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  # Copyright 2010 United States Government as represented by the
  # Administrator of the National Aeronautics and Space Administration.
  # Copyright 2011 Justin Santa Barbara
  # All Rights Reserved.
  #
  #    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.
  
  """Generic Node base class for all workers that run on hosts."""
  
  import errno
  import inspect
  import os
  import random
  import signal
  import sys
  import time
  
  import eventlet
  import greenlet
  from oslo.config import cfg
  
  from cinder import context
  from cinder import db
  from cinder import exception
  from cinder import flags
  from cinder.openstack.common import importutils
  from cinder.openstack.common import log as logging
  from cinder.openstack.common import rpc
  from cinder import utils
  from cinder import version
  from cinder import wsgi
  
  LOG = logging.getLogger(__name__)
  
  service_opts = [
      cfg.IntOpt('report_interval',
                 default=10,
                 help='seconds between nodes reporting state to datastore'),
      cfg.IntOpt('periodic_interval',
                 default=60,
                 help='seconds between running periodic tasks'),
      cfg.IntOpt('periodic_fuzzy_delay',
                 default=60,
                 help='range of seconds to randomly delay when starting the'
                      ' periodic task scheduler to reduce stampeding.'
                      ' (Disable by setting to 0)'),
      cfg.StrOpt('osapi_volume_listen',
                 default="0.0.0.0",
                 help='IP address for OpenStack Volume API to listen'),
      cfg.IntOpt('osapi_volume_listen_port',
                 default=8776,
                 help='port for os volume api to listen'), ]
  
  FLAGS = flags.FLAGS
  FLAGS.register_opts(service_opts)
  
  
  class SignalExit(SystemExit):
      def __init__(self, signo, exccode=1):
          super(SignalExit, self).__init__(exccode)
          self.signo = signo
  
  
  class Launcher(object):
      """Launch one or more services and wait for them to complete."""
  
      def __init__(self):
          """Initialize the service launcher.
  
          :returns: None
  
          """
          self._services = []
  
      @staticmethod
      def run_server(server):
          """Start and wait for a server to finish.
  
          :param service: Server to run and wait for.
          :returns: None
  
          """
          server.start()
          server.wait()
  
      def launch_server(self, server):
          """Load and start the given server.
  
          :param server: The server you would like to start.
          :returns: None
  
          """
          gt = eventlet.spawn(self.run_server, server)
          self._services.append(gt)
  
      def stop(self):
          """Stop all services which are currently running.
  
          :returns: None
  
          """
          for service in self._services:
              service.kill()
  
      def wait(self):
          """Waits until all services have been stopped, and then returns.
  
          :returns: None
  
          """
          def sigterm(sig, frame):
              LOG.audit(_("SIGTERM received"))
              # NOTE(jk0): Raise a ^C which is caught by the caller and cleanly
              # shuts down the service. This does not yet handle eventlet
              # threads.
              raise KeyboardInterrupt
  
          signal.signal(signal.SIGTERM, sigterm)
  
          for service in self._services:
              try:
                  service.wait()
              except greenlet.GreenletExit:
                  pass
  
  
  class ServerWrapper(object):
      def __init__(self, server, workers):
          self.server = server
          self.workers = workers
          self.children = set()
          self.forktimes = []
  
  
  class ProcessLauncher(object):
      def __init__(self):
          self.children = {}
          self.sigcaught = None
          self.running = True
          rfd, self.writepipe = os.pipe()
          self.readpipe = eventlet.greenio.GreenPipe(rfd, 'r')
  
          signal.signal(signal.SIGTERM, self._handle_signal)
          signal.signal(signal.SIGINT, self._handle_signal)
  
      def _handle_signal(self, signo, frame):
          self.sigcaught = signo
          self.running = False
  
          # Allow the process to be killed again and die from natural causes
          signal.signal(signal.SIGTERM, signal.SIG_DFL)
          signal.signal(signal.SIGINT, signal.SIG_DFL)
  
      def _pipe_watcher(self):
          # This will block until the write end is closed when the parent
          # dies unexpectedly
          self.readpipe.read()
  
          LOG.info(_('Parent process has died unexpectedly, exiting'))
  
          sys.exit(1)
  
      def _child_process(self, server):
          # Setup child signal handlers differently
          def _sigterm(*args):
              signal.signal(signal.SIGTERM, signal.SIG_DFL)
              raise SignalExit(signal.SIGTERM)
  
          signal.signal(signal.SIGTERM, _sigterm)
          # Block SIGINT and let the parent send us a SIGTERM
          # signal.signal(signal.SIGINT, signal.SIG_IGN)
          # This differs from the behavior in nova in that we dont ignore this
          # It allows the non-wsgi services to be terminated properly
          signal.signal(signal.SIGINT, _sigterm)
  
          # Reopen the eventlet hub to make sure we don't share an epoll
          # fd with parent and/or siblings, which would be bad
          eventlet.hubs.use_hub()
  
          # Close write to ensure only parent has it open
          os.close(self.writepipe)
          # Create greenthread to watch for parent to close pipe
          eventlet.spawn(self._pipe_watcher)
  
          # Reseed random number generator
          random.seed()
  
          launcher = Launcher()
          launcher.run_server(server)
  
      def _start_child(self, wrap):
          if len(wrap.forktimes) > wrap.workers:
              # Limit ourselves to one process a second (over the period of
              # number of workers * 1 second). This will allow workers to
              # start up quickly but ensure we don't fork off children that
              # die instantly too quickly.
              if time.time() - wrap.forktimes[0] < wrap.workers:
                  LOG.info(_('Forking too fast, sleeping'))
                  time.sleep(1)
  
              wrap.forktimes.pop(0)
  
          wrap.forktimes.append(time.time())
  
          pid = os.fork()
          if pid == 0:
              # NOTE(johannes): All exceptions are caught to ensure this
              # doesn't fallback into the loop spawning children. It would
              # be bad for a child to spawn more children.
              status = 0
              try:
                  self._child_process(wrap.server)
              except SignalExit as exc:
                  signame = {signal.SIGTERM: 'SIGTERM',
                             signal.SIGINT: 'SIGINT'}[exc.signo]
                  LOG.info(_('Caught %s, exiting'), signame)
                  status = exc.code
              except SystemExit as exc:
                  status = exc.code
              except BaseException:
                  LOG.exception(_('Unhandled exception'))
                  status = 2
              finally:
                  wrap.server.stop()
  
              os._exit(status)
  
          LOG.info(_('Started child %d'), pid)
  
          wrap.children.add(pid)
          self.children[pid] = wrap
  
          return pid
  
      def launch_server(self, server, workers=1):
          wrap = ServerWrapper(server, workers)
  
          LOG.info(_('Starting %d workers'), wrap.workers)
          while self.running and len(wrap.children) < wrap.workers:
              self._start_child(wrap)
  
      def _wait_child(self):
          try:
              # Don't block if no child processes have exited
              pid, status = os.waitpid(0, os.WNOHANG)
              if not pid:
                  return None
          except OSError as exc:
              if exc.errno not in (errno.EINTR, errno.ECHILD):
                  raise
              return None
  
          if os.WIFSIGNALED(status):
              sig = os.WTERMSIG(status)
              LOG.info(_('Child %(pid)d killed by signal %(sig)d'), locals())
          else:
              code = os.WEXITSTATUS(status)
              LOG.info(_('Child %(pid)d exited with status %(code)d'), locals())
  
          if pid not in self.children:
              LOG.warning(_('pid %d not in child list'), pid)
              return None
  
          wrap = self.children.pop(pid)
          wrap.children.remove(pid)
          return wrap
  
      def wait(self):
          """Loop waiting on children to die and respawning as necessary."""
          while self.running:
              wrap = self._wait_child()
              if not wrap:
                  # Yield to other threads if no children have exited
                  # Sleep for a short time to avoid excessive CPU usage
                  # (see bug #1095346)
                  eventlet.greenthread.sleep(.01)
                  continue
  
              while self.running and len(wrap.children) < wrap.workers:
                  self._start_child(wrap)
  
          if self.sigcaught:
              signame = {signal.SIGTERM: 'SIGTERM',
                         signal.SIGINT: 'SIGINT'}[self.sigcaught]
              LOG.info(_('Caught %s, stopping children'), signame)
  
          for pid in self.children:
              try:
                  os.kill(pid, signal.SIGTERM)
              except OSError as exc:
                  if exc.errno != errno.ESRCH:
                      raise
  
          # Wait for children to die
          if self.children:
              LOG.info(_('Waiting on %d children to exit'), len(self.children))
              while self.children:
                  self._wait_child()
  
  
  class Service(object):
      """Service object for binaries running on hosts.
  
      A service takes a manager and enables rpc by listening to queues based
      on topic. It also periodically runs tasks on the manager and reports
      it state to the database services table."""
  
      def __init__(self, host, binary, topic, manager, report_interval=None,
                   periodic_interval=None, periodic_fuzzy_delay=None,
                   service_name=None, *args, **kwargs):
          self.host = host
          self.binary = binary
          self.topic = topic
          self.manager_class_name = manager
          manager_class = importutils.import_class(self.manager_class_name)
          self.manager = manager_class(host=self.host,
                                       service_name=service_name,
                                       *args, **kwargs)
          self.report_interval = report_interval
          self.periodic_interval = periodic_interval
          self.periodic_fuzzy_delay = periodic_fuzzy_delay
          super(Service, self).__init__(*args, **kwargs)
          self.saved_args, self.saved_kwargs = args, kwargs
          self.timers = []
  
      def start(self):
          version_string = version.version_string()
          LOG.audit(_('Starting %(topic)s node (version %(version_string)s)'),
                    {'topic': self.topic, 'version_string': version_string})
          self.manager.init_host()
          self.model_disconnected = False
          ctxt = context.get_admin_context()
          try:
              service_ref = db.service_get_by_args(ctxt,
                                                   self.host,
                                                   self.binary)
              self.service_id = service_ref['id']
          except exception.NotFound:
              self._create_service_ref(ctxt)
  
          self.conn = rpc.create_connection(new=True)
          LOG.debug(_("Creating Consumer connection for Service %s") %
                    self.topic)
  
          rpc_dispatcher = self.manager.create_rpc_dispatcher()
  
          # Share this same connection for these Consumers
          self.conn.create_consumer(self.topic, rpc_dispatcher, fanout=False)
  
          node_topic = '%s.%s' % (self.topic, self.host)
          self.conn.create_consumer(node_topic, rpc_dispatcher, fanout=False)
  
          self.conn.create_consumer(self.topic, rpc_dispatcher, fanout=True)
  
          # Consume from all consumers in a thread
          self.conn.consume_in_thread()
  
          if self.report_interval:
              pulse = utils.LoopingCall(self.report_state)
              pulse.start(interval=self.report_interval,
                          initial_delay=self.report_interval)
              self.timers.append(pulse)
  
          if self.periodic_interval:
              if self.periodic_fuzzy_delay:
                  initial_delay = random.randint(0, self.periodic_fuzzy_delay)
              else:
                  initial_delay = None
  
              periodic = utils.LoopingCall(self.periodic_tasks)
              periodic.start(interval=self.periodic_interval,
                             initial_delay=initial_delay)
              self.timers.append(periodic)
  
      def _create_service_ref(self, context):
          zone = FLAGS.storage_availability_zone
          service_ref = db.service_create(context,
                                          {'host': self.host,
                                           'binary': self.binary,
                                           'topic': self.topic,
                                           'report_count': 0,
                                           'availability_zone': zone})
          self.service_id = service_ref['id']
  
      def __getattr__(self, key):
          manager = self.__dict__.get('manager', None)
          return getattr(manager, key)
  
      @classmethod
      def create(cls, host=None, binary=None, topic=None, manager=None,
                 report_interval=None, periodic_interval=None,
                 periodic_fuzzy_delay=None, service_name=None):
          """Instantiates class and passes back application object.
  
          :param host: defaults to FLAGS.host
          :param binary: defaults to basename of executable
          :param topic: defaults to bin_name - 'cinder-' part
          :param manager: defaults to FLAGS.<topic>_manager
          :param report_interval: defaults to FLAGS.report_interval
          :param periodic_interval: defaults to FLAGS.periodic_interval
          :param periodic_fuzzy_delay: defaults to FLAGS.periodic_fuzzy_delay
  
          """
          if not host:
              host = FLAGS.host
          if not binary:
              binary = os.path.basename(inspect.stack()[-1][1])
          if not topic:
              topic = binary
          if not manager:
              subtopic = topic.rpartition('cinder-')[2]
              manager = FLAGS.get('%s_manager' % subtopic, None)
          if report_interval is None:
              report_interval = FLAGS.report_interval
          if periodic_interval is None:
              periodic_interval = FLAGS.periodic_interval
          if periodic_fuzzy_delay is None:
              periodic_fuzzy_delay = FLAGS.periodic_fuzzy_delay
          service_obj = cls(host, binary, topic, manager,
                            report_interval=report_interval,
                            periodic_interval=periodic_interval,
                            periodic_fuzzy_delay=periodic_fuzzy_delay,
                            service_name=service_name)
  
          return service_obj
  
      def kill(self):
          """Destroy the service object in the datastore."""
          self.stop()
          try:
              db.service_destroy(context.get_admin_context(), self.service_id)
          except exception.NotFound:
              LOG.warn(_('Service killed that has no database entry'))
  
