Synnefo » snf-ganeti

#

#

# Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 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.

Locking: there's a single, large lock in the L{JobQueue} class. It's

used by all other classes in this module.

@var JOBQUEUE_THREADS: the number of worker threads we start for

    processing jobs

"""

import logging

import errno

import time

import weakref

import threading

import itertools

try:

  # pylint: disable=E0611

  from pyinotify import pyinotify

except ImportError:

  import pyinotify

from ganeti import asyncnotifier

from ganeti import constants

from ganeti import serializer

from ganeti import workerpool

from ganeti import locking

from ganeti import opcodes

from ganeti import errors

from ganeti import mcpu

from ganeti import utils

from ganeti import jstore

from ganeti import rpc

from ganeti import runtime

from ganeti import netutils

from ganeti import compat

from ganeti import ht

from ganeti import query

from ganeti import qlang

from ganeti import pathutils

JOBQUEUE_THREADS = 25

# member lock names to be passed to @ssynchronized decorator

_LOCK = "_lock"

_QUEUE = "_queue"

class CancelJob(Exception):

  """Special exception to cancel a job.

  """

def TimeStampNow():

  """Returns the current timestamp.

  @rtype: tuple

  @return: the current time in the (seconds, microseconds) format

  """

  return utils.SplitTime(time.time())

class _SimpleJobQuery:

  """Wrapper for job queries.

  Instance keeps list of fields cached, useful e.g. in L{_JobChangesChecker}.

  """

  def __init__(self, fields):

    """Initializes this class.

    """

    self._query = query.Query(query.JOB_FIELDS, fields)

  def __call__(self, job):

    """Executes a job query using cached field list.

    """

    return self._query.OldStyleQuery([(job.id, job)], sort_by_name=False)[0]

class _QueuedOpCode(object):

  """Encapsulates an opcode object.

  @ivar log: holds the execution log and consists of tuples

  of the form C{(log_serial, timestamp, level, message)}

  @ivar input: the OpCode we encapsulate

  @ivar status: the current status

  @ivar result: the result of the LU execution

  @ivar start_timestamp: timestamp for the start of the execution

  @ivar exec_timestamp: timestamp for the actual LU Exec() function invocation

  @ivar stop_timestamp: timestamp for the end of the execution

  """

  __slots__ = ["input", "status", "result", "log", "priority",

               "start_timestamp", "exec_timestamp", "end_timestamp",

               "__weakref__"]

  def __init__(self, op):

    """Initializes instances of this class.

    @type op: L{opcodes.OpCode}

    @param op: the opcode we encapsulate

    """

    self.input = op

    self.status = constants.OP_STATUS_QUEUED

    self.result = None

    self.log = []

    self.start_timestamp = None

    self.exec_timestamp = None

    self.end_timestamp = None

    # Get initial priority (it might change during the lifetime of this opcode)

    self.priority = getattr(op, "priority", constants.OP_PRIO_DEFAULT)

  @classmethod

  def Restore(cls, state):

    """Restore the _QueuedOpCode from the serialized form.

    @type state: dict

    @param state: the serialized state

    @rtype: _QueuedOpCode

    @return: a new _QueuedOpCode instance

    """

    obj = _QueuedOpCode.__new__(cls)

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

    obj.status = state["status"]

    obj.result = state["result"]

    obj.log = state["log"]

    obj.start_timestamp = state.get("start_timestamp", None)

    obj.exec_timestamp = state.get("exec_timestamp", None)

    obj.end_timestamp = state.get("end_timestamp", None)

    obj.priority = state.get("priority", constants.OP_PRIO_DEFAULT)

    return obj

  def Serialize(self):

    """Serializes this _QueuedOpCode.

    @rtype: dict

    @return: the dictionary holding the serialized state

    """

    return {

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

      "status": self.status,

      "result": self.result,

      "log": self.log,

      "start_timestamp": self.start_timestamp,

      "exec_timestamp": self.exec_timestamp,

      "end_timestamp": self.end_timestamp,

      "priority": self.priority,

      }

class _QueuedJob(object):

  """In-memory job representation.

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

  be taken care of by users of this class.

  @type queue: L{JobQueue}

  @ivar queue: the parent queue

  @ivar id: the job ID

  @type ops: list

  @ivar ops: the list of _QueuedOpCode that constitute the job

  @type log_serial: int

  @ivar log_serial: holds the index for the next log entry

  @ivar received_timestamp: the timestamp for when the job was received

  @ivar start_timestmap: the timestamp for start of execution

  @ivar end_timestamp: the timestamp for end of execution

  @ivar writable: Whether the job is allowed to be modified

  """

  # pylint: disable=W0212

  __slots__ = ["queue", "id", "ops", "log_serial", "ops_iter", "cur_opctx",

               "received_timestamp", "start_timestamp", "end_timestamp",

               "__weakref__", "processor_lock", "writable"]

  def __init__(self, queue, job_id, ops, writable):

    """Constructor for the _QueuedJob.

