2 from zope.interface import Interface
3 from foolscap.api import StringConstraint, ListOf, TupleOf, SetOf, DictOf, \
4 ChoiceOf, IntegerConstraint, Any, RemoteInterface, Referenceable
12 Hash = StringConstraint(maxLength=HASH_SIZE,
13 minLength=HASH_SIZE)# binary format 32-byte SHA256 hash
14 Nodeid = StringConstraint(maxLength=20,
15 minLength=20) # binary format 20-byte SHA1 hash
16 FURL = StringConstraint(1000)
17 StorageIndex = StringConstraint(16)
18 URI = StringConstraint(300) # kind of arbitrary
20 MAX_BUCKETS = 256 # per peer -- zfec offers at most 256 shares per file
22 DEFAULT_MAX_SEGMENT_SIZE = 128*1024
24 ShareData = StringConstraint(None)
25 URIExtensionData = StringConstraint(1000)
26 Number = IntegerConstraint(8) # 2**(8*8) == 16EiB ~= 18e18 ~= 18 exabytes
28 ReadSize = int # the 'int' constraint is 2**31 == 2Gib -- large files are processed in not-so-large increments
29 WriteEnablerSecret = Hash # used to protect mutable bucket modifications
30 LeaseRenewSecret = Hash # used to protect bucket lease renewal requests
31 LeaseCancelSecret = Hash # used to protect bucket lease cancellation requests
33 class RIBucketWriter(RemoteInterface):
34 """ Objects of this kind live on the server side. """
35 def write(offset=Offset, data=ShareData):
40 If the data that has been written is incomplete or inconsistent then
41 the server will throw the data away, else it will store it for future
47 """Abandon all the data that has been written.
52 class RIBucketReader(RemoteInterface):
53 def read(offset=Offset, length=ReadSize):
56 def advise_corrupt_share(reason=str):
57 """Clients who discover hash failures in shares that they have
58 downloaded from me will use this method to inform me about the
59 failures. I will record their concern so that my operator can
60 manually inspect the shares in question. I return None.
62 This is a wrapper around RIStorageServer.advise_corrupt_share()
63 that is tied to a specific share, and therefore does not need the
64 extra share-identifying arguments. Please see that method for full
69 TestVector = ListOf(TupleOf(Offset, ReadSize, str, str))
70 # elements are (offset, length, operator, specimen)
71 # operator is one of "lt, le, eq, ne, ge, gt"
72 # nop always passes and is used to fetch data while writing.
73 # you should use length==len(specimen) for everything except nop
74 DataVector = ListOf(TupleOf(Offset, ShareData))
75 # (offset, data). This limits us to 30 writes of 1MiB each per call
76 TestAndWriteVectorsForShares = DictOf(int,
79 ChoiceOf(None, Offset), # new_length
81 ReadVector = ListOf(TupleOf(Offset, ReadSize))
82 ReadData = ListOf(ShareData)
83 # returns data[offset:offset+length] for each element of TestVector
86 class RIStorageServer(RemoteInterface):
87 __remote_name__ = "RIStorageServer.tahoe.allmydata.com"
91 Return a dictionary of version information.
93 return DictOf(str, Any())
95 def allocate_buckets(storage_index=StorageIndex,
96 renew_secret=LeaseRenewSecret,
97 cancel_secret=LeaseCancelSecret,
98 sharenums=SetOf(int, maxLength=MAX_BUCKETS),
99 allocated_size=Offset, canary=Referenceable):
101 @param storage_index: the index of the bucket to be created or
103 @param sharenums: these are the share numbers (probably between 0 and
104 99) that the sender is proposing to store on this
106 @param renew_secret: This is the secret used to protect bucket refresh
107 This secret is generated by the client and
108 stored for later comparison by the server. Each
109 server is given a different secret.
110 @param cancel_secret: Like renew_secret, but protects bucket decref.
111 @param canary: If the canary is lost before close(), the bucket is
113 @return: tuple of (alreadygot, allocated), where alreadygot is what we
114 already have and allocated is what we hereby agree to accept.
115 New leases are added for shares in both lists.
117 return TupleOf(SetOf(int, maxLength=MAX_BUCKETS),
118 DictOf(int, RIBucketWriter, maxKeys=MAX_BUCKETS))
120 def add_lease(storage_index=StorageIndex,
121 renew_secret=LeaseRenewSecret,
122 cancel_secret=LeaseCancelSecret):
124 Add a new lease on the given bucket. If the renew_secret matches an
125 existing lease, that lease will be renewed instead. If there is no
126 bucket for the given storage_index, return silently. (note that in
127 tahoe-1.3.0 and earlier, IndexError was raised if there was no
130 return Any() # returns None now, but future versions might change
132 def renew_lease(storage_index=StorageIndex, renew_secret=LeaseRenewSecret):
134 Renew the lease on a given bucket, resetting the timer to 31 days.
135 Some networks will use this, some will not. If there is no bucket for
136 the given storage_index, IndexError will be raised.
138 For mutable shares, if the given renew_secret does not match an
139 existing lease, IndexError will be raised with a note listing the
140 server-nodeids on the existing leases, so leases on migrated shares
141 can be renewed or cancelled. For immutable shares, IndexError
142 (without the note) will be raised.
146 def get_buckets(storage_index=StorageIndex):
147 return DictOf(int, RIBucketReader, maxKeys=MAX_BUCKETS)
151 def slot_readv(storage_index=StorageIndex,
152 shares=ListOf(int), readv=ReadVector):
153 """Read a vector from the numbered shares associated with the given
154 storage index. An empty shares list means to return data from all
155 known shares. Returns a dictionary with one key per share."""
156 return DictOf(int, ReadData) # shnum -> results
158 def slot_testv_and_readv_and_writev(storage_index=StorageIndex,
159 secrets=TupleOf(WriteEnablerSecret,
162 tw_vectors=TestAndWriteVectorsForShares,
166 General-purpose test-read-and-set operation for mutable slots:
167 (1) For submitted shnums, compare the test vectors against extant
168 shares, or against an empty share for shnums that do not exist.
169 (2) Use the read vectors to extract "old data" from extant shares.
170 (3) If all tests in (1) passed, then apply the write vectors
171 (possibly creating new shares).
172 (4) Return whether the tests passed, and the "old data", which does
173 not include any modifications made by the writes.
175 The operation does not interleave with other operations on the same
178 This method is, um, large. The goal is to allow clients to update all
179 the shares associated with a mutable file in a single round trip.
181 @param storage_index: the index of the bucket to be created or
183 @param write_enabler: a secret that is stored along with the slot.
184 Writes are accepted from any caller who can
185 present the matching secret. A different secret
186 should be used for each slot*server pair.
187 @param renew_secret: This is the secret used to protect bucket refresh
188 This secret is generated by the client and
189 stored for later comparison by the server. Each
190 server is given a different secret.
191 @param cancel_secret: Like renew_secret, but protects bucket decref.
193 The 'secrets' argument is a tuple of (write_enabler, renew_secret,
194 cancel_secret). The first is required to perform any write. The
195 latter two are used when allocating new shares. To simply acquire a
196 new lease on existing shares, use an empty testv and an empty writev.
198 Each share can have a separate test vector (i.e. a list of
199 comparisons to perform). If all vectors for all shares pass, then all
200 writes for all shares are recorded. Each comparison is a 4-tuple of
201 (offset, length, operator, specimen), which effectively does a
202 bool( (read(offset, length)) OPERATOR specimen ) and only performs
203 the write if all these evaluate to True. Basic test-and-set uses 'eq'.
204 Write-if-newer uses a seqnum and (offset, length, 'lt', specimen).
205 Write-if-same-or-newer uses 'le'.
207 Reads from the end of the container are truncated, and missing shares
208 behave like empty ones, so to assert that a share doesn't exist (for
209 use when creating a new share), use (0, 1, 'eq', '').
211 The write vector will be applied to the given share, expanding it if
212 necessary. A write vector applied to a share number that did not
213 exist previously will cause that share to be created. Write vectors
214 must not overlap (if they do, this will either cause an error or
215 apply them in an unspecified order). Duplicate write vectors, with
216 the same offset and data, are currently tolerated but are not
219 In Tahoe-LAFS v1.8.3 or later (except 1.9.0a1), if you send a write
220 vector whose offset is beyond the end of the current data, the space
221 between the end of the current data and the beginning of the write
222 vector will be filled with zero bytes. In earlier versions the
223 contents of this space was unspecified (and might end up containing
224 secrets). Storage servers with the new zero-filling behavior will
225 advertise a true value for the 'fills-holes-with-zero-bytes' key
226 (under 'http://allmydata.org/tahoe/protocols/storage/v1') in their
229 Each write vector is accompanied by a 'new_length' argument, which
230 can be used to truncate the data. If new_length is not None and it is
231 less than the current size of the data (after applying all write
232 vectors), then the data will be truncated to new_length. If
233 new_length==0, the share will be deleted.
235 In Tahoe-LAFS v1.8.2 and earlier, new_length could also be used to
236 enlarge the file by sending a number larger than the size of the data
237 after applying all write vectors. That behavior was not used, and as
238 of Tahoe-LAFS v1.8.3 it no longer works and the new_length is ignored
241 If a storage client knows that the server supports zero-filling, for
242 example from the 'fills-holes-with-zero-bytes' key in its version
243 information, it can extend the file efficiently by writing a single
244 zero byte just before the new end-of-file. Otherwise it must
245 explicitly write zeroes to all bytes between the old and new
246 end-of-file. In any case it should avoid sending new_length larger
247 than the size of the data after applying all write vectors.
249 The read vector is used to extract data from all known shares,
250 *before* any writes have been applied. The same read vector is used
251 for all shares. This captures the state that was tested by the test
252 vector, for extant shares.
254 This method returns two values: a boolean and a dict. The boolean is
255 True if the write vectors were applied, False if not. The dict is
256 keyed by share number, and each value contains a list of strings, one
257 for each element of the read vector.
259 If the write_enabler is wrong, this will raise BadWriteEnablerError.
260 To enable share migration (using update_write_enabler), the exception
261 will have the nodeid used for the old write enabler embedded in it,
262 in the following string::
264 The write enabler was recorded by nodeid '%s'.
266 Note that the nodeid here is encoded using the same base32 encoding
267 used by Foolscap and allmydata.util.idlib.nodeid_b2a().
269 return TupleOf(bool, DictOf(int, ReadData))
271 def advise_corrupt_share(share_type=str, storage_index=StorageIndex,
272 shnum=int, reason=str):
273 """Clients who discover hash failures in shares that they have
274 downloaded from me will use this method to inform me about the
275 failures. I will record their concern so that my operator can
276 manually inspect the shares in question. I return None.
278 'share_type' is either 'mutable' or 'immutable'. 'storage_index' is a
279 (binary) storage index string, and 'shnum' is the integer share
280 number. 'reason' is a human-readable explanation of the problem,
281 probably including some expected hash values and the computed ones
282 that did not match. Corruption advisories for mutable shares should
283 include a hash of the public key (the same value that appears in the
284 mutable-file verify-cap), since the current share format does not
289 class IStorageBucketWriter(Interface):
291 Objects of this kind live on the client side.
293 def put_block(segmentnum, data):
295 @param segmentnum=int
296 @param data=ShareData: For most segments, this data will be 'blocksize'
297 bytes in length. The last segment might be shorter.
298 @return: a Deferred that fires (with None) when the operation completes
301 def put_crypttext_hashes(hashes):
303 @param hashes=ListOf(Hash)
304 @return: a Deferred that fires (with None) when the operation completes
307 def put_block_hashes(blockhashes):
309 @param blockhashes=ListOf(Hash)
310 @return: a Deferred that fires (with None) when the operation completes
313 def put_share_hashes(sharehashes):
315 @param sharehashes=ListOf(TupleOf(int, Hash))
316 @return: a Deferred that fires (with None) when the operation completes
319 def put_uri_extension(data):
320 """This block of data contains integrity-checking information (hashes
321 of plaintext, crypttext, and shares), as well as encoding parameters
322 that are necessary to recover the data. This is a serialized dict
323 mapping strings to other strings. The hash of this data is kept in
324 the URI and verified before any of the data is used. All buckets for
325 a given file contain identical copies of this data.
