#!/usr/bin/env python
# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright (c) 2011 OpenStack, LLC.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""
Helper script for starting/stopping/reloading Glance server programs.
Thanks for some of the code, Swifties ;)
"""

from __future__ import with_statement

import errno
import gettext
import os
import optparse
import resource
import signal
import sys
import time

# If ../glance/__init__.py exists, add ../ to Python search path, so that
# it will override what happens to be installed in /usr/(local/)lib/python...
possible_topdir = os.path.normpath(os.path.join(os.path.abspath(sys.argv[0]),
                                   os.pardir,
                                   os.pardir))
if os.path.exists(os.path.join(possible_topdir, 'glance', '__init__.py')):
    sys.path.insert(0, possible_topdir)

gettext.install('glance', unicode=1)

from glance import version
from glance.common import config

ALL_COMMANDS = ['start', 'stop', 'shutdown', 'restart',
                'reload', 'force-reload']
ALL_SERVERS = ['glance-api', 'glance-registry', 'glance-scrubber']
GRACEFUL_SHUTDOWN_SERVERS = ['glance-api', 'glance-registry',
                             'glance-scrubber']
MAX_DESCRIPTORS = 32768
MAX_MEMORY = (1024 * 1024 * 1024) * 2  # 2 GB
USAGE = """%prog [options] <SERVER> <COMMAND> [CONFPATH]

Where <SERVER> is one of:

    all, api, registry, scrubber

And command is one of:

    start, stop, shutdown, restart, reload, force-reload

And CONFPATH is the optional configuration file to use."""


def pid_files(server, options):
    pid_files = []
    if options['pid_file']:
        if os.path.exists(os.path.abspath(options['pid_file'])):
            pid_files = [os.path.abspath(options['pid_file'])]
    else:
        if os.path.exists('/var/run/glance/%s.pid' % server):
            pid_files = ['/var/run/glance/%s.pid' % server]
    for pid_file in pid_files:
        pid = int(open(pid_file).read().strip())
        yield pid_file, pid


def do_start(server, options, args):
    server_type = '-'.join(server.split('-')[:-1])

    for pid_file, pid in pid_files(server, options):
        if os.path.exists('/proc/%s' % pid):
            print "%s appears to already be running: %s" % (server, pid_file)
            return
        else:
            print "Removing stale pid file %s" % pid_file
            os.unlink(pid_file)

    try:
        resource.setrlimit(resource.RLIMIT_NOFILE,
                (MAX_DESCRIPTORS, MAX_DESCRIPTORS))
        resource.setrlimit(resource.RLIMIT_DATA,
                (MAX_MEMORY, MAX_MEMORY))
    except ValueError:
        print "Unable to increase file descriptor limit.  Running as non-root?"
    os.environ['PYTHON_EGG_CACHE'] = '/tmp'

    def write_pid_file(pid_file, pid):
        dir, file = os.path.split(pid_file)
        if not os.path.exists(dir):
            try:
                os.makedirs(dir)
            except OSError, err:
                if err.errno == errno.EACCES:
                    sys.exit('Unable to create %s.  Running as non-root?'
                             % dir)
        fp = open(pid_file, 'w')
        fp.write('%d\n' % pid)
        fp.close()

    def launch(ini_file, pid_file):
        args = [server, ini_file]
        print 'Starting %s with %s' % (server, ini_file)

        pid = os.fork()
        if pid == 0:
            os.setsid()
            with open(os.devnull, 'r+b') as nullfile:
                for desc in (0, 1, 2):  # close stdio
                    try:
                        os.dup2(nullfile.fileno(), desc)
                    except OSError:
                        pass
            try:
                os.execlp('%s' % server, server, ini_file)
            except OSError, e:
                sys.exit('unable to launch %s. Got error: %s'
                         % (server, "%s" % e))
            sys.exit(0)
        else:
            write_pid_file(pid_file, pid)

    if not options['pid_file']:
        pid_file = '/var/run/glance/%s.pid' % server
    else:
        pid_file = os.path.abspath(options['pid_file'])
    conf_file = config.find_config_file(server, options, args)
    if not conf_file:
        sys.exit("Could not find any configuration file to use!")
    launch_args = [(conf_file, pid_file)]

    # start all servers
    for conf_file, pid_file in launch_args:
        launch(conf_file, pid_file)


def do_stop(server, options, args, graceful=False):
    if graceful and server in GRACEFUL_SHUTDOWN_SERVERS:
        sig = signal.SIGHUP
    else:
        sig = signal.SIGTERM

    did_anything = False
    pfiles = pid_files(server, options)
    for pid_file, pid in pfiles:
        did_anything = True
        try:
            print 'Stopping %s  pid: %s  signal: %s' % (server, pid, sig)
            os.kill(pid, sig)
        except OSError:
            print "Process %d not running" % pid
        try:
            os.unlink(pid_file)
        except OSError:
            pass
    for pid_file, pid in pfiles:
        for _junk in xrange(150):  # 15 seconds
            if not os.path.exists('/proc/%s' % pid):
                break
            time.sleep(0.1)
        else:
            print 'Waited 15 seconds for pid %s (%s) to die; giving up' % \
                  (pid, pid_file)
    if not did_anything:
        print 'No %s running' % server


if __name__ == '__main__':
    oparser = optparse.OptionParser(usage=USAGE, version='%%prog %s'
                                    % version.version_string())
    oparser.add_option('--pid-file', default=None, metavar="PATH",
                       help="File to use as pid file. Default: "
                       "/var/run/glance/$server.pid")
    config.add_common_options(oparser)
    (options, args) = config.parse_options(oparser)

    if len(args) < 2:
        oparser.print_usage()
        sys.exit(1)

    server = args.pop(0).lower()
    if server == 'all':
        servers = ALL_SERVERS
    else:
        if not server.startswith('glance-'):
            server = 'glance-%s' % server
        if server not in ALL_SERVERS:
            server_list = ", ".join([s.replace('glance-', '')
                                     for s in ALL_SERVERS])
            msg = ("Unknown server '%(server)s' specified. Please specify "
                   "all, or one of the servers: %(server_list)s" % locals())
            sys.exit(msg)
        servers = [server]

    command = args.pop(0).lower()
    if command not in ALL_COMMANDS:
        command_list = ", ".join(ALL_COMMANDS)
        msg = ("Unknown command %(command)s specified. Please specify a "
               "command in this list: %(command_list)s" % locals())
        sys.exit(msg)

    if command == 'start':
        for server in servers:
            do_start(server, options, args)

    if command == 'stop':
        for server in servers:
            do_stop(server, options, args)

    if command == 'shutdown':
        for server in servers:
            do_stop(server, options, args, graceful=True)

    if command == 'restart':
        for server in servers:
            do_stop(server, options, args)
        for server in servers:
            do_start(server, options, args)

    if command == 'reload' or command == 'force-reload':
        for server in servers:
            do_stop(server, options, args, graceful=True)
            do_start(server, options, args)