From: Daira Hopwood Date: Thu, 25 Apr 2013 23:30:04 +0000 (+0100) Subject: Lock remote operations on sharesets. fixes #1869 X-Git-Url: https://git.rkrishnan.org/Site/Content/Exhibitors/class-simplejson.JSONDecoder.html?a=commitdiff_plain;h=a5bf599fc9c94c0fdf1e374c7a35dd443a74ab4c;p=tahoe-lafs%2Ftahoe-lafs.git Lock remote operations on sharesets. fixes #1869 Signed-off-by: Daira Hopwood --- diff --git a/src/allmydata/interfaces.py b/src/allmydata/interfaces.py index 858deb75..6b437a6d 100644 --- a/src/allmydata/interfaces.py +++ b/src/allmydata/interfaces.py @@ -328,11 +328,15 @@ class IStorageBackend(Interface): def get_sharesets_for_prefix(prefix): """ - Return an iterable containing IShareSet objects for all storage - indices matching the given base-32 prefix, for which this backend - holds shares. - XXX This will probably need to return a Deferred, but for now it - is synchronous. + Return a Deferred that fires with an iterable of IShareSet objects + for all storage indices matching the given base-32 prefix, for + which this backend holds shares. + + A caller will typically perform operations that take locks on some + of the sharesets returned by this method. Nothing prevents sharesets + matching the prefix from being deleted or added between listing the + sharesets and taking any such locks; callers must be able to tolerate + this. """ def get_shareset(storageindex): diff --git a/src/allmydata/storage/backends/base.py b/src/allmydata/storage/backends/base.py index b56266c8..570da2ce 100644 --- a/src/allmydata/storage/backends/base.py +++ b/src/allmydata/storage/backends/base.py @@ -1,4 +1,6 @@ +from weakref import WeakValueDictionary + from twisted.application import service from twisted.internet import defer @@ -11,6 +13,18 @@ from allmydata.storage.leasedb import SHARETYPE_MUTABLE class Backend(service.MultiService): def __init__(self): service.MultiService.__init__(self) + self._lock_table = WeakValueDictionary() + + def _get_lock(self, storage_index): + # Getting a shareset ensures that a lock exists for that storage_index. + # The _lock_table won't let go of an entry while the ShareSet (or any + # other objects that reference the lock) are live, or while it is locked. + + lock = self._lock_table.get(storage_index, None) + if lock is None: + lock = defer.DeferredLock() + self._lock_table[storage_index] = lock + return lock def must_use_tubid_as_permutation_seed(self): # New backends cannot have been around before #466, and so have no backward @@ -23,11 +37,10 @@ class ShareSet(object): This class implements shareset logic that could work for all backends, but might be useful to override for efficiency. """ - # TODO: queue operations on a shareset to ensure atomicity for each fully - # successful operation (#1869). - def __init__(self, storage_index): + def __init__(self, storage_index, lock): self.storage_index = storage_index + self.lock = lock def get_storage_index(self): return self.storage_index @@ -38,9 +51,25 @@ class ShareSet(object): def make_bucket_reader(self, account, share): return BucketReader(account, share) + def get_shares(self): + return self.lock.run(self._locked_get_shares) + + def get_share(self, shnum): + return self.lock.run(self._locked_get_share, shnum) + + def delete_share(self, shnum): + return self.lock.run(self._locked_delete_share, shnum) + def testv_and_readv_and_writev(self, write_enabler, test_and_write_vectors, read_vector, expiration_time, account): + return self.lock.run(self._locked_testv_and_readv_and_writev, write_enabler, + test_and_write_vectors, read_vector, + expiration_time, account) + + def _locked_testv_and_readv_and_writev(self, write_enabler, + test_and_write_vectors, read_vector, + expiration_time, account): # The implementation here depends on the following helper methods, # which must be provided by subclasses: # @@ -52,7 +81,7 @@ class ShareSet(object): # """create a mutable share with the given shnum and write_enabler""" sharemap = {} - d = self.get_shares() + d = self._locked_get_shares() def _got_shares( (shares, corrupted) ): d2 = defer.succeed(None) for share in shares: @@ -150,6 +179,9 @@ class ShareSet(object): return d def readv(self, wanted_shnums, read_vector): + return self.lock.run(self._locked_readv, wanted_shnums, read_vector) + + def _locked_readv(self, wanted_shnums, read_vector): """ Read a vector from the numbered shares in this shareset. An empty shares list means to return data from all known shares. @@ -160,7 +192,7 @@ class ShareSet(object): """ shnums = [] dreads = [] - d = self.get_shares() + d = self._locked_get_shares() def _got_shares( (shares, corrupted) ): # We ignore corrupted shares. for share in shares: diff --git a/src/allmydata/storage/backends/cloud/cloud_backend.py b/src/allmydata/storage/backends/cloud/cloud_backend.py index 786c993b..efe4e627 100644 --- a/src/allmydata/storage/backends/cloud/cloud_backend.py +++ b/src/allmydata/storage/backends/cloud/cloud_backend.py @@ -80,12 +80,13 @@ class CloudBackend(Backend): # XXX we want this to be deterministic, so we return the sharesets sorted # by their si_strings, but we shouldn't need to explicitly re-sort them # because list_objects returns a sorted list. - return [CloudShareSet(si_a2b(s), self._container, self._incomingset) for s in sorted(si_strings)] + return [self.get_shareset(si_a2b(s)) for s in sorted(si_strings)] d.addCallback(_get_sharesets) return d def get_shareset(self, storage_index): - return CloudShareSet(storage_index, self._container, self._incomingset) + return CloudShareSet(storage_index, self._get_lock(storage_index), + self._container, self._incomingset) def fill_in_space_stats(self, stats): # TODO: query space usage of container if supported. @@ -101,8 +102,8 @@ class CloudBackend(Backend): class CloudShareSet(ShareSet): implements(IShareSet) - def __init__(self, storage_index, container, incomingset): - ShareSet.