Revision 7ee7c0c7
| b/lib/locking.py | ||
|---|---|---|
| 26 | 26 |
# Wouldn't it be better to define LockingError in the locking module? |
| 27 | 27 |
# Well, for now that's how the rest of the code does it... |
| 28 | 28 |
from ganeti import errors |
| 29 |
from ganeti import utils |
|
| 29 | 30 |
|
| 30 | 31 |
|
| 31 | 32 |
class SharedLock: |
| ... | ... | |
| 555 | 556 |
|
| 556 | 557 |
return delete_failed |
| 557 | 558 |
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|
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# Locking levels, must be acquired in increasing order. |
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| 561 |
# Current rules are: |
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# - at level LEVEL_CLUSTER resides the Big Ganeti Lock (BGL) which must be |
|
| 563 |
# acquired before performing any operation, either in shared or in exclusive |
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| 564 |
# mode. acquiring the BGL in exclusive mode is discouraged and should be |
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| 565 |
# avoided. |
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# - at levels LEVEL_NODE and LEVEL_INSTANCE reside node and instance locks. |
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# If you need more than one node, or more than one instance, acquire them at |
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| 568 |
# the same time. |
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# - level LEVEL_CONFIG contains the configuration lock, which you must acquire |
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# before reading or changing the config file. |
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LEVEL_CLUSTER = 0 |
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LEVEL_NODE = 1 |
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LEVEL_INSTANCE = 2 |
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LEVEL_CONFIG = 3 |
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|
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LEVELS = [LEVEL_CLUSTER, |
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LEVEL_NODE, |
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LEVEL_INSTANCE, |
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LEVEL_CONFIG] |
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# Lock levels which are modifiable |
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LEVELS_MOD = [LEVEL_NODE, LEVEL_INSTANCE] |
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|
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# Constant for the big ganeti lock and config lock |
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BGL = 'BGL' |
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CONFIG = 'config' |
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|
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class GanetiLockManager: |
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"""The Ganeti Locking Library |
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The purpouse of this small library is to manage locking for ganeti clusters |
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in a central place, while at the same time doing dynamic checks against |
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possible deadlocks. It will also make it easier to transition to a different |
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lock type should we migrate away from python threads. |
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""" |
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_instance = None |
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|
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def __init__(self, nodes=None, instances=None): |
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"""Constructs a new GanetiLockManager object. |
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|
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There should be only a |
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GanetiLockManager object at any time, so this function raises an error if this |
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is not the case. |
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|
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Args: |
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nodes: list of node names |
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instances: list of instance names |
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""" |
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assert self.__class__._instance is None, "double GanetiLockManager instance" |
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self.__class__._instance = self |
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# The keyring contains all the locks, at their level and in the correct |
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# locking order. |
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self.__keyring = {
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LEVEL_CLUSTER: LockSet([BGL]), |
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LEVEL_NODE: LockSet(nodes), |
