From: Daira Hopwood Date: Wed, 12 Dec 2012 06:23:16 +0000 (+0000) Subject: Changes and additions to interface documentation. X-Git-Url: https://git.rkrishnan.org/?a=commitdiff_plain;h=1ede4495bdabe7638ebdf19f8ee18d0d3ab34adb;p=tahoe-lafs%2Ftahoe-lafs.git Changes and additions to interface documentation. Signed-off-by: David-Sarah Hopwood --- diff --git a/src/allmydata/interfaces.py b/src/allmydata/interfaces.py index 8774bde2..62581be6 100644 --- a/src/allmydata/interfaces.py +++ b/src/allmydata/interfaces.py @@ -99,23 +99,29 @@ class RIStorageServer(RemoteInterface): sharenums=SetOf(int, maxLength=MAX_BUCKETS), allocated_size=Offset, canary=Referenceable): """ - @param storage_index: the index of the bucket to be created or - increfed. - @param sharenums: these are the share numbers (probably between 0 and - 99) that the sender is proposing to store on this - server. - @param renew_secret: This is the secret used to protect bucket refresh - This secret is generated by the client and - stored for later comparison by the server. Each - server is given a different secret. - @param cancel_secret: This no longer allows lease cancellation, but - must still be a unique value identifying the - lease. XXX stop relying on it to be unique. - @param canary: If the canary is lost before close(), the bucket is - deleted. + Allocate BucketWriters for a set of shares on this server. + + renew_secret and cancel_secret are ignored as of Tahoe-LAFS v1.11.0, + but for backward compatibility with older servers, should be + calculated in the same way as previous clients (see + allmydata.util.hashutil.file_{renewal,cancel}_secret_hash). + + Servers that ignore renew_secret and cancel_secret in methods + of this interface, will advertise a true value for the + 'ignores-lease-renewal-and-cancel-secrets' key (under + 'http://allmydata.org/tahoe/protocols/storage/v1') in their + version information. + + @param storage_index: the index of the shares to be created. + @param sharenums: the share numbers that the sender is proposing to store + on this server. + @param renew_secret: previously used to authorize lease renewal. + @param cancel_secret: previously used to authorize lease cancellation. + @param canary: if the canary is lost before close(), the writes are + abandoned. @return: tuple of (alreadygot, allocated), where alreadygot is what we already have and allocated is what we hereby agree to accept. - New leases are added for shares in both lists. + Leases are added if necessary for shares in both lists. """ return TupleOf(SetOf(int, maxLength=MAX_BUCKETS), DictOf(int, RIBucketWriter, maxKeys=MAX_BUCKETS)) @@ -163,9 +169,6 @@ class RIStorageServer(RemoteInterface): """ return Any() # always None - # XXX add a method that allows adding/renewing leases on only some shnums. - # See ticket #1816. - def get_buckets(storage_index=StorageIndex): return DictOf(int, RIBucketReader, maxKeys=MAX_BUCKETS) @@ -199,24 +202,23 @@ class RIStorageServer(RemoteInterface): This method is, um, large. The goal is to allow clients to update all the shares associated with a mutable file in a single round trip. - @param storage_index: the index of the bucket to be created or - increfed. + @param storage_index: the index of the shareset to be operated on. @param write_enabler: a secret that is stored along with the slot. Writes are accepted from any caller who can present the matching secret. A different secret should be used for each slot*server pair. - @param renew_secret: This is the secret used to protect bucket refresh - This secret is generated by the client and - stored for later comparison by the server. Each - server is given a different secret. - @param cancel_secret: This no longer allows lease cancellation, but - must still be a unique value identifying the - lease. XXX stop relying on it to be unique. + @param renew_secret: previously used to authorize lease renewal. + @param cancel_secret: previously used to authorize lease cancellation. The 'secrets' argument is a tuple of (write_enabler, renew_secret, - cancel_secret). The first is required to perform any write. The - latter two are used when allocating new shares. To simply acquire a - new lease on existing shares, use an empty testv and an empty writev. + cancel_secret). The first is required to perform any write. + renew_secret and cancel_secret are ignored as of Tahoe-LAFS v1.11.0, + but for backward compatibility with older servers, should be + calculated in the same way as previous clients (see + allmydata.util.hashutil.file_{renewal,cancel}_secret_hash). + + To