327 The serialization format is specified with the following pseudocode:
328 for k in sorted(dict.keys()):
329 assert re.match(r'^[a-zA-Z_\-]+$', k)
330 write(k + ':' + netstring(dict[k]))
332 @param data=URIExtensionData
333 @return: a Deferred that fires (with None) when the operation completes
337 """Finish writing and close the bucket. The share is not finalized
338 until this method is called: if the uploading client disconnects
339 before calling close(), the partially-written share will be
342 @return: a Deferred that fires (with None) when the operation completes
346 class IStorageBucketReader(Interface):
347 def get_block_data(blocknum, blocksize, size):
348 """Most blocks will be the same size. The last block might be shorter
357 def get_crypttext_hashes():
359 @return: ListOf(Hash)
362 def get_block_hashes(at_least_these=()):
364 @param at_least_these=SetOf(int)
365 @return: ListOf(Hash)
368 def get_share_hashes():
370 @return: ListOf(TupleOf(int, Hash))
373 def get_uri_extension():
375 @return: URIExtensionData
379 class IStorageBroker(Interface):
380 def get_servers_for_psi(peer_selection_index):
382 @return: list of IServer instances
384 def get_connected_servers():
386 @return: frozenset of connected IServer instances
388 def get_known_servers():
390 @return: frozenset of IServer instances
392 def get_all_serverids():
394 @return: frozenset of serverid strings
396 def get_nickname_for_serverid(serverid):
398 @return: unicode nickname, or None
401 # methods moved from IntroducerClient, need review
402 def get_all_connections():
403 """Return a frozenset of (nodeid, service_name, rref) tuples, one for
404 each active connection we've established to a remote service. This is
405 mostly useful for unit tests that need to wait until a certain number
406 of connections have been made."""
408 def get_all_connectors():
409 """Return a dict that maps from (nodeid, service_name) to a
410 RemoteServiceConnector instance for all services that we are actively
411 trying to connect to. Each RemoteServiceConnector has the following
414 service_name: the type of service provided, like 'storage'
415 announcement_time: when we first heard about this service
416 last_connect_time: when we last established a connection
417 last_loss_time: when we last lost a connection
419 version: the peer's version, from the most recent connection
420 oldest_supported: the peer's oldest supported version, same
422 rref: the RemoteReference, if connected, otherwise None
423 remote_host: the IAddress, if connected, otherwise None
425 This method is intended for monitoring interfaces, such as a web page
426 that describes connecting and connected peers.
429 def get_all_peerids():
430 """Return a frozenset of all peerids to whom we have a connection (to
431 one or more services) established. Mostly useful for unit tests."""
433 def get_all_connections_for(service_name):
434 """Return a frozenset of (nodeid, service_name, rref) tuples, one
435 for each active connection that provides the given SERVICE_NAME."""
437 def get_permuted_peers(service_name, key):
438 """Returns an ordered list of (peerid, rref) tuples, selecting from
439 the connections that provide SERVICE_NAME, using a hash-based
440 permutation keyed by KEY. This randomizes the service list in a
441 repeatable way, to distribute load over many peers.
445 class IDisplayableServer(Interface):
456 class IServer(IDisplayableServer):
457 """I live in the client, and represent a single server."""
458 def start_connecting(tub, trigger_cb):
462 """Once a server is connected, I return a RemoteReference.
463 Before a server is connected for the first time, I return None.
465 Note that the rref I return will start producing DeadReferenceErrors
466 once the connection is lost.
470 class IMutableSlotWriter(Interface):
472 The interface for a writer around a mutable slot on a remote server.
474 def set_checkstring(checkstring, *args):
476 Set the checkstring that I will pass to the remote server when
479 @param checkstring A packed checkstring to use.
481 Note that implementations can differ in which semantics they
482 wish to support for set_checkstring -- they can, for example,
483 build the checkstring themselves from its constituents, or
487 def get_checkstring():
489 Get the checkstring that I think currently exists on the remote
493 def put_block(data, segnum, salt):
495 Add a block and salt to the share.
498 def put_encprivkey(encprivkey):
500 Add the encrypted private key to the share.
503 def put_blockhashes(blockhashes):
505 @param blockhashes=list
506 Add the block hash tree to the share.
509 def put_sharehashes(sharehashes):
511 @param sharehashes=dict
512 Add the share hash chain to the share.
517 Return the part of the share that needs to be signed.
520 def put_signature(signature):
522 Add the signature to the share.
525 def put_verification_key(verification_key):
527 Add the verification key to the share.
530 def finish_publishing():
532 Do anything necessary to finish writing the share to a remote
533 server. I require that no further publishing needs to take place
534 after this method has been called.
538 class IURI(Interface):
539 def init_from_string(uri):
540 """Accept a string (as created by my to_string() method) and populate
541 this instance with its data. I am not normally called directly,
542 please use the module-level uri.from_string() function to convert
543 arbitrary URI strings into IURI-providing instances."""
546 """Return False if this URI be used to modify the data. Return True
547 if this URI cannot be used to modify the data."""
550 """Return True if the data can be modified by *somebody* (perhaps
551 someone who has a more powerful URI than this one)."""
553 # TODO: rename to get_read_cap()
555 """Return another IURI instance that represents a read-only form of
556 this one. If is_readonly() is True, this returns self."""
558 def get_verify_cap():
559 """Return an instance that provides IVerifierURI, which can be used
560 to check on the availability of the file or directory, without
561 providing enough capabilities to actually read or modify the
562 contents. This may return None if the file does not need checking or
563 verification (e.g. LIT URIs).
567 """Return a string of printable ASCII characters, suitable for
568 passing into init_from_string."""
571 class IVerifierURI(Interface, IURI):
572 def init_from_string(uri):
573 """Accept a string (as created by my to_string() method) and populate
574 this instance with its data. I am not normally called directly,
575 please use the module-level uri.from_string() function to convert
576 arbitrary URI strings into IURI-providing instances."""
579 """Return a string of printable ASCII characters, suitable for
580 passing into init_from_string."""
583 class IDirnodeURI(Interface):
584 """I am a URI that represents a dirnode."""
587 class IFileURI(Interface):
588 """I am a URI that represents a filenode."""
590 """Return the length (in bytes) of the file that I represent."""
593 class IImmutableFileURI(IFileURI):
596 class IMutableFileURI(Interface):
599 class IDirectoryURI(Interface):
602 class IReadonlyDirectoryURI(Interface):
606 class CapConstraintError(Exception):
607 """A constraint on a cap was violated."""
609 class MustBeDeepImmutableError(CapConstraintError):
610 """Mutable children cannot be added to an immutable directory.
611 Also, caps obtained from an immutable directory can trigger this error
612 if they are later found to refer to a mutable object and then used."""
614 class MustBeReadonlyError(CapConstraintError):
615 """Known write caps cannot be specified in a ro_uri field. Also,
616 caps obtained from a ro_uri field can trigger this error if they
617 are later found to be write caps and then used."""
619 class MustNotBeUnknownRWError(CapConstraintError):
620 """Cannot add an unknown child cap specified in a rw_uri field."""
623 class IReadable(Interface):
624 """I represent a readable object -- either an immutable file, or a
625 specific version of a mutable file.
629 """Return True if this reference provides mutable access to the given
630 file or directory (i.e. if you can modify it), or False if not. Note
631 that even if this reference is read-only, someone else may hold a
632 read-write reference to it.
634 For an IReadable returned by get_best_readable_version(), this will
635 always return True, but for instances of subinterfaces such as
636 IMutableFileVersion, it may return False."""
639 """Return True if this file or directory is mutable (by *somebody*,
640 not necessarily you), False if it is is immutable. Note that a file
641 might be mutable overall, but your reference to it might be
642 read-only. On the other hand, all references to an immutable file
643 will be read-only; there are no read-write references to an immutable
646 def get_storage_index():
647 """Return the storage index of the file."""
650 """Return the length (in bytes) of this readable object."""
652 def download_to_data():
653 """Download all of the file contents. I return a Deferred that fires
654 with the contents as a byte string."""
656 def read(consumer, offset=0, size=None):
657 """Download a portion (possibly all) of the file's contents, making
658 them available to the given IConsumer. Return a Deferred that fires
659 (with the consumer) when the consumer is unregistered (either because
660 the last byte has been given to it, or because the consumer threw an
661 exception during write(), possibly because it no longer wants to
662 receive data). The portion downloaded will start at 'offset' and
663 contain 'size' bytes (or the remainder of the file if size==None).
665 The consumer will be used in non-streaming mode: an IPullProducer
666 will be attached to it.
668 The consumer will not receive data right away: several network trips
669 must occur first. The order of events will be::
671 consumer.registerProducer(p, streaming)
672 (if streaming == False)::
673 consumer does p.resumeProducing()
675 consumer does p.resumeProducing()
676 consumer.write(data).. (repeat until all data is written)
677 consumer.unregisterProducer()
678 deferred.callback(consumer)
680 If a download error occurs, or an exception is raised by
681 consumer.registerProducer() or consumer.write(), I will call
682 consumer.unregisterProducer() and then deliver the exception via
683 deferred.errback(). To cancel the download, the consumer should call
684 p.stopProducing(), which will result in an exception being delivered
685 via deferred.errback().
687 See src/allmydata/util/consumer.py for an example of a simple
688 download-to-memory consumer.
692 class IWriteable(Interface):
694 I define methods that callers can use to update SDMF and MDMF
695 mutable files on a Tahoe-LAFS grid.
697 # XXX: For the moment, we have only this. It is possible that we
698 # want to move overwrite() and modify() in here too.
699 def update(data, offset):
701 I write the data from my data argument to the MDMF file,
702 starting at offset. I continue writing data until my data
703 argument is exhausted, appending data to the file as necessary.
705 # assert IMutableUploadable.providedBy(data)
706 # to append data: offset=node.get_size_of_best_version()
707 # do we want to support compacting MDMF?
708 # for an MDMF file, this can be done with O(data.get_size())
709 # memory. For an SDMF file, any modification takes
710 # O(node.get_size_of_best_version()).
713 class IMutableFileVersion(IReadable):
714 """I provide access to a particular version of a mutable file. The
715 access is read/write if I was obtained from a filenode derived from
716 a write cap, or read-only if the filenode was derived from a read cap.
719 def get_sequence_number():
720 """Return the sequence number of this version."""
723 """Return the IMutableFileServerMap instance that was used to create
728 """Return this filenode's writekey, or None if the node does not have
729 write-capability. This may be used to assist with data structures
730 that need to make certain data available only to writers, such as the
731 read-write child caps in dirnodes. The recommended process is to have
732 reader-visible data be submitted to the filenode in the clear (where
733 it will be encrypted by the filenode using the readkey), but encrypt
734 writer-visible data using this writekey.
737 # TODO: Can this be overwrite instead of replace?
738 def replace(new_contents):
739 """Replace the contents of the mutable file, provided that no other
740 node has published (or is attempting to publish, concurrently) a
741 newer version of the file than this one.
743 I will avoid modifying any share that is different than the version
744 given by get_sequence_number(). However, if another node is writing
745 to the file at the same time as me, I may manage to update some shares
746 while they update others. If I see any evidence of this, I will signal
747 UncoordinatedWriteError, and the file will be left in an inconsistent
748 state (possibly the version you provided, possibly the old version,
749 possibly somebody else's version, and possibly a mix of shares from
752 The recommended response to UncoordinatedWriteError is to either
753 return it to the caller (since they failed to coordinate their
754 writes), or to attempt some sort of recovery. It may be sufficient to
755 wait a random interval (with exponential backoff) and repeat your
756 operation. If I do not signal UncoordinatedWriteError, then I was
757 able to write the new version without incident.
759 I return a Deferred that fires (with a PublishStatus object) when the
760 update has completed.
763 def modify(modifier_cb):
764 """Modify the contents of the file, by downloading this version,
765 applying the modifier function (or bound method), then uploading
766 the new version. This will succeed as long as no other node
767 publishes a version between the download and the upload.
768 I return a Deferred that fires (with a PublishStatus object) when
769 the update is complete.
771 The modifier callable will be given three arguments: a string (with
772 the old contents), a 'first_time' boolean, and a servermap. As with
773 download_to_data(), the old contents will be from this version,
774 but the modifier can use the servermap to make other decisions
775 (such as refusing to apply the delta if there are multiple parallel
776 versions, or if there is evidence of a newer unrecoverable version).
777 'first_time' will be True the first time the modifier is called,
778 and False on any subsequent calls.
