#!/usr/bin/python -u
#

# Copyright (C) 2006, 2007 Google Inc.
#
# This program 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 2 of the License, or
# (at your option) any later version.
#
# This program 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 this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.


"""Master daemon program.

Some classes deviates from the standard style guide since the
inheritance from parent classes requires it.

"""


import sys
import SocketServer
import time
import collections
import Queue
import random
import signal
import simplejson
import logging

from cStringIO import StringIO
from optparse import OptionParser

from ganeti import config
from ganeti import constants
from ganeti import mcpu
from ganeti import opcodes
from ganeti import jqueue
from ganeti import locking
from ganeti import luxi
from ganeti import utils
from ganeti import errors
from ganeti import ssconf
from ganeti import logger
from ganeti import workerpool


CLIENT_REQUEST_WORKERS = 16

EXIT_NOTMASTER = constants.EXIT_NOTMASTER
EXIT_NODESETUP_ERROR = constants.EXIT_NODESETUP_ERROR


class ClientRequestWorker(workerpool.BaseWorker):
  def RunTask(self, server, request, client_address):
    """Process the request.

    This is copied from the code in ThreadingMixIn.

    """
    try:
      server.finish_request(request, client_address)
      server.close_request(request)
    except:
      server.handle_error(request, client_address)
      server.close_request(request)


class IOServer(SocketServer.UnixStreamServer):
  """IO thread class.

  This class takes care of initializing the other threads, setting
  signal handlers (which are processed only in this thread), and doing
  cleanup at shutdown.

  """
  def __init__(self, address, rqhandler, context):
    """IOServer constructor

    Args:
      address: the address to bind this IOServer to
      rqhandler: RequestHandler type object
      context: Context Object common to all worker threads

    """
    SocketServer.UnixStreamServer.__init__(self, address, rqhandler)
    self.do_quit = False
    self.context = context

    # We'll only start threads once we've forked.
    self.jobqueue = None
    self.request_workers = None

    signal.signal(signal.SIGINT, self.handle_quit_signals)
    signal.signal(signal.SIGTERM, self.handle_quit_signals)

  def setup_queue(self):
    self.jobqueue = jqueue.JobQueue(self.context)
    self.request_workers = workerpool.WorkerPool(CLIENT_REQUEST_WORKERS,
                                                 ClientRequestWorker)

  def process_request(self, request, client_address):
    """Add task to workerpool to process request.

    """
    self.request_workers.AddTask(self, request, client_address)

  def handle_quit_signals(self, signum, frame):
    print "received %s in %s" % (signum, frame)
    self.do_quit = True

  def serve_forever(self):
    """Handle one request at a time until told to quit."""
    while not self.do_quit:
      self.handle_request()
      print "served request, quit=%s" % (self.do_quit)

  def server_cleanup(self):
    """Cleanup the server.

    This involves shutting down the processor threads and the master
    socket.

    """
    try:
      self.server_close()
      utils.RemoveFile(constants.MASTER_SOCKET)
    finally:
      if self.request_workers:
        self.request_workers.TerminateWorkers()
      if self.jobqueue:
        self.jobqueue.Shutdown()


class ClientRqHandler(SocketServer.BaseRequestHandler):
  """Client handler"""
  EOM = '\3'
  READ_SIZE = 4096

  def setup(self):
    self._buffer = ""
    self._msgs = collections.deque()
    self._ops = ClientOps(self.server)

  def handle(self):
    while True:
      msg = self.read_message()
      if msg is None:
        logging.info("client closed connection")
        break

      request = simplejson.loads(msg)
      logging.debug("request: %s", request)
      if not isinstance(request, dict):
        logging.error("wrong request received: %s", msg)
        break

      method = request.get(luxi.KEY_METHOD, None)
      args = request.get(luxi.KEY_ARGS, None)
      if method is None or args is None:
        logging.error("no method or args in request")
        break

      success = False
      try:
        result = self._ops.handle_request(method, args)
        success = True
      except:
        logging.error("Unexpected exception", exc_info=True)
        err = sys.exc_info()
        result = "Caught exception: %s" % str(err[1])

      response = {
        luxi.KEY_SUCCESS: success,
        luxi.KEY_RESULT: result,
        }
      logging.debug("response: %s", response)
      self.send_message(simplejson.dumps(response))

