uncloud-mravi/uncloud/hack/db.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
# 2020 Nico Schottelius (nico.schottelius at ungleich.ch)
#
# This file is part of uncloud.
#
# uncloud is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# uncloud is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with uncloud. If not, see <http://www.gnu.org/licenses/>.
#
#

import etcd3
import json
import logging

from functools import wraps
from uncloud import UncloudException

log = logging.getLogger(__name__)


def readable_errors(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        try:
            return func(*args, **kwargs)
        except etcd3.exceptions.ConnectionFailedError as e:
            raise UncloudException('Cannot connect to etcd: is etcd running and reachable? {}'.format(e))
        except etcd3.exceptions.ConnectionTimeoutError as e:
            raise UncloudException('etcd connection timeout. {}'.format(e))

    return wrapper


class DB(object):
    def __init__(self, config, prefix="/"):
        self.config = config

        # Root for everything
        self.base_prefix= '/nicohack'

        # Can be set from outside
        self.prefix = prefix

        try:
            self.connect()
        except FileNotFoundError as e:
            raise UncloudException("Is the path to the etcd certs correct? {}".format(e))

    @readable_errors
    def connect(self):
        self._db_clients = []
        for endpoint in self.config.etcd_hosts:
            client = etcd3.client(host=endpoint, **self.config.etcd_args)
            self._db_clients.append(client)

    def realkey(self, key):
        return "{}{}/{}".format(self.base_prefix,
                                self.prefix,
                                key)

    @readable_errors
    def get(self, key, as_json=False, **kwargs):
        value, _ = self._db_clients[0].get(self.realkey(key), **kwargs)

        if as_json:
            value = json.loads(value)

        return value

    @readable_errors
    def get_prefix(self, key, as_json=False, **kwargs):
        key_range = self._db_clients[0].get_prefix(self.realkey(key), **kwargs)

        return key_range


    @readable_errors
    def set(self, key, value, as_json=False, **kwargs):
        if as_json:
            value = json.dumps(value)

        log.debug("Setting {} = {}".format(self.realkey(key), value))
        # FIXME: iterate over clients in case of failure ?
        return self._db_clients[0].put(self.realkey(key), value, **kwargs)

    @readable_errors
    def increment(self, key, **kwargs):
        print(self.realkey(key))


        print("prelock")
        lock = self._db_clients[0].lock('/nicohack/foo')
        print("prelockacq")
        lock.acquire()
        print("prelockrelease")
        lock.release()

        with self._db_clients[0].lock("/nicohack/mac/last_used_index") as lock:
            print("in lock")
            pass

#        with self._db_clients[0].lock(self.realkey(key)) as lock:#            value = int(self.get(self.realkey(key), **kwargs))
#            self.set(self.realkey(key), str(value + 1), **kwargs)


if __name__ == '__main__':
    endpoints = [ "https://etcd1.ungleich.ch:2379",
                  "https://etcd2.ungleich.ch:2379",
                  "https://etcd3.ungleich.ch:2379" ]

    db = DB(url=endpoints)