780 The callable should return a string with the new contents. The
781 callable must be prepared to be called multiple times, and must
782 examine the input string to see if the change that it wants to make
783 is already present in the old version. If it does not need to make
784 any changes, it can either return None, or return its input string.
786 If the modifier raises an exception, it will be returned in the
791 # The hierarchy looks like this:
798 class IFilesystemNode(Interface):
800 """Return the strongest 'cap instance' associated with this node.
801 (writecap for writeable-mutable files/directories, readcap for
802 immutable or readonly-mutable files/directories). To convert this
803 into a string, call .to_string() on the result."""
806 """Return a readonly cap instance for this node. For immutable or
807 readonly nodes, get_cap() and get_readcap() return the same thing."""
809 def get_repair_cap():
810 """Return an IURI instance that can be used to repair the file, or
811 None if this node cannot be repaired (either because it is not
812 distributed, like a LIT file, or because the node does not represent
813 sufficient authority to create a repair-cap, like a read-only RSA
814 mutable file node [which cannot create the correct write-enablers]).
817 def get_verify_cap():
818 """Return an IVerifierURI instance that represents the
819 'verifiy/refresh capability' for this node. The holder of this
820 capability will be able to renew the lease for this node, protecting
821 it from garbage-collection. They will also be able to ask a server if
822 it holds a share for the file or directory.
826 """Return the URI string corresponding to the strongest cap associated
827 with this node. If this node is read-only, the URI will only offer
828 read-only access. If this node is read-write, the URI will offer
831 If you have read-write access to a node and wish to share merely
832 read-only access with others, use get_readonly_uri().
836 """Return the URI string that can be used by others to get write
837 access to this node, if it is writeable. If this is a read-only node,
840 def get_readonly_uri():
841 """Return the URI string that can be used by others to get read-only
842 access to this node. The result is a read-only URI, regardless of
843 whether this node is read-only or read-write.
845 If you have merely read-only access to this node, get_readonly_uri()
846 will return the same thing as get_uri().
849 def get_storage_index():
850 """Return a string with the (binary) storage index in use on this
851 download. This may be None if there is no storage index (i.e. LIT
852 files and directories)."""
855 """Return True if this reference provides mutable access to the given
856 file or directory (i.e. if you can modify it), or False if not. Note
857 that even if this reference is read-only, someone else may hold a
858 read-write reference to it."""
861 """Return True if this file or directory is mutable (by *somebody*,
862 not necessarily you), False if it is is immutable. Note that a file
863 might be mutable overall, but your reference to it might be
864 read-only. On the other hand, all references to an immutable file
865 will be read-only; there are no read-write references to an immutable
870 """Return True if this is an unknown node."""
872 def is_allowed_in_immutable_directory():
873 """Return True if this node is allowed as a child of a deep-immutable
874 directory. This is true if either the node is of a known-immutable type,
875 or it is unknown and read-only.
879 """Raise any error associated with this node."""
881 # XXX: These may not be appropriate outside the context of an IReadable.
883 """Return the length (in bytes) of the data this node represents. For
884 directory nodes, I return the size of the backing store. I return
885 synchronously and do not consult the network, so for mutable objects,
886 I will return the most recently observed size for the object, or None
887 if I don't remember a size. Use get_current_size, which returns a
888 Deferred, if you want more up-to-date information."""
890 def get_current_size():
891 """I return a Deferred that fires with the length (in bytes) of the
892 data this node represents.
896 class IFileNode(IFilesystemNode):
897 """I am a node that represents a file: a sequence of bytes. I am not a
898 container, like IDirectoryNode."""
899 def get_best_readable_version():
900 """Return a Deferred that fires with an IReadable for the 'best'
901 available version of the file. The IReadable provides only read
902 access, even if this filenode was derived from a write cap.
904 For an immutable file, there is only one version. For a mutable
905 file, the 'best' version is the recoverable version with the
906 highest sequence number. If no uncoordinated writes have occurred,
907 and if enough shares are available, then this will be the most
908 recent version that has been uploaded. If no version is recoverable,
909 the Deferred will errback with an UnrecoverableFileError.
912 def download_best_version():
913 """Download the contents of the version that would be returned
914 by get_best_readable_version(). This is equivalent to calling
915 download_to_data() on the IReadable given by that method.
917 I return a Deferred that fires with a byte string when the file
918 has been fully downloaded. To support streaming download, use
919 the 'read' method of IReadable. If no version is recoverable,
920 the Deferred will errback with an UnrecoverableFileError.
923 def get_size_of_best_version():
924 """Find the size of the version that would be returned by
925 get_best_readable_version().
927 I return a Deferred that fires with an integer. If no version
928 is recoverable, the Deferred will errback with an
929 UnrecoverableFileError.
933 class IImmutableFileNode(IFileNode, IReadable):
934 """I am a node representing an immutable file. Immutable files have
938 class IMutableFileNode(IFileNode):
939 """I provide access to a 'mutable file', which retains its identity
940 regardless of what contents are put in it.
942 The consistency-vs-availability problem means that there might be
943 multiple versions of a file present in the grid, some of which might be
944 unrecoverable (i.e. have fewer than 'k' shares). These versions are
945 loosely ordered: each has a sequence number and a hash, and any version
946 with seqnum=N was uploaded by a node that has seen at least one version
949 The 'servermap' (an instance of IMutableFileServerMap) is used to
950 describe the versions that are known to be present in the grid, and which
951 servers are hosting their shares. It is used to represent the 'state of
952 the world', and is used for this purpose by my test-and-set operations.
953 Downloading the contents of the mutable file will also return a
954 servermap. Uploading a new version into the mutable file requires a
955 servermap as input, and the semantics of the replace operation is
956 'replace the file with my new version if it looks like nobody else has
957 changed the file since my previous download'. Because the file is
958 distributed, this is not a perfect test-and-set operation, but it will do
959 its best. If the replace process sees evidence of a simultaneous write,
960 it will signal an UncoordinatedWriteError, so that the caller can take
964 Most readers will want to use the 'best' current version of the file, and
965 should use my 'download_best_version()' method.
967 To unconditionally replace the file, callers should use overwrite(). This
968 is the mode that user-visible mutable files will probably use.
970 To apply some delta to the file, call modify() with a callable modifier
971 function that can apply the modification that you want to make. This is
972 the mode that dirnodes will use, since most directory modification
973 operations can be expressed in terms of deltas to the directory state.
976 Three methods are available for users who need to perform more complex
977 operations. The first is get_servermap(), which returns an up-to-date
978 servermap using a specified mode. The second is download_version(), which
979 downloads a specific version (not necessarily the 'best' one). The third
980 is 'upload', which accepts new contents and a servermap (which must have
981 been updated with MODE_WRITE). The upload method will attempt to apply
982 the new contents as long as no other node has modified the file since the
983 servermap was updated. This might be useful to a caller who wants to
984 merge multiple versions into a single new one.
986 Note that each time the servermap is updated, a specific 'mode' is used,
987 which determines how many peers are queried. To use a servermap for my
988 replace() method, that servermap must have been updated in MODE_WRITE.
989 These modes are defined in allmydata.mutable.common, and consist of
990 MODE_READ, MODE_WRITE, MODE_ANYTHING, and MODE_CHECK. Please look in
991 allmydata/mutable/servermap.py for details about the differences.
993 Mutable files are currently limited in size (about 3.5MB max) and can
994 only be retrieved and updated all-at-once, as a single big string. Future
995 versions of our mutable files will remove this restriction.
997 def get_best_mutable_version():
998 """Return a Deferred that fires with an IMutableFileVersion for
999 the 'best' available version of the file. The best version is
1000 the recoverable version with the highest sequence number. If no
1001 uncoordinated writes have occurred, and if enough shares are
1002 available, then this will be the most recent version that has
1005 If no version is recoverable, the Deferred will errback with an
1006 UnrecoverableFileError.
1009 def overwrite(new_contents):
1010 """Unconditionally replace the contents of the mutable file with new
1011 ones. This simply chains get_servermap(MODE_WRITE) and upload(). This
1012 is only appropriate to use when the new contents of the file are
1013 completely unrelated to the old ones, and you do not care about other
1016 I return a Deferred that fires (with a PublishStatus object) when the
1017 update has completed.
1020 def modify(modifier_cb):
1021 """Modify the contents of the file, by downloading the current
1022 version, applying the modifier function (or bound method), then
1023 uploading the new version. I return a Deferred that fires (with a
1024 PublishStatus object) when the update is complete.
1026 The modifier callable will be given three arguments: a string (with
1027 the old contents), a 'first_time' boolean, and a servermap. As with
1028 download_best_version(), the old contents will be from the best
1029 recoverable version, but the modifier can use the servermap to make
1030 other decisions (such as refusing to apply the delta if there are
1031 multiple parallel versions, or if there is evidence of a newer
1032 unrecoverable version). 'first_time' will be True the first time the
1033 modifier is called, and False on any subsequent calls.
1035 The callable should return a string with the new contents. The
1036 callable must be prepared to be called multiple times, and must
1037 examine the input string to see if the change that it wants to make
1038 is already present in the old version. If it does not need to make
1039 any changes, it can either return None, or return its input string.
1041 If the modifier raises an exception, it will be returned in the
1045 def get_servermap(mode):
1046 """Return a Deferred that fires with an IMutableFileServerMap
1047 instance, updated using the given mode.
1050 def download_version(servermap, version):
1051 """Download a specific version of the file, using the servermap
1052 as a guide to where the shares are located.
1054 I return a Deferred that fires with the requested contents, or
1055 errbacks with UnrecoverableFileError. Note that a servermap that was
1056 updated with MODE_ANYTHING or MODE_READ may not know about shares for
1057 all versions (those modes stop querying servers as soon as they can
1058 fulfil their goals), so you may want to use MODE_CHECK (which checks
1059 everything) to get increased visibility.
1062 def upload(new_contents, servermap):
1063 """Replace the contents of the file with new ones. This requires a
1064 servermap that was previously updated with MODE_WRITE.
1066 I attempt to provide test-and-set semantics, in that I will avoid
1067 modifying any share that is different than the version I saw in the
1068 servermap. However, if another node is writing to the file at the
1069 same time as me, I may manage to update some shares while they update
1070 others. If I see any evidence of this, I will signal
1071 UncoordinatedWriteError, and the file will be left in an inconsistent
1072 state (possibly the version you provided, possibly the old version,
1073 possibly somebody else's version, and possibly a mix of shares from
1076 The recommended response to UncoordinatedWriteError is to either
1077 return it to the caller (since they failed to coordinate their
1078 writes), or to attempt some sort of recovery. It may be sufficient to
1079 wait a random interval (with exponential backoff) and repeat your
1080 operation. If I do not signal UncoordinatedWriteError, then I was
1081 able to write the new version without incident.
1083 I return a Deferred that fires (with a PublishStatus object) when the
1084 publish has completed. I will update the servermap in-place with the
1085 location of all new shares.
1089 """Return this filenode's writekey, or None if the node does not have
1090 write-capability. This may be used to assist with data structures
1091 that need to make certain data available only to writers, such as the
1092 read-write child caps in dirnodes. The recommended process is to have
1093 reader-visible data be submitted to the filenode in the clear (where
1094 it will be encrypted by the filenode using the readkey), but encrypt
1095 writer-visible data using this writekey.
1099 """Returns the mutable file protocol version."""
1102 class NotEnoughSharesError(Exception):
1103 """Download was unable to get enough shares"""
1105 class NoSharesError(Exception):
1106 """Download was unable to get any shares at all."""
1108 class DownloadStopped(Exception):
1111 class UploadUnhappinessError(Exception):
1112 """Upload was unable to satisfy 'servers_of_happiness'"""
1114 class UnableToFetchCriticalDownloadDataError(Exception):
1115 """I was unable to fetch some piece of critical data that is supposed to
1116 be identically present in all shares."""
1118 class NoServersError(Exception):
1119 """Upload wasn't given any servers to work with, usually indicating a
1120 network or Introducer problem."""
1122 class ExistingChildError(Exception):
1123 """A directory node was asked to add or replace a child that already
1124 exists, and overwrite= was set to False."""
1126 class NoSuchChildError(Exception):
1127 """A directory node was asked to fetch a child that does not exist."""