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LEVEL_INSTANCE: LockSet(instances), |
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LEVEL_CONFIG: LockSet([CONFIG]), |
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} |
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|
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def _names(self, level): |
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"""List the lock names at the given level. |
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Used for debugging/testing purposes. |
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Args: |
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level: the level whose list of locks to get |
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""" |
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assert level in LEVELS, "Invalid locking level %s" % level |
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return self.__keyring[level]._names() |
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def _is_owned(self, level): |
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"""Check whether we are owning locks at the given level |
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""" |
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return self.__keyring[level]._is_owned() |
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def _list_owned(self, level): |
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"""Get the set of owned locks at the given level |
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|
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""" |
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return self.__keyring[level]._list_owned() |
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|
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def _upper_owned(self, level): |
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"""Check that we don't own any lock at a level greater than the given one. |
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|
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""" |
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# This way of checking only works if LEVELS[i] = i, which we check for in |
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# the test cases. |
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return utils.any((self._is_owned(l) for l in LEVELS[level + 1:])) |
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|
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def _BGL_owned(self): |
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"""Check if the current thread owns the BGL. |
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| 657 |
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| 658 |
Both an exclusive or a shared acquisition work. |
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| 660 |
""" |
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return BGL in self.__keyring[LEVEL_CLUSTER]._list_owned() |
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|
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def _contains_BGL(self, level, names): |
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"""Check if acting on the given level and set of names will change the |
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status of the Big Ganeti Lock. |
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|
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""" |
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return level == LEVEL_CLUSTER and (names is None or BGL in names) |
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def acquire(self, level, names, blocking=1, shared=0): |
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"""Acquire a set of resource locks, at the same level. |
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Args: |
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level: the level at which the locks shall be acquired. |
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It must be a memmber of LEVELS. |
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names: the names of the locks which shall be acquired. |
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(special lock names, or instance/node names) |
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shared: whether to acquire in shared mode. By default an exclusive lock |
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will be acquired. |
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blocking: whether to block while trying to acquire or to operate in try-lock mode. |
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this locking mode is not supported yet. |
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""" |
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assert level in LEVELS, "Invalid locking level %s" % level |
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|
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# Check that we are either acquiring the Big Ganeti Lock or we already own |
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# it. Some "legacy" opcodes need to be sure they are run non-concurrently |
