File manager

# coding=utf-8
#
# Copyright © Cloud Linux GmbH & Cloud Linux Software, Inc 2010-2019 All Rights Reserved
#
# Licensed under CLOUD LINUX LICENSE AGREEMENT
# http://cloudlinux.com/docs/LICENSE.TXT

import logging
import subprocess

from lvestats.core.plugin import LveStatsPlugin

LVECTL = '/usr/sbin/lvectl'


class LVERecord(object):
    def __init__(self, cpu, iterations):
        self.cpu = cpu
        self.count = 0
        self.iterations = iterations

    def inc(self):
        self.count += 1

    def check(self):
        return self.count >= self.iterations

    def has_changed(self, stat):
        if self.cpu != stat.cpu or stat.nproc > 0:
            self.count = 0
            self.cpu = stat.cpu
            return True
        return False


class LVEDestroyer(LveStatsPlugin):
    def __init__(self):
        self.log = logging.getLogger(__name__)
        self.default_stat = None
        self.iterations = 0
        self.lves = {}
        self.to_be_destroyed = []
        self._enabled = False

    def set_config(self, config):
        self._enabled = False
        try:
            self.iterations = int(config['iterations'])
            if self.iterations > 0:
                self._enabled = True
            self.lves = {}
            self.default_stat = None
        except (KeyError, ValueError):
            pass

    def set_default(self, stat):
        if self._enabled:
            self.default_stat = stat
            self.to_be_destroyed = []

    def is_stat_tracked(self, stat) -> bool:
        # if any of this LVE's settings differ from the default, then don't track this LVE for destruction
        return ((stat.cpu != self.default_stat.cpu)
                or (stat.io != self.default_stat.io)
                or (stat.lmem != self.default_stat.lmem)
                or (stat.lep != self.default_stat.lep)
                or (stat.lmemphy != self.default_stat.lmemphy)
                or (stat.lcpuw != self.default_stat.lcpuw)
                or (stat.lnproc != self.default_stat.lnproc))

    def check_lve(self, stat):
        r = self.lves[stat.id]
        if not r.has_changed(stat):
            if r.check():
                self.to_be_destroyed.append(stat.id)
                self.lves.pop(stat.id)
            else:
                r.inc()

    def add_stat(self, stat):
        if self._enabled:
            id_ = stat.id
            if id_ == 0:
                self.set_default(stat)
                return
            if id_ in self.lves:
                self.check_lve(stat)
            elif self.is_stat_tracked(stat):
                return
            else:
                self.lves[id_] = LVERecord(stat.cpu, self.iterations)

    def process_destroy(self):
        if self._enabled:
            if self.to_be_destroyed:
                try:
                    # run the command and suppress it's output
                    with subprocess.Popen(
                        [LVECTL, "destroy-many"],
                        stdin=subprocess.PIPE,
                        stdout=subprocess.PIPE,
                        stderr=subprocess.PIPE,
                    ) as proc:
                        # send input string to suprocess
                        self.log.info("Destroying: %s", " ".join(map(str, self.to_be_destroyed)))
                        proc.communicate(" ".join(map(str, self.to_be_destroyed)).encode())
                except OSError:
                    self.log.error("Error: failed to run %s destroy-many", LVECTL)

    def execute(self, lve_data):
        stats = lve_data['stats']
        self.set_default(stats[0])
        for stat in stats.values():
            self.add_stat(stat)
        self.process_destroy()