1129 # avoid UnicodeEncodeErrors when converting to str
1130 return self.__repr__()
1132 class ChildOfWrongTypeError(Exception):
1133 """An operation was attempted on a child of the wrong type (file or directory)."""
1136 class IDirectoryNode(IFilesystemNode):
1137 """I represent a filesystem node that is a container, with a
1138 name-to-child mapping, holding the tahoe equivalent of a directory. All
1139 child names are unicode strings, and all children are some sort of
1140 IFilesystemNode (a file, subdirectory, or unknown node).
1145 The dirnode ('1') URI returned by this method can be used in
1146 set_uri() on a different directory ('2') to 'mount' a reference to
1147 this directory ('1') under the other ('2'). This URI is just a
1148 string, so it can be passed around through email or other out-of-band
1152 def get_readonly_uri():
1154 The dirnode ('1') URI returned by this method can be used in
1155 set_uri() on a different directory ('2') to 'mount' a reference to
1156 this directory ('1') under the other ('2'). This URI is just a
1157 string, so it can be passed around through email or other out-of-band
1162 """I return a Deferred that fires with a dictionary mapping child
1163 name (a unicode string) to (node, metadata_dict) tuples, in which
1164 'node' is an IFilesystemNode and 'metadata_dict' is a dictionary of
1167 def has_child(name):
1168 """I return a Deferred that fires with a boolean, True if there
1169 exists a child of the given name, False if not. The child name must
1170 be a unicode string."""
1173 """I return a Deferred that fires with a specific named child node,
1174 which is an IFilesystemNode. The child name must be a unicode string.
1175 I raise NoSuchChildError if I do not have a child by that name."""
1177 def get_metadata_for(name):
1178 """I return a Deferred that fires with the metadata dictionary for
1179 a specific named child node. The child name must be a unicode string.
1180 This metadata is stored in the *edge*, not in the child, so it is
1181 attached to the parent dirnode rather than the child node.
1182 I raise NoSuchChildError if I do not have a child by that name."""
1184 def set_metadata_for(name, metadata):
1185 """I replace any existing metadata for the named child with the new
1186 metadata. The child name must be a unicode string. This metadata is
1187 stored in the *edge*, not in the child, so it is attached to the
1188 parent dirnode rather than the child node. I return a Deferred
1189 (that fires with this dirnode) when the operation is complete.
1190 I raise NoSuchChildError if I do not have a child by that name."""
1192 def get_child_at_path(path):
1193 """Transform a child path into an IFilesystemNode.
1195 I perform a recursive series of 'get' operations to find the named
1196 descendant node. I return a Deferred that fires with the node, or
1197 errbacks with NoSuchChildError if the node could not be found.
1199 The path can be either a single string (slash-separated) or a list of
1200 path-name elements. All elements must be unicode strings.
1203 def get_child_and_metadata_at_path(path):
1204 """Transform a child path into an IFilesystemNode and metadata.
1206 I am like get_child_at_path(), but my Deferred fires with a tuple of
1207 (node, metadata). The metadata comes from the last edge. If the path
1208 is empty, the metadata will be an empty dictionary.
1211 def set_uri(name, writecap, readcap=None, metadata=None, overwrite=True):
1212 """I add a child (by writecap+readcap) at the specific name. I return
1213 a Deferred that fires when the operation finishes. If overwrite= is
1214 True, I will replace any existing child of the same name, otherwise
1215 an existing child will cause me to return ExistingChildError. The
1216 child name must be a unicode string.
1218 The child caps could be for a file, or for a directory. If you have
1219 both the writecap and readcap, you should provide both arguments.
1220 If you have only one cap and don't know whether it is read-only,
1221 provide it as the writecap argument and leave the readcap as None.
1222 If you have only one cap that is known to be read-only, provide it
1223 as the readcap argument and leave the writecap as None.
1224 The filecaps are typically obtained from an IFilesystemNode with
1225 get_uri() and get_readonly_uri().
1227 If metadata= is provided, I will use it as the metadata for the named
1228 edge. This will replace any existing metadata. If metadata= is left
1229 as the default value of None, I will set ['mtime'] to the current
1230 time, and I will set ['ctime'] to the current time if there was not
1231 already a child by this name present. This roughly matches the
1232 ctime/mtime semantics of traditional filesystems. See the
1233 "About the metadata" section of webapi.txt for futher information.
1235 If this directory node is read-only, the Deferred will errback with a
1236 NotWriteableError."""
1238 def set_children(entries, overwrite=True):
1239 """Add multiple children (by writecap+readcap) to a directory node.
1240 Takes a dictionary, with childname as keys and (writecap, readcap)
1241 tuples (or (writecap, readcap, metadata) triples) as values. Returns
1242 a Deferred that fires (with this dirnode) when the operation
1243 finishes. This is equivalent to calling set_uri() multiple times, but
1244 is much more efficient. All child names must be unicode strings.
1247 def set_node(name, child, metadata=None, overwrite=True):
1248 """I add a child at the specific name. I return a Deferred that fires
1249 when the operation finishes. This Deferred will fire with the child
1250 node that was just added. I will replace any existing child of the
1251 same name. The child name must be a unicode string. The 'child'
1252 instance must be an instance providing IFilesystemNode.
1254 If metadata= is provided, I will use it as the metadata for the named
1255 edge. This will replace any existing metadata. If metadata= is left
1256 as the default value of None, I will set ['mtime'] to the current
1257 time, and I will set ['ctime'] to the current time if there was not
1258 already a child by this name present. This roughly matches the
1259 ctime/mtime semantics of traditional filesystems. See the
1260 "About the metadata" section of webapi.txt for futher information.
1262 If this directory node is read-only, the Deferred will errback with a
1263 NotWriteableError."""
1265 def set_nodes(entries, overwrite=True):
1266 """Add multiple children to a directory node. Takes a dict mapping
1267 unicode childname to (child_node, metdata) tuples. If metdata=None,
1268 the original metadata is left unmodified. Returns a Deferred that
1269 fires (with this dirnode) when the operation finishes. This is
1270 equivalent to calling set_node() multiple times, but is much more
1273 def add_file(name, uploadable, metadata=None, overwrite=True):
1274 """I upload a file (using the given IUploadable), then attach the
1275 resulting ImmutableFileNode to the directory at the given name. I set
1276 metadata the same way as set_uri and set_node. The child name must be
1279 I return a Deferred that fires (with the IFileNode of the uploaded
1280 file) when the operation completes."""
1282 def delete(name, must_exist=True, must_be_directory=False, must_be_file=False):
1283 """I remove the child at the specific name. I return a Deferred that
1284 fires when the operation finishes. The child name must be a unicode
1285 string. If must_exist is True and I do not have a child by that name,
1286 I raise NoSuchChildError. If must_be_directory is True and the child
1287 is a file, or if must_be_file is True and the child is a directory,
1288 I raise ChildOfWrongTypeError."""
1290 def create_subdirectory(name, initial_children={}, overwrite=True, metadata=None):
1291 """I create and attach a directory at the given name. The new
1292 directory can be empty, or it can be populated with children
1293 according to 'initial_children', which takes a dictionary in the same
1294 format as set_nodes (i.e. mapping unicode child name to (childnode,
1295 metadata) tuples). The child name must be a unicode string. I return
1296 a Deferred that fires (with the new directory node) when the
1297 operation finishes."""
1299 def move_child_to(current_child_name, new_parent, new_child_name=None,
1301 """I take one of my children and move them to a new parent. The child
1302 is referenced by name. On the new parent, the child will live under
1303 'new_child_name', which defaults to 'current_child_name'. TODO: what
1304 should we do about metadata? I return a Deferred that fires when the
1305 operation finishes. The child name must be a unicode string. I raise
1306 NoSuchChildError if I do not have a child by that name."""
1308 def build_manifest():
1309 """I generate a table of everything reachable from this directory.
1310 I also compute deep-stats as described below.
1312 I return a Monitor. The Monitor's results will be a dictionary with
1315 res['manifest']: a list of (path, cap) tuples for all nodes
1316 (directories and files) reachable from this one.
1317 'path' will be a tuple of unicode strings. The
1318 origin dirnode will be represented by an empty path
1320 res['verifycaps']: a list of (printable) verifycap strings, one for
1321 each reachable non-LIT node. This is a set:
1322 it will contain no duplicates.
1323 res['storage-index']: a list of (base32) storage index strings,
1324 one for each reachable non-LIT node. This is
1325 a set: it will contain no duplicates.
1326 res['stats']: a dictionary, the same that is generated by
1327 start_deep_stats() below.
1329 The Monitor will also have an .origin_si attribute with the (binary)
1330 storage index of the starting point.
1333 def start_deep_stats():
1334 """Return a Monitor, examining all nodes (directories and files)
1335 reachable from this one. The Monitor's results will be a dictionary
1336 with the following keys::
1338 count-immutable-files: count of how many CHK files are in the set
1339 count-mutable-files: same, for mutable files (does not include
1341 count-literal-files: same, for LIT files
1342 count-files: sum of the above three
1344 count-directories: count of directories
1346 size-immutable-files: total bytes for all CHK files in the set
1347 size-mutable-files (TODO): same, for current version of all mutable
1348 files, does not include directories
1349 size-literal-files: same, for LIT files
1350 size-directories: size of mutable files used by directories
1352 largest-directory: number of bytes in the largest directory
1353 largest-directory-children: number of children in the largest
1355 largest-immutable-file: number of bytes in the largest CHK file
1357 size-mutable-files is not yet implemented, because it would involve
1358 even more queries than deep_stats does.
1360 The Monitor will also have an .origin_si attribute with the (binary)
1361 storage index of the starting point.
1363 This operation will visit every directory node underneath this one,
1364 and can take a long time to run. On a typical workstation with good
1365 bandwidth, this can examine roughly 15 directories per second (and
1366 takes several minutes of 100% CPU for ~1700 directories).
1370 class ICodecEncoder(Interface):
1371 def set_params(data_size, required_shares, max_shares):
1372 """Set up the parameters of this encoder.
1374 This prepares the encoder to perform an operation that converts a
1375 single block of data into a number of shares, such that a future
1376 ICodecDecoder can use a subset of these shares to recover the
1377 original data. This operation is invoked by calling encode(). Once
1378 the encoding parameters are set up, the encode operation can be
1379 invoked multiple times.
1381 set_params() prepares the encoder to accept blocks of input data that
1382 are exactly 'data_size' bytes in length. The encoder will be prepared
1383 to produce 'max_shares' shares for each encode() operation (although
1384 see the 'desired_share_ids' to use less CPU). The encoding math will
1385 be chosen such that the decoder can get by with as few as
1386 'required_shares' of these shares and still reproduce the original
1387 data. For example, set_params(1000, 5, 5) offers no redundancy at
1388 all, whereas set_params(1000, 1, 10) provides 10x redundancy.
1390 Numerical Restrictions: 'data_size' is required to be an integral
1391 multiple of 'required_shares'. In general, the caller should choose
1392 required_shares and max_shares based upon their reliability
1393 requirements and the number of peers available (the total storage
1394 space used is roughly equal to max_shares*data_size/required_shares),
1395 then choose data_size to achieve the memory footprint desired (larger
1396 data_size means more efficient operation, smaller data_size means
1397 smaller memory footprint).
1399 In addition, 'max_shares' must be equal to or greater than
1400 'required_shares'. Of course, setting them to be equal causes
1401 encode() to degenerate into a particularly slow form of the 'split'
1404 See encode() for more details about how these parameters are used.
1406 set_params() must be called before any other ICodecEncoder methods
1411 """Return the 3-tuple of data_size, required_shares, max_shares"""
1413 def get_encoder_type():
1414 """Return a short string that describes the type of this encoder.
1416 There is required to be a global table of encoder classes. This method
1417 returns an index into this table; the value at this index is an
1418 encoder class, and this encoder is an instance of that class.
1421 def get_block_size():
1422 """Return the length of the shares that encode() will produce.
1425 def encode_proposal(data, desired_share_ids=None):
1426 """Encode some data.
1428 'data' must be a string (or other buffer object), and len(data) must
1429 be equal to the 'data_size' value passed earlier to set_params().
1431 This will return a Deferred that will fire with two lists. The first
1432 is a list of shares, each of which is a string (or other buffer
1433 object) such that len(share) is the same as what get_share_size()
1434 returned earlier. The second is a list of shareids, in which each is
1435 an integer. The lengths of the two lists will always be equal to each
1436 other. The user should take care to keep each share closely
1437 associated with its shareid, as one is useless without the other.
