def _setup_download(self):
self._started = time.time()
self._status.set_status("Retrieving Shares")
# how many shares do we need?
(seqnum,
root_hash,
IV,
segsize,
datalength,
k,
N,
prefix,
offsets_tuple) = self.verinfo
# first, which servers can we use?
versionmap = self.servermap.make_versionmap()
shares = versionmap[self.verinfo]
# this sharemap is consumed as we decide to send requests
self.remaining_sharemap = DictOfSets()
for (shnum, peerid, timestamp) in shares:
self.remaining_sharemap.add(shnum, peerid)
# If the servermap update fetched anything, it fetched at least 1
# KiB, so we ask for that much.
# TODO: Change the cache methods to allow us to fetch all of the
# data that they have, then change this method to do that.
any_cache = self._node._read_from_cache(self.verinfo, shnum,
0, 1000)
ss = self.servermap.connections[peerid]
reader = MDMFSlotReadProxy(ss,
self._storage_index,
shnum,
any_cache)
reader.peerid = peerid
self.readers[shnum] = reader
assert len(self.remaining_sharemap) >= k
self.shares = {} # maps shnum to validated blocks
self._active_readers = [] # list of active readers for this dl.
self._block_hash_trees = {} # shnum => hashtree
# We need one share hash tree for the entire file; its leaves
# are the roots of the block hash trees for the shares that
# comprise it, and its root is in the verinfo.
self.share_hash_tree = hashtree.IncompleteHashTree(N)
self.share_hash_tree.set_hashes({0: root_hash})
