X-Git-Url: https://code.grnet.gr/git/ganeti-local/blobdiff_plain/b6b87034f8ff84b8051a8b3cbcc5f8dd1942c328..25c45709f7cfd0becb17ea002baad5b04bdb8cc6:/lib/locking.py?ds=sidebyside diff --git a/lib/locking.py b/lib/locking.py index b027661..d89388c 100644 --- a/lib/locking.py +++ b/lib/locking.py @@ -1,7 +1,7 @@ # # -# Copyright (C) 2006, 2007 Google Inc. +# Copyright (C) 2006, 2007, 2008, 2009, 2010 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 @@ -18,31 +18,52 @@ # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA # 02110-1301, USA. -# Disable "Invalid name ..." message -# pylint: disable-msg=C0103 - """Module implementing the Ganeti locking code.""" +# pylint: disable-msg=W0212 + +# W0212 since e.g. LockSet methods use (a lot) the internals of +# SharedLock + import os import select import threading import time import errno +import weakref +import logging +import heapq from ganeti import errors from ganeti import utils +from ganeti import compat + + +_EXCLUSIVE_TEXT = "exclusive" +_SHARED_TEXT = "shared" + +_DEFAULT_PRIORITY = 0 -def ssynchronized(lock, shared=0): +def ssynchronized(mylock, shared=0): """Shared Synchronization decorator. Calls the function holding the given lock, either in exclusive or shared mode. It requires the passed lock to be a SharedLock (or support its semantics). + @type mylock: lockable object or string + @param mylock: lock to acquire or class member name of the lock to acquire + """ def wrap(fn): def sync_function(*args, **kwargs): + if isinstance(mylock, basestring): + assert args, "cannot ssynchronize on non-class method: self not found" + # args[0] is "self" + lock = getattr(args[0], mylock) + else: + lock = mylock lock.acquire(shared=shared) try: return fn(*args, **kwargs) @@ -52,6 +73,59 @@ def ssynchronized(lock, shared=0): return wrap +class RunningTimeout(object): + """Class to calculate remaining timeout when doing several operations. + + """ + __slots__ = [ + "_allow_negative", + "_start_time", + "_time_fn", + "_timeout", + ] + + def __init__(self, timeout, allow_negative, _time_fn=time.time): + """Initializes this class. + + @type timeout: float + @param timeout: Timeout duration + @type allow_negative: bool + @param allow_negative: Whether to return values below zero + @param _time_fn: Time function for unittests + + """ + object.__init__(self) + + if timeout is not None and timeout < 0.0: + raise ValueError("Timeout must not be negative") + + self._timeout = timeout + self._allow_negative = allow_negative + self._time_fn = _time_fn + + self._start_time = None + + def Remaining(self): + """Returns the remaining timeout. + + """ + if self._timeout is None: + return None + + # Get start time on first calculation + if self._start_time is None: + self._start_time = self._time_fn() + + # Calculate remaining time + remaining_timeout = self._start_time + self._timeout - self._time_fn() + + if not self._allow_negative: + # Ensure timeout is always >= 0 + return max(0.0, remaining_timeout) + + return remaining_timeout + + class _SingleNotifyPipeConditionWaiter(object): """Helper class for SingleNotifyPipeCondition @@ -81,10 +155,18 @@ class _SingleNotifyPipeConditionWaiter(object): @param timeout: Timeout for waiting (can be None) """ - start_time = time.time() - remaining_time = timeout + running_timeout = RunningTimeout(timeout, True) + + while True: + remaining_time = running_timeout.Remaining() + + if remaining_time is not None: + if remaining_time < 0.0: + break + + # Our calculation uses seconds, poll() wants milliseconds + remaining_time *= 1000 - while timeout is None or remaining_time > 0: try: result = self._poller.poll(remaining_time) except EnvironmentError, err: @@ -96,10 +178,6 @@ class _SingleNotifyPipeConditionWaiter(object): if result and result[0][0] == self._fd: break - # Re-calculate timeout if necessary - if timeout is not None: - remaining_time = start_time + timeout - time.time() - class _BaseCondition(object): """Base class containing common code for conditions. @@ -111,6 +189,9 @@ class _BaseCondition(object): "_lock", "acquire", "release", + "_is_owned", + "_acquire_restore", + "_release_save", ] def __init__(self, lock): @@ -122,9 +203,18 @@ class _BaseCondition(object): """ object.