1439 The length of this output list will normally be the same as the value
1440 provided to the 'max_shares' parameter of set_params(). This may be
1441 different if 'desired_share_ids' is provided.
1443 'desired_share_ids', if provided, is required to be a sequence of
1444 ints, each of which is required to be >= 0 and < max_shares. If not
1445 provided, encode() will produce 'max_shares' shares, as if
1446 'desired_share_ids' were set to range(max_shares). You might use this
1447 if you initially thought you were going to use 10 peers, started
1448 encoding, and then two of the peers dropped out: you could use
1449 desired_share_ids= to skip the work (both memory and CPU) of
1450 producing shares for the peers that are no longer available.
1454 def encode(inshares, desired_share_ids=None):
1455 """Encode some data. This may be called multiple times. Each call is
1458 inshares is a sequence of length required_shares, containing buffers
1459 (i.e. strings), where each buffer contains the next contiguous
1460 non-overlapping segment of the input data. Each buffer is required to
1461 be the same length, and the sum of the lengths of the buffers is
1462 required to be exactly the data_size promised by set_params(). (This
1463 implies that the data has to be padded before being passed to
1464 encode(), unless of course it already happens to be an even multiple
1465 of required_shares in length.)
1467 Note: the requirement to break up your data into
1468 'required_shares' chunks of exactly the right length before
1469 calling encode() is surprising from point of view of a user
1470 who doesn't know how FEC works. It feels like an
1471 implementation detail that has leaked outside the abstraction
1472 barrier. Is there a use case in which the data to be encoded
1473 might already be available in pre-segmented chunks, such that
1474 it is faster or less work to make encode() take a list rather
1475 than splitting a single string?
1477 Yes, there is: suppose you are uploading a file with K=64,
1478 N=128, segsize=262,144. Then each in-share will be of size
1479 4096. If you use this .encode() API then your code could first
1480 read each successive 4096-byte chunk from the file and store
1481 each one in a Python string and store each such Python string
1482 in a Python list. Then you could call .encode(), passing that
1483 list as "inshares". The encoder would generate the other 64
1484 "secondary shares" and return to you a new list containing
1485 references to the same 64 Python strings that you passed in
1486 (as the primary shares) plus references to the new 64 Python
1489 (You could even imagine that your code could use readv() so
1490 that the operating system can arrange to get all of those
1491 bytes copied from the file into the Python list of Python
1492 strings as efficiently as possible instead of having a loop
1493 written in C or in Python to copy the next part of the file
1494 into the next string.)
1496 On the other hand if you instead use the .encode_proposal()
1497 API (above), then your code can first read in all of the
1498 262,144 bytes of the segment from the file into a Python
1499 string, then call .encode_proposal() passing the segment data
1500 as the "data" argument. The encoder would basically first
1501 split the "data" argument into a list of 64 in-shares of 4096
1502 byte each, and then do the same thing that .encode() does. So
1503 this would result in a little bit more copying of data and a
1504 little bit higher of a "maximum memory usage" during the
1505 process, although it might or might not make a practical
1506 difference for our current use cases.
1508 Note that "inshares" is a strange name for the parameter if
1509 you think of the parameter as being just for feeding in data
1510 to the codec. It makes more sense if you think of the result
1511 of this encoding as being the set of shares from inshares plus
1512 an extra set of "secondary shares" (or "check shares"). It is
1513 a surprising name! If the API is going to be surprising then
1514 the name should be surprising. If we switch to
1515 encode_proposal() above then we should also switch to an
1518 'desired_share_ids', if provided, is required to be a sequence of
1519 ints, each of which is required to be >= 0 and < max_shares. If not
1520 provided, encode() will produce 'max_shares' shares, as if
1521 'desired_share_ids' were set to range(max_shares). You might use this
1522 if you initially thought you were going to use 10 peers, started
1523 encoding, and then two of the peers dropped out: you could use
1524 desired_share_ids= to skip the work (both memory and CPU) of
1525 producing shares for the peers that are no longer available.
1527 For each call, encode() will return a Deferred that fires with two
1528 lists, one containing shares and the other containing the shareids.
1529 The get_share_size() method can be used to determine the length of
1530 the share strings returned by encode(). Each shareid is a small
1531 integer, exactly as passed into 'desired_share_ids' (or
1532 range(max_shares), if desired_share_ids was not provided).
1534 The shares and their corresponding shareids are required to be kept
1535 together during storage and retrieval. Specifically, the share data is
1536 useless by itself: the decoder needs to be told which share is which
1537 by providing it with both the shareid and the actual share data.
1539 This function will allocate an amount of memory roughly equal to::
1541 (max_shares - required_shares) * get_share_size()
1543 When combined with the memory that the caller must allocate to
1544 provide the input data, this leads to a memory footprint roughly
1545 equal to the size of the resulting encoded shares (i.e. the expansion
1546 factor times the size of the input segment).
1551 # returning a list of (shareidN,shareN) tuples instead of a pair of
1552 # lists (shareids..,shares..). Brian thought the tuples would
1553 # encourage users to keep the share and shareid together throughout
1554 # later processing, Zooko pointed out that the code to iterate
1555 # through two lists is not really more complicated than using a list
1556 # of tuples and there's also a performance improvement
1558 # having 'data_size' not required to be an integral multiple of
1559 # 'required_shares'. Doing this would require encode() to perform
1560 # padding internally, and we'd prefer to have any padding be done
1561 # explicitly by the caller. Yes, it is an abstraction leak, but
1562 # hopefully not an onerous one.
1565 class ICodecDecoder(Interface):
1566 def set_params(data_size, required_shares, max_shares):
1567 """Set the params. They have to be exactly the same ones that were
1568 used for encoding."""
1570 def get_needed_shares():
1571 """Return the number of shares needed to reconstruct the data.
1572 set_params() is required to be called before this."""
1574 def decode(some_shares, their_shareids):
1575 """Decode a partial list of shares into data.
1577 'some_shares' is required to be a sequence of buffers of sharedata, a
1578 subset of the shares returned by ICodecEncode.encode(). Each share is
1579 required to be of the same length. The i'th element of their_shareids
1580 is required to be the shareid of the i'th buffer in some_shares.
1582 This returns a Deferred that fires with a sequence of buffers. This
1583 sequence will contain all of the segments of the original data, in
1584 order. The sum of the lengths of all of the buffers will be the
1585 'data_size' value passed into the original ICodecEncode.set_params()
1586 call. To get back the single original input block of data, use
1587 ''.join(output_buffers), or you may wish to simply write them in
1588 order to an output file.
1590 Note that some of the elements in the result sequence may be
1591 references to the elements of the some_shares input sequence. In
1592 particular, this means that if those share objects are mutable (e.g.
1593 arrays) and if they are changed, then both the input (the
1594 'some_shares' parameter) and the output (the value given when the
1595 deferred is triggered) will change.
1597 The length of 'some_shares' is required to be exactly the value of
1598 'required_shares' passed into the original ICodecEncode.set_params()
1603 class IEncoder(Interface):
1604 """I take an object that provides IEncryptedUploadable, which provides
1605 encrypted data, and a list of shareholders. I then encode, hash, and
1606 deliver shares to those shareholders. I will compute all the necessary
1607 Merkle hash trees that are necessary to validate the crypttext that
1608 eventually comes back from the shareholders. I provide the URI Extension
1609 Block Hash, and the encoding parameters, both of which must be included
1612 I do not choose shareholders, that is left to the IUploader. I must be
1613 given a dict of RemoteReferences to storage buckets that are ready and
1614 willing to receive data.
1618 """Specify the number of bytes that will be encoded. This must be
1619 peformed before get_serialized_params() can be called.
1621 def set_params(params):
1622 """Override the default encoding parameters. 'params' is a tuple of
1623 (k,d,n), where 'k' is the number of required shares, 'd' is the
1624 servers_of_happiness, and 'n' is the total number of shares that will
1627 Encoding parameters can be set in three ways. 1: The Encoder class
1628 provides defaults (3/7/10). 2: the Encoder can be constructed with
1629 an 'options' dictionary, in which the
1630 needed_and_happy_and_total_shares' key can be a (k,d,n) tuple. 3:
1631 set_params((k,d,n)) can be called.
1633 If you intend to use set_params(), you must call it before
1634 get_share_size or get_param are called.
1637 def set_encrypted_uploadable(u):
1638 """Provide a source of encrypted upload data. 'u' must implement
1639 IEncryptedUploadable.
1641 When this is called, the IEncryptedUploadable will be queried for its
1642 length and the storage_index that should be used.
1644 This returns a Deferred that fires with this Encoder instance.
1646 This must be performed before start() can be called.
1649 def get_param(name):
1650 """Return an encoding parameter, by name.
1652 'storage_index': return a string with the (16-byte truncated SHA-256
1653 hash) storage index to which these shares should be
1656 'share_counts': return a tuple describing how many shares are used:
1657 (needed_shares, servers_of_happiness, total_shares)
1659 'num_segments': return an int with the number of segments that
1662 'segment_size': return an int with the size of each segment.
1664 'block_size': return the size of the individual blocks that will
1665 be delivered to a shareholder's put_block() method. By
1666 knowing this, the shareholder will be able to keep all
1667 blocks in a single file and still provide random access
1668 when reading them. # TODO: can we avoid exposing this?
1670 'share_size': an int with the size of the data that will be stored
1671 on each shareholder. This is aggregate amount of data
1672 that will be sent to the shareholder, summed over all
1673 the put_block() calls I will ever make. It is useful to
1674 determine this size before asking potential
1675 shareholders whether they will grant a lease or not,
1676 since their answers will depend upon how much space we
1677 need. TODO: this might also include some amount of
1678 overhead, like the size of all the hashes. We need to
1679 decide whether this is useful or not.
1681 'serialized_params': a string with a concise description of the
1682 codec name and its parameters. This may be passed
1683 into the IUploadable to let it make sure that
1684 the same file encoded with different parameters
1685 will result in different storage indexes.
1687 Once this is called, set_size() and set_params() may not be called.
1690 def set_shareholders(shareholders, servermap):
1691 """Tell the encoder where to put the encoded shares. 'shareholders'
1692 must be a dictionary that maps share number (an integer ranging from
1693 0 to n-1) to an instance that provides IStorageBucketWriter.
1694 'servermap' is a dictionary that maps share number (as defined above)
1695 to a set of peerids. This must be performed before start() can be
1699 """Begin the encode/upload process. This involves reading encrypted
1700 data from the IEncryptedUploadable, encoding it, uploading the shares
1701 to the shareholders, then sending the hash trees.
1703 set_encrypted_uploadable() and set_shareholders() must be called
1704 before this can be invoked.
1706 This returns a Deferred that fires with a verify cap when the upload
1707 process is complete. The verifycap, plus the encryption key, is
1708 sufficient to construct the read cap.
1712 class IDecoder(Interface):
1713 """I take a list of shareholders and some setup information, then
1714 download, validate, decode, and decrypt data from them, writing the
1715 results to an output file.
1717 I do not locate the shareholders, that is left to the IDownloader. I must
1718 be given a dict of RemoteReferences to storage buckets that are ready to
1723 """I take a file-like object (providing write and close) to which all
1724 the plaintext data will be written.
1726 TODO: producer/consumer . Maybe write() should return a Deferred that
1727 indicates when it will accept more data? But probably having the
1728 IDecoder be a producer is easier to glue to IConsumer pieces.
1731 def set_shareholders(shareholders):
1732 """I take a dictionary that maps share identifiers (small integers)
1733 to RemoteReferences that provide RIBucketReader. This must be called
1737 """I start the download. This process involves retrieving data and
1738 hash chains from the shareholders, using the hashes to validate the
1739 data, decoding the shares into segments, decrypting the segments,
1740 then writing the resulting plaintext to the output file.
1742 I return a Deferred that will fire (with self) when the download is
1747 class IDownloadTarget(Interface):
1748 # Note that if the IDownloadTarget is also an IConsumer, the downloader
1749 # will register itself as a producer. This allows the target to invoke
1750 # downloader.pauseProducing, resumeProducing, and stopProducing.
1752 """Called before any calls to write() or close(). If an error
1753 occurs before any data is available, fail() may be called without
1754 a previous call to open().
1756 'size' is the length of the file being downloaded, in bytes."""
