Compute and set alarm severity and reason.

This must run quickly. If computing alarm severity is expensive, override this method to start a thread that computes the data and create a background task to manage the thread, then return.

Parameters:

**kwargsdict [str, typing.Any]

Keyword arguments. If called by TopicCallback, the arguments will be as follows:

data : salobj.BaseMsgType Message from the topic described by topic_callback.
topic_callback : TopicCallback Topic callback wrapper.

Navigation

PollingRule¶