X-Git-Url: https://code.grnet.gr/git/ganeti-local/blobdiff_plain/26082b7eb795cfbdf3dca0d86c808789687e4a62..4a78c361a6de3bcbf98f02abfe41ae3b11de2b00:/lib/locking.py diff --git a/lib/locking.py b/lib/locking.py index a0e418e..ea044d5 100644 --- a/lib/locking.py +++ b/lib/locking.py @@ -33,6 +33,7 @@ import weakref import logging import heapq import itertools +import time from ganeti import errors from ganeti import utils @@ -161,7 +162,7 @@ class _BaseCondition(object): except AttributeError: self._acquire_restore = self._base_acquire_restore try: - self._is_owned = lock._is_owned + self._is_owned = lock.is_owned except AttributeError: self._is_owned = self._base_is_owned @@ -404,12 +405,13 @@ class SharedLock(object): "__pending_by_prio", "__pending_shared", "__shr", + "__time_fn", "name", ] __condition_class = _PipeConditionWithMode - def __init__(self, name, monitor=None): + def __init__(self, name, monitor=None, _time_fn=time.time): """Construct a new SharedLock. @param name: the name of the lock @@ -421,6 +423,9 @@ class SharedLock(object): self.name = name + # Used for unittesting + self.__time_fn = _time_fn + # Internal lock self.__lock = threading.Lock() @@ -536,7 +541,7 @@ class SharedLock(object): else: return self.__is_exclusive() - def _is_owned(self, shared=-1): + def is_owned(self, shared=-1): """Is the current thread somehow owning the lock at this time? @param shared: @@ -551,7 +556,9 @@ class SharedLock(object): finally: self.__lock.release() - is_owned = _is_owned + #: Necessary to remain compatible with threading.Condition, which tries to + #: retrieve a locks' "_is_owned" attribute + _is_owned = is_owned def _count_pending(self): """Returns the number of pending acquires. @@ -682,24 +689,27 @@ class SharedLock(object): assert priority not in self.__pending_shared self.__pending_shared[priority] = wait_condition + wait_start = self.__time_fn() + acquired = False + try: # Wait until we become the topmost acquire in the queue or the timeout # expires. - # TODO: Decrease timeout with spurious notifications - while not (self.__is_on_top(wait_condition) and - self.__can_acquire(shared)): - # Wait for notification - wait_condition.wait(timeout) - self.__check_deleted() + while True: + if self.__is_on_top(wait_condition) and self.__can_acquire(shared): + self.__do_acquire(shared) + acquired = True + break - # A lot of code assumes blocking acquires always succeed. Loop - # internally for that case. - if timeout is not None: + # A lot of code assumes blocking acquires always succeed, therefore we + # can never return False for a blocking acquire + if (timeout is not None and + utils.TimeoutExpired(wait_start, timeout, _time_fn=self.__time_fn)): break - if self.__is_on_top(wait_condition) and self.__can_acquire(shared): - self.__do_acquire(shared) - return True + # Wait for notification + wait_condition.wait(timeout) + self.__check_deleted() finally: # Remove condition from queue if there are no more waiters if not wait_condition.has_waiting(): @@ -709,7 +719,7 @@ class SharedLock(object): # (e.g. on lock deletion) self.__pending_shared.pop(priority, None) - return False + return acquired def acquire(self, shared=0, timeout=None, priority=None, test_notify=None): @@ -796,19 +806,38 @@ class SharedLock(object): # Autodetect release type if self.__is_exclusive(): self.__exc = None + notify = True else: self.__shr.remove(threading.currentThread()) + notify = not self.__shr - # Notify topmost condition in queue - (priority, prioqueue) = self.__find_first_pending_queue() - if prioqueue: - cond = prioqueue[0] - cond.notifyAll() - if cond.shared: - # Prevent further shared acquires from sneaking in while waiters are - # notified - self.__pending_shared.pop(priority, None) + # Notify topmost condition in queue if there are no owners left (for + # shared locks) + if notify: + self.__notify_topmost() + finally: + self.__lock.release() + + def __notify_topmost(self): + """Notifies topmost condition in queue of pending acquires. + """ + (priority, prioqueue) = self.__find_first_pending_queue() + if prioqueue: + cond = prioqueue[0] + cond.notifyAll() + if cond.shared: + # Prevent further shared acquires from sneaking in while waiters are + # notified + self.