1759 """Output some data to the target."""
1762 """Inform the target that there is no more data to be written."""
1765 """fail() is called to indicate that the download has failed. 'why'
1766 is a Failure object indicating what went wrong. No further methods
1767 will be invoked on the IDownloadTarget after fail()."""
1769 def register_canceller(cb):
1770 """The CiphertextDownloader uses this to register a no-argument function
1771 that the target can call to cancel the download. Once this canceller
1772 is invoked, no further calls to write() or close() will be made."""
1775 """When the CiphertextDownloader is done, this finish() function will be
1776 called. Whatever it returns will be returned to the invoker of
1777 Downloader.download.
1781 class IDownloader(Interface):
1782 def download(uri, target):
1783 """Perform a CHK download, sending the data to the given target.
1784 'target' must provide IDownloadTarget.
1786 Returns a Deferred that fires (with the results of target.finish)
1787 when the download is finished, or errbacks if something went wrong."""
1790 class IEncryptedUploadable(Interface):
1791 def set_upload_status(upload_status):
1792 """Provide an IUploadStatus object that should be filled with status
1793 information. The IEncryptedUploadable is responsible for setting
1794 key-determination progress ('chk'), size, storage_index, and
1795 ciphertext-fetch progress. It may delegate some of this
1796 responsibility to others, in particular to the IUploadable."""
1799 """This behaves just like IUploadable.get_size()."""
1801 def get_all_encoding_parameters():
1802 """Return a Deferred that fires with a tuple of
1803 (k,happy,n,segment_size). The segment_size will be used as-is, and
1804 must match the following constraints: it must be a multiple of k, and
1805 it shouldn't be unreasonably larger than the file size (if
1806 segment_size is larger than filesize, the difference must be stored
1809 This usually passes through to the IUploadable method of the same
1812 The encoder strictly obeys the values returned by this method. To
1813 make an upload use non-default encoding parameters, you must arrange
1814 to control the values that this method returns.
1817 def get_storage_index():
1818 """Return a Deferred that fires with a 16-byte storage index.
1821 def read_encrypted(length, hash_only):
1822 """This behaves just like IUploadable.read(), but returns crypttext
1823 instead of plaintext. If hash_only is True, then this discards the
1824 data (and returns an empty list); this improves efficiency when
1825 resuming an interrupted upload (where we need to compute the
1826 plaintext hashes, but don't need the redundant encrypted data)."""
1828 def get_plaintext_hashtree_leaves(first, last, num_segments):
1829 """OBSOLETE; Get the leaf nodes of a merkle hash tree over the
1830 plaintext segments, i.e. get the tagged hashes of the given segments.
1831 The segment size is expected to be generated by the
1832 IEncryptedUploadable before any plaintext is read or ciphertext
1833 produced, so that the segment hashes can be generated with only a
1836 This returns a Deferred which fires with a sequence of hashes, using:
1838 tuple(segment_hashes[first:last])
1840 'num_segments' is used to assert that the number of segments that the
1841 IEncryptedUploadable handled matches the number of segments that the
1842 encoder was expecting.
1844 This method must not be called until the final byte has been read
1845 from read_encrypted(). Once this method is called, read_encrypted()
1846 can never be called again.
1849 def get_plaintext_hash():
1850 """OBSOLETE; Get the hash of the whole plaintext.
1852 This returns a Deferred which fires with a tagged SHA-256 hash of the
1853 whole plaintext, obtained from hashutil.plaintext_hash(data).
1857 """Just like IUploadable.close()."""
1860 class IUploadable(Interface):
1861 def set_upload_status(upload_status):
1862 """Provide an IUploadStatus object that should be filled with status
1863 information. The IUploadable is responsible for setting
1864 key-determination progress ('chk')."""
1866 def set_default_encoding_parameters(params):
1867 """Set the default encoding parameters, which must be a dict mapping
1868 strings to ints. The meaningful keys are 'k', 'happy', 'n', and
1869 'max_segment_size'. These might have an influence on the final
1870 encoding parameters returned by get_all_encoding_parameters(), if the
1871 Uploadable doesn't have more specific preferences.
1873 This call is optional: if it is not used, the Uploadable will use
1874 some built-in defaults. If used, this method must be called before
1875 any other IUploadable methods to have any effect.
1879 """Return a Deferred that will fire with the length of the data to be
1880 uploaded, in bytes. This will be called before the data is actually
1881 used, to compute encoding parameters.
1884 def get_all_encoding_parameters():
1885 """Return a Deferred that fires with a tuple of
1886 (k,happy,n,segment_size). The segment_size will be used as-is, and
1887 must match the following constraints: it must be a multiple of k, and
1888 it shouldn't be unreasonably larger than the file size (if
1889 segment_size is larger than filesize, the difference must be stored
1892 The relative values of k and n allow some IUploadables to request
1893 better redundancy than others (in exchange for consuming more space
1896 Larger values of segment_size reduce hash overhead, while smaller
1897 values reduce memory footprint and cause data to be delivered in
1898 smaller pieces (which may provide a smoother and more predictable
1899 download experience).
1901 The encoder strictly obeys the values returned by this method. To
1902 make an upload use non-default encoding parameters, you must arrange
1903 to control the values that this method returns. One way to influence
1904 them may be to call set_encoding_parameters() before calling
1905 get_all_encoding_parameters().
1908 def get_encryption_key():
1909 """Return a Deferred that fires with a 16-byte AES key. This key will
1910 be used to encrypt the data. The key will also be hashed to derive
1913 Uploadables that want to achieve convergence should hash their file
1914 contents and the serialized_encoding_parameters to form the key
1915 (which of course requires a full pass over the data). Uploadables can
1916 use the upload.ConvergentUploadMixin class to achieve this
1919 Uploadables that do not care about convergence (or do not wish to
1920 make multiple passes over the data) can simply return a
1921 strongly-random 16 byte string.
1923 get_encryption_key() may be called multiple times: the IUploadable is
1924 required to return the same value each time.
1928 """Return a Deferred that fires with a list of strings (perhaps with
1929 only a single element) that, when concatenated together, contain the
1930 next 'length' bytes of data. If EOF is near, this may provide fewer
1931 than 'length' bytes. The total number of bytes provided by read()
1932 before it signals EOF must equal the size provided by get_size().
1934 If the data must be acquired through multiple internal read
1935 operations, returning a list instead of a single string may help to
1936 reduce string copies. However, the length of the concatenated strings
1937 must equal the amount of data requested, unless EOF is encountered.
1938 Long reads, or short reads without EOF, are not allowed. read()
1939 should return the same amount of data as a local disk file read, just
1940 in a different shape and asynchronously.
1942 'length' will typically be equal to (min(get_size(),1MB)/req_shares),
1943 so a 10kB file means length=3kB, 100kB file means length=30kB,
1944 and >=1MB file means length=300kB.
1946 This method provides for a single full pass through the data. Later
1947 use cases may desire multiple passes or access to only parts of the
1948 data (such as a mutable file making small edits-in-place). This API
1949 will be expanded once those use cases are better understood.
1953 """The upload is finished, and whatever filehandle was in use may be
1957 class IMutableUploadable(Interface):
1959 I represent content that is due to be uploaded to a mutable filecap.
1961 # This is somewhat simpler than the IUploadable interface above
1962 # because mutable files do not need to be concerned with possibly
1963 # generating a CHK, nor with per-file keys. It is a subset of the
1964 # methods in IUploadable, though, so we could just as well implement
1965 # the mutable uploadables as IUploadables that don't happen to use
1966 # those methods (with the understanding that the unused methods will
1967 # never be called on such objects)
1970 Returns a Deferred that fires with the size of the content held
1976 Returns a list of strings that, when concatenated, are the next
1977 length bytes of the file, or fewer if there are fewer bytes
1978 between the current location and the end of the file.
1983 The process that used the Uploadable is finished using it, so
1984 the uploadable may be closed.
1988 class IUploadResults(Interface):
1989 """I am returned by immutable upload() methods and contain the results of
1992 Note that some of my methods return empty values (0 or an empty dict)
1993 when called for non-distributed LIT files."""
1995 def get_file_size():
1996 """Return the file size, in bytes."""
1999 """Return the (string) URI of the object uploaded, a CHK readcap."""
2001 def get_ciphertext_fetched():
2002 """Return the number of bytes fetched by the helpe for this upload,
2003 or 0 if the helper did not need to fetch any bytes (or if there was
2006 def get_preexisting_shares():
2007 """Return the number of shares that were already present in the grid."""
2009 def get_pushed_shares():
2010 """Return the number of shares that were uploaded."""
2013 """Return a dict mapping share identifier to set of IServer
2014 instances. This indicates which servers were given which shares. For
2015 immutable files, the shareid is an integer (the share number, from 0
2016 to N-1). For mutable files, it is a string of the form
2017 'seq%d-%s-sh%d', containing the sequence number, the roothash, and
2018 the share number."""
2020 def get_servermap():
2021 """Return dict mapping IServer instance to a set of share numbers."""
2024 """Return dict of timing information, mapping name to seconds. All
2026 total : total upload time, start to finish
2027 storage_index : time to compute the storage index
2028 peer_selection : time to decide which peers will be used
2029 contacting_helper : initial helper query to upload/no-upload decision
2030 helper_total : initial helper query to helper finished pushing
2031 cumulative_fetch : helper waiting for ciphertext requests
2032 total_fetch : helper start to last ciphertext response
2033 cumulative_encoding : just time spent in zfec
2034 cumulative_sending : just time spent waiting for storage servers
2035 hashes_and_close : last segment push to shareholder close
2036 total_encode_and_push : first encode to shareholder close
2039 def get_uri_extension_data():
2040 """Return the dict of UEB data created for this file."""
2042 def get_verifycapstr():
2043 """Return the (string) verify-cap URI for the uploaded object."""
2046 class IDownloadResults(Interface):
2047 """I am created internally by download() methods. I contain a number of
2048 public attributes that contain details about the download process.::
2050 .file_size : the size of the file, in bytes
2051 .servers_used : set of server peerids that were used during download
2052 .server_problems : dict mapping server peerid to a problem string. Only
2053 servers that had problems (bad hashes, disconnects)
2055 .servermap : dict mapping server peerid to a set of share numbers. Only
2056 servers that had any shares are listed here.
2057 .timings : dict of timing information, mapping name to seconds (float)
2058 peer_selection : time to ask servers about shares
2059 servers_peer_selection : dict of peerid to DYHB-query time
2060 uri_extension : time to fetch a copy of the URI extension block
2061 hashtrees : time to fetch the hash trees
2062 segments : time to fetch, decode, and deliver segments
2063 cumulative_fetch : time spent waiting for storage servers
2064 cumulative_decode : just time spent in zfec
2065 cumulative_decrypt : just time spent in decryption
2066 total : total download time, start to finish
2067 fetch_per_server : dict of server to list of per-segment fetch times
2071 class IUploader(Interface):
2072 def upload(uploadable):
2073 """Upload the file. 'uploadable' must impement IUploadable. This
2074 returns a Deferred that fires with an IUploadResults instance, from
2075 which the URI of the file can be obtained as results.uri ."""
2077 def upload_ssk(write_capability, new_version, uploadable):
2078 """TODO: how should this work?"""
2080 class ICheckable(Interface):
2081 def check(monitor, verify=False, add_lease=False):
2082 """Check up on my health, optionally repairing any problems.
2084 This returns a Deferred that fires with an instance that provides
2085 ICheckResults, or None if the object is non-distributed (i.e. LIT
2088 The monitor will be checked periodically to see if the operation has
2089 been cancelled. If so, no new queries will be sent, and the Deferred
2090 will fire (with a OperationCancelledError) immediately.
2092 Filenodes and dirnodes (which provide IFilesystemNode) are also
2093 checkable. Instances that represent verifier-caps will be checkable
2094 but not downloadable. Some objects (like LIT files) do not actually
2095 live in the grid, and their checkers return None (non-distributed
2096 files are always healthy).
2098 If verify=False, a relatively lightweight check will be performed: I
2099 will ask all servers if they have a share for me, and I will believe
2100 whatever they say. If there are at least N distinct shares on the
2101 grid, my results will indicate r.is_healthy()==True. This requires a
2102 roundtrip to each server, but does not transfer very much data, so
2103 the network bandwidth is fairly low.
