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#

#

# 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.

"""Module implementing the job queue handling."""

import logging

import threading

from ganeti import constants

from ganeti import workerpool

from ganeti import errors

from ganeti import mcpu

JOBQUEUE_THREADS = 5

class _QueuedOpCode(object):

  """Encasulates an opcode object.

  Access must be synchronized by using an external lock.

  """

  def __init__(self, op):

    self.input = op

    self.status = constants.OP_STATUS_QUEUED

    self.result = None

class _QueuedJob(object):

  """In-memory job representation.

  This is what we use to track the user-submitted jobs.

  """

  def __init__(self, ops, job_id):

    if not ops:

      # TODO

      raise Exception("No opcodes")

    self.id = job_id

    self._lock = threading.Lock()

    # _ops should not be modified again because we don't acquire the lock

    # to use it.

    self._ops = [_QueuedOpCode(op) for op in ops]

  def _GetStatusUnlocked(self):

    status = constants.JOB_STATUS_QUEUED

    all_success = True

    for op in self._ops:

      if op.status == constants.OP_STATUS_SUCCESS:

        continue

      all_success = False

      if op.status == constants.OP_STATUS_QUEUED:

        pass

      elif op.status == constants.OP_STATUS_ERROR:

        status = constants.JOB_STATUS_ERROR

      elif op.status == constants.OP_STATUS_RUNNING:

        status = constants.JOB_STATUS_RUNNING

    if all_success:

      status = constants.JOB_STATUS_SUCCESS

    return status

  def GetStatus(self):

    self._lock.acquire()

    try:

      return self._GetStatusUnlocked()

    finally:

      self._lock.release()

  def Run(self, proc):

    """Job executor.

    This functions processes a this job in the context of given processor

    instance.

    Args:

    - proc: Ganeti Processor to run the job with

    """

    try:

      count = len(self._ops)

      for idx, op in enumerate(self._ops):

        try:

          self._lock.acquire()

          try:

            logging.debug("Op %s/%s: Starting %s", idx + 1, count, op)

            op.status = constants.OP_STATUS_RUNNING

          finally:

            self._lock.release()

          result = proc.ExecOpCode(op.input)

          self._lock.acquire()

          try:

            logging.debug("Op %s/%s: Successfully finished %s",

                          idx + 1, count, op)

            op.status = constants.OP_STATUS_SUCCESS

            op.result = result

          finally:

            self._lock.release()

        except Exception, err:

          self._lock.acquire()

          try:

            logging.debug("Op %s/%s: Error in %s", idx + 1, count, op)

            op.status = constants.OP_STATUS_ERROR

            op.result = str(err)

          finally:

            self._lock.release()

          raise

    except errors.GenericError, err:

      logging.error("ganeti exception %s", exc_info=err)

    except Exception, err:

      logging.error("unhandled exception %s", exc_info=err)

    except:

      logging.error("unhandled unknown exception %s", exc_info=err)

class _JobQueueWorker(workerpool.BaseWorker):

  def RunTask(self, job):

    logging.debug("Worker %s processing job %s",

                  self.worker_id, job.id)

    # TODO: feedback function

    proc = mcpu.Processor(self.pool.context, feedback=lambda x: None)

    try:

      job.Run(proc)

    finally:

      logging.debug("Worker %s finished job %s, status = %s",

                    self.worker_id, job.id, job.GetStatus())

class _JobQueueWorkerPool(workerpool.WorkerPool):

  def __init__(self, context):

    super(_JobQueueWorkerPool, self).__init__(JOBQUEUE_THREADS,

                                              _JobQueueWorker)

    self.context = context

class JobQueue:

  """The job queue.

   """

  def __init__(self, context):

    self._lock = threading.Lock()

    self._last_job_id = 0

    self._jobs = {}

    self._wpool = _JobQueueWorkerPool(context)

  def _NewJobIdUnlocked(self):

    """Generates a new job identifier.

    Returns: A string representing the job identifier.

    """

    self._last_job_id += 1

    return str(self._last_job_id)

  def SubmitJob(self, ops):

    """Add a new job to the queue.

    This enters the job into our job queue and also puts it on the new

    queue, in order for it to be picked up by the queue processors.

    Args:

    - ops: Sequence of opcodes

    """

    # Get job identifier

    self._lock.acquire()

    try:

      job_id = self._NewJobIdUnlocked()

    finally:

      self._lock.release()

    job = _QueuedJob(ops, job_id)

    # Add it to our internal queue

    self._lock.acquire()

    try:

      self._jobs[job_id] = job

    finally:

      self._lock.release()

    # Add to worker pool

    self._wpool.AddTask(job)

    return job_id

  def ArchiveJob(self, job_id):

    raise NotImplementedError()

  def CancelJob(self, job_id):

    raise NotImplementedError()

  def _GetJobInfo(self, job, fields):

    row = []

    for fname in fields:

      if fname == "id":

        row.append(job.id)

      elif fname == "status":

        row.append(job.GetStatus())

      elif fname == "result":

        # TODO

        row.append(map(lambda op: op.result, job._ops))

      else:

        raise errors.OpExecError("Invalid job query field '%s'" % fname)

    return row

  def QueryJobs(self, job_ids, fields):

    """Returns a list of jobs in queue.

    Args:

    - job_ids: Sequence of job identifiers or None for all

    - fields: Names of fields to return

    """

    self._lock.acquire()

    try:

      if not job_ids:

        job_ids = self._jobs.keys()

      # TODO: define sort order?

      job_ids.sort()

      jobs = []

      for job_id in job_ids:

        job = self._jobs.get(job_id, None)

        if job is None:

          jobs.append(None)

        else:

          jobs.append(self._GetJobInfo(job, fields))

      return jobs

    finally:

      self._lock.release()

  def Shutdown(self):

    """Stops the job queue.

    """

    self._wpool.TerminateWorkers()