__pending_shared.pop(priority, None) + + def _notify_topmost(self): + """Exported version of L{__notify_topmost}. + + """ + self.__lock.acquire() + try: + return self.__notify_topmost() finally: self.__lock.release() @@ -950,17 +979,53 @@ class LockSet: """ return self.__lockdict - def _is_owned(self): - """Is the current thread a current level owner?""" + def is_owned(self): + """Is the current thread a current level owner? + + @note: Use L{check_owned} to check if a specific lock is held + + """ return threading.currentThread() in self.__owners + def check_owned(self, names, shared=-1): + """Check if locks are owned in a specific mode. + + @type names: sequence or string + @param names: Lock names (or a single lock name) + @param shared: See L{SharedLock.is_owned} + @rtype: bool + @note: Use L{is_owned} to check if the current thread holds I{any} lock and + L{list_owned} to get the names of all owned locks + + """ + if isinstance(names, basestring): + names = [names] + + # Avoid check if no locks are owned anyway + if names and self.is_owned(): + candidates = [] + + # Gather references to all locks (in case they're deleted in the meantime) + for lname in names: + try: + lock = self.__lockdict[lname] + except KeyError: + raise errors.LockError("Non-existing lock '%s' in set '%s' (it may" + " have been removed)" % (lname, self.name)) + else: + candidates.append(lock) + + return compat.all(lock.is_owned(shared=shared) for lock in candidates) + else: + return False + def _add_owned(self, name=None): """Note the current thread owns the given lock""" if name is None: - if not self._is_owned(): + if not self.is_owned(): self.__owners[threading.currentThread()] = set() else: - if self._is_owned(): + if self.is_owned(): self.__owners[threading.currentThread()].add(name) else: self.__owners[threading.currentThread()] = set([name]) @@ -968,29 +1033,29 @@ class LockSet: def _del_owned(self, name=None): """Note the current thread owns the given lock""" - assert not (name is None and self.__lock._is_owned()), \ + assert not (name is None and self.__lock.is_owned()), \ "Cannot hold internal lock when deleting owner status" if name is not None: self.__owners[threading.currentThread()].remove(name) # Only remove the key if we don't hold the set-lock as well - if (not self.__lock._is_owned() and + if (not self.__lock.is_owned() and not self.__owners[threading.currentThread()]): del self.__owners[threading.currentThread()] - def _list_owned(self): + def list_owned(self): """Get the set of resource names owned by the current thread""" - if self._is_owned(): + if self.is_owned(): return self.__owners[threading.currentThread()].copy() else: return set() def _release_and_delete_owned(self): """Release and delete all resources owned by the current thread""" - for lname in self._list_owned(): + for lname in self.list_owned(): lock = self.__lockdict[lname] - if lock._is_owned(): + if lock.is_owned(): lock.release() self._del_owned(name=lname) @@ -1012,7 +1077,7 @@ class LockSet: # If we don't already own the set-level lock acquired # we'll get it and note we need to release it later. release_lock = False - if not self.__lock._is_owned(): + if not self.__lock.is_owned(): release_lock = True self.__lock.acquire(shared=1) try: @@ -1049,8 +1114,8 @@ class LockSet: assert timeout is None or timeout >= 0.0 # Check we don't already own locks at this level - assert not self._is_owned(), ("Cannot acquire locks in the same set twice" - " (lockset %s)" % self.name) + assert not self.is_owned(), ("Cannot acquire locks in the same set twice" + " (lockset %s)" % self.name) if priority is None: priority = _DEFAULT_PRIORITY @@ -1180,7 +1245,7 @@ class LockSet: # We shouldn't have problems adding the lock to the owners list, but # if we did we'll try to release this lock and re-raise exception. # Of course something is going to be really wrong after this. - if lock._is_owned(): + if lock.is_owned(): lock.release() raise @@ -1197,14 +1262,14 @@ class LockSet: The locks must have been acquired in exclusive mode. """ - assert self._is_owned(), ("downgrade on lockset %s while not owning any" - " lock" % self.name) + assert self.is_owned(), ("downgrade on lockset %s while not owning any" + " lock" % self.name) # Support passing in a single resource to downgrade rather than many if isinstance(names, basestring): names = [names] - owned = self._list_owned() + owned = self.list_owned() if names is None: names = owned @@ -1218,12 +1283,12 @@ class LockSet: self.