__init__(self) - # Recursive locks are not supported - assert not hasattr(lock, "_acquire_restore") - assert not hasattr(lock, "_release_save") + try: + self._release_save = lock._release_save + except AttributeError: + self._release_save = self._base_release_save + try: + self._acquire_restore = lock._acquire_restore + except AttributeError: + self._acquire_restore = self._base_acquire_restore + try: + self._is_owned = lock._is_owned + except AttributeError: + self._is_owned = self._base_is_owned self._lock = lock @@ -132,16 +222,21 @@ class _BaseCondition(object): self.acquire = lock.acquire self.release = lock.release - def _is_owned(self): + def _base_is_owned(self): """Check whether lock is owned by current thread. """ if self._lock.acquire(0): self._lock.release() return False - return True + def _base_release_save(self): + self._lock.release() + + def _base_acquire_restore(self, _): + self._lock.acquire() + def _check_owned(self): """Raise an exception if the current thread doesn't own the lock. @@ -161,7 +256,7 @@ class SingleNotifyPipeCondition(_BaseCondition): """ - __slots__ = _BaseCondition.__slots__ + [ + __slots__ = [ "_poller", "_read_fd", "_write_fd", @@ -220,19 +315,19 @@ class SingleNotifyPipeCondition(_BaseCondition): self._poller.register(self._read_fd, select.POLLHUP) wait_fn = self._waiter_class(self._poller, self._read_fd) - self.release() + state = self._release_save() try: # Wait for notification wait_fn(timeout) finally: # Re-acquire lock - self.acquire() + self._acquire_restore(state) finally: self._nwaiters -= 1 if self._nwaiters == 0: self._Cleanup() - def notifyAll(self): + def notifyAll(self): # pylint: disable-msg=C0103 """Close the writing side of the pipe to notify all waiters. """ @@ -254,8 +349,8 @@ class PipeCondition(_BaseCondition): there are any waiting threads. """ - __slots__ = _BaseCondition.__slots__ + [ - "_nwaiters", + __slots__ = [ + "_waiters", "_single_condition", ] @@ -266,7 +361,7 @@ class PipeCondition(_BaseCondition): """ _BaseCondition.__init__(self, lock) - self._nwaiters = 0 + self._waiters = set() self._single_condition = self._single_condition_class(self._lock) def wait(self, timeout=None): @@ -280,17 +375,16 @@ class PipeCondition(_BaseCondition): # Keep local reference to the pipe. It could be replaced by another thread # notifying while we're waiting. - my_condition = self._single_condition + cond = self._single_condition - assert self._nwaiters >= 0 - self._nwaiters += 1 + self._waiters.add(threading.currentThread()) try: - my_condition.wait(timeout) + cond.wait(timeout) finally: - assert self._nwaiters > 0 - self._nwaiters -= 1 + self._check_owned() + self._waiters.remove(threading.currentThread()) - def notifyAll(self): + def notifyAll(self): # pylint: disable-msg=C0103 """Notify all currently waiting threads. """ @@ -298,102 +392,88 @@ class PipeCondition(_BaseCondition): self._single_condition.notifyAll() self._single_condition = self._single_condition_class(self._lock) - def has_waiting(self): - """Returns whether there are active waiters. + def get_waiting(self): + """Returns a list of all waiting threads. """ self._check_owned() - return bool(self._nwaiters) + return self._waiters + def has_waiting(self): + """Returns whether there are active waiters. -class _CountingCondition(object): - """Wrapper for Python's built-in threading.Condition class. + """ + self._check_owned() - This wrapper keeps a count of active waiters. We can't access the internal - "__waiters" attribute of threading.Condition because it's not thread-safe. + return bool(self._waiters) - """ + +class _PipeConditionWithMode(PipeCondition): __slots__ = [ - "_cond", - "_nwaiters", + "shared", ] - def __init__(self, lock): + def __init__(self, lock, shared): """Initializes this class. """ - object.__init__(self) - self._cond = threading.Condition(lock=lock) - self._nwaiters = 0 - - def notifyAll(self): - """Notifies the condition. - - """ - return self._cond.notifyAll() - - def wait(self, timeout=None): - """Waits for the condition to be notified. - - @type timeout: float or None - @param timeout: Waiting timeout (can be None) - - """ - assert self._nwaiters >= 0 - - self._nwaiters += 1 - try: - return self._cond.wait(timeout=timeout) - finally: - self._nwaiters -= 1 - - def has_waiting(self): - """Returns whether there are active waiters. - - """ - return bool(self._nwaiters) + self.shared = shared + PipeCondition.__init__(self, lock) class SharedLock(object): """Implements a shared lock. - Multiple threads can acquire the lock in a shared way, calling - acquire_shared(). In order to acquire the lock in an exclusive way threads - can call acquire_exclusive(). + Multiple threads can acquire the lock in a shared way by calling + C{acquire(shared=1)}. In order to acquire the lock in an exclusive way + threads can call C{acquire(shared=0)}. + + Notes on data structures: C{__pending} contains a priority queue (heapq) of + all pending acquires: C{[(priority1: prioqueue1), (priority2: prioqueue2), + ...]