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# so even if we've migrated we need to at least share the BGL to be |
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# compatible with them. Of course if we own the BGL exclusively there's no |
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# point in acquiring any other lock, unless perhaps we are half way through |
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# the migration of the current opcode. |
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assert (self._contains_BGL(level, names) or self._BGL_owned()), ( |
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"You must own the Big Ganeti Lock before acquiring any other") |
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# Check we don't own locks at the same or upper levels. |
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assert not self._upper_owned(level), ("Cannot acquire locks at a level"
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" while owning some at a greater one") |
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|
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# Acquire the locks in the set. |
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return self.__keyring[level].acquire(names, shared=shared, |
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blocking=blocking) |
|
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|
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def release(self, level, names=None): |
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"""Release a set of resource locks, at the same level. |
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| 705 |
|
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You must have acquired the locks, either in shared or in exclusive mode, |
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before releasing them. |
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|
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Args: |
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level: the level at which the locks shall be released. |
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It must be a memmber of LEVELS. |
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names: the names of the locks which shall be released. |
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(defaults to all the locks acquired at that level). |
|
| 714 |
|
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| 715 |
""" |
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assert level in LEVELS, "Invalid locking level %s" % level |
|
| 717 |
assert (not self._contains_BGL(level, names) or |
|
| 718 |
not self._upper_owned(LEVEL_CLUSTER)), ( |
|
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"Cannot release the Big Ganeti Lock while holding something" |
|
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" at upper levels") |
|
| 721 |
|
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| 722 |
# Release will complain if we don't own the locks already |
|
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return self.__keyring[level].release(names) |
|
| 724 |
|
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| 725 |
def add(self, level, names, acquired=0, shared=0): |
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| 726 |
"""Add locks at the specified level. |
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| 728 |
Args: |
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| 729 |
level: the level at which the locks shall be added. |
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| 730 |
It must be a memmber of LEVELS_MOD. |
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| 731 |
names: names of the locks to acquire |
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| 732 |
acquired: whether to acquire the newly added locks |
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| 733 |
shared: whether the acquisition will be shared |
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| 734 |
""" |
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| 735 |
assert level in LEVELS_MOD, "Invalid or immutable level %s" % level |
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| 736 |
assert self._BGL_owned(), ("You must own the BGL before performing other"
|
|
| 737 |
" operations") |
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| 738 |
assert not self._upper_owned(level), ("Cannot add locks at a level"
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" while owning some at a greater one") |
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| 740 |
return self.__keyring[level].add(names, acquired=acquired, shared=shared) |
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| 741 |
|
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| 742 |
def remove(self, level, names, blocking=1): |
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| 743 |
"""Remove locks from the specified level. |
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| 744 |
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| 745 |
You must either already own the locks you are trying to remove exclusively |
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or not own any lock at an upper level. |