    @type queue: L{JobQueue}

    @param queue: our parent queue

    @type job_id: job_id

    @param job_id: our job id

    @type ops: list

    @param ops: the list of opcodes we hold, which will be encapsulated

        in _QueuedOpCodes

    @type writable: bool

    @param writable: Whether job can be modified

    """

    if not ops:

      raise errors.GenericError("A job needs at least one opcode")

    self.queue = queue

    self.id = int(job_id)

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

    self.log_serial = 0

    self.received_timestamp = TimeStampNow()

    self.start_timestamp = None

    self.end_timestamp = None

    self._InitInMemory(self, writable)

  @staticmethod

  def _InitInMemory(obj, writable):

    """Initializes in-memory variables.

    """

    obj.writable = writable

    obj.ops_iter = None

    obj.cur_opctx = None

    # Read-only jobs are not processed and therefore don't need a lock

    if writable:

      obj.processor_lock = threading.Lock()

    else:

      obj.processor_lock = None

  def __repr__(self):

    status = ["%s.%s" % (self.__class__.__module__, self.__class__.__name__),

              "id=%s" % self.id,

              "ops=%s" % ",".join([op.input.Summary() for op in self.ops])]

    return "<%s at %#x>" % (" ".join(status), id(self))

  @classmethod

  def Restore(cls, queue, state, writable):

    """Restore a _QueuedJob from serialized state:

    @type queue: L{JobQueue}

    @param queue: to which queue the restored job belongs

    @type state: dict

    @param state: the serialized state

    @type writable: bool

    @param writable: Whether job can be modified

    @rtype: _JobQueue

    @return: the restored _JobQueue instance

    """

    obj = _QueuedJob.__new__(cls)

    obj.queue = queue

    obj.id = int(state["id"])

    obj.received_timestamp = state.get("received_timestamp", None)

    obj.start_timestamp = state.get("start_timestamp", None)

    obj.end_timestamp = state.get("end_timestamp", None)

    obj.ops = []

    obj.log_serial = 0

    for op_state in state["ops"]:

      op = _QueuedOpCode.Restore(op_state)

      for log_entry in op.log:

        obj.log_serial = max(obj.log_serial, log_entry[0])

      obj.ops.append(op)

    cls._InitInMemory(obj, writable)

    return obj

  def Serialize(self):

    """Serialize the _JobQueue instance.

    @rtype: dict

    @return: the serialized state

    """

    return {

      "id": self.id,

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

      "start_timestamp": self.start_timestamp,

      "end_timestamp": self.end_timestamp,

      "received_timestamp": self.received_timestamp,

      }

  def CalcStatus(self):

    """Compute the status of this job.

    This function iterates over all the _QueuedOpCodes in the job and

    based on their status, computes the job status.

    The algorithm is:

      - if we find a cancelled, or finished with error, the job

        status will be the same

      - otherwise, the last opcode with the status one of:

          - waitlock

          - canceling

          - running

        will determine the job status

      - otherwise, it means either all opcodes are queued, or success,

        and the job status will be the same

    @return: the job status

    """

    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_WAITING:

        status = constants.JOB_STATUS_WAITING

      elif op.status == constants.OP_STATUS_RUNNING:

        status = constants.JOB_STATUS_RUNNING

      elif op.status == constants.OP_STATUS_CANCELING:

        status = constants.JOB_STATUS_CANCELING

        break

      elif op.status == constants.OP_STATUS_ERROR:

        status = constants.JOB_STATUS_ERROR

        # The whole job fails if one opcode failed

        break

      elif op.status == constants.OP_STATUS_CANCELED:

        status = constants.OP_STATUS_CANCELED

        break

    if all_success:

      status = constants.JOB_STATUS_SUCCESS

    return status

  def CalcPriority(self):

    """Gets the current priority for this job.

    Only unfinished opcodes are considered. When all are done, the default

    priority is used.

    @rtype: int

    """

    priorities = [op.priority for op in self.ops

                  if op.status not in constants.OPS_FINALIZED]

    if not priorities:

      # All opcodes are done, assume default priority

      return constants.OP_PRIO_DEFAULT

    return min(priorities)

  def GetLogEntries(self, newer_than):

    """Selectively returns the log entries.

    @type newer_than: None or int

    @param newer_than: if this is None, return all log entries,

        otherwise return only the log entries with serial higher

        than this value

    @rtype: list

    @return: the list of the log entries selected

    """

    if newer_than is None:

      serial = -1

    else:

      serial = newer_than

    entries = []

    for op in self.ops:

      entries.extend(filter(lambda entry: entry[0] > serial, op.log))

    return entries

  def GetInfo(self, fields):

    """Returns information about a job.