__lockdict[lockname].downgrade() # Do we own the lockset in exclusive mode? - if self.__lock._is_owned(shared=0): + if self.__lock.is_owned(shared=0): # Have all locks been downgraded? - if not compat.any(lock._is_owned(shared=0) + if not compat.any(lock.is_owned(shared=0) for lock in self.__lockdict.values()): self.__lock.downgrade() - assert self.__lock._is_owned(shared=1) + assert self.__lock.is_owned(shared=1) return True @@ -1238,24 +1303,24 @@ class LockSet: (defaults to all the locks acquired at that level). """ - assert self._is_owned(), ("release() on lock set %s while not owner" % - self.name) + assert self.is_owned(), ("release() on lock set %s while not owner" % + self.name) # Support passing in a single resource to release rather than many if isinstance(names, basestring): names = [names] if names is None: - names = self._list_owned() + names = self.list_owned() else: names = set(names) - assert self._list_owned().issuperset(names), ( + assert self.list_owned().issuperset(names), ( "release() on unheld resources %s (set %s)" % - (names.difference(self._list_owned()), self.name)) + (names.difference(self.list_owned()), self.name)) # First of all let's release the "all elements" lock, if set. # After this 'add' can work again - if self.__lock._is_owned(): + if self.__lock.is_owned(): self.__lock.release() self._del_owned() @@ -1277,7 +1342,7 @@ class LockSet: """ # Check we don't already own locks at this level - assert not self._is_owned() or self.__lock._is_owned(shared=0), \ + assert not self.is_owned() or self.__lock.is_owned(shared=0), \ ("Cannot add locks if the set %s is only partially owned, or shared" % self.name) @@ -1288,7 +1353,7 @@ class LockSet: # If we don't already own the set-level lock acquired in an exclusive way # we'll get it and note we need to release it later. release_lock = False - if not self.__lock._is_owned(): + if not self.__lock.is_owned(): release_lock = True self.__lock.acquire() @@ -1351,7 +1416,7 @@ class LockSet: # If we own any subset of this lock it must be a superset of what we want # to delete. The ownership must also be exclusive, but that will be checked # by the lock itself. - assert not self._is_owned() or self._list_owned().issuperset(names), ( + assert not self.is_owned() or self.list_owned().issuperset(names), ( "remove() on acquired lockset %s while not owning all elements" % self.name) @@ -1368,8 +1433,8 @@ class LockSet: removed.append(lname) except (KeyError, errors.LockError): # This cannot happen if we were already holding it, verify: - assert not self._is_owned(), ("remove failed while holding lockset %s" - % self.name) + assert not self.is_owned(), ("remove failed while holding lockset %s" % + self.name) else: # If no LockError was raised we are the ones who deleted the lock. # This means we can safely remove it from lockdict, as any further or @@ -1380,7 +1445,7 @@ class LockSet: # it's the job of the one who actually deleted it. del self.__lockdict[lname] # And let's remove it from our private list if we owned it. - if self._is_owned(): + if self.is_owned(): self._del_owned(name=lname) return removed @@ -1399,24 +1464,35 @@ LEVEL_CLUSTER = 0 LEVEL_INSTANCE = 1 LEVEL_NODEGROUP = 2 LEVEL_NODE = 3 +LEVEL_NODE_RES = 4 -LEVELS = [LEVEL_CLUSTER, - LEVEL_INSTANCE, - LEVEL_NODEGROUP, - LEVEL_NODE] +LEVELS = [ + LEVEL_CLUSTER, + LEVEL_INSTANCE, + LEVEL_NODEGROUP, + LEVEL_NODE, + LEVEL_NODE_RES, + ] # Lock levels which are modifiable -LEVELS_MOD = [LEVEL_NODE, LEVEL_NODEGROUP, LEVEL_INSTANCE] - +LEVELS_MOD = frozenset([ + LEVEL_NODE_RES, + LEVEL_NODE, + LEVEL_NODEGROUP, + LEVEL_INSTANCE, + ]) + +#: Lock level names (make sure to use singular form) LEVEL_NAMES = { LEVEL_CLUSTER: "cluster", LEVEL_INSTANCE: "instance", LEVEL_NODEGROUP: "nodegroup", LEVEL_NODE: "node", + LEVEL_NODE_RES: "node-res", } # Constant for the big ganeti lock -BGL = 'BGL' +BGL = "BGL" class GanetiLockManager: @@ -1451,13 +1527,17 @@ class GanetiLockManager: # The keyring contains all the locks, at their level and in the correct # locking order. self.