  def read_message(self):
    while not self._msgs:
      data = self.request.recv(self.READ_SIZE)
      if not data:
        return None
      new_msgs = (self._buffer + data).split(self.EOM)
      self._buffer = new_msgs.pop()
      self._msgs.extend(new_msgs)
    return self._msgs.popleft()

  def send_message(self, msg):
    #print "sending", msg
    self.request.sendall(msg + self.EOM)


class ClientOps:
  """Class holding high-level client operations."""
  def __init__(self, server):
    self.server = server

  def handle_request(self, method, args):
    queue = self.server.jobqueue

    # TODO: Parameter validation

    if method == luxi.REQ_SUBMIT_JOB:
      ops = [opcodes.OpCode.LoadOpCode(state) for state in args]
      return queue.SubmitJob(ops)

    elif method == luxi.REQ_CANCEL_JOB:
      (job_id, ) = args
      return queue.CancelJob(job_id)

    elif method == luxi.REQ_ARCHIVE_JOB:
      (job_id, ) = args
      return queue.ArchiveJob(job_id)

    elif method == luxi.REQ_QUERY_JOBS:
      (job_ids, fields) = args
      return queue.QueryJobs(job_ids, fields)

    else:
      raise ValueError("Invalid operation")


class GanetiContext(object):
  """Context common to all ganeti threads.

  This class creates and holds common objects shared by all threads.

  """
  _instance = None

  def __init__(self):
    """Constructs a new GanetiContext object.

    There should be only a GanetiContext object at any time, so this
    function raises an error if this is not the case.

    """
    assert self.__class__._instance is None, "double GanetiContext instance"

    # Create a ConfigWriter...
    self.cfg = config.ConfigWriter()
    # And a GanetiLockingManager...
    self.glm = locking.GanetiLockManager(
                self.cfg.GetNodeList(),
                self.cfg.GetInstanceList())

    # setting this also locks the class against attribute modifications
    self.__class__._instance = self

  def __setattr__(self, name, value):
    """Setting GanetiContext attributes is forbidden after initialization.

    """
    assert self.__class__._instance is None, "Attempt to modify Ganeti Context"
    object.__setattr__(self, name, value)


def CheckMaster(debug):
  """Checks the node setup.

  If this is the master, the function will return. Otherwise it will
  exit with an exit code based on the node status.

  """
  try:
    ss = ssconf.SimpleStore()
    master_name = ss.GetMasterNode()
  except errors.ConfigurationError, err:
    print "Cluster configuration incomplete: '%s'" % str(err)
    sys.exit(EXIT_NODESETUP_ERROR)

  try:
    myself = utils.HostInfo()
  except errors.ResolverError, err:
    sys.stderr.write("Cannot resolve my own name (%s)\n" % err.args[0])
    sys.exit(EXIT_NODESETUP_ERROR)

  if myself.name != master_name:
    if debug:
      sys.stderr.write("Not master, exiting.\n")
    sys.exit(EXIT_NOTMASTER)


def ParseOptions():
  """Parse the command line options.

  Returns:
    (options, args) as from OptionParser.parse_args()

  """
  parser = OptionParser(description="Ganeti master daemon",
                        usage="%prog [-f] [-d]",
                        version="%%prog (ganeti) %s" %
                        constants.RELEASE_VERSION)

  parser.add_option("-f", "--foreground", dest="fork",
                    help="Don't detach from the current terminal",
                    default=True, action="store_false")
  parser.add_option("-d", "--debug", dest="debug",
                    help="Enable some debug messages",
                    default=False, action="store_true")
  options, args = parser.parse_args()
  return options, args


def main():
  """Main function"""

  options, args = ParseOptions()
  utils.debug = options.debug
  utils.no_fork = True

  CheckMaster(options.debug)

  master = IOServer(constants.MASTER_SOCKET, ClientRqHandler, GanetiContext())

  # become a daemon
  if options.fork:
    utils.Daemonize(logfile=constants.LOG_MASTERDAEMON,
                    noclose_fds=[master.fileno()])

  logger.SetupDaemon(constants.LOG_MASTERDAEMON, debug=options.debug,
                     stderr_logging=not options.fork)

  logging.info("ganeti master daemon startup")

  master.setup_queue()
  try:
    master.serve_forever()
  finally:
    master.server_cleanup()


if __name__ == "__main__":
  main()