__init__(self, storage_index) + def __init__(self, storage_index, lock, container, incomingset): + ShareSet.__init__(self, storage_index, lock) self._container = container self._incomingset = incomingset self._key = get_share_key(storage_index) @@ -110,7 +111,7 @@ class CloudShareSet(ShareSet): def get_overhead(self): return 0 - def get_shares(self): + def _locked_get_shares(self): d = self._container.list_objects(prefix=self._key) def _get_shares(res): si = self.get_storage_index() @@ -135,7 +136,7 @@ class CloudShareSet(ShareSet): d.addCallback(lambda shares: (shares, set()) ) return d - def get_share(self, shnum): + def _locked_get_share(self, shnum): key = "%s%d" % (self._key, shnum) d = self._container.list_objects(prefix=key) def _get_share(res): @@ -146,7 +147,7 @@ class CloudShareSet(ShareSet): d.addCallback(_get_share) return d - def delete_share(self, shnum): + def _locked_delete_share(self, shnum): key = "%s%d" % (self._key, shnum) return delete_chunks(self._container, key) diff --git a/src/allmydata/storage/backends/disk/disk_backend.py b/src/allmydata/storage/backends/disk/disk_backend.py index d507d152..e3d09a53 100644 --- a/src/allmydata/storage/backends/disk/disk_backend.py +++ b/src/allmydata/storage/backends/disk/disk_backend.py @@ -80,7 +80,7 @@ class DiskBackend(Backend): def get_shareset(self, storage_index): sharehomedir = si_si2dir(self._sharedir, storage_index) incominghomedir = si_si2dir(self._incomingdir, storage_index) - return DiskShareSet(storage_index, sharehomedir, incominghomedir) + return DiskShareSet(storage_index, self._get_lock(storage_index), sharehomedir, incominghomedir) def fill_in_space_stats(self, stats): stats['storage_server.reserved_space'] = self._reserved_space @@ -123,8 +123,8 @@ class DiskBackend(Backend): class DiskShareSet(ShareSet): implements(IShareSet) - def __init__(self, storage_index, sharehomedir, incominghomedir=None): - ShareSet.__init__(self, storage_index) + def __init__(self, storage_index, lock, sharehomedir, incominghomedir=None): + ShareSet.__init__(self, storage_index, lock) self._sharehomedir = sharehomedir self._incominghomedir = incominghomedir @@ -132,7 +132,7 @@ class DiskShareSet(ShareSet): return (fileutil.get_used_space(self._sharehomedir) + fileutil.get_used_space(self._incominghomedir)) - def get_shares(self): + def _locked_get_shares(self): si = self.get_storage_index() shares = {} corrupted = set() @@ -149,11 +149,11 @@ class DiskShareSet(ShareSet): valid = [shares[shnum] for shnum in sorted(shares.keys())] return defer.succeed( (valid, corrupted) ) - def get_share(self, shnum): + def _locked_get_share(self, shnum): return get_disk_share(os.path.join(self._sharehomedir, str(shnum)), self.get_storage_index(), shnum) - def delete_share(self, shnum): + def _locked_delete_share(self, shnum): fileutil.remove(os.path.join(self._sharehomedir, str(shnum))) return defer.succeed(None) diff --git a/src/allmydata/storage/backends/null/null_backend.py b/src/allmydata/storage/backends/null/null_backend.py index dbd5c9e7..b8e80c3d 100644 --- a/src/allmydata/storage/backends/null/null_backend.py +++ b/src/allmydata/storage/backends/null/null_backend.py @@ -44,7 +44,7 @@ class NullBackend(Backend): def get_shareset(self, storage_index): shareset = self._sharesets.get(storage_index, None) if shareset is None: - shareset = NullShareSet(storage_index) + shareset = NullShareSet(storage_index, self._get_lock(storage_index)) self._sharesets[storage_index] = shareset return shareset @@ -55,8 +55,8 @@ class NullBackend(Backend): class NullShareSet(ShareSet): implements(IShareSet) - def __init__(self, storage_index): - self.storage_index = storage_index + def __init__(self, storage_index, lock): + ShareSet.__init__(self, storage_index, lock) self._incoming_shnums = set() self._immutable_shnums = set() self._mutable_shnums = set() @@ -69,7 +69,7 @@ class NullShareSet(ShareSet): def get_overhead(self): return 0 - def get_shares(self): + def _locked_get_shares(self): shares = {} for shnum in self._immutable_shnums: shares[shnum] = ImmutableNullShare(self, shnum) @@ -78,7 +78,7 @@ class NullShareSet(ShareSet): # This backend never has any corrupt shares. return defer.succeed( ([shares[shnum] for shnum in sorted(shares.keys())], set()) ) - def get_share(self, shnum): + def _locked_get_share(self, shnum): if shnum in self._immutable_shnums: return defer.succeed(ImmutableNullShare(self, shnum)) elif shnum in self._mutable_shnums: @@ -87,7 +87,7 @@ class NullShareSet(ShareSet): def _not_found(): raise IndexError("no such share %d" % (shnum,)) return defer.execute(_not_found) - def delete_share(self, shnum, include_incoming=False): + def _locked_delete_share(self, shnum, include_incoming=False): if include_incoming and (shnum in self._incoming_shnums): self._incoming_shnums.remove(shnum) if shnum in self._immutable_shnums: