Synnefo » snf-ganeti

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#

# Copyright (C) 2006, 2007 Google Inc.

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# 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

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# This program is distributed in the hope that it will be useful, but

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# General Public License for more details.

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# 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 logic behind the cluster operations

This module implements the logic for doing operations in the cluster. There

are two kinds of classes defined:

  - logical units, which know how to deal with their specific opcode only

  - the processor, which dispatches the opcodes to their logical units

"""

import logging

import random

import time

from ganeti import opcodes

from ganeti import constants

from ganeti import errors

from ganeti import rpc

from ganeti import cmdlib

from ganeti import locking

from ganeti import utils

class _LockAcquireTimeout(Exception):

  """Internal exception to report timeouts on acquiring locks.

  """

class _LockTimeoutStrategy(object):

  """Class with lock acquire timeout strategy.

  """

  __slots__ = [

    "_attempts",

    "_random_fn",

    "_start_time",

    ]

  _MAX_ATTEMPTS = 10

  """How many retries before going into blocking mode"""

  _ATTEMPT_FACTOR = 1.75

  """Factor between attempts"""

  def __init__(self, _random_fn=None):

    """Initializes this class.

    @param _random_fn: Random number generator for unittests

    """

    object.__init__(self)

    self._start_time = None

    self._attempts = 0

    if _random_fn is None:

      self._random_fn = random.random

    else:

      self._random_fn = _random_fn

  def NextAttempt(self):

    """Advances to the next attempt.

    """

    assert self._attempts >= 0

    self._attempts += 1

  def CalcRemainingTimeout(self):

    """Returns the remaining timeout.

    """

    assert self._attempts >= 0

    if self._attempts == self._MAX_ATTEMPTS:

      # Only blocking acquires after 10 retries

      return None

    if self._attempts > self._MAX_ATTEMPTS:

      raise RuntimeError("Blocking acquire ran into timeout")

    # Get start time on first calculation

    if self._start_time is None:

      self._start_time = time.time()

    # Calculate remaining time for this attempt

    timeout = (self._start_time + (self._ATTEMPT_FACTOR ** self._attempts) -

               time.time())

    if timeout > 10.0:

      # Cap timeout at 10 seconds. This gives other jobs a chance to run

      # even if we're still trying to get our locks, before finally moving

      # to a blocking acquire.

      timeout = 10.0

    elif timeout < 0.1:

      # Lower boundary

      timeout = 0.1

    # Add a small variation (-/+ 5%) to timeouts. This helps in situations

    # where two or more jobs are fighting for the same lock(s).

    variation_range = timeout * 0.1

    timeout += (self._random_fn() * variation_range) - (variation_range * 0.5)

    assert timeout >= 0.0, "Timeout must be positive"

    return timeout

class OpExecCbBase:

  """Base class for OpCode execution callbacks.

  """

  def NotifyStart(self):

    """Called when we are about to execute the LU.

    This function is called when we're about to start the lu's Exec() method,

    that is, after we have acquired all locks.

    """

  def Feedback(self, *args):

    """Sends feedback from the LU code to the end-user.

    """

  def ReportLocks(self, msg):

    """Report lock operations.

    """

class Processor(object):

  """Object which runs OpCodes"""

  DISPATCH_TABLE = {

    # Cluster

    opcodes.OpPostInitCluster: cmdlib.LUPostInitCluster,

    opcodes.OpDestroyCluster: cmdlib.LUDestroyCluster,

    opcodes.OpQueryClusterInfo: cmdlib.LUQueryClusterInfo,

    opcodes.OpVerifyCluster: cmdlib.LUVerifyCluster,

    opcodes.OpQueryConfigValues: cmdlib.LUQueryConfigValues,

    opcodes.OpRenameCluster: cmdlib.LURenameCluster,

    opcodes.OpVerifyDisks: cmdlib.LUVerifyDisks,

    opcodes.OpSetClusterParams: cmdlib.LUSetClusterParams,

    opcodes.OpRedistributeConfig: cmdlib.LURedistributeConfig,

    opcodes.OpRepairDiskSizes: cmdlib.LURepairDiskSizes,

    # node lu

    opcodes.OpAddNode: cmdlib.LUAddNode,

    opcodes.OpQueryNodes: cmdlib.LUQueryNodes,

    opcodes.OpQueryNodeVolumes: cmdlib.LUQueryNodeVolumes,

    opcodes.OpQueryNodeStorage: cmdlib.LUQueryNodeStorage,

    opcodes.OpModifyNodeStorage: cmdlib.LUModifyNodeStorage,

    opcodes.OpRepairNodeStorage: cmdlib.LURepairNodeStorage,

    opcodes.OpRemoveNode: cmdlib.LURemoveNode,

    opcodes.OpSetNodeParams: cmdlib.LUSetNodeParams,

    opcodes.OpPowercycleNode: cmdlib.LUPowercycleNode,

    opcodes.OpEvacuateNode: cmdlib.LUEvacuateNode,

    opcodes.OpMigrateNode: cmdlib.LUMigrateNode,

    # instance lu

    opcodes.OpCreateInstance: cmdlib.LUCreateInstance,

    opcodes.OpReinstallInstance: cmdlib.LUReinstallInstance,

    opcodes.OpRemoveInstance: cmdlib.LURemoveInstance,

    opcodes.OpRenameInstance: cmdlib.LURenameInstance,

    opcodes.OpActivateInstanceDisks: cmdlib.LUActivateInstanceDisks,

    opcodes.OpShutdownInstance: cmdlib.LUShutdownInstance,

    opcodes.OpStartupInstance: cmdlib.LUStartupInstance,

    opcodes.OpRebootInstance: cmdlib.LURebootInstance,

    opcodes.OpDeactivateInstanceDisks: cmdlib.LUDeactivateInstanceDisks,

    opcodes.OpReplaceDisks: cmdlib.LUReplaceDisks,

    opcodes.OpRecreateInstanceDisks: cmdlib.LURecreateInstanceDisks,

    opcodes.OpFailoverInstance: cmdlib.LUFailoverInstance,

    opcodes.OpMigrateInstance: cmdlib.LUMigrateInstance,

    opcodes.OpMoveInstance: cmdlib.LUMoveInstance,

    opcodes.OpConnectConsole: cmdlib.LUConnectConsole,

    opcodes.OpQueryInstances: cmdlib.LUQueryInstances,

    opcodes.OpQueryInstanceData: cmdlib.LUQueryInstanceData,

    opcodes.OpSetInstanceParams: cmdlib.LUSetInstanceParams,

    opcodes.OpGrowDisk: cmdlib.LUGrowDisk,

    # os lu

    opcodes.OpDiagnoseOS: cmdlib.LUDiagnoseOS,

    # exports lu

    opcodes.OpQueryExports: cmdlib.LUQueryExports,

    opcodes.OpExportInstance: cmdlib.LUExportInstance,

    opcodes.OpRemoveExport: cmdlib.LURemoveExport,

    # tags lu

    opcodes.OpGetTags: cmdlib.LUGetTags,

    opcodes.OpSearchTags: cmdlib.LUSearchTags,

    opcodes.OpAddTags: cmdlib.LUAddTags,

    opcodes.OpDelTags: cmdlib.LUDelTags,

    # test lu

    opcodes.OpTestDelay: cmdlib.LUTestDelay,

    opcodes.OpTestAllocator: cmdlib.LUTestAllocator,

    }

  def __init__(self, context):

    """Constructor for Processor

    """

    self.context = context

    self._cbs = None

    self.rpc = rpc.RpcRunner(context.cfg)

    self.hmclass = HooksMaster

  def _ReportLocks(self, level, names, shared, timeout, acquired, result):

    """Reports lock operations.

