remote_tarantool_server.py

from __future__ import print_function

import sys
import os
import random
import string
import time

from .tarantool_admin import TarantoolAdmin


# a time during which try to acquire a lock
AWAIT_TIME = 60  # seconds

# on which port bind a socket for binary protocol
BINARY_PORT = 3301


def get_random_string():
    return ''.join(random.choice(string.ascii_lowercase) for _ in range(16))


class RemoteTarantoolServer(object):
    def __init__(self):
        self.host = os.environ['REMOTE_TARANTOOL_HOST']

        self.args = {}
        self.args['primary'] = BINARY_PORT
        self.args['admin'] = os.environ['REMOTE_TARANTOOL_CONSOLE_PORT']

        assert(self.args['primary'] != self.args['admin'])

        # a name to using for a lock
        self.whoami = get_random_string()

        self.admin = TarantoolAdmin(self.host, self.args['admin'])
        self.lock_is_acquired = False

        # emulate stopped server
        self.acquire_lock()
        self.admin.execute('box.cfg{listen = box.NULL}')

    def acquire_lock(self):
        deadline = time.time() + AWAIT_TIME
        while True:
            res = self.admin.execute('return acquire_lock("%s")' % self.whoami)
            ok = res[0]
            err = res[1] if not ok else None
            if ok:
                break
            if time.time() > deadline:
                raise RuntimeError('can not acquire "%s" lock: %s' % (
                    self.whoami, str(err)))
            print('waiting to acquire "%s" lock' % self.whoami,
                  file=sys.stderr)
            time.sleep(1)
        self.lock_is_acquired = True

    def touch_lock(self):
        assert(self.lock_is_acquired)
        res = self.admin.execute('return touch_lock("%s")' % self.whoami)
        ok = res[0]
        err = res[1] if not ok else None
        if not ok:
            raise RuntimeError('can not update "%s" lock: %s' % (
                self.whoami, str(err)))

    def release_lock(self):
        res = self.admin.execute('return release_lock("%s")' % self.whoami)
        ok = res[0]
        err = res[1] if not ok else None
        if not ok:
            raise RuntimeError('can not release "%s" lock: %s' % (
                self.whoami, str(err)))
        self.lock_is_acquired = False

    def start(self):
        if not self.lock_is_acquired:
            self.acquire_lock()
        self.admin.execute('box.cfg{listen = "0.0.0.0:%s"}' %
                           self.args['primary'])

    def stop(self):
        self.admin.execute('box.cfg{listen = box.NULL}')
        self.release_lock()

    def is_started(self):
        return self.lock_is_acquired

    def clean(self):
        pass

    def __del__(self):
        self.admin.disconnect()