2105 If verify=True, a more resource-intensive check will be performed:
2106 every share will be downloaded, and the hashes will be validated on
2107 every bit. I will ignore any shares that failed their hash checks. If
2108 there are at least N distinct valid shares on the grid, my results
2109 will indicate r.is_healthy()==True. This requires N/k times as much
2110 download bandwidth (and server disk IO) as a regular download. If a
2111 storage server is holding a corrupt share, or is experiencing memory
2112 failures during retrieval, or is malicious or buggy, then
2113 verification will detect the problem, but checking will not.
2115 If add_lease=True, I will ensure that an up-to-date lease is present
2116 on each share. The lease secrets will be derived from by node secret
2117 (in BASEDIR/private/secret), so either I will add a new lease to the
2118 share, or I will merely renew the lease that I already had. In a
2119 future version of the storage-server protocol (once Accounting has
2120 been implemented), there may be additional options here to define the
2121 kind of lease that is obtained (which account number to claim, etc).
2123 TODO: any problems seen during checking will be reported to the
2124 health-manager.furl, a centralized object that is responsible for
2125 figuring out why files are unhealthy so corrective action can be
2129 def check_and_repair(monitor, verify=False, add_lease=False):
2130 """Like check(), but if the file/directory is not healthy, attempt to
2133 Any non-healthy result will cause an immediate repair operation, to
2134 generate and upload new shares. After repair, the file will be as
2135 healthy as we can make it. Details about what sort of repair is done
2136 will be put in the check-and-repair results. The Deferred will not
2137 fire until the repair is complete.
2139 This returns a Deferred that fires with an instance of
2140 ICheckAndRepairResults."""
2143 class IDeepCheckable(Interface):
2144 def start_deep_check(verify=False, add_lease=False):
2145 """Check upon the health of me and everything I can reach.
2147 This is a recursive form of check(), useable only on dirnodes.
2149 I return a Monitor, with results that are an IDeepCheckResults
2152 TODO: If any of the directories I traverse are unrecoverable, the
2153 Monitor will report failure. If any of the files I check upon are
2154 unrecoverable, those problems will be reported in the
2155 IDeepCheckResults as usual, and the Monitor will not report a
2159 def start_deep_check_and_repair(verify=False, add_lease=False):
2160 """Check upon the health of me and everything I can reach. Repair
2161 anything that isn't healthy.
2163 This is a recursive form of check_and_repair(), useable only on
2166 I return a Monitor, with results that are an
2167 IDeepCheckAndRepairResults object.
2169 TODO: If any of the directories I traverse are unrecoverable, the
2170 Monitor will report failure. If any of the files I check upon are
2171 unrecoverable, those problems will be reported in the
2172 IDeepCheckResults as usual, and the Monitor will not report a
2177 class ICheckResults(Interface):
2178 """I contain the detailed results of a check/verify operation.
2181 def get_storage_index():
2182 """Return a string with the (binary) storage index."""
2184 def get_storage_index_string():
2185 """Return a string with the (printable) abbreviated storage index."""
2188 """Return the (string) URI of the object that was checked."""
2191 """Return a boolean, True if the file/dir is fully healthy, False if
2192 it is damaged in any way. Non-distributed LIT files always return
2195 def is_recoverable():
2196 """Return a boolean, True if the file/dir can be recovered, False if
2197 not. Unrecoverable files are obviously unhealthy. Non-distributed LIT
2198 files always return True."""
2200 def needs_rebalancing():
2201 """Return a boolean, True if the file/dirs reliability could be
2202 improved by moving shares to new servers. Non-distributed LIT files
2203 always return False."""
2205 # the following methods all return None for non-distributed LIT files
2207 def get_encoding_needed():
2208 """Return 'k', the number of shares required for recovery"""
2210 def get_encoding_expected():
2211 """Return 'N', the number of total shares generated"""
2213 def get_share_counter_good():
2214 """Return the number of distinct good shares that were found. For
2215 mutable files, this counts shares for the 'best' version."""
2217 def get_share_counter_wrong():
2218 """For mutable files, return the number of shares for versions other
2219 than the 'best' one (which is defined as being the recoverable
2220 version with the highest sequence number, then the highest roothash).
2221 These are either leftover shares from an older version (perhaps on a
2222 server that was offline when an update occurred), shares from an
2223 unrecoverable newer version, or shares from an alternate current
2224 version that results from an uncoordinated write collision. For a
2225 healthy file, this will equal 0. For immutable files, this will
2228 def get_corrupt_shares():
2229 """Return a list of 'share locators', one for each share that was
2230 found to be corrupt (integrity failure). Each share locator is a list
2231 of (IServer, storage_index, sharenum)."""
2233 def get_incompatible_shares():
2234 """Return a list of 'share locators', one for each share that was
2235 found to be of an unknown format. Each share locator is a list of
2236 (IServer, storage_index, sharenum)."""
2238 def get_servers_responding():
2239 """Return a list of IServer objects, one for each server that
2240 responded to the share query (even if they said they didn't have
2241 shares, and even if they said they did have shares but then didn't
2242 send them when asked, or dropped the connection, or returned a
2243 Failure, and even if they said they did have shares and sent
2244 incorrect ones when asked)"""
2246 def get_host_counter_good_shares():
2247 """Return the number of distinct storage servers with good shares. If
2248 this number is less than get_share_counters()[good], then some shares
2249 are doubled up, increasing the correlation of failures. This
2250 indicates that one or more shares should be moved to an otherwise
2251 unused server, if one is available.
2254 def get_version_counter_recoverable():
2255 """Return the number of recoverable versions of the file. For a
2256 healthy file, this will equal 1."""
2258 def get_version_counter_unrecoverable():
2259 """Return the number of unrecoverable versions of the file. For a
2260 healthy file, this will be 0."""
2263 """Return a dict mapping share identifier to list of IServer objects.
2264 This indicates which servers are holding which shares. For immutable
2265 files, the shareid is an integer (the share number, from 0 to N-1).
2266 For mutable files, it is a string of the form 'seq%d-%s-sh%d',
2267 containing the sequence number, the roothash, and the share number."""
2270 """Return a string with a brief (one-line) summary of the results."""
2273 """Return a list of strings with more detailed results."""
2276 class ICheckAndRepairResults(Interface):
2277 """I contain the detailed results of a check/verify/repair operation.
2279 The IFilesystemNode.check()/verify()/repair() methods all return
2280 instances that provide ICheckAndRepairResults.
2283 def get_storage_index():
2284 """Return a string with the (binary) storage index."""
2286 def get_storage_index_string():
2287 """Return a string with the (printable) abbreviated storage index."""
2289 def get_repair_attempted():
2290 """Return a boolean, True if a repair was attempted. We might not
2291 attempt to repair the file because it was healthy, or healthy enough
2292 (i.e. some shares were missing but not enough to exceed some
2293 threshold), or because we don't know how to repair this object."""
2295 def get_repair_successful():
2296 """Return a boolean, True if repair was attempted and the file/dir
2297 was fully healthy afterwards. False if no repair was attempted or if
2298 a repair attempt failed."""
2300 def get_pre_repair_results():
2301 """Return an ICheckResults instance that describes the state of the
2302 file/dir before any repair was attempted."""
2304 def get_post_repair_results():
2305 """Return an ICheckResults instance that describes the state of the
2306 file/dir after any repair was attempted. If no repair was attempted,
2307 the pre-repair and post-repair results will be identical."""
2310 class IDeepCheckResults(Interface):
2311 """I contain the results of a deep-check operation.
2313 This is returned by a call to ICheckable.deep_check().
2316 def get_root_storage_index_string():
2317 """Return the storage index (abbreviated human-readable string) of
2318 the first object checked."""
2321 """Return a dictionary with the following keys::
2323 count-objects-checked: count of how many objects were checked
2324 count-objects-healthy: how many of those objects were completely
2326 count-objects-unhealthy: how many were damaged in some way
2327 count-objects-unrecoverable: how many were unrecoverable
2328 count-corrupt-shares: how many shares were found to have
2329 corruption, summed over all objects
2333 def get_corrupt_shares():
2334 """Return a set of (IServer, storage_index, sharenum) for all shares
2335 that were found to be corrupt. storage_index is binary."""
2337 def get_all_results():
2338 """Return a dictionary mapping pathname (a tuple of strings, ready to
2339 be slash-joined) to an ICheckResults instance, one for each object
2340 that was checked."""
2342 def get_results_for_storage_index(storage_index):
2343 """Retrive the ICheckResults instance for the given (binary)
2344 storage index. Raises KeyError if there are no results for that
2348 """Return a dictionary with the same keys as
2349 IDirectoryNode.deep_stats()."""
2352 class IDeepCheckAndRepairResults(Interface):
2353 """I contain the results of a deep-check-and-repair operation.
2355 This is returned by a call to ICheckable.deep_check_and_repair().
2358 def get_root_storage_index_string():
2359 """Return the storage index (abbreviated human-readable string) of
2360 the first object checked."""
2363 """Return a dictionary with the following keys::
2365 count-objects-checked: count of how many objects were checked
2366 count-objects-healthy-pre-repair: how many of those objects were
2367 completely healthy (before any
2369 count-objects-unhealthy-pre-repair: how many were damaged in
2371 count-objects-unrecoverable-pre-repair: how many were unrecoverable
2372 count-objects-healthy-post-repair: how many of those objects were
2373 completely healthy (after any
2375 count-objects-unhealthy-post-repair: how many were damaged in
2377 count-objects-unrecoverable-post-repair: how many were
2379 count-repairs-attempted: repairs were attempted on this many
2380 objects. The count-repairs- keys will
2381 always be provided, however unless
2382 repair=true is present, they will all
2384 count-repairs-successful: how many repairs resulted in healthy
2386 count-repairs-unsuccessful: how many repairs resulted did not
2387 results in completely healthy objects
2388 count-corrupt-shares-pre-repair: how many shares were found to
2389 have corruption, summed over all
2390 objects examined (before any
2392 count-corrupt-shares-post-repair: how many shares were found to
2393 have corruption, summed over all
2394 objects examined (after any
2399 """Return a dictionary with the same keys as
2400 IDirectoryNode.deep_stats()."""
2402 def get_corrupt_shares():
2403 """Return a set of (IServer, storage_index, sharenum) for all shares
2404 that were found to be corrupt before any repair was attempted.
2405 storage_index is binary.
2407 def get_remaining_corrupt_shares():
2408 """Return a set of (IServer, storage_index, sharenum) for all shares
2409 that were found to be corrupt after any repair was completed.
2410 storage_index is binary. These are shares that need manual inspection
2411 and probably deletion.
2413 def get_all_results():
2414 """Return a dictionary mapping pathname (a tuple of strings, ready to
2415 be slash-joined) to an ICheckAndRepairResults instance, one for each
2416 object that was checked."""
2418 def get_results_for_storage_index(storage_index):
2419 """Retrive the ICheckAndRepairResults instance for the given (binary)
2420 storage index. Raises KeyError if there are no results for that
2424 class IRepairable(Interface):
2425 def repair(check_results):
2426 """Attempt to repair the given object. Returns a Deferred that fires
2427 with a IRepairResults object.
2429 I must be called with an object that implements ICheckResults, as
2430 proof that you have actually discovered a problem with this file. I
2431 will use the data in the checker results to guide the repair process,
2432 such as which servers provided bad data and should therefore be
2433 avoided. The ICheckResults object is inside the
2434 ICheckAndRepairResults object, which is returned by the
2435 ICheckable.check() method::
2437 d = filenode.check(repair=False)
2438 def _got_results(check_and_repair_results):
2439 check_results = check_and_repair_results.get_pre_repair_results()
2440 return filenode.repair(check_results)
2441 d.addCallback(_got_results)
2446 class IRepairResults(Interface):
2447 """I contain the results of a repair operation."""
2448 def get_successful():
2449 """Returns a boolean: True if the repair made the file healthy, False
2450 if not. Repair failure generally indicates a file that has been
2451 damaged beyond repair."""
2454 class IClient(Interface):
2455 def upload(uploadable):
2456 """Upload some data into a CHK, get back the UploadResults for it.
2457 @param uploadable: something that implements IUploadable
2458 @return: a Deferred that fires with the UploadResults instance.
