By writing something like "25 75 100" into a file named 'encoding_parameters'
in the central Introducer's base directory, all clients which use that
introducer will be advised to use 25-out-of-100 encoding for files (i.e.
100 shares will be produced, 25 are required to reconstruct, and the upload
process will be happy if it can find homes for at least 75 shares). The
default values are "3 7 10". For small meshes, the defaults are probably
good, but for larger ones it may be appropriate to increase the number of
shares.
Added metadata to the bucket store, which is used to hold the share number
(but the bucket doesn't know that, it just gets a string).
Modified the codec interfaces a bit.
Try to pass around URIs to/from download/upload instead of verifierids.
URI format is still in flux.
Change the current (primitive) file encoder to use a ReplicatingEncoder
because it provides ICodecEncoder. We will be moving to the (less primitive)
file encoder (currently in allmydata.encode_new) eventually, but for now
this change lets us test out PyRS or zooko's upcoming C-based RS codec in
something larger than a single unit test. This primitive file encoder only
uses a single segment, and has no merkle trees.
Also added allmydata.util.deferredutil for a DeferredList wrapper that
errbacks (but only when all component Deferreds have fired) if there were
any errors, which unfortunately is not a behavior available from the standard
DeferredList.