__keyring = { - LEVEL_CLUSTER: LockSet([BGL], "BGL", monitor=self._monitor), - LEVEL_NODE: LockSet(nodes, "nodes", monitor=self._monitor), - LEVEL_NODEGROUP: LockSet(nodegroups, "nodegroups", monitor=self._monitor), - LEVEL_INSTANCE: LockSet(instances, "instances", + LEVEL_CLUSTER: LockSet([BGL], "cluster", monitor=self._monitor), + LEVEL_NODE: LockSet(nodes, "node", monitor=self._monitor), + LEVEL_NODE_RES: LockSet(nodes, "node-res", monitor=self._monitor), + LEVEL_NODEGROUP: LockSet(nodegroups, "nodegroup", monitor=self._monitor), + LEVEL_INSTANCE: LockSet(instances, "instance", monitor=self._monitor), } + assert compat.all(ls.name == LEVEL_NAMES[level] + for (level, ls) in self.__keyring.items()) + def AddToLockMonitor(self, provider): """Registers a new lock with the monitor. @@ -1474,14 +1554,6 @@ class GanetiLockManager: """ return self._monitor.QueryLocks(fields) - def OldStyleQueryLocks(self, fields): - """Queries information from all locks, returning old-style data. - - See L{LockMonitor.OldStyleQueryLocks}. - - """ - return self._monitor.OldStyleQueryLocks(fields) - def _names(self, level): """List the lock names at the given level. @@ -1493,21 +1565,25 @@ class GanetiLockManager: assert level in LEVELS, "Invalid locking level %s" % level return self.__keyring[level]._names() - def _is_owned(self, level): + def is_owned(self, level): """Check whether we are owning locks at the given level """ - return self.__keyring[level]._is_owned() + return self.__keyring[level].is_owned() - is_owned = _is_owned - - def _list_owned(self, level): + def list_owned(self, level): """Get the set of owned locks at the given level """ - return self.__keyring[level]._list_owned() + return self.__keyring[level].list_owned() + + def check_owned(self, level, names, shared=-1): + """Check if locks at a certain level are owned in a specific mode. - list_owned = _list_owned + @see: L{LockSet.check_owned} + + """ + return self.__keyring[level].check_owned(names, shared=shared) def _upper_owned(self, level): """Check that we don't own any lock at a level greater than the given one. @@ -1515,7 +1591,7 @@ class GanetiLockManager: """ # This way of checking only works if LEVELS[i] = i, which we check for in # the test cases. - return compat.any((self._is_owned(l) for l in LEVELS[level + 1:])) + return compat.any((self.is_owned(l) for l in LEVELS[level + 1:])) def _BGL_owned(self): # pylint: disable=C0103 """Check if the current thread owns the BGL. @@ -1523,7 +1599,7 @@ class GanetiLockManager: Both an exclusive or a shared acquisition work. """ - return BGL in self.__keyring[LEVEL_CLUSTER]._list_owned() + return BGL in self.__keyring[LEVEL_CLUSTER].list_owned() @staticmethod def _contains_BGL(level, names): # pylint: disable=C0103 @@ -1605,7 +1681,7 @@ class GanetiLockManager: not self._upper_owned(LEVEL_CLUSTER)), ( "Cannot release the Big Ganeti Lock while holding something" " at upper levels (%r)" % - (utils.CommaJoin(["%s=%r" % (LEVEL_NAMES[i], self._list_owned(i)) + (utils.CommaJoin(["%s=%r" % (LEVEL_NAMES[i], self.list_owned(i)) for i in self.__keyring.keys()]), )) # Release will complain if we don't own the locks already @@ -1650,7 +1726,7 @@ class GanetiLockManager: # Check we either own the level or don't own anything from here # up. LockSet.remove() will check the case in which we don't own # all the needed resources, or we have a shared ownership. - assert self._is_owned(level) or not self._upper_owned(level), ( + assert self.is_owned(level) or not self._upper_owned(level), ( "Cannot remove locks at a level while not owning it or" " owning some at a greater one") return self.__keyring[level].remove(names) @@ -1751,14 +1827,3 @@ class LockMonitor(object): # Prepare query response return query.GetQueryResponse(qobj, ctx) - - def OldStyleQueryLocks(self, fields): - """Queries information from all locks, returning old-style data. - - @type fields: list of strings - @param fields: List of fields to return - - """ - (qobj, ctx) = self._Query(fields) - - return qobj.OldStyleQuery(ctx)