Synnefo » snf-ganeti

#

#

# Copyright (C) 2006, 2007, 2008 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 os

import logging

import errno

import re

import time

import weakref

try:

  # pylint: disable-msg=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

JOBQUEUE_THREADS = 25

JOBS_PER_ARCHIVE_DIRECTORY = 10000

# The Big JobQueue lock. As for all B*Lock conversions, it must be acquired in

# shared mode to ensure exclusion with legacy code, which acquires it

# exclusively. It can not be acquired at all only after concurrency with all

# new and legacy code is ensured.

_big_jqueue_lock = locking.SharedLock()

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 _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",

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

               "__weakref__"]

  def __init__(self, op):

    """Constructor for the _QuededOpCode.

    @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

  @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)

    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,

      }

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 lock_status: In-memory locking information for debugging

  """

  # pylint: disable-msg=W0212

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

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

               "lock_status", "change",

               "__weakref__"]

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

    """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

    """

    if not ops:

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

    self.queue = queue

    self.id = 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

    # In-memory attributes

    self.lock_status = 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):

    """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

    @rtype: _JobQueue

    @return: the restored _JobQueue instance

    """

    obj = _QueuedJob.__new__(cls)

    obj.queue = queue

    obj.id = 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)

    # In-memory attributes

    obj.lock_status = 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)

    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_WAITLOCK:

        status = constants.JOB_STATUS_WAITLOCK

      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 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

    """

    row = []

    for fname in fields:

      if fname == "id":

        row.append(self.id)

      elif fname == "status":

        row.append(self.CalcStatus())

      elif fname == "ops":

        row.append([op.input.__getstate__() for op in self.ops])

      elif fname == "opresult":

        row.append([op.result for op in self.ops])

      elif fname == "opstatus":

        row.append([op.status for op in self.ops])

      elif fname == "oplog":

        row.append([op.log for op in self.ops])

      elif fname == "opstart":

        row.append([op.start_timestamp for op in self.ops])

      elif fname == "opexec":

        row.append([op.exec_timestamp for op in self.ops])

      elif fname == "opend":

        row.append([op.end_timestamp for op in self.ops])

      elif fname == "received_ts":

        row.append(self.received_timestamp)

      elif fname == "start_ts":

        row.append(self.start_timestamp)

      elif fname == "end_ts":

        row.append(self.end_timestamp)

      elif fname == "lock_status":

        row.append(self.lock_status)

      elif fname == "summary":

        row.append([op.input.Summary() for op in self.ops])

      else:

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

    return row

  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

    """

    try:

      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

    finally:

      self.queue.UpdateJobUnlocked(self)

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 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_WAITLOCK.

    """

    self._queue.acquire(shared=1)

    try:

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

                                 constants.OP_STATUS_CANCELING)

      # All locks are acquired by now

      self._job.lock_status = None

      # Cancel here if we were asked to

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

        raise CancelJob()

      self._op.status = constants.OP_STATUS_RUNNING

      self._op.exec_timestamp = TimeStampNow()

    finally:

      self._queue.release()

  @locking.ssynchronized(_big_jqueue_lock, 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 ReportLocks(self, msg):

    """Write locking information to the job.

    Called whenever the LU processor is waiting for a lock or has acquired one.

    """

    # Not getting the queue lock because this is a single assignment

    self._job.lock_status = msg

class _WaitForJobChangesHelper(object):

  """Helper class using initofy 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.

  @type job_id: string

  @ivar job_id: id of the job we're watching

  @type prev_job_info: string

  @ivar prev_job_info: previous job info, as passed by the luxi client

  @type prev_log_serial: string

  @ivar prev_log_serial: previous job serial, as passed by the luxi client

  @type queue: L{JobQueue}

  @ivar queue: job queue (used for a few utility functions)

  @type job_path: string

  @ivar job_path: absolute path of the job file

  @type wm: pyinotify.WatchManager (or None)

  @ivar wm: inotify watch manager to watch for changes

  @type inotify_handler: L{asyncnotifier.SingleFileEventHandler}

  @ivar inotify_handler: single file event handler, used for watching

  @type notifier: pyinotify.Notifier

  @ivar notifier: inotify single-threaded notifier, used for watching

  """

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

    self.job_id = job_id

    self.fields = fields

    self.prev_job_info = prev_job_info

    self.prev_log_serial = prev_log_serial

    self.queue = queue

    # pylint: disable-msg=W0212

    self.job_path = self.queue._GetJobPath(self.job_id)

    self.wm = None

    self.inotify_handler = None

    self.notifier = None

  def _SetupInotify(self):

    """Create the inotify

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

    """

    if self.wm:

      return

    self.wm = pyinotify.WatchManager()

    self.inotify_handler = asyncnotifier.SingleFileEventHandler(self.wm,

                                                                self.OnInotify,

                                                                self.job_path)

    self.notifier = pyinotify.Notifier(self.wm, self.inotify_handler)

    self.inotify_handler.enable()

  def _LoadDiskStatus(self):

    job = self.queue.SafeLoadJobFromDisk(self.job_id)

    if not job:

      raise errors.JobLost()

    self.job_status = job.CalcStatus()

    job_info = job.GetInfo(self.fields)

    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.