    @type level: int

    @param level: Lock level

    @type names: list or string

    @param names: Lock names

    @type shared: bool

    @param shared: Whether the locks should be acquired in shared mode

    @type timeout: None or float

    @param timeout: Timeout for acquiring the locks

    @type acquired: bool

    @param acquired: Whether the locks have already been acquired

    @type result: None or set

    @param result: Result from L{locking.GanetiLockManager.acquire}

    """

    parts = []

    # Build message

    if acquired:

      if result is None:

        parts.append("timeout")

      else:

        parts.append("acquired")

    else:

      parts.append("waiting")

      if timeout is None:

        parts.append("blocking")

      else:

        parts.append("timeout=%0.6fs" % timeout)

    parts.append(locking.LEVEL_NAMES[level])

    if names == locking.ALL_SET:

      parts.append("ALL")

    elif isinstance(names, basestring):

      parts.append(names)

    else:

      parts.append(",".join(names))

    if shared:

      parts.append("shared")

    else:

      parts.append("exclusive")

    msg = "/".join(parts)

    logging.debug("LU locks %s", msg)

    if self._cbs:

      self._cbs.ReportLocks(msg)

  def _AcquireLocks(self, level, names, shared, timeout):

    """Acquires locks via the Ganeti lock manager.

    @type level: int

    @param level: Lock level

    @type names: list or string

    @param names: Lock names

    @type shared: bool

    @param shared: Whether the locks should be acquired in shared mode

    @type timeout: None or float

    @param timeout: Timeout for acquiring the locks

    """

    self._ReportLocks(level, names, shared, timeout, False, None)

    acquired = self.context.glm.acquire(level, names, shared=shared,

                                        timeout=timeout)

    self._ReportLocks(level, names, shared, timeout, True, acquired)

    return acquired

  def _ExecLU(self, lu):

    """Logical Unit execution sequence.

    """

    write_count = self.context.cfg.write_count

    lu.CheckPrereq()

    hm = HooksMaster(self.rpc.call_hooks_runner, lu)

    h_results = hm.RunPhase(constants.HOOKS_PHASE_PRE)

    lu.HooksCallBack(constants.HOOKS_PHASE_PRE, h_results,

                     self._Feedback, None)

    if getattr(lu.op, "dry_run", False):

      # in this mode, no post-hooks are run, and the config is not

      # written (as it might have been modified by another LU, and we

      # shouldn't do writeout on behalf of other threads

      self.LogInfo("dry-run mode requested, not actually executing"

                   " the operation")

      return lu.dry_run_result

    try:

      result = lu.Exec(self._Feedback)

      h_results = hm.RunPhase(constants.HOOKS_PHASE_POST)

      result = lu.HooksCallBack(constants.HOOKS_PHASE_POST, h_results,

                                self._Feedback, result)

    finally:

      # FIXME: This needs locks if not lu_class.REQ_BGL

      if write_count != self.context.cfg.write_count:

        hm.RunConfigUpdate()

    return result

  def _LockAndExecLU(self, lu, level, calc_timeout):

    """Execute a Logical Unit, with the needed locks.

    This is a recursive function that starts locking the given level, and

    proceeds up, till there are no more locks to acquire. Then it executes the

    given LU and its opcodes.

    """

    adding_locks = level in lu.add_locks

    acquiring_locks = level in lu.needed_locks

    if level not in locking.LEVELS:

      if self._cbs:

        self._cbs.NotifyStart()

      result = self._ExecLU(lu)

    elif adding_locks and acquiring_locks:

      # We could both acquire and add locks at the same level, but for now we

      # don't need this, so we'll avoid the complicated code needed.

      raise NotImplementedError("Can't declare locks to acquire when adding"

                                " others")

    elif adding_locks or acquiring_locks:

      lu.DeclareLocks(level)

      share = lu.share_locks[level]

      try:

        assert adding_locks ^ acquiring_locks, \

          "Locks must be either added or acquired"

        if acquiring_locks:

          # Acquiring locks

          needed_locks = lu.needed_locks[level]

          acquired = self._AcquireLocks(level, needed_locks, share,

                                        calc_timeout())

          if acquired is None:

            raise _LockAcquireTimeout()

          lu.acquired_locks[level] = acquired

        else:

          # Adding locks

          add_locks = lu.add_locks[level]

          lu.remove_locks[level] = add_locks

          try:

            self.context.glm.add(level, add_locks, acquired=1, shared=share)

          except errors.LockError:

            raise errors.OpPrereqError(

              "Couldn't add locks (%s), probably because of a race condition"

              " with another job, who added them first" % add_locks)

          lu.acquired_locks[level] = add_locks

        try:

          result = self._LockAndExecLU(lu, level + 1, calc_timeout)

        finally:

          if level in lu.remove_locks:

            self.context.glm.remove(level, lu.remove_locks[level])

      finally:

        if self.context.glm.is_owned(level):

          self.context.glm.release(level)

    else:

      result = self._LockAndExecLU(lu, level + 1, calc_timeout)

    return result

  def ExecOpCode(self, op, cbs):

    """Execute an opcode.

    @type op: an OpCode instance

    @param op: the opcode to be executed

    @type cbs: L{OpExecCbBase}

    @param cbs: Runtime callbacks

    """

    if not isinstance(op, opcodes.OpCode):

      raise errors.ProgrammerError("Non-opcode instance passed"

                                   " to ExecOpcode")

    self._cbs = cbs

    try:

      lu_class = self.DISPATCH_TABLE.get(op.__class__, None)

      if lu_class is None:

        raise errors.OpCodeUnknown("Unknown opcode")

      timeout_strategy = _LockTimeoutStrategy()

      calc_timeout = timeout_strategy.CalcRemainingTimeout

      while True:

        try:

          # Acquire the Big Ganeti Lock exclusively if this LU requires it,

          # and in a shared fashion otherwise (to prevent concurrent run with

          # an exclusive LU.

          if self._AcquireLocks(locking.LEVEL_CLUSTER, locking.BGL,

                                not lu_class.REQ_BGL, calc_timeout()) is None:

            raise _LockAcquireTimeout()

          try:

            lu = lu_class(self, op, self.context, self.rpc)

            lu.ExpandNames()

            assert lu.needed_locks is not None, "needed_locks not set by LU"

            return self._LockAndExecLU(lu, locking.LEVEL_INSTANCE, calc_timeout)

          finally:

            self.context.glm.release(locking.LEVEL_CLUSTER)

        except _LockAcquireTimeout:

          # Timeout while waiting for lock, try again

          pass

        timeout_strategy.NextAttempt()

    finally:

      self._cbs = None

  def _Feedback(self, *args):

    """Forward call to feedback callback function.

    """

    if self._cbs:

      self._cbs.Feedback(*args)

  def LogStep(self, current, total, message):

    """Log a change in LU execution progress.

    """

    logging.debug("Step %d/%d %s", current, total, message)

    self._Feedback("STEP %d/%d %s" % (current, total, message))

  def LogWarning(self, message, *args, **kwargs):

    """Log a warning to the logs and the user.

    The optional keyword argument is 'hint' and can be used to show a

    hint to the user (presumably related to the warning). If the

    message is empty, it will not be printed at all, allowing one to

    show only a hint.

    """

    assert not kwargs or (len(kwargs) == 1 and "hint" in kwargs), \

           "Invalid keyword arguments for LogWarning (%s)" % str(kwargs)

    if args:

      message = message % tuple(args)

    if message:

      logging.warning(message)

      self._Feedback(" - WARNING: %s" % message)

    if "hint" in kwargs:

      self._Feedback("      Hint: %s" % kwargs["hint"])

  def LogInfo(self, message, *args):

    """Log an informational message to the logs and the user.

    """

    if args:

      message = message % tuple(args)

    logging.info(message)

    self._Feedback(" - INFO: %s" % message)

class HooksMaster(object):

  """Hooks master.

  This class distributes the run commands to the nodes based on the

  specific LU class.

  In order to remove the direct dependency on the rpc module, the

  constructor needs a function which actually does the remote

  call. This will usually be rpc.call_hooks_runner, but any function

  which behaves the same works.