2459 To get the URI for this file, use results.uri .
2462 def create_mutable_file(contents=""):
2463 """Create a new mutable file (with initial) contents, get back the
2466 @param contents: (bytestring, callable, or None): this provides the
2467 initial contents of the mutable file. If 'contents' is a bytestring,
2468 it will be used as-is. If 'contents' is a callable, it will be
2469 invoked with the new MutableFileNode instance and is expected to
2470 return a bytestring with the initial contents of the file (the
2471 callable can use node.get_writekey() to decide how to encrypt the
2472 initial contents, e.g. for a brand new dirnode with initial
2473 children). contents=None is equivalent to an empty string. Using
2474 content_maker= is more efficient than creating a mutable file and
2475 setting its contents in two separate operations.
2477 @return: a Deferred that fires with an IMutableFileNode instance.
2480 def create_dirnode(initial_children={}):
2481 """Create a new unattached dirnode, possibly with initial children.
2483 @param initial_children: dict with keys that are unicode child names,
2484 and values that are (childnode, metadata) tuples.
2486 @return: a Deferred that fires with the new IDirectoryNode instance.
2489 def create_node_from_uri(uri, rouri):
2490 """Create a new IFilesystemNode instance from the uri, synchronously.
2491 @param uri: a string or IURI-providing instance, or None. This could
2492 be for a LiteralFileNode, a CHK file node, a mutable file
2493 node, or a directory node
2494 @param rouri: a string or IURI-providing instance, or None. If the
2495 main uri is None, I will use the rouri instead. If I
2496 recognize the format of the main uri, I will ignore the
2497 rouri (because it can be derived from the writecap).
2499 @return: an instance that provides IFilesystemNode (or more usefully
2500 one of its subclasses). File-specifying URIs will result in
2501 IFileNode-providing instances, like ImmutableFileNode,
2502 LiteralFileNode, or MutableFileNode. Directory-specifying
2503 URIs will result in IDirectoryNode-providing instances, like
2508 class INodeMaker(Interface):
2509 """The NodeMaker is used to create IFilesystemNode instances. It can
2510 accept a filecap/dircap string and return the node right away. It can
2511 also create new nodes (i.e. upload a file, or create a mutable file)
2512 asynchronously. Once you have one of these nodes, you can use other
2513 methods to determine whether it is a file or directory, and to download
2514 or modify its contents.
2516 The NodeMaker encapsulates all the authorities that these
2517 IFilesystemNodes require (like references to the StorageFarmBroker). Each
2518 Tahoe process will typically have a single NodeMaker, but unit tests may
2519 create simplified/mocked forms for testing purposes.
2521 def create_from_cap(writecap, readcap=None, **kwargs):
2522 """I create an IFilesystemNode from the given writecap/readcap. I can
2523 only provide nodes for existing file/directory objects: use my other
2524 methods to create new objects. I return synchronously."""
2526 def create_mutable_file(contents=None, keysize=None):
2527 """I create a new mutable file, and return a Deferred that will fire
2528 with the IMutableFileNode instance when it is ready. If contents= is
2529 provided (a bytestring), it will be used as the initial contents of
2530 the new file, otherwise the file will contain zero bytes. keysize= is
2531 for use by unit tests, to create mutable files that are smaller than
2534 def create_new_mutable_directory(initial_children={}):
2535 """I create a new mutable directory, and return a Deferred that will
2536 fire with the IDirectoryNode instance when it is ready. If
2537 initial_children= is provided (a dict mapping unicode child name to
2538 (childnode, metadata_dict) tuples), the directory will be populated
2539 with those children, otherwise it will be empty."""
2542 class IClientStatus(Interface):
2543 def list_all_uploads():
2544 """Return a list of uploader objects, one for each upload that
2545 currently has an object available (tracked with weakrefs). This is
2546 intended for debugging purposes."""
2548 def list_active_uploads():
2549 """Return a list of active IUploadStatus objects."""
2551 def list_recent_uploads():
2552 """Return a list of IUploadStatus objects for the most recently
2555 def list_all_downloads():
2556 """Return a list of downloader objects, one for each download that
2557 currently has an object available (tracked with weakrefs). This is
2558 intended for debugging purposes."""
2560 def list_active_downloads():
2561 """Return a list of active IDownloadStatus objects."""
2563 def list_recent_downloads():
2564 """Return a list of IDownloadStatus objects for the most recently
2565 started downloads."""
2568 class IUploadStatus(Interface):
2570 """Return a timestamp (float with seconds since epoch) indicating
2571 when the operation was started."""
2573 def get_storage_index():
2574 """Return a string with the (binary) storage index in use on this
2575 upload. Returns None if the storage index has not yet been
2579 """Return an integer with the number of bytes that will eventually
2580 be uploaded for this file. Returns None if the size is not yet known.
2583 """Return True if this upload is using a Helper, False if not."""
2586 """Return a string describing the current state of the upload
2590 """Returns a tuple of floats, (chk, ciphertext, encode_and_push),
2591 each from 0.0 to 1.0 . 'chk' describes how much progress has been
2592 made towards hashing the file to determine a CHK encryption key: if
2593 non-convergent encryption is in use, this will be trivial, otherwise
2594 the whole file must be hashed. 'ciphertext' describes how much of the
2595 ciphertext has been pushed to the helper, and is '1.0' for non-helper
2596 uploads. 'encode_and_push' describes how much of the encode-and-push
2597 process has finished: for helper uploads this is dependent upon the
2598 helper providing progress reports. It might be reasonable to add all
2599 three numbers and report the sum to the user."""
2602 """Return True if the upload is currently active, False if not."""
2605 """Return an instance of UploadResults (which contains timing and
2606 sharemap information). Might return None if the upload is not yet
2610 """Each upload status gets a unique number: this method returns that
2611 number. This provides a handle to this particular upload, so a web
2612 page can generate a suitable hyperlink."""
2615 class IDownloadStatus(Interface):
2617 """Return a timestamp (float with seconds since epoch) indicating
2618 when the operation was started."""
2620 def get_storage_index():
2621 """Return a string with the (binary) storage index in use on this
2622 download. This may be None if there is no storage index (i.e. LIT
2626 """Return an integer with the number of bytes that will eventually be
2627 retrieved for this file. Returns None if the size is not yet known.
2631 """Return True if this download is using a Helper, False if not."""
2634 """Return a string describing the current state of the download
2638 """Returns a float (from 0.0 to 1.0) describing the amount of the
2639 download that has completed. This value will remain at 0.0 until the
2640 first byte of plaintext is pushed to the download target."""
2643 """Return True if the download is currently active, False if not."""
2646 """Each download status gets a unique number: this method returns
2647 that number. This provides a handle to this particular download, so a
2648 web page can generate a suitable hyperlink."""
2651 class IServermapUpdaterStatus(Interface):
2654 class IPublishStatus(Interface):
2657 class IRetrieveStatus(Interface):
2661 class NotCapableError(Exception):
2662 """You have tried to write to a read-only node."""
2664 class BadWriteEnablerError(Exception):
2667 class RIControlClient(RemoteInterface):
2669 def wait_for_client_connections(num_clients=int):
2670 """Do not return until we have connections to at least NUM_CLIENTS
2674 def upload_from_file_to_uri(filename=str,
2675 convergence=ChoiceOf(None,
2676 StringConstraint(2**20))):
2677 """Upload a file to the grid. This accepts a filename (which must be
2678 absolute) that points to a file on the node's local disk. The node will
2679 read the contents of this file, upload it to the grid, then return the
2680 URI at which it was uploaded. If convergence is None then a random
2681 encryption key will be used, else the plaintext will be hashed, then
2682 that hash will be mixed together with the "convergence" string to form
2687 def download_from_uri_to_file(uri=URI, filename=str):
2688 """Download a file from the grid, placing it on the node's local disk
2689 at the given filename (which must be absolute[?]). Returns the
2690 absolute filename where the file was written."""
2695 def get_memory_usage():
2696 """Return a dict describes the amount of memory currently in use. The
2697 keys are 'VmPeak', 'VmSize', and 'VmData'. The values are integers,
2698 measuring memory consupmtion in bytes."""
2699 return DictOf(str, int)
2701 def speed_test(count=int, size=int, mutable=Any()):
2702 """Write 'count' tempfiles to disk, all of the given size. Measure
2703 how long (in seconds) it takes to upload them all to the servers.
2704 Then measure how long it takes to download all of them. If 'mutable'
2705 is 'create', time creation of mutable files. If 'mutable' is
2706 'upload', then time access to the same mutable file instead of
2709 Returns a tuple of (upload_time, download_time).
2711 return (float, float)
2713 def measure_peer_response_time():
2714 """Send a short message to each connected peer, and measure the time
2715 it takes for them to respond to it. This is a rough measure of the
2716 application-level round trip time.
2718 @return: a dictionary mapping peerid to a float (RTT time in seconds)
2721 return DictOf(str, float)
2724 UploadResults = Any() #DictOf(str, str)
2727 class RIEncryptedUploadable(RemoteInterface):
2728 __remote_name__ = "RIEncryptedUploadable.tahoe.allmydata.com"
2733 def get_all_encoding_parameters():
2734 return (int, int, int, long)
2736 def read_encrypted(offset=Offset, length=ReadSize):
2743 class RICHKUploadHelper(RemoteInterface):
2744 __remote_name__ = "RIUploadHelper.tahoe.allmydata.com"
2748 Return a dictionary of version information.
2750 return DictOf(str, Any())
2752 def upload(reader=RIEncryptedUploadable):
2753 return UploadResults
2756 class RIHelper(RemoteInterface):
2757 __remote_name__ = "RIHelper.tahoe.allmydata.com"
2761 Return a dictionary of version information.
2763 return DictOf(str, Any())
2765 def upload_chk(si=StorageIndex):
2766 """See if a file with a given storage index needs uploading. The
2767 helper will ask the appropriate storage servers to see if the file
2768 has already been uploaded. If so, the helper will return a set of
2769 'upload results' that includes whatever hashes are needed to build
2770 the read-cap, and perhaps a truncated sharemap.
2772 If the file has not yet been uploaded (or if it was only partially
2773 uploaded), the helper will return an empty upload-results dictionary
2774 and also an RICHKUploadHelper object that will take care of the
2775 upload process. The client should call upload() on this object and
2776 pass it a reference to an RIEncryptedUploadable object that will
2777 provide ciphertext. When the upload is finished, the upload() method
2778 will finish and return the upload results.
2780 return (UploadResults, ChoiceOf(RICHKUploadHelper, None))
2783 class RIStatsProvider(RemoteInterface):
2784 __remote_name__ = "RIStatsProvider.tahoe.allmydata.com"
2786 Provides access to statistics and monitoring information.
2791 returns a dictionary containing 'counters' and 'stats', each a
2792 dictionary with string counter/stat name keys, and numeric or None values.
2793 counters are monotonically increasing measures of work done, and
2794 stats are instantaneous measures (potentially time averaged
2797 return DictOf(str, DictOf(str, ChoiceOf(float, int, long, None)))
2800 class RIStatsGatherer(RemoteInterface):
2801 __remote_name__ = "RIStatsGatherer.tahoe.allmydata.com"
2803 Provides a monitoring service for centralised collection of stats
2806 def provide(provider=RIStatsProvider, nickname=str):
2808 @param provider: a stats collector instance that should be polled
2809 periodically by the gatherer to collect stats.
2810 @param nickname: a name useful to identify the provided client
2815 class IStatsProducer(Interface):
2818 returns a dictionary, with str keys representing the names of stats
2819 to be monitored, and numeric values.
2822 class RIKeyGenerator(RemoteInterface):
2823 __remote_name__ = "RIKeyGenerator.tahoe.allmydata.com"
2825 Provides a service offering to make RSA key pairs.
2828 def get_rsa_key_pair(key_size=int):
2830 @param key_size: the size of the signature key.
2831 @return: tuple(verifying_key, signing_key)
2833 return TupleOf(str, str)
2836 class FileTooLargeError(Exception):
2840 class IValidatedThingProxy(Interface):
2842 """ Acquire a thing and validate it. Return a deferred that is
2843 eventually fired with self if the thing is valid or errbacked if it
2844 can't be acquired or validated."""
2847 class InsufficientVersionError(Exception):
2848 def __init__(self, needed, got):
2849 self.needed = needed
2853 return "InsufficientVersionError(need '%s', got %s)" % (self.needed,
2856 class EmptyPathnameComponentError(Exception):
2857 """The webapi disallows empty pathname components."""