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| 747 |
|
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| 748 |
Args: |
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| 749 |
level: the level at which the locks shall be removed. |
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It must be a memmber of LEVELS_MOD. |
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| 751 |
names: the names of the locks which shall be removed. |
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| 752 |
(special lock names, or instance/node names) |
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| 753 |
blocking: whether to block while trying to operate in try-lock mode. |
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| 754 |
this locking mode is not supported yet. |
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| 755 |
|
|
| 756 |
""" |
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| 757 |
assert level in LEVELS_MOD, "Invalid or immutable level %s" % level |
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| 758 |
assert self._BGL_owned(), ("You must own the BGL before performing other"
|
|
| 759 |
" operations") |
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| 760 |
# Check we either own the level or don't own anything from here up. |
|
| 761 |
# LockSet.remove() will check the case in which we don't own all the needed |
|
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# resources, or we have a shared ownership. |
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| 763 |
assert self._is_owned(level) or not self._upper_owned(level), ( |
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| 764 |
"Cannot remove locks at a level while not owning it or" |
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" owning some at a greater one") |
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| 766 |
return self.__keyring[level].remove(names, blocking) |
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|
|
| b/test/ganeti.locking_unittest.py | ||
|---|---|---|
| 412 | 412 |
self.ls.release() |
| 413 | 413 |
|
| 414 | 414 |
|
| 415 |
class TestGanetiLockManager(unittest.TestCase): |
|
| 416 |
|
|
| 417 |
def setUp(self): |
|
| 418 |
self.nodes=['n1', 'n2'] |
|
| 419 |
self.instances=['i1', 'i2', 'i3'] |
|
| 420 |
self.GL = locking.GanetiLockManager(nodes=self.nodes, |
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| 421 |
instances=self.instances) |
|
| 422 |
self.done = Queue.Queue(0) |
|
| 423 |
|
|
| 424 |
def tearDown(self): |
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| 425 |
# Don't try this at home... |
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| 426 |
locking.GanetiLockManager._instance = None |
|
| 427 |
|
|
| 428 |
def testLockingConstants(self): |
|
| 429 |
# The locking library internally cheats by assuming its constants have some |
|
| 430 |
# relationships with each other. Check those hold true. |
|
| 431 |
for i in range(len(locking.LEVELS)): |
|
| 432 |
self.assertEqual(i, locking.LEVELS[i]) |
|
| 433 |
|
|
| 434 |
def testDoubleGLFails(self): |
|
| 435 |
# We are not passing test=True, so instantiating a new one should fail |
|
| 436 |
self.assertRaises(AssertionError, locking.GanetiLockManager) |
|
| 437 |
|
|
| 438 |
def testLockNames(self): |
|
| 439 |
self.assertEqual(self.GL._names(locking.LEVEL_CLUSTER), set(['BGL'])) |
|
| 440 |
self.assertEqual(self.GL._names(locking.LEVEL_NODE), set(self.nodes)) |
|
| 441 |
self.assertEqual(self.GL._names(locking.LEVEL_INSTANCE), set(self.instances)) |
|
| 442 |
self.assertEqual(self.GL._names(locking.LEVEL_CONFIG), set(['config'])) |
|
| 443 |
|
|
| 444 |
def testInitAndResources(self): |
|
| 445 |
locking.GanetiLockManager._instance = None |
|
| 446 |
self.GL = locking.GanetiLockManager() |
|
| 447 |
self.assertEqual(self.GL._names(locking.LEVEL_CLUSTER), set(['BGL'])) |
|
| 448 |
self.assertEqual(self.GL._names(locking.LEVEL_NODE), set()) |
|
| 449 |
self.assertEqual(self.GL._names(locking.LEVEL_INSTANCE), set()) |
|
| 450 |
self.assertEqual(self.GL._names(locking.LEVEL_CONFIG), set(['config'])) |
|
| 451 |
|
|
| 452 |
locking.GanetiLockManager._instance = None |
|
| 453 |
self.GL = locking.GanetiLockManager(nodes=self.nodes) |
|
| 454 |
self.assertEqual(self.GL._names(locking.LEVEL_CLUSTER), set(['BGL'])) |
|
| 455 |
self.assertEqual(self.GL._names(locking.LEVEL_NODE), set(self.nodes)) |
|
| 456 |
self.assertEqual(self.GL._names(locking.LEVEL_INSTANCE), set()) |
|
| 457 |
self.assertEqual(self.GL._names(locking.LEVEL_CONFIG), set(['config'])) |
|
| 458 |
|
|
| 459 |
locking.GanetiLockManager._instance = None |
|
| 460 |
self.GL = locking.GanetiLockManager(instances=self.instances) |
|
| 461 |
self.assertEqual(self.GL._names(locking.LEVEL_CLUSTER), set(['BGL'])) |
|
| 462 |
self.assertEqual(self.GL._names(locking.LEVEL_NODE), set()) |
|
| 463 |
self.assertEqual(self.GL._names(locking.LEVEL_INSTANCE), set(self.instances)) |
|
| 464 |
self.assertEqual(self.GL._names(locking.LEVEL_CONFIG), set(['config'])) |
|
| 465 |
|
|
| 466 |
def testAcquireRelease(self): |
|
| 467 |
self.GL.acquire(locking.LEVEL_CLUSTER, ['BGL'], shared=1) |
|
| 468 |