  """

  def __init__(self, callfn, lu):

    self.callfn = callfn

    self.lu = lu

    self.op = lu.op

    self.env, node_list_pre, node_list_post = self._BuildEnv()

    self.node_list = {constants.HOOKS_PHASE_PRE: node_list_pre,

                      constants.HOOKS_PHASE_POST: node_list_post}

  def _BuildEnv(self):

    """Compute the environment and the target nodes.

    Based on the opcode and the current node list, this builds the

    environment for the hooks and the target node list for the run.

    """

    env = {

      "PATH": "/sbin:/bin:/usr/sbin:/usr/bin",

      "GANETI_HOOKS_VERSION": constants.HOOKS_VERSION,

      "GANETI_OP_CODE": self.op.OP_ID,

      "GANETI_OBJECT_TYPE": self.lu.HTYPE,

      "GANETI_DATA_DIR": constants.DATA_DIR,

      }

    if self.lu.HPATH is not None:

      lu_env, lu_nodes_pre, lu_nodes_post = self.lu.BuildHooksEnv()

      if lu_env:

        for key in lu_env:

          env["GANETI_" + key] = lu_env[key]

    else:

      lu_nodes_pre = lu_nodes_post = []

    return env, frozenset(lu_nodes_pre), frozenset(lu_nodes_post)

  def _RunWrapper(self, node_list, hpath, phase):

    """Simple wrapper over self.callfn.

    This method fixes the environment before doing the rpc call.

    """

    env = self.env.copy()

    env["GANETI_HOOKS_PHASE"] = phase

    env["GANETI_HOOKS_PATH"] = hpath

    if self.lu.cfg is not None:

      env["GANETI_CLUSTER"] = self.lu.cfg.GetClusterName()

      env["GANETI_MASTER"] = self.lu.cfg.GetMasterNode()

    env = dict([(str(key), str(val)) for key, val in env.iteritems()])

    return self.callfn(node_list, hpath, phase, env)

  def RunPhase(self, phase, nodes=None):

    """Run all the scripts for a phase.

    This is the main function of the HookMaster.

    @param phase: one of L{constants.HOOKS_PHASE_POST} or

        L{constants.HOOKS_PHASE_PRE}; it denotes the hooks phase

    @param nodes: overrides the predefined list of nodes for the given phase

    @return: the processed results of the hooks multi-node rpc call

    @raise errors.HooksFailure: on communication failure to the nodes

    @raise errors.HooksAbort: on failure of one of the hooks

    """

    if not self.node_list[phase] and not nodes:

      # empty node list, we should not attempt to run this as either

      # we're in the cluster init phase and the rpc client part can't

      # even attempt to run, or this LU doesn't do hooks at all

      return

    hpath = self.lu.HPATH

    if nodes is not None:

      results = self._RunWrapper(nodes, hpath, phase)

    else:

      results = self._RunWrapper(self.node_list[phase], hpath, phase)

    errs = []

    if not results:

      msg = "Communication Failure"

      if phase == constants.HOOKS_PHASE_PRE:

        raise errors.HooksFailure(msg)

      else:

        self.lu.LogWarning(msg)

        return results

    for node_name in results:

      res = results[node_name]

      if res.offline:

        continue

      msg = res.fail_msg

      if msg:

        self.lu.LogWarning("Communication failure to node %s: %s",

                           node_name, msg)

        continue

      for script, hkr, output in res.payload:

        if hkr == constants.HKR_FAIL:

          if phase == constants.HOOKS_PHASE_PRE:

            errs.append((node_name, script, output))

          else:

            if not output:

              output = "(no output)"

            self.lu.LogWarning("On %s script %s failed, output: %s" %

                               (node_name, script, output))

    if errs and phase == constants.HOOKS_PHASE_PRE:

      raise errors.HooksAbort(errs)

    return results

  def RunConfigUpdate(self):

    """Run the special configuration update hook

    This is a special hook that runs only on the master after each

    top-level LI if the configuration has been updated.

    """

    phase = constants.HOOKS_PHASE_POST

    hpath = constants.HOOKS_NAME_CFGUPDATE

    nodes = [self.lu.cfg.GetMasterNode()]

    self._RunWrapper(nodes, hpath, phase)