- Make some important utility functions clearer and more thoroughly
documented.
- Assert in upload.servers_of_happiness that the buckets attributes
of PeerTrackers passed to it are mutually disjoint.
- Get rid of some silly non-Pythonisms that I didn't see when I first
wrote these patches.
- Make sure that should_add_server returns true when queried about a
shnum that it doesn't know about yet.
- Change Tahoe2PeerSelector.preexisting_shares to map a shareid to a set
of peerids, alter dependencies to deal with that.
- Remove upload.should_add_servers, because it is no longer necessary
- Move upload.shares_of_happiness and upload.shares_by_server to a utility
file.
- Change some points in Tahoe2PeerSelector.
- Compute servers_of_happiness using a bipartite matching algorithm that
we know is optimal instead of an ad-hoc greedy algorithm that isn't.
- Change servers_of_happiness to just take a sharemap as an argument,
change its callers to merge existing_shares and used_peers before
calling it.
- Change an error message in the encoder to be more appropriate for
servers of happiness.
- Clarify the wording of an error message in immutable/upload.py
- Refactor a happiness failure message to happinessutil.py, and make
immutable/upload.py and immutable/encode.py use it.
- Move the word "only" as far to the right as possible in failure
messages.
- Use a better definition of progress during peer selection.
- Do read-only peer share detection queries in parallel, not sequentially.
- Clean up logging semantics; print the query statistics whenever an
upload is unsuccessful, not just in one case.
New checker and verifier use the new download class. They are robust against various sorts of failures or corruption. They return detailed results explaining what they learned about your immutable files. Some grotesque sorts of corruption are not properly handled yet, and those ones are marked as TODO or commented-out in the unit tests.
There is also a repairer module in this patch with the beginnings of a repairer in it. That repairer is mostly just the interface to the outside world -- the core operation of actually reconstructing the missing data blocks and uploading them is not in there yet.
This patch also refactors the unit tests in test_immutable so that the handling of each kind of corruption is reported as passing or failing separately, can be separately TODO'ified, etc. The unit tests are also improved in various ways to require more of the code under test or to stop requiring unreasonable things of it. :-)
The code for validating the share hash tree and the block hash tree has been rewritten to make sure it handles all cases, to share metadata about the file (such as the share hash tree, block hash trees, and UEB) among different share downloads, and not to require hashes to be stored on the server unnecessarily, such as the roots of the block hash trees (not needed since they are also the leaves of the share hash tree), and the root of the share hash tree (not needed since it is also included in the UEB). It also passes the latest tests including handling corrupted shares well.
ValidatedReadBucketProxy takes a share_hash_tree argument to its constructor, which is a reference to a share hash tree shared by all ValidatedReadBucketProxies for that immutable file download.
ValidatedReadBucketProxy requires the block_size and share_size to be provided in its constructor, and it then uses those to compute the offsets and lengths of blocks when it needs them, instead of reading those values out of the share. The user of ValidatedReadBucketProxy therefore has to have first used a ValidatedExtendedURIProxy to compute those two values from the validated contents of the URI. This is pleasingly simplifies safety analysis: the client knows which span of bytes corresponds to a given block from the validated URI data, rather than from the unvalidated data stored on the storage server. It also simplifies unit testing of verifier/repairer, because now it doesn't care about the contents of the "share size" and "block size" fields in the share. It does not relieve the need for share data v2 layout, because we still need to store and retrieve the offsets of the fields which come after the share data, therefore we still need to use share data v2 with its 8-byte fields if we want to store share data larger than about 2^32.
Specify which subset of the block hashes and share hashes you need while downloading a particular share. In the future this will hopefully be used to fetch only a subset, for network efficiency, but currently all of them are fetched, regardless of which subset you specify.
ReadBucketProxy hides the question of whether it has "started" or not (sent a request to the server to get metadata) from its user.
Download is optimized to do as few roundtrips and as few requests as possible, hopefully speeding up download a bit.
To fix this error from the Windows buildslave:
[ERROR]: allmydata.test.test_immutable.Test.test_download_from_only_3_remaining_shares
Traceback (most recent call last):
File "C:\Documents and Settings\buildslave\windows-native-tahoe\windows\build\src\allmydata\immutable\download.py", line 135, in _bad
raise NotEnoughSharesError("ran out of peers, last error was %s" % (f,))
allmydata.interfaces.NotEnoughSharesError: ran out of peers, last error was [Failure instance: Traceback: <class 'struct.error'>: unpack requires a string argument of length 4
c:\documents and settings\buildslave\windows-native-tahoe\windows\build\support\lib\site-packages\foolscap-0.3.2-py2.5.egg\foolscap\call.py:667:_done
c:\documents and settings\buildslave\windows-native-tahoe\windows\build\support\lib\site-packages\foolscap-0.3.2-py2.5.egg\foolscap\call.py:53:complete
c:\Python25\lib\site-packages\twisted\internet\defer.py:239:callback
c:\Python25\lib\site-packages\twisted\internet\defer.py:304:_startRunCallbacks
--- <exception caught here> ---
c:\Python25\lib\site-packages\twisted\internet\defer.py:317:_runCallbacks
C:\Documents and Settings\buildslave\windows-native-tahoe\windows\build\src\allmydata\immutable\layout.py:374:_got_length
C:\Python25\lib\struct.py:87:unpack
]
===============================================================================