    @type fields: list

    @param fields: names of fields to return

    @rtype: list

    @return: list with one element for each field

    @raise errors.OpExecError: when an invalid field

        has been passed

    """

    return _SimpleJobQuery(fields)(self)

  def MarkUnfinishedOps(self, status, result):

    """Mark unfinished opcodes with a given status and result.

    This is an utility function for marking all running or waiting to

    be run opcodes with a given status. Opcodes which are already

    finalised are not changed.

    @param status: a given opcode status

    @param result: the opcode result

    """

    not_marked = True

    for op in self.ops:

      if op.status in constants.OPS_FINALIZED:

        assert not_marked, "Finalized opcodes found after non-finalized ones"

        continue

      op.status = status

      op.result = result

      not_marked = False

  def Finalize(self):

    """Marks the job as finalized.

    """

    self.end_timestamp = TimeStampNow()

  def Cancel(self):

    """Marks job as canceled/-ing if possible.

    @rtype: tuple; (bool, string)

    @return: Boolean describing whether job was successfully canceled or marked

      as canceling and a text message

    """

    status = self.CalcStatus()

    if status == constants.JOB_STATUS_QUEUED:

      self.MarkUnfinishedOps(constants.OP_STATUS_CANCELED,

                             "Job canceled by request")

      self.Finalize()

      return (True, "Job %s canceled" % self.id)

    elif status == constants.JOB_STATUS_WAITING:

      # The worker will notice the new status and cancel the job

      self.MarkUnfinishedOps(constants.OP_STATUS_CANCELING, None)

      return (True, "Job %s will be canceled" % self.id)

    else:

      logging.debug("Job %s is no longer waiting in the queue", self.id)

      return (False, "Job %s is no longer waiting in the queue" % self.id)

class _OpExecCallbacks(mcpu.OpExecCbBase):

  def __init__(self, queue, job, op):

    """Initializes this class.

    @type queue: L{JobQueue}

    @param queue: Job queue

    @type job: L{_QueuedJob}

    @param job: Job object

    @type op: L{_QueuedOpCode}

    @param op: OpCode

    """

    assert queue, "Queue is missing"

    assert job, "Job is missing"

    assert op, "Opcode is missing"

    self._queue = queue

    self._job = job

    self._op = op

  def _CheckCancel(self):

    """Raises an exception to cancel the job if asked to.

    """

    # Cancel here if we were asked to

    if self._op.status == constants.OP_STATUS_CANCELING:

      logging.debug("Canceling opcode")

      raise CancelJob()

  @locking.ssynchronized(_QUEUE, shared=1)

  def NotifyStart(self):

    """Mark the opcode as running, not lock-waiting.

    This is called from the mcpu code as a notifier function, when the LU is

    finally about to start the Exec() method. Of course, to have end-user

    visible results, the opcode must be initially (before calling into

    Processor.ExecOpCode) set to OP_STATUS_WAITING.

    """

    assert self._op in self._job.ops

    assert self._op.status in (constants.OP_STATUS_WAITING,

                               constants.OP_STATUS_CANCELING)

    # Cancel here if we were asked to

    self._CheckCancel()

    logging.debug("Opcode is now running")

    self._op.status = constants.OP_STATUS_RUNNING

    self._op.exec_timestamp = TimeStampNow()

    # And finally replicate the job status

    self._queue.UpdateJobUnlocked(self._job)

  @locking.ssynchronized(_QUEUE, shared=1)

  def _AppendFeedback(self, timestamp, log_type, log_msg):

    """Internal feedback append function, with locks

    """

    self._job.log_serial += 1

    self._op.log.append((self._job.log_serial, timestamp, log_type, log_msg))

    self._queue.UpdateJobUnlocked(self._job, replicate=False)

  def Feedback(self, *args):

    """Append a log entry.

    """

    assert len(args) < 3

    if len(args) == 1:

      log_type = constants.ELOG_MESSAGE

      log_msg = args[0]

    else:

      (log_type, log_msg) = args

    # The time is split to make serialization easier and not lose

    # precision.

    timestamp = utils.SplitTime(time.time())

    self._AppendFeedback(timestamp, log_type, log_msg)

  def CheckCancel(self):

    """Check whether job has been cancelled.

    """

    assert self._op.status in (constants.OP_STATUS_WAITING,

                               constants.OP_STATUS_CANCELING)

    # Cancel here if we were asked to

    self._CheckCancel()

  def SubmitManyJobs(self, jobs):

    """Submits jobs for processing.

    See L{JobQueue.SubmitManyJobs}.

    """

    # Locking is done in job queue

    return self._queue.SubmitManyJobs(jobs)

class _JobChangesChecker(object):

  def __init__(self, fields, prev_job_info, prev_log_serial):

    """Initializes this class.

    @type fields: list of strings

    @param fields: Fields requested by LUXI client

    @type prev_job_info: string

    @param prev_job_info: previous job info, as passed by the LUXI client

    @type prev_log_serial: string

    @param prev_log_serial: previous job serial, as passed by the LUXI client

    """

    self._squery = _SimpleJobQuery(fields)

    self._prev_job_info = prev_job_info

    self._prev_log_serial = prev_log_serial

  def __call__(self, job):

    """Checks whether job has changed.

    @type job: L{_QueuedJob}

    @param job: Job object

    """

    assert not job.writable, "Expected read-only job"

    status = job.CalcStatus()

    job_info = self._squery(job)

    log_entries = job.GetLogEntries(self._prev_log_serial)

    # Serializing and deserializing data can cause type changes (e.g. from

    # tuple to list) or precision loss. We're doing it here so that we get

    # the same modifications as the data received from the client. Without

    # this, the comparison afterwards might fail without the data being

    # significantly different.

    # TODO: we just deserialized from disk, investigate how to make sure that

    # the job info and log entries are compatible to avoid this further step.

    # TODO: Doing something like in testutils.py:UnifyValueType might be more

    # efficient, though floats will be tricky

    job_info = serializer.LoadJson(serializer.DumpJson(job_info))

    log_entries = serializer.LoadJson(serializer.DumpJson(log_entries))

    # Don't even try to wait if the job is no longer running, there will be

    # no changes.

    if (status not in (constants.JOB_STATUS_QUEUED,

                       constants.JOB_STATUS_RUNNING,

                       constants.JOB_STATUS_WAITING) or

        job_info != self._prev_job_info or

        (log_entries and self._prev_log_serial != log_entries[0][0])):

      logging.debug("Job %s changed", job.id)

      return (job_info, log_entries)

    return None

class _JobFileChangesWaiter(object):

  def __init__(self, filename):

    """Initializes this class.

    @type filename: string

    @param filename: Path to job file

    @raises errors.InotifyError: if the notifier cannot be setup

    """

    self._wm = pyinotify.WatchManager()

    self._inotify_handler = \

      asyncnotifier.SingleFileEventHandler(self._wm, self._OnInotify, filename)

    self._notifier = \

      pyinotify.Notifier(self._wm, default_proc_fun=self._inotify_handler)

    try:

      self._inotify_handler.enable()

    except Exception:

      # pyinotify doesn't close file descriptors automatically

      self._notifier.stop()

      raise

  def _OnInotify(self, notifier_enabled):

    """Callback for inotify.

    """

    if not notifier_enabled:

      self._inotify_handler.enable()

  def Wait(self, timeout):

    """Waits for the job file to change.

    @type timeout: float

    @param timeout: Timeout in seconds

    @return: Whether there have been events

    """

    assert timeout >= 0

    have_events = self._notifier.check_events(timeout * 1000)

    if have_events:

      self._notifier.read_events()

    self._notifier.process_events()

    return have_events

  def Close(self):

    """Closes underlying notifier and its file descriptor.

    """

    self._notifier.stop()

class _JobChangesWaiter(object):

  def __init__(self, filename):

    """Initializes this class.

    @type filename: string

    @param filename: Path to job file

    """

    self._filewaiter = None

    self._filename = filename

  def Wait(self, timeout):

    """Waits for a job to change.

    @type timeout: float

    @param timeout: Timeout in seconds

    @return: Whether there have been events

    """

    if self._filewaiter:

      return self._filewaiter.Wait(timeout)

    # Lazy setup: Avoid inotify setup cost when job file has already changed.

    # If this point is reached, return immediately and let caller check the job

    # file again in case there were changes since the last check. This avoids a

    # race condition.

    self._filewaiter = _JobFileChangesWaiter(self._filename)

    return True

  def Close(self):

    """Closes underlying waiter.

    """

    if self._filewaiter:

      self._filewaiter.Close()

class _WaitForJobChangesHelper(object):

  """Helper class using inotify to wait for changes in a job file.

  This class takes a previous job status and serial, and alerts the client when

  the current job status has changed.

  """

  @staticmethod

  def _CheckForChanges(counter, job_load_fn, check_fn):

    if counter.next() > 0:

      # If this isn't the first check the job is given some more time to change

      # again. This gives better performance for jobs generating many

      # changes/messages.

      time.sleep(0.1)

    job = job_load_fn()

    if not job:

      raise errors.JobLost()

    result = check_fn(job)

    if result is None:

      raise utils.RetryAgain()

    return result

  def __call__(self, filename, job_load_fn,

               fields, prev_job_info, prev_log_serial, timeout):

    """Waits for changes on a job.