}. Each per-priority queue contains a normal in-order list of conditions + to be notified when the lock can be acquired. Shared locks are grouped + together by priority and the condition for them is stored in + C{__pending_shared} if it already exists. C{__pending_by_prio} keeps + references for the per-priority queues indexed by priority for faster access. - The lock prevents starvation but does not guarantee that threads will acquire - the shared lock in the order they queued for it, just that they will - eventually do so. + @type name: string + @ivar name: the name of the lock """ __slots__ = [ - "__active_shr_c", - "__inactive_shr_c", + "__weakref__", "__deleted", "__exc", "__lock", "__pending", + "__pending_by_prio", + "__pending_shared", "__shr", + "name", ] - __condition_class = PipeCondition + __condition_class = _PipeConditionWithMode - def __init__(self): + def __init__(self, name, monitor=None): """Construct a new SharedLock. + @param name: the name of the lock + @type monitor: L{LockMonitor} + @param monitor: Lock monitor with which to register + """ object.__init__(self) + self.name = name + # Internal lock self.__lock = threading.Lock() # Queue containing waiting acquires self.__pending = [] - - # Active and inactive conditions for shared locks - self.__active_shr_c = self.__condition_class(self.__lock) - self.__inactive_shr_c = self.__condition_class(self.__lock) + self.__pending_by_prio = {} + self.__pending_shared = {} # Current lock holders self.__shr = set() @@ -402,12 +482,78 @@ class SharedLock(object): # is this lock in the deleted state? self.__deleted = False + # Register with lock monitor + if monitor: + monitor.RegisterLock(self) + + def GetInfo(self, fields): + """Retrieves information for querying locks. + + @type fields: list of strings + @param fields: List of fields to return + + """ + self.__lock.acquire() + try: + info = [] + + # Note: to avoid unintentional race conditions, no references to + # modifiable objects should be returned unless they were created in this + # function. + for fname in fields: + if fname == "name": + info.append(self.name) + elif fname == "mode": + if self.__deleted: + info.append("deleted") + assert not (self.__exc or self.__shr) + elif self.__exc: + info.append(_EXCLUSIVE_TEXT) + elif self.__shr: + info.append(_SHARED_TEXT) + else: + info.append(None) + elif fname == "owner": + if self.__exc: + owner = [self.__exc] + else: + owner = self.__shr + + if owner: + assert not self.__deleted + info.append([i.getName() for i in owner]) + else: + info.append(None) + elif fname == "pending": + data = [] + + # Sorting instead of copying and using heaq functions for simplicity + for (_, prioqueue) in sorted(self.__pending): + for cond in prioqueue: + if cond.shared: + mode = _SHARED_TEXT + else: + mode = _EXCLUSIVE_TEXT + + # This function should be fast as it runs with the lock held. + # Hence not using utils.NiceSort. + data.append((mode, sorted(i.getName() + for i in cond.get_waiting()))) + + info.append(data) + else: + raise errors.OpExecError("Invalid query field '%s'" % fname) + + return info + finally: + self.__lock.release() + def __check_deleted(self): """Raises an exception if the lock has been deleted. """ if self.__deleted: - raise errors.LockError("Deleted lock") + raise errors.LockError("Deleted lock %s" % self.name) def __is_sharer(self): """Is the current thread sharing the lock at this time? @@ -458,7 +604,23 @@ class SharedLock(object): """ self.__lock.acquire() try: - return len(self.__pending) + return sum(len(prioqueue) for (_, prioqueue) in self.__pending) + finally: + self.__lock.release() + + def _check_empty(self): + """Checks whether there are any pending acquires. + + @rtype: bool + + """ + self.__lock.acquire() + try: + # Order is important: __find_first_pending_queue modifies __pending + return not (self.__find_first_pending_queue() or + self.__pending or + self.__pending_by_prio or + self.__pending_shared) finally: self.__lock.release() @@ -480,26 +642,52 @@ class SharedLock(object): else: return len(self.__shr) == 0 and self.__exc is None + def __find_first_pending_queue(self): + """Tries to find the topmost queued entry with pending acquires. + + Removes empty entries while going through the list. + + """ + while self.