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

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

  def _CheckForChanges(self):

    self._LoadDiskStatus()

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

    # no changes.

    if (self.job_status not in (constants.JOB_STATUS_QUEUED,

                                constants.JOB_STATUS_RUNNING,

                                constants.JOB_STATUS_WAITLOCK) or

        self.prev_job_info != self.job_info or

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

      logging.debug("Job %s changed", self.job_id)

      return (self.job_info, self.log_entries)

    raise utils.RetryAgain()

  def OnInotify(self, notifier_enabled):

    if not notifier_enabled:

      self.inotify_handler.enable()

  def WaitFn(self, timeout):

    self._SetupInotify()

    if self.notifier.check_events(timeout*1000):

      self.notifier.read_events()

    self.notifier.process_events()

  def WaitForChanges(self, timeout):

    try:

      return utils.Retry(self._CheckForChanges,

                         utils.RETRY_REMAINING_TIME,

                         timeout,

                         wait_fn=self.WaitFn)

    except (errors.InotifyError, errors.JobLost):

      return None

    except utils.RetryTimeout:

      return constants.JOB_NOTCHANGED

  def Close(self):

    if self.wm:

      self.notifier.stop()

class _JobQueueWorker(workerpool.BaseWorker):

  """The actual job workers.

  """

  def RunTask(self, job): # pylint: disable-msg=W0221

    """Job executor.

    This functions processes a job. It is closely tied to the _QueuedJob and

    _QueuedOpCode classes.

    @type job: L{_QueuedJob}

    @param job: the job to be processed

    """

    logging.info("Processing job %s", job.id)

    proc = mcpu.Processor(self.pool.queue.context, job.id)

    queue = job.queue

    try:

      try:

        count = len(job.ops)

        for idx, op in enumerate(job.ops):

          op_summary = op.input.Summary()

          if op.status == constants.OP_STATUS_SUCCESS:

            # this is a job that was partially completed before master

            # daemon shutdown, so it can be expected that some opcodes

            # are already completed successfully (if any did error

            # out, then the whole job should have been aborted and not

            # resubmitted for processing)

            logging.info("Op %s/%s: opcode %s already processed, skipping",

                         idx + 1, count, op_summary)

            continue

          try:

            logging.info("Op %s/%s: Starting opcode %s", idx + 1, count,

                         op_summary)

            queue.acquire(shared=1)

            try:

              if op.status == constants.OP_STATUS_CANCELED:

                raise CancelJob()

              assert op.status == constants.OP_STATUS_QUEUED

              op.status = constants.OP_STATUS_WAITLOCK

              op.result = None

              op.start_timestamp = TimeStampNow()

              if idx == 0: # first opcode

                job.start_timestamp = op.start_timestamp

              queue.UpdateJobUnlocked(job)

              input_opcode = op.input

            finally:

              queue.release()

            # Make sure not to hold queue lock while calling ExecOpCode

            result = proc.ExecOpCode(input_opcode,

                                     _OpExecCallbacks(queue, job, op))

            queue.acquire(shared=1)

            try:

              op.status = constants.OP_STATUS_SUCCESS

              op.result = result

              op.end_timestamp = TimeStampNow()

              queue.UpdateJobUnlocked(job)

            finally:

              queue.release()

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

                         idx + 1, count, op_summary)

          except CancelJob:

            # Will be handled further up

            raise

          except Exception, err:

            queue.acquire(shared=1)

            try:

              try:

                op.status = constants.OP_STATUS_ERROR

                if isinstance(err, errors.GenericError):

                  op.result = errors.EncodeException(err)

                else:

                  op.result = str(err)

                op.end_timestamp = TimeStampNow()

                logging.info("Op %s/%s: Error in opcode %s: %s",

                             idx + 1, count, op_summary, err)

              finally:

                queue.UpdateJobUnlocked(job)

            finally:

              queue.release()

            raise

      except CancelJob:

        queue.acquire(shared=1)

        try:

          job.MarkUnfinishedOps(constants.OP_STATUS_CANCELED,

                                "Job canceled by request")

        finally:

          queue.release()

      except errors.GenericError, err:

        logging.exception("Ganeti exception")

      except:

        logging.exception("Unhandled exception")

    finally:

      queue.acquire(shared=1)

      try:

        try:

          job.lock_status = None

          job.end_timestamp = TimeStampNow()

          queue.UpdateJobUnlocked(job)

        finally:

          job_id = job.id

          status = job.CalcStatus()

      finally:

        queue.release()

      logging.info("Finished job %s, status = %s", job_id, status)

class _JobQueueWorkerPool(workerpool.WorkerPool):

  """Simple class implementing a job-processing workerpool.

  """

  def __init__(self, queue):

    super(_JobQueueWorkerPool, self).__init__("JobQueue",

                                              JOBQUEUE_THREADS,

                                              _JobQueueWorker)

    self.queue = queue

def _RequireOpenQueue(fn):

  """Decorator for "public" functions.

  This function should be used for all 'public' functions. That is,

  functions usually called from other classes. Note that this should

  be applied only to methods (not plain functions), since it expects

  that the decorated function is called with a first argument that has

  a '_queue_filelock' argument.

  @warning: Use this decorator only after locking.ssynchronized

  Example::

    @locking.ssynchronized(_big_jqueue_lock)

    @_RequireOpenQueue

    def Example(self):

      pass

  """

  def wrapper(self, *args, **kwargs):

    # pylint: disable-msg=W0212

    assert self._queue_filelock is not None, "Queue should be open"

    return fn(self, *args, **kwargs)

  return wrapper