      def stop(self):
          # Try to shut the connection down, but if we get any sort of
          # errors, go ahead and ignore them.. as we're shutting down anyway
          try:
              self.conn.close()
          except Exception:
              pass
          for x in self.timers:
              try:
                  x.stop()
              except Exception:
                  pass
          self.timers = []
  
      def wait(self):
          for x in self.timers:
              try:
                  x.wait()
              except Exception:
                  pass
  
      def periodic_tasks(self, raise_on_error=False):
          """Tasks to be run at a periodic interval."""
          ctxt = context.get_admin_context()
          self.manager.periodic_tasks(ctxt, raise_on_error=raise_on_error)
  
      def report_state(self):
          """Update the state of this service in the datastore."""
          ctxt = context.get_admin_context()
          zone = FLAGS.storage_availability_zone
          state_catalog = {}
          try:
              try:
                  service_ref = db.service_get(ctxt, self.service_id)
              except exception.NotFound:
                  LOG.debug(_('The service database object disappeared, '
                              'Recreating it.'))
                  self._create_service_ref(ctxt)
                  service_ref = db.service_get(ctxt, self.service_id)
  
              state_catalog['report_count'] = service_ref['report_count'] + 1
              if zone != service_ref['availability_zone']:
                  state_catalog['availability_zone'] = zone
  
              db.service_update(ctxt,
                                self.service_id, state_catalog)
  
              # TODO(termie): make this pattern be more elegant.
              if getattr(self, 'model_disconnected', False):
                  self.model_disconnected = False
                  LOG.error(_('Recovered model server connection!'))
  
          # TODO(vish): this should probably only catch connection errors
          except Exception:  # pylint: disable=W0702
              if not getattr(self, 'model_disconnected', False):
                  self.model_disconnected = True
                  LOG.exception(_('model server went away'))
  
  
  class WSGIService(object):
      """Provides ability to launch API from a 'paste' configuration."""
  
      def __init__(self, name, loader=None):
          """Initialize, but do not start the WSGI server.
  
          :param name: The name of the WSGI server given to the loader.
          :param loader: Loads the WSGI application using the given name.
          :returns: None
  
          """
          self.name = name
          self.manager = self._get_manager()
          self.loader = loader or wsgi.Loader()
          self.app = self.loader.load_app(name)
          self.host = getattr(FLAGS, '%s_listen' % name, "0.0.0.0")
          self.port = getattr(FLAGS, '%s_listen_port' % name, 0)
          self.server = wsgi.Server(name,
                                    self.app,
                                    host=self.host,
                                    port=self.port)
  
      def _get_manager(self):
          """Initialize a Manager object appropriate for this service.
  
          Use the service name to look up a Manager subclass from the
          configuration and initialize an instance. If no class name
          is configured, just return None.
  
          :returns: a Manager instance, or None.
  
          """
          fl = '%s_manager' % self.name
          if fl not in FLAGS:
              return None
  
          manager_class_name = FLAGS.get(fl, None)
          if not manager_class_name:
              return None
  
          manager_class = importutils.import_class(manager_class_name)
          return manager_class()
  
      def start(self):
          """Start serving this service using loaded configuration.
  
          Also, retrieve updated port number in case '0' was passed in, which
          indicates a random port should be used.
  
          :returns: None
  
          """
          if self.manager:
              self.manager.init_host()
          self.server.start()
          self.port = self.server.port
  
      def stop(self):
          """Stop serving this API.
  
          :returns: None
  
          """
          self.server.stop()
  
      def wait(self):
          """Wait for the service to stop serving this API.
  
          :returns: None
  
          """
          self.server.wait()
  
  
  # NOTE(vish): the global launcher is to maintain the existing
  #             functionality of calling service.serve +
  #             service.wait
  _launcher = None
  
  
  def serve(*servers):
      global _launcher
      if not _launcher:
          _launcher = Launcher()
      for server in servers:
          _launcher.launch_server(server)
  
  
  def wait():
      LOG.debug(_('Full set of FLAGS:'))
      for flag in FLAGS:
          flag_get = FLAGS.get(flag, None)
          # hide flag contents from log if contains a password
          # should use secret flag when switch over to openstack-common
          if ("_password" in flag or "_key" in flag or
                  (flag == "sql_connection" and "mysql:" in flag_get)):
              LOG.debug(_('%(flag)s : FLAG SET ') % locals())
          else:
              LOG.debug('%(flag)s : %(flag_get)s' % locals())
      try:
          _launcher.wait()
      except KeyboardInterrupt:
          _launcher.stop()
      rpc.cleanup()
  