__pending: + (priority, prioqueue) = self.__pending[0] + + if not prioqueue: + heapq.heappop(self.__pending) + del self.__pending_by_prio[priority] + assert priority not in self.__pending_shared + continue + + if prioqueue: + return prioqueue + + return None + def __is_on_top(self, cond): """Checks whether the passed condition is on top of the queue. The caller must make sure the queue isn't empty. """ - return self.__pending[0] == cond + return cond == self.__find_first_pending_queue()[0] - def __acquire_unlocked(self, shared, timeout): + def __acquire_unlocked(self, shared, timeout, priority): """Acquire a shared lock. @param shared: whether to acquire in shared mode; by default an exclusive lock will be acquired @param timeout: maximum waiting time before giving up + @type priority: integer + @param priority: Priority for acquiring lock """ self.__check_deleted() # We cannot acquire the lock if we already have it - assert not self.__is_owned(), "double acquire() on a non-recursive lock" + assert not self.__is_owned(), ("double acquire() on a non-recursive lock" + " %s" % self.name) + + # Remove empty entries from queue + self.__find_first_pending_queue() # Check whether someone else holds the lock or there are pending acquires. if not self.__pending and self.__can_acquire(shared): @@ -507,20 +695,37 @@ class SharedLock(object): self.__do_acquire(shared) return True - if shared: - wait_condition = self.__active_shr_c + prioqueue = self.__pending_by_prio.get(priority, None) - # Check if we're not yet in the queue - if wait_condition not in self.__pending: - self.__pending.append(wait_condition) + if shared: + # Try to re-use condition for shared acquire + wait_condition = self.__pending_shared.get(priority, None) + assert (wait_condition is None or + (wait_condition.shared and wait_condition in prioqueue)) else: - wait_condition = self.__condition_class(self.__lock) - # Always add to queue - self.__pending.append(wait_condition) + wait_condition = None + + if wait_condition is None: + if prioqueue is None: + assert priority not in self.__pending_by_prio + + prioqueue = [] + heapq.heappush(self.__pending, (priority, prioqueue)) + self.__pending_by_prio[priority] = prioqueue + + wait_condition = self.__condition_class(self.__lock, shared) + prioqueue.append(wait_condition) + + if shared: + # Keep reference for further shared acquires on same priority. This is + # better than trying to find it in the list of pending acquires. + assert priority not in self.__pending_shared + self.__pending_shared[priority] = wait_condition 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 @@ -537,30 +742,38 @@ class SharedLock(object): return True finally: # Remove condition from queue if there are no more waiters - if not wait_condition.has_waiting() and not self.__deleted: - self.__pending.remove(wait_condition) + if not wait_condition.has_waiting(): + prioqueue.remove(wait_condition) + if wait_condition.shared: + del self.__pending_shared[priority] return False - def acquire(self, shared=0, timeout=None, test_notify=None): + def acquire(self, shared=0, timeout=None, priority=None, + test_notify=None): """Acquire a shared lock. - @type shared: int + @type shared: integer (0/1) used as a boolean @param shared: whether to acquire in shared mode; by default an exclusive lock will be acquired @type timeout: float @param timeout: maximum waiting time before giving up + @type priority: integer + @param priority: Priority for acquiring lock @type test_notify: callable or None @param test_notify: Special callback function for unittesting """ + if priority is None: + priority = _DEFAULT_PRIORITY + self.__lock.acquire() try: # We already got the lock, notify now if __debug__ and callable(test_notify): test_notify() - return self.__acquire_unlocked(shared, timeout) + return self.__acquire_unlocked(shared, timeout, priority) finally: self.__lock.release() @@ -583,18 +796,14 @@ class SharedLock(object): self.__shr.remove(threading.currentThread()) # Notify topmost condition in queue - if self.__pending: - first_condition = self.__pending[0] - first_condition.notifyAll() - - if first_condition == self.__active_shr_c: - self.__active_shr_c = self.__inactive_shr_c - self.__inactive_shr_c = first_condition + prioqueue = self.__find_first_pending_queue() + if prioqueue: + prioqueue[0].notifyAll() finally: self.