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import os
import weakref
from datetime import datetime
from .base import SubsystemBase
from volttron.platform.messaging.headers import TIMESTAMP
from volttron.platform.agent.utils import (get_aware_utc_now,
format_timestamp)
"""The heartbeat subsystem adds an optional periodic publish to all agents.
Heartbeats can be started with agents and toggled on and off at runtime.
"""
__docformat__ = 'reStructuredText'
__version__ = '1.0'
[docs]class Heartbeat(SubsystemBase):
def __init__(self, owner, core, rpc, pubsub, heartbeat_autostart,
heartbeat_period):
self.owner = owner
self.core = weakref.ref(core)
self.pubsub = weakref.ref(pubsub)
self.autostart = heartbeat_autostart
self.period = heartbeat_period
self.enabled = False
def onsetup(sender, **kwargs):
rpc.export(self.start, 'heartbeat.start')
rpc.export(self.start_with_period, 'heartbeat.start_with_period')
rpc.export(self.stop, 'heartbeat.stop')
rpc.export(self.restart, 'heartbeat.restart')
rpc.export(self.set_period, 'heartbeat.set_period')
def onstart(sender, **kwargs):
if self.autostart:
self.start()
core.onsetup.connect(onsetup, self)
core.onstart.connect(onstart, self)
[docs] def start(self):
"""RPC method
Starts an agent's heartbeat.
"""
if not self.enabled:
self.greenlet = self.core().periodic(self.period, self.publish)
self.enabled = True
[docs] def start_with_period(self, period):
"""RPC method
Set period and start heartbeat.
:param period: Time in seconds between publishes.
"""
self.set_period(period)
self.start()
[docs] def stop(self):
"""RPC method
Stop an agent's heartbeat.
"""
if self.enabled:
self.greenlet.kill()
self.enabled = False
[docs] def restart(self):
"""RPC method
Restart the heartbeat with the current period. The heartbeat will
be immediately sending the heartbeat to the message bus.
"""
self.stop()
self.start()
[docs] def set_period(self, period):
"""RPC method
Set heartbeat period.
:param period: Time in seconds between publishes.
"""
if self.enabled:
self.stop()
self.period = period
self.start()
else:
self.period = period
[docs] def publish(self):
topic = 'heartbeat/' + self.core().identity
headers = {TIMESTAMP: format_timestamp(get_aware_utc_now())}
message = self.owner.vip.health.get_status_value()
self.pubsub().publish('pubsub', topic, headers, message)