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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 os

import logging

import threading

import errno

import re

from ganeti import constants

from ganeti import serializer

from ganeti import workerpool

from ganeti import opcodes

from ganeti import errors

from ganeti import mcpu

from ganeti import utils

JOBQUEUE_THREADS = 5

class _QueuedOpCode(object):

  """Encasulates an opcode object.

  Access is synchronized by the '_lock' attribute.

  """

  def __init__(self, op):

    self.__Setup(op, constants.OP_STATUS_QUEUED, None)

  def __Setup(self, input, status, result):

    self._lock = threading.Lock()

    self.input = input

    self.status = status

    self.result = result

  @classmethod

  def Restore(cls, state):

    obj = object.__new__(cls)

    obj.__Setup(opcodes.OpCode.LoadOpCode(state["input"]),

                state["status"], state["result"])

    return obj

  @utils.LockedMethod

  def Serialize(self):

    return {

      "input": self.input.__getstate__(),

      "status": self.status,

      "result": self.result,

      }

  @utils.LockedMethod

  def GetInput(self):

    """Returns the original opcode.

    """

    return self.input

  @utils.LockedMethod

  def SetStatus(self, status, result):

    """Update the opcode status and result.

    """

    self.status = status

    self.result = result

  @utils.LockedMethod

  def GetStatus(self):

    """Get the opcode status.

    """

    return self.status

  @utils.LockedMethod

  def GetResult(self):

    """Get the opcode result.

    """

    return self.result

class _QueuedJob(object):

  """In-memory job representation.

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

  """

  def __init__(self, storage, job_id, ops):

    if not ops:

      # TODO

      raise Exception("No opcodes")

    self.__Setup(storage, job_id, [_QueuedOpCode(op) for op in ops])

  def __Setup(self, storage, job_id, ops):

    self.storage = storage

    self.id = job_id

    self._ops = ops

  @classmethod

  def Restore(cls, storage, state):

    obj = object.__new__(cls)

    obj.__Setup(storage, state["id"],

                [_QueuedOpCode.Restore(op_state) for op_state in state["ops"]])

    return obj

  def Serialize(self):

    return {

      "id": self.id,

      "ops": [op.Serialize() for op in self._ops],

      }

  def SetUnclean(self, msg):

    try:

      for op in self._ops:

        op.SetStatus(constants.OP_STATUS_ERROR, msg)

    finally:

      self.storage.UpdateJob(self)

  def GetStatus(self):

    status = constants.JOB_STATUS_QUEUED

    all_success = True

    for op in self._ops:

      op_status = op.GetStatus()

      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_RUNNING:

        status = constants.JOB_STATUS_RUNNING

      elif op_status == constants.OP_STATUS_ERROR:

        status = constants.JOB_STATUS_ERROR

        # The whole job fails if one opcode failed

        break

    if all_success:

      status = constants.JOB_STATUS_SUCCESS

    return status

  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:

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

          op.SetStatus(constants.OP_STATUS_RUNNING, None)

          self.storage.UpdateJob(self)

          result = proc.ExecOpCode(op.input)

          op.SetStatus(constants.OP_STATUS_SUCCESS, result)

          self.storage.UpdateJob(self)

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

                        idx + 1, count, op)

        except Exception, err:

          try:

            op.SetStatus(constants.OP_STATUS_ERROR, str(err))

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

          finally:

            self.storage.UpdateJob(self)

          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 JobStorage(object):

  _RE_JOB_FILE = re.compile(r"^job-(\d+)$")

  def __init__(self):

    self._lock = threading.Lock()

    self._memcache = {}

    # Make sure our directory exists

    try:

      os.mkdir(constants.QUEUE_DIR, 0700)

    except OSError, err:

      if err.errno not in (errno.EEXIST, ):

        raise

    # Get queue lock

    self.lock_fd = open(constants.JOB_QUEUE_LOCK_FILE, "w")

    try:

      utils.LockFile(self.lock_fd)

    except:

      self.lock_fd.close()

      raise

    # Read version

    try:

      version_fd = open(constants.JOB_QUEUE_VERSION_FILE, "r")

    except IOError, err:

      if err.errno not in (errno.ENOENT, ):

        raise

      # Setup a new queue

      self._InitQueueUnlocked()

      # Try to open again

      version_fd = open(constants.JOB_QUEUE_VERSION_FILE, "r")

    try:

      # Try to read version

      version = int(version_fd.read(128))

      # Verify version

      if version != constants.JOB_QUEUE_VERSION:

        raise errors.JobQueueError("Found version %s, expected %s",

                                   version, constants.JOB_QUEUE_VERSION)

    finally:

      version_fd.close()

    serial_fd = open(constants.JOB_QUEUE_SERIAL_FILE, "r")

    try:

      # Read last serial

      self._last_serial = int(serial_fd.read(1024).strip())

    finally:

      serial_fd.close()

  def Close(self):

    assert self.lock_fd, "Queue should be open"

    self.lock_fd.close()

    self.lock_fd = None

  def _InitQueueUnlocked(self):

    assert self.lock_fd, "Queue should be open"

    utils.WriteFile(constants.JOB_QUEUE_VERSION_FILE,

                    data="%s\n" % constants.JOB_QUEUE_VERSION)

    utils.WriteFile(constants.JOB_QUEUE_SERIAL_FILE,

                    data="%s\n" % 0)

  def _NewSerialUnlocked(self):

    """Generates a new job identifier.