__lock.release() - def delete(self, timeout=None): + def delete(self, timeout=None, priority=None): """Delete a Shared Lock. This operation will declare the lock for removal. First the lock will be @@ -603,8 +812,13 @@ class SharedLock(object): @type timeout: float @param timeout: maximum waiting time before giving up + @type priority: integer + @param priority: Priority for acquiring lock """ + if priority is None: + priority = _DEFAULT_PRIORITY + self.__lock.acquire() try: assert not self.__is_sharer(), "Cannot delete() a lock while sharing it" @@ -615,7 +829,7 @@ class SharedLock(object): acquired = self.__is_exclusive() if not acquired: - acquired = self.__acquire_unlocked(0, timeout) + acquired = self.__acquire_unlocked(0, timeout, priority) assert self.__is_exclusive() and not self.__is_sharer(), \ "Lock wasn't acquired in exclusive mode" @@ -624,14 +838,27 @@ class SharedLock(object): self.__deleted = True self.__exc = None + assert not (self.__exc or self.__shr), "Found owner during deletion" + # Notify all acquires. They'll throw an error. - while self.__pending: - self.__pending.pop().notifyAll() + for (_, prioqueue) in self.__pending: + for cond in prioqueue: + cond.notifyAll() + + assert self.__deleted return acquired finally: self.__lock.release() + def _release_save(self): + shared = self.__is_sharer() + self.release() + return shared + + def _acquire_restore(self, shared): + self.acquire(shared=shared) + # Whenever we want to acquire a full LockSet we pass None as the value # to acquire. Hide this behind this nicely named constant. @@ -654,23 +881,35 @@ class LockSet: All the locks needed in the same set must be acquired together, though. + @type name: string + @ivar name: the name of the lockset + """ - def __init__(self, members=None): + def __init__(self, members, name, monitor=None): """Constructs a new LockSet. + @type members: list of strings @param members: initial members of the set + @type monitor: L{LockMonitor} + @param monitor: Lock monitor with which to register member locks """ + assert members is not None, "members parameter is not a list" + self.name = name + + # Lock monitor + self.__monitor = monitor + # Used internally to guarantee coherency. - self.__lock = SharedLock() + self.__lock = SharedLock(name) # The lockdict indexes the relationship name -> lock # The order-of-locking is implied by the alphabetical order of names self.__lockdict = {} - if members is not None: - for name in members: - self.__lockdict[name] = SharedLock() + for mname in members: + self.__lockdict[mname] = SharedLock(self._GetLockName(mname), + monitor=monitor) # The owner dict contains the set of locks each thread owns. For # performance each thread can access its own key without a global lock on @@ -681,6 +920,12 @@ class LockSet: # will be trouble. self.__owners = {} + def _GetLockName(self, mname): + """Returns the name for a member lock. + + """ + return "%s/%s" % (self.name, mname) + def _is_owned(self): """Is the current thread a current level owner?""" return threading.currentThread() in self.__owners @@ -720,7 +965,9 @@ class LockSet: def _release_and_delete_owned(self): """Release and delete all resources owned by the current thread""" for lname in self._list_owned(): - self.__lockdict[lname].release() + lock = self.__lockdict[lname] + if lock._is_owned(): + lock.release() self._del_owned(name=lname) def __names(self): @@ -751,15 +998,20 @@ class LockSet: self.__lock.release() return set(result) - def acquire(self, names, timeout=None, shared=0, test_notify=None): + def acquire(self, names, timeout=None, shared=0, priority=None, + test_notify=None): """Acquire a set of resource locks. + @type names: list of strings (or string) @param names: the names of the locks which shall be acquired (special lock names, or instance/node names) + @type shared: integer (0/1) used as a boolean @param shared: whether to acquire in shared mode; by default an exclusive lock will be acquired @type timeout: float or None @param timeout: Maximum time to acquire all locks + @type priority: integer + @param priority: Priority for acquiring locks @type test_notify: callable or None @param test_notify: Special callback function for unittesting @@ -773,28 +1025,24 @@ 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" + assert not self._is_owned(), ("Cannot acquire locks in the same set twice" + " (lockset %s)" % self.name) + + if priority is None: + priority = _DEFAULT_PRIORITY # We need to keep track of how long we spent waiting for a lock. The # timeout passed to this function is over all lock acquires. - remaining_timeout = timeout - if timeout is None: - start = None - calc_remaining_timeout = lambda: None - else: - start = time.time() - calc_remaining_timeout = lambda: max(0.0, (start + timeout) - time.time()) + running_timeout = RunningTimeout(timeout, False) try: if names is not None: # Support passing in a single resource to acquire rather than many if isinstance(names, basestring): names = [names] - else: - names = sorted(names) - return self.