self.assertEquals(self.GL._list_owned(locking.LEVEL_CLUSTER), set(['BGL'])) |
|
| 469 |
self.GL.acquire(locking.LEVEL_NODE, ['n1', 'n2'], shared=1) |
|
| 470 |
self.GL.release(locking.LEVEL_NODE) |
|
| 471 |
self.GL.acquire(locking.LEVEL_NODE, ['n1']) |
|
| 472 |
self.assertEquals(self.GL._list_owned(locking.LEVEL_NODE), set(['n1'])) |
|
| 473 |
self.GL.acquire(locking.LEVEL_INSTANCE, ['i1', 'i2']) |
|
| 474 |
self.GL.acquire(locking.LEVEL_CONFIG, ['config']) |
|
| 475 |
self.GL.release(locking.LEVEL_INSTANCE, ['i2']) |
|
| 476 |
self.assertEquals(self.GL._list_owned(locking.LEVEL_INSTANCE), set(['i1'])) |
|
| 477 |
self.GL.release(locking.LEVEL_NODE) |
|
| 478 |
self.GL.release(locking.LEVEL_INSTANCE) |
|
| 479 |
self.GL.release(locking.LEVEL_CONFIG) |
|
| 480 |
self.assertRaises(errors.LockError, self.GL.acquire, |
|
| 481 |
locking.LEVEL_INSTANCE, ['i5']) |
|
| 482 |
self.GL.acquire(locking.LEVEL_INSTANCE, ['i3'], shared=1) |
|
| 483 |
self.assertEquals(self.GL._list_owned(locking.LEVEL_INSTANCE), set(['i3'])) |
|
| 484 |
|
|
| 485 |
def testBGLDependency(self): |
|
| 486 |
self.assertRaises(AssertionError, self.GL.acquire, |
|
| 487 |
locking.LEVEL_NODE, ['n1', 'n2']) |
|
| 488 |
self.assertRaises(AssertionError, self.GL.acquire, |
|
| 489 |
locking.LEVEL_INSTANCE, ['i3']) |
|
| 490 |
self.GL.acquire(locking.LEVEL_CLUSTER, ['BGL'], shared=1) |
|
| 491 |
self.GL.acquire(locking.LEVEL_NODE, ['n1']) |
|
| 492 |
self.assertRaises(AssertionError, self.GL.release, |
|
| 493 |
locking.LEVEL_CLUSTER, ['BGL']) |
|
| 494 |
self.assertRaises(AssertionError, self.GL.release, |
|
| 495 |
locking.LEVEL_CLUSTER) |
|
| 496 |
self.GL.release(locking.LEVEL_NODE) |
|
| 497 |
self.GL.acquire(locking.LEVEL_INSTANCE, ['i1', 'i2']) |
|
| 498 |
self.assertRaises(AssertionError, self.GL.release, |
|
| 499 |
locking.LEVEL_CLUSTER, ['BGL']) |
|
| 500 |
self.assertRaises(AssertionError, self.GL.release, |
|
| 501 |
locking.LEVEL_CLUSTER) |
|
| 502 |
self.GL.release(locking.LEVEL_INSTANCE) |
|
| 503 |
self.GL.acquire(locking.LEVEL_CONFIG, ['config']) |
|
| 504 |
self.assertRaises(AssertionError, self.GL.release, |
|
| 505 |
locking.LEVEL_CLUSTER) |
|
| 506 |
|
|
| 507 |
def testWrongOrder(self): |
|
| 508 |
self.GL.acquire(locking.LEVEL_CLUSTER, ['BGL'], shared=1) |
|
| 509 |
self.GL.acquire(locking.LEVEL_INSTANCE, ['i3']) |
|
| 510 |
self.assertRaises(AssertionError, self.GL.acquire, |
|
| 511 |
locking.LEVEL_NODE, ['n1']) |
|
| 512 |
self.assertRaises(AssertionError, self.GL.acquire, |
|
| 513 |
locking.LEVEL_INSTANCE, ['i2']) |
|
| 514 |
self.GL.acquire(locking.LEVEL_CONFIG, ['config']) |
|
| 515 |
self.assertRaises(AssertionError, self.GL.acquire, |
|
| 516 |
locking.LEVEL_CONFIG, ['config']) |
|
| 517 |
self.GL.release(locking.LEVEL_INSTANCE) |
|
| 518 |
self.assertRaises(AssertionError, self.GL.acquire, |
|
| 519 |
locking.LEVEL_NODE, ['n1']) |
|
| 520 |
self.assertRaises(AssertionError, self.GL.acquire, |
|
| 521 |
locking.LEVEL_INSTANCE, ['i2']) |
|
| 522 |
self.assertRaises(AssertionError, self.GL.acquire, |
|
| 523 |
locking.LEVEL_CONFIG, ['config']) |
|
| 524 |
|
|
| 525 |
# Helper function to run as a thread that shared the BGL and then acquires |
|
| 526 |
# some locks at another level. |
|
| 527 |
def _doLock(self, level, names, shared): |
|
| 528 |
try: |
|
| 529 |
self.GL.acquire(locking.LEVEL_CLUSTER, ['BGL'], shared=1) |
|
| 530 |
self.GL.acquire(level, names, shared=shared) |
|
| 531 |
self.done.put('DONE')
|
|
| 532 |
self.GL.release(level) |
|
| 533 |
self.GL.release(locking.LEVEL_CLUSTER) |
|
| 534 |
except errors.LockError: |
|
| 535 |
self.done.put('ERR')
|
|
| 536 |
|
|
| 537 |
def testConcurrency(self): |
|
| 538 |
self.GL.acquire(locking.LEVEL_CLUSTER, ['BGL'], shared=1) |
|
| 539 |
Thread(target=self._doLock, args=(locking.LEVEL_INSTANCE, 'i1', 1)).start() |
|
| 540 |
self.assertEqual(self.done.get(True, 1), 'DONE') |
|
| 541 |
self.GL.acquire(locking.LEVEL_NODE, ['n1']) |
|
| 542 |
self.GL.acquire(locking.LEVEL_INSTANCE, ['i3']) |
|
| 543 |
self.GL.acquire(locking.LEVEL_CONFIG, ['config']) |
|
| 544 |
Thread(target=self._doLock, args=(locking.LEVEL_INSTANCE, 'i1', 1)).start() |
|
| 545 |
self.assertEqual(self.done.get(True, 1), 'DONE') |
|
| 546 |
Thread(target=self._doLock, args=(locking.LEVEL_INSTANCE, 'i3', 1)).start() |
|
| 547 |
self.assertRaises(Queue.Empty, self.done.get, True, 0.2) |
|
| 548 |
self.GL.release(locking.LEVEL_CONFIG) |
|
| 549 |
self.GL.release(locking.LEVEL_INSTANCE) |
|
| 550 |
self.assertEqual(self.done.get(True, 1), 'DONE') |
|
| 551 |
self.GL.acquire(locking.LEVEL_INSTANCE, ['i2'], shared=1) |
|
| 552 |
Thread(target=self._doLock, args=(locking.LEVEL_INSTANCE, 'i2', 1)).start() |
|
| 553 |
self.assertEqual(self.done.get(True, 1), 'DONE') |
|
| 554 |
Thread(target=self._doLock, args=(locking.LEVEL_INSTANCE, 'i2', 0)).start() |
|
| 555 |
self.assertRaises(Queue.Empty, self.done.get, True, 0.2) |
|
| 556 |
self.GL.release(locking.LEVEL_INSTANCE) |
|
| 557 |
self.assertEqual(self.done.get(True, 1), 'DONE') |
|
| 558 |
|
|
| 559 |
|
|
| 415 | 560 |
if __name__ == '__main__': |
| 416 | 561 |
unittest.main() |
| 417 | 562 |
#suite = unittest.TestLoader().loadTestsFromTestCase(TestSharedLock) |
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