simply acquire a new lease on existing shares, use an empty testv + and an empty writev. Each share can have a separate test vector (i.e. a list of comparisons to perform). If all vectors for all shares pass, then all @@ -309,6 +311,277 @@ class RIStorageServer(RemoteInterface): """ +class IStorageBackend(Interface): + """ + Objects of this kind live on the server side and are used by the + storage server object. + """ + def get_available_space(): + """ + Returns available space for share storage in bytes, or + None if this information is not available or if the available + space is unlimited. + + If the backend is configured for read-only mode then this will + return 0. + """ + + def get_sharesets_for_prefix(prefix): + """ + Return an iterable containing IShareSet objects for all storage + indices matching the given base-32 prefix, for which this backend + holds shares. + XXX This will probably need to return a Deferred, but for now it + is synchronous. + """ + + def get_shareset(storageindex): + """ + Get an IShareSet object for the given storage index. + This method is synchronous. + """ + + def fill_in_space_stats(stats): + """ + Fill in the 'stats' dict with space statistics for this backend, in + 'storage_server.*' keys. + """ + + def advise_corrupt_share(storageindex, sharetype, shnum, reason): + """ + Clients who discover hash failures in shares that they have + downloaded from me will use this method to inform me about the + failures. I will record their concern so that my operator can + manually inspect the shares in question. This method is synchronous. + + 'sharetype' is either 'mutable' or 'immutable'. 'shnum' is the integer + share number. 'reason' is a human-readable explanation of the problem, + probably including some expected hash values and the computed ones + that did not match. Corruption advisories for mutable shares should + include a hash of the public key (the same value that appears in the + mutable-file verify-cap), since the current share format does not + store that on disk. + + @param storageindex=str + @param sharetype=str + @param shnum=int + @param reason=str + """ + + def must_use_tubid_as_permutation_seed(): + """ + Is this a disk backend with existing shares? If True, then the server + must assume that it was around before #466, so must use its TubID as a + permutation-seed. + """ + + +class IShareSet(Interface): + def get_storage_index(): + """ + Returns the storage index for this shareset. + """ + + def get_storage_index_string(): + """ + Returns the base32-encoded storage index for this shareset. + """ + + def get_overhead(): + """ + Returns an estimate of the storage overhead, in bytes, of this shareset + (exclusive of the space used by its shares). + """ + + def get_shares(): + """ + Returns a Deferred that fires with a pair + (list of IShareBase objects, set of corrupted shnums). + The share objects include only completed shares in this shareset. + """ + + def get_share(shnum): + """ + Returns a Deferred that fires with an IShareBase object if the given + share exists, or fails with IndexError otherwise. + """ + + def delete_share(shnum): + """ + Delete a stored share. Returns a Deferred that fires when complete. + This does not delete incoming shares. + """ + + def has_incoming(shnum): + """ + Returns True if this shareset has an incoming (partial) share with this + number, otherwise False. + """ + + def make_bucket_writer(account, shnum, allocated_data_length, canary): + """ + Create a bucket writer that can be used to write data to a given share. + + @param account=Account + @param shnum=int: A share number in this shareset + @param allocated_data_length=int: The maximum space allocated for the + share, in bytes + @param canary=Referenceable: If the canary is lost before close(), the + bucket is deleted. + @return an IStorageBucketWriter for the given share + """ + + def make_bucket_reader(account, share): + """ + Create a bucket reader that can be used to read data from a given share. + + @param account=Account + @param share=IShareForReading + @return an IStorageBucketReader for the given share + """ + + def readv(wanted_shnums, read_vector): + """ + Read a vector from the numbered shares in this shareset. An empty + wanted_shnums list means to return data from all known shares. + Return a Deferred that fires with a dict mapping the share number + to the corresponding ReadData. + + @param wanted_shnums=ListOf(int) + @param read_vector=ReadVector + @return DeferredOf(DictOf(int, ReadData)): shnum -> results, with one key per share + """ + + def testv_and_readv_and_writev(write_enabler, test_and_write_vectors, read_vector, account): + """ + General-purpose atomic test-read-and-set operation for mutable slots. + Perform a bunch of comparisons against the existing shares in this + shareset. If they all pass: use the read vectors to extract data from + all the shares, then apply a bunch of write vectors to those shares. + Return a Deferred that fires with a pair consisting of a boolean that is + True iff the test vectors passed, and a dict mapping the share number + to the corresponding ReadData. Reads do not include any modifications + made by the writes. + + See the similar method in RIStorageServer for more detail. + + @param write_enabler=WriteEnablerSecret + @param test_and_write_vectors=TestAndWriteVectorsForShares + @param read_vector=ReadVector + @param account=Account + @return DeferredOf(TupleOf(bool, DictOf(int, ReadData))) + """ + + +class IShareBase(Interface): + """ + I represent an immutable or mutable share stored by a particular backend. + I may hold some, all, or none of the share data in memory. + """ + def get_storage_index(): + """ + Returns the storage index. + """ + + def get_storage_index_string(): + """ + Returns the base32-encoded storage index. + """ + + def get_shnum(): + """ + Returns the share number. + """ + + def get_data_length(): + """ + Returns the data length in bytes. + """ + + def get_size(): + """ + Returns the size of the share in bytes. + """ + + def get_used_space(): + """ + Returns the amount of backend storage including overhead (which may + have to be estimated), in bytes, used by this share. + """ + + def unlink(): + """ + Signal that this share can be removed from the backend storage. This does + not guarantee that the share data will be immediately inaccessible, or + that it will be securely erased. + Returns a Deferred that fires after the share has been removed. + + This may be called on a share that is being written and is not closed. + """ + + +class IShareForReading(IShareBase): + """ + I represent an immutable share that can be read from. + """ + def read_share_data(offset, length): + """ + Return a Deferred that fires with the read result. + """ + + def readv(read_vector): + """ + Given a list of (offset, length) pairs, return a Deferred that fires with + a list of read results. + """ + + +class IShareForWriting(IShareBase): + """ + I represent an immutable share that is being written. + """ + def get_allocated_data_length(): + """ + Returns the allocated data length of the share in bytes. This is the maximum + amount of data that can be written (not including headers and leases). + """ + + def write_share_data(offset, data): + """ + Write data at the given offset. Return a Deferred that fires when we + are ready to accept the next write. + + Data must be written with no backtracking, i.e. offset must not be before + the previous end-of-data. + """ + + def close(): + """ + Complete writing to this share. + """ + + +class IMutableShare(IShareBase): + """ + I represent a mutable share. + """ + def check_write_enabler(write_enabler): + """ + @param write_enabler=WriteEnablerSecret + """ + + def check_testv(test_vector): + """ + @param test_vector=TestVector + """ + + def writev(datav, new_length): + """ + @param datav=DataVector + @param new_length=ChoiceOf(None, Offset) + """ + + class IStorageBucketWriter(Interface): """ Objects of this kind live on the client side. @@ -344,7 +617,7 @@ class IStorageBucketWriter(Interface): of plaintext, crypttext, and shares), as well as encoding parameters that are necessary to recover the data. This is a serialized dict mapping strings to other strings. The hash of this data is kept in - the URI and verified before any of the data is used. All buckets for + the URI and verified before any of the data is used. All shares for a given file contain identical copies of this data. The serialization format is specified with the following pseudocode: @@ -357,10 +630,9 @@ class IStorageBucketWriter(Interface): """ def close(): - """Finish writing and close the bucket. The share is not finalized - until this method is called: if the uploading client disconnects - before calling close(), the partially-written share will be - discarded. + """ + Finish writing and finalize the share. If the uploading client disconnects + before calling close(), the partially-written share will be discarded. @return: a Deferred that fires (with None) when the operation completes """