import os
import time

from landscape.accumulate import Accumulator
from landscape.lib.monitor import CoverageMonitor
from landscape.monitor.plugin import MonitorPlugin


class LoadAverage(MonitorPlugin):
"""Plugin captures information about load average."""

persist_name = "load-average"
scope = "load"
# Prevent the Plugin base-class from scheduling looping calls.
run_interval = None

def __init__(self, interval=15, monitor_interval=60*60,
create_time=time.time, get_load_average=os.getloadavg):
self._interval = interval
self._monitor_interval = monitor_interval
self._create_time = create_time
self._load_averages = []
self._get_load_average = get_load_average

def register(self, registry):
super(LoadAverage, self).register(registry)
self._accumulate = Accumulator(self._persist, registry.step_size)

self.registry.reactor.call_every(self._interval, self.run)

self._monitor = CoverageMonitor(self._interval, 0.8,
"load average snapshot",
create_time=self._create_time)
self.registry.reactor.call_every(self._monitor_interval,
self._monitor.log)
self.registry.reactor.call_on("stop", self._monitor.log, priority=2000)
self.call_on_accepted("load-average", self.send_message, True)

def create_message(self):
load_averages = self._load_averages
self._load_averages = []
return {"type": "load-average", "load-averages": load_averages}

def exchange(self, urgent=False):
self.registry.broker.call_if_accepted("load-average",
self.send_message, urgent)

def send_message(self, urgent=False):
message = self.create_message()
if len(message["load-averages"]):
self.registry.broker.send_message(message, self._session_id,
urgent=urgent)

def run(self):
self._monitor.ping()
new_timestamp = int(self._create_time())
new_load_average = self._get_load_average()[0]
step_data = self._accumulate(new_timestamp, new_load_average,
"accumulate")
if step_data:
self._load_averages.append(step_data)