__acquire_inner(names, False, shared, - calc_remaining_timeout, test_notify) + return self.__acquire_inner(names, False, shared, priority, + running_timeout.Remaining, test_notify) else: # If no names are given acquire the whole set by not letting new names @@ -802,19 +1050,19 @@ class LockSet: # Some of them may then be deleted later, but we'll cope with this. # # We'd like to acquire this lock in a shared way, as it's nice if - # everybody else can use the instances at the same time. If are + # everybody else can use the instances at the same time. If we are # acquiring them exclusively though they won't be able to do this # anyway, though, so we'll get the list lock exclusively as well in # order to be able to do add() on the set while owning it. - if not self.__lock.acquire(shared=shared, - timeout=calc_remaining_timeout()): + if not self.__lock.acquire(shared=shared, priority=priority, + timeout=running_timeout.Remaining()): raise _AcquireTimeout() try: # note we own the set-lock self._add_owned() - return self.__acquire_inner(self.__names(), True, shared, - calc_remaining_timeout, test_notify) + return self.__acquire_inner(self.__names(), True, shared, priority, + running_timeout.Remaining, test_notify) except: # 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. @@ -826,26 +1074,37 @@ class LockSet: except _AcquireTimeout: return None - def __acquire_inner(self, names, want_all, shared, timeout_fn, test_notify): - """ + def __acquire_inner(self, names, want_all, shared, priority, + timeout_fn, test_notify): + """Inner logic for acquiring a number of locks. + + @param names: Names of the locks to be acquired + @param want_all: Whether all locks in the set should be acquired + @param shared: Whether to acquire in shared mode + @param timeout_fn: Function returning remaining timeout + @param priority: Priority for acquiring locks + @param test_notify: Special callback function for unittesting """ acquire_list = [] # First we look the locks up on __lockdict. We have no way of being sure # they will still be there after, but this makes it a lot faster should - # just one of them be the already wrong - for lname in utils.UniqueSequence(names): + # just one of them be the already wrong. Using a sorted sequence to prevent + # deadlocks. + for lname in sorted(utils.UniqueSequence(names)): try: lock = self.__lockdict[lname] # raises KeyError if lock is not there - acquire_list.append((lname, lock)) except KeyError: if want_all: # We are acquiring all the set, it doesn't matter if this particular # element is not there anymore. continue - raise errors.LockError("Non-existing lock in set (%s)" % lname) + raise errors.LockError("Non-existing lock %s in set %s" % + (lname, self.name)) + + acquire_list.append((lname, lock)) # This will hold the locknames we effectively acquired. acquired = set() @@ -863,12 +1122,11 @@ class LockSet: test_notify_fn = None timeout = timeout_fn() - if timeout is not None and timeout < 0: - raise _AcquireTimeout() try: # raises LockError if the lock was deleted acq_success = lock.acquire(shared=shared, timeout=timeout, + priority=priority, test_notify=test_notify_fn) except errors.LockError: if want_all: @@ -876,14 +1134,16 @@ class LockSet: # particular element is not there anymore. continue - raise errors.LockError("Non-existing lock in set (%s)" % lname) + raise errors.LockError("Non-existing lock %s in set %s" % + (lname, self.name)) if not acq_success: # Couldn't get lock or timeout occurred if timeout is None: # This shouldn't happen as SharedLock.acquire(timeout=None) is # blocking. - raise errors.LockError("Failed to get lock %s" % lname) + raise errors.LockError("Failed to get lock %s (set %s)" % + (lname, self.name)) raise _AcquireTimeout() @@ -913,11 +1173,13 @@ class LockSet: You must have acquired the locks, either in shared or in exclusive mode, before releasing them. + @type names: list of strings, or None @param names: the names of the locks which shall be released (defaults to all the locks acquired at that level). """ - assert