    Job identifiers are unique during the lifetime of a cluster.

    Returns: A string representing the job identifier.

    """

    assert self.lock_fd, "Queue should be open"

    # New number

    serial = self._last_serial + 1

    # Write to file

    utils.WriteFile(constants.JOB_QUEUE_SERIAL_FILE,

                    data="%s\n" % serial)

    # Keep it only if we were able to write the file

    self._last_serial = serial

    return serial

  def _GetJobPath(self, job_id):

    return os.path.join(constants.QUEUE_DIR, "job-%s" % job_id)

  def _GetJobIDsUnlocked(self, archived=False):

    """Return all known job IDs.

    If the parameter archived is True, archived jobs IDs will be

    included. Currently this argument is unused.

    The method only looks at disk because it's a requirement that all

    jobs are present on disk (so in the _memcache we don't have any

    extra IDs).

    """

    jfiles = self._ListJobFiles()

    return [int(m.group(1)) for m in

            [self._RE_JOB_FILE.match(name) for name in jfiles]]

  def _ListJobFiles(self):

    assert self.lock_fd, "Queue should be open"

    return [name for name in utils.ListVisibleFiles(constants.QUEUE_DIR)

            if self._RE_JOB_FILE.match(name)]

  def _LoadJobUnlocked(self, job_id):

    assert self.lock_fd, "Queue should be open"

    if job_id in self._memcache:

      logging.debug("Found job %d in memcache", job_id)

      return self._memcache[job_id]

    filepath = self._GetJobPath(job_id)

    logging.debug("Loading job from %s", filepath)

    try:

      fd = open(filepath, "r")

    except IOError, err:

      if err.errno in (errno.ENOENT, ):

        return None

      raise

    try:

      data = serializer.LoadJson(fd.read())

    finally:

      fd.close()

    job = _QueuedJob.Restore(self, data)

    self._memcache[job_id] = job

    logging.debug("Added job %d to the cache", job_id)

    return job

  def _GetJobsUnlocked(self, job_ids):

    if not job_ids:

      job_ids = self._GetJobIDsUnlocked()

    return [self._LoadJobUnlocked(job_id) for job_id in job_ids]

  @utils.LockedMethod

  def GetJobs(self, job_ids):

    return self._GetJobsUnlocked(job_ids)

  @utils.LockedMethod

  def AddJob(self, ops):

    assert self.lock_fd, "Queue should be open"

    # Get job identifier

    job_id = self._NewSerialUnlocked()

    job = _QueuedJob(self, job_id, ops)

    # Write to disk

    self._UpdateJobUnlocked(job)

    logging.debug("Added new job %d to the cache", job_id)

    self._memcache[job_id] = job

    return job

  def _UpdateJobUnlocked(self, job):

    assert self.lock_fd, "Queue should be open"

    filename = self._GetJobPath(job.id)

    logging.debug("Writing job %s to %s", job.id, filename)

    utils.WriteFile(filename,

                    data=serializer.DumpJson(job.Serialize(), indent=False))

    self._CleanCacheUnlocked(exceptions=[job.id])

  def _CleanCacheUnlocked(self, exceptions=None):

    """Clean the memory cache.

    The exceptions argument contains job IDs that should not be

    cleaned.

    """

    assert isinstance(exceptions, list)

    for job in self._memcache.values():

      if job.id in exceptions:

        continue

      if job.GetStatus() not in (constants.JOB_STATUS_QUEUED,

                                 constants.JOB_STATUS_RUNNING):

        logging.debug("Cleaning job %d from the cache", job.id)

        try:

          del self._memcache[job.id]

        except KeyError:

          pass

  @utils.LockedMethod

  def UpdateJob(self, job):

    return self._UpdateJobUnlocked(job)

  def ArchiveJob(self, job_id):

    raise NotImplementedError()

class JobQueue:

  """The job queue.

   """

  def __init__(self, context):

    self._lock = threading.Lock()

    self._jobs = JobStorage()

    self._wpool = _JobQueueWorkerPool(context)

    for job in self._jobs.GetJobs(None):

      status = job.GetStatus()

      if status in (constants.JOB_STATUS_QUEUED, ):

        self._wpool.AddTask(job)

      elif status in (constants.JOB_STATUS_RUNNING, ):

        logging.warning("Unfinished job %s found: %s", job.id, job)

        job.SetUnclean("Unclean master daemon shutdown")

  @utils.LockedMethod

  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

    """

    job = self._jobs.AddJob(ops)

    # 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 == "ops":

        row.append([op.GetInput().__getstate__() for op in job._ops])

      elif fname == "opresult":

        row.append([op.GetResult() for op in job._ops])

      elif fname == "opstatus":

        row.append([op.GetStatus() for op in 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:

      jobs = []

      for job in self._jobs.GetJobs(job_ids):

        if job is None:

          jobs.append(None)

        else:

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

      return jobs

    finally:

      self._lock.release()

  @utils.LockedMethod

  def Shutdown(self):

    """Stops the job queue.

    """

    self._wpool.TerminateWorkers()

    self._jobs.Close()