this cleans up KeyGenerator to be a service (a subservice of the
KeyGeneratorService as instantiated by the key-generator.tac app)
this means that the timer which replenishes the keypool will be
shutdown cleanly when the service is stopped.
adds checks on the key_generator service and client into the system
test 'test_mutable' such that one of the nodes (clients[3]) uses
the key_generator service, and checks that mutable file creation
in that node, via a variety of means, are all consuming keys from
the key_generator.
This removes the guess-partial-information attack vector, and reduces
the amount of overhead that we consume with each file. It also introduces
a forwards-compability break: older versions of the code (before the
previous download-time "make hashes optional" patch) will be unable
to read files uploaded by this version, as they will complain about the
missing hashes. This patch is experimental, and is being pushed into
trunk to obtain test coverage. We may undo it before releasing 1.0.
Now upload or encode methods take a required argument named "convergence" which can be either None, indicating no convergent encryption at all, or a string, which is the "added secret" to be mixed in to the content hash key. If you want traditional convergent encryption behavior, set the added secret to be the empty string.
This patch also renames "content hash key" to "convergent encryption" in a argument names and variable names. (A different and larger renaming is needed in order to clarify that Tahoe supports immutable files which are not encrypted content-hash-key a.k.a. convergent encryption.)
This patch also changes a few unit tests to use non-convergent encryption, because it doesn't matter for what they are testing and non-convergent encryption is slightly faster.
This removes the guess-partial-information attack vector, and reduces
the amount of overhead that we consume with each file. It also introduces
a forwards-compability break: older versions of the code (before the
previous download-time "make hashes optional" patch) will be unable
to read files uploaded by this version, as they will complain about the
missing hashes. This patch is experimental, and is being pushed into
trunk to obtain test coverage. We may undo it before releasing 1.0.
base62 encoding fits more information into alphanumeric chars while avoiding the troublesome non-alphanumeric chars of base64 encoding. In particular, this allows us to work around the ext3 "32,000 entries in a directory" limit while retaining the convenient property that the intermediate directory names are leading prefixes of the storage index file names.
The filesystem which gets my vote for most undeservedly popular is ext3, and it has a hard limit of 32,000 entries in a directory. Many other filesystems (even ones that I like more than I like ext3) have either hard limits or bad performance consequences or weird edge cases when you get too many entries in a single directory.
This patch makes it so that there is a layer of intermediate directories between the "shares" directory and the actual storage-index directory (the one whose name contains the entire storage index (z-base-32 encoded) and which contains one or more share files named by their share number).
The intermediate directories are named by the first 14 bits of the storage index, which means there are at most 16384 of them. (This also means that the intermediate directory names are not a leading prefix of the storage-index directory names -- to do that would have required us to have intermediate directories limited to either 1024 (2-char), which is too few, or 32768 (3-chars of a full 5 bits each), which would overrun ext3's funny hard limit of 32,000.))
This closes#150, and please see the "convertshares.py" script attached to #150 to convert your old tahoe-0.7.0 storage/shares directory into a new tahoe-0.8.0 storage/shares directory.
in trying to test my fix for the failure of the offloaded unit test on windows
(by closing the reader before unlinking the encoding file - which, perhaps
disturbingly doesn't actually make a difference in my windows environment)
I was unable too because the unit test failed every time with a connection lost
error.
after much more time than I'd like to admit it took, I eventually managed to
track that down to a part of the unit test which is supposed to be be dropping
a connection. it looks like the exceptions that get thrown on unix, or at
least all the specific environments brian tested in, for that dropped
connection are different from what is thrown on my box (which is running py2.4
and twisted 2.4.0, for reference) adding ConnectionLost to the list of
expected exceptions makes the test pass.
though curiously still my test logs a NotEnoughWritersError error, and I'm not
currently able to fathom why that exception isn't leading to any overall
failure of the unit test itself.
for general interest, a large part of the time spent trying to track this down
was lost to the state of logging. I added a whole bunch of logging to try
and track down where the tests were failing, but then spent a bunch of time
searching in vain for that log output. as far as I can tell at this point
the unit tests are themselves logging to foolscap's log module, but that isn't
being directed anywhere, so all the test's logging is being black holed.
* rename my_private_dir.cap to root_dir.cap
* move it into the private subdir
* change the cmdline argument "--root-uri=[private]" to "--dir-uri=[root]"