self._is_owned(), "release() on lock set while not owner" + 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): @@ -928,8 +1190,8 @@ class LockSet: else: names = set(names) assert self._list_owned().issuperset(names), ( - "release() on unheld resources %s" % - names.difference(self._list_owned())) + "release() on unheld resources %s (set %s)" % + (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 @@ -946,14 +1208,18 @@ class LockSet: def add(self, names, acquired=0, shared=0): """Add a new set of elements to the set + @type names: list of strings @param names: names of the new elements to add + @type acquired: integer (0/1) used as a boolean @param acquired: pre-acquire the new resource? + @type shared: integer (0/1) used as a boolean @param shared: is the pre-acquisition shared? """ # Check we don't already own locks at this level assert not self._is_owned() or self.__lock._is_owned(shared=0), \ - "Cannot add locks if the set is only partially owned, or shared" + ("Cannot add locks if the set %s is only partially owned, or shared" % + self.name) # Support passing in a single resource to add rather than many if isinstance(names, basestring): @@ -972,12 +1238,15 @@ class LockSet: # This must be an explicit raise, not an assert, because assert is # turned off when using optimization, and this can happen because of # concurrency even if the user doesn't want it. - raise errors.LockError("duplicate add() (%s)" % invalid_names) + raise errors.LockError("duplicate add(%s) on lockset %s" % + (invalid_names, self.name)) for lockname in names: - lock = SharedLock() + lock = SharedLock(self._GetLockName(lockname), monitor=self.__monitor) if acquired: + # No need for priority or timeout here as this lock has just been + # created lock.acquire(shared=shared) # now the lock cannot be deleted, we have it! try: @@ -1007,6 +1276,7 @@ class LockSet: You can either not hold anything in the lockset or already hold a superset of the elements you want to delete, exclusively. + @type names: list of strings @param names: names of the resource to remove. @return: a list of locks which we removed; the list is always @@ -1022,7 +1292,8 @@ class LockSet: # 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), ( - "remove() on acquired lockset while not owning all elements") + "remove() on acquired lockset %s while not owning all elements" % + self.name) removed = [] @@ -1037,7 +1308,8 @@ 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" + 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 @@ -1110,13 +1382,24 @@ class GanetiLockManager: self.__class__._instance = self + self._monitor = LockMonitor() + # The keyring contains all the locks, at their level and in the correct # locking order. self.__keyring = { - LEVEL_CLUSTER: LockSet([BGL]), - LEVEL_NODE: LockSet(nodes), - LEVEL_INSTANCE: LockSet(instances), - } + LEVEL_CLUSTER: LockSet([BGL], "BGL", monitor=self._monitor), + LEVEL_NODE: LockSet(nodes, "nodes", monitor=self._monitor), + LEVEL_INSTANCE: LockSet(instances, "instances", + monitor=self._monitor), + } + + def QueryLocks(self, fields, sync): + """Queries information from all locks. + + See L{LockMonitor.QueryLocks}. + + """ + return self._monitor.QueryLocks(fields, sync) def _names(self, level): """List the lock names at the given level. @@ -1149,9 +1432,9 @@ class GanetiLockManager: """ # This way of checking only works if LEVELS[i] = i, which we check for in # the test cases. - return utils.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): + def _BGL_owned(self): # pylint: disable-msg=C0103 """Check if the current thread owns the BGL. Both an exclusive or a shared acquisition work. @@ -1159,7 +1442,8 @@ class GanetiLockManager: """ return BGL in self.__keyring[LEVEL_CLUSTER]._list_owned() - def _contains_BGL(self, level, names): + @staticmethod + def _contains_BGL(level, names): # pylint: disable-msg=C0103 """Check if the level contains the BGL. Check if acting on the given level and set of names will change @@ -1168,17 +1452,21 @@ class GanetiLockManager: """ return level == LEVEL_CLUSTER and (names is None or BGL in names) - def acquire(self, level, names, timeout=None, shared=0): + def acquire(self, level, names, timeout=None, shared=0, priority=None): """Acquire a set of resource locks, at the same level. - @param level: the level at which the locks shall be acquired; - it must be a member of LEVELS. + @type level: member of locking.LEVELS + @param level: the level at which the locks shall be acquired + @type names: list of strings (or string) @param names: the names of the locks which shall be acquired (special lock names, or instance/node names) + @type shared: integer (0/1) used as a boolean @param shared: whether to acquire in shared mode; by default an exclusive lock will be acquired @type timeout: float @param timeout: Maximum time to acquire all locks + @type priority: integer + @param priority: Priority for acquiring lock """ assert level in LEVELS, "Invalid locking level %s" % level @@ -1197,7 +1485,8 @@ class GanetiLockManager: " while owning some at a greater one") # Acquire the locks in the set. - return self.__keyring[level].acquire(names, shared=shared, timeout=timeout) + return self.__keyring[level].acquire(names, shared=shared, timeout=timeout, + priority=priority) def release(self, level, names=None): """Release a set of resource locks, at the same level. @@ -1205,8 +1494,9 @@ class GanetiLockManager: You must have acquired the locks, either in shared or in exclusive mode, before releasing them. - @param level: the level at which the locks shall be released; - it must be a member of LEVELS + @type level: member of locking.LEVELS + @param level: the level at which the locks shall be released + @type names: list of strings, or None @param names: the names of the locks which shall be released (defaults to all the locks acquired at that level) @@ -1216,8 +1506,8 @@ class GanetiLockManager: not self._upper_owned(LEVEL_CLUSTER)), ( "Cannot release the Big Ganeti Lock while holding something" " at upper levels (%r)" % - (", ".join(["%s=%r" % (LEVEL_NAMES[i], self._list_owned(i)) - for i in self.__keyring.keys()]), )) + (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 return self.__keyring[level].release(names) @@ -1225,10 +1515,13 @@ class GanetiLockManager: def add(self, level, names, acquired=0, shared=0): """Add locks at the specified level. - @param level: the level at which the locks shall be added; - it must be a member of LEVELS_MOD. + @type level: member of locking.LEVELS_MOD + @param level: the level at which the locks shall be added + @type names: list of strings @param names: names of the locks to acquire + @type acquired: integer (0/1) used as a boolean @param acquired: whether to acquire the newly added locks + @type shared: integer (0/1) used as a boolean @param shared: whether the acquisition will be shared """ @@ -1245,8 +1538,9 @@ class GanetiLockManager: You must either already own the locks you are trying to remove exclusively or not own any lock at an upper level. - @param level: the level at which the locks shall be removed; - it must be a member of LEVELS_MOD + @type level: member of locking.LEVELS_MOD + @param level: the level at which the locks shall be removed + @type names: list of strings @param names: the names of the locks which shall be removed (special lock names, or instance/node names) @@ -1261,3 +1555,59 @@ class GanetiLockManager: "Cannot remove locks at a level while not owning it or" " owning some at a greater one") return self.__keyring[level].remove(names) + + +class LockMonitor(object): + _LOCK_ATTR = "_lock" + + def __init__(self): + """Initializes this class. + + """ + self._lock = SharedLock("LockMonitor") + + # Tracked locks. Weak references are used to avoid issues with circular + # references and deletion. + self._locks = weakref.WeakKeyDictionary() + + @ssynchronized(_LOCK_ATTR) + def RegisterLock(self, lock): + """Registers a new lock. + + """ + logging.debug("Registering lock %s", lock.name) + assert lock not in self._locks, "Duplicate lock registration" + assert not compat.any(lock.name == i.name for i in self._locks.keys()), \ + "Found duplicate lock name" + self._locks[lock] = None + + @ssynchronized(_LOCK_ATTR) + def _GetLockInfo(self, fields): + """Get information from all locks while the monitor lock is held. + + """ + result = {} + + for lock in self._locks.keys(): + assert lock.name not in result, "Found duplicate lock name" + result[lock.name] = lock.GetInfo(fields) + + return result + + def QueryLocks(self, fields, sync): + """Queries information from all locks. + + @type fields: list of strings + @param fields: List of fields to return + @type sync: boolean + @param sync: Whether to operate in synchronous mode + + """ + if sync: + raise NotImplementedError("Synchronous queries are not implemented") + + # Get all data without sorting + result = self._GetLockInfo(fields) + + # Sort by name + return [result[name] for name in utils.NiceSort(result.keys())]