tahoe-lafs/src/allmydata/immutable/filenode.py
Zooko O'Whielacronx 600196f571 immutable: refactor download to do only download-and-decode, not decryption
FileDownloader takes a verify cap and produces ciphertext, instead of taking a read cap and producing plaintext.
FileDownloader does all integrity checking including the mandatory ciphertext hash tree and the optional ciphertext flat hash, rather than expecting its target to do some of that checking.
Rename immutable.download.Output to immutable.download.DecryptingOutput. An instance of DecryptingOutput can be passed to FileDownloader to use as the latter's target.  Text pushed to the DecryptingOutput is decrypted and then pushed to *its* target.
DecryptingOutput satisfies the IConsumer interface, and if its target also satisfies IConsumer, then it forwards and pause/unpause signals to its producer (which is the FileDownloader).
This patch also changes some logging code to use the new logging mixin class.
Check integrity of a segment and decrypt the segment one block-sized buffer at a time instead of copying the buffers together into one segment-sized buffer (reduces peak memory usage, I think, and is probably a tad faster/less CPU, depending on your encoding parameters).
Refactor FileDownloader so that processing of segments and of tail-segment share as much code is possible.
FileDownloader and FileNode take caps as instances of URI (Python objects), not as strings.
2009-01-08 11:53:49 -07:00

310 lines
11 KiB
Python

import os.path, stat
from cStringIO import StringIO
from zope.interface import implements
from twisted.internet import defer
from twisted.internet.interfaces import IPushProducer, IConsumer
from twisted.protocols import basic
from foolscap.eventual import eventually
from allmydata.interfaces import IFileNode, IFileURI, ICheckable, \
IDownloadTarget
from allmydata.util import log, base32
from allmydata.util.assertutil import precondition
from allmydata import uri as urimodule
from allmydata.immutable.checker import Checker
from allmydata.check_results import CheckAndRepairResults
from allmydata.immutable.repairer import Repairer
from allmydata.immutable import download
class _ImmutableFileNodeBase(object):
implements(IFileNode, ICheckable)
def __init__(self, uri, client):
precondition(urimodule.IImmutableFileURI.providedBy(uri), uri)
self.u = IFileURI(uri)
self._client = client
def get_readonly_uri(self):
return self.get_uri()
def is_mutable(self):
return False
def is_readonly(self):
return True
def __hash__(self):
return self.u.__hash__()
def __eq__(self, other):
if IFileNode.providedBy(other):
return self.u.__eq__(other.u)
else:
return False
def __ne__(self, other):
if IFileNode.providedBy(other):
return self.u.__eq__(other.u)
else:
return True
class PortionOfFile:
# like a list slice (things[2:14]), but for a file on disk
def __init__(self, fn, offset=0, size=None):
self.f = open(fn, "rb")
self.f.seek(offset)
self.bytes_left = size
def read(self, size=None):
# bytes_to_read = min(size, self.bytes_left), but None>anything
if size is None:
bytes_to_read = self.bytes_left
elif self.bytes_left is None:
bytes_to_read = size
else:
bytes_to_read = min(size, self.bytes_left)
data = self.f.read(bytes_to_read)
if self.bytes_left is not None:
self.bytes_left -= len(data)
return data
class DownloadCache:
implements(IDownloadTarget)
def __init__(self, node, cachefile):
self._downloader = node._client.getServiceNamed("downloader")
self._uri = node.get_uri()
self._storage_index = node.get_storage_index()
self.milestones = set() # of (offset,size,Deferred)
self.cachefile = cachefile
self.download_in_progress = False
# five states:
# new FileNode, no downloads ever performed
# new FileNode, leftover file (partial)
# new FileNode, leftover file (whole)
# download in progress, not yet complete
# download complete
def when_range_available(self, offset, size):
assert isinstance(offset, (int,long))
assert isinstance(size, (int,long))
d = defer.Deferred()
self.milestones.add( (offset,size,d) )
self._check_milestones()
if self.milestones and not self.download_in_progress:
self.download_in_progress = True
log.msg(format=("immutable filenode read [%(si)s]: " +
"starting download"),
si=base32.b2a(self._storage_index),
umid="h26Heg", level=log.OPERATIONAL)
d2 = self._downloader.download(self._uri, self)
d2.addBoth(self._download_done)
d2.addErrback(self._download_failed)
d2.addErrback(log.err, umid="cQaM9g")
return d
def read(self, consumer, offset, size):
assert offset+size <= self.get_filesize()
f = PortionOfFile(self.cachefile.get_filename(), offset, size)
d = basic.FileSender().beginFileTransfer(f, consumer)
d.addCallback(lambda lastSent: consumer)
return d
def _download_done(self, res):
# clear download_in_progress, so failed downloads can be re-tried
self.download_in_progress = False
return res
def _download_failed(self, f):
# tell anyone who's waiting that we failed
for m in self.milestones:
(offset,size,d) = m
eventually(d.errback, f)
self.milestones.clear()
def _check_milestones(self):
current_size = self.get_filesize()
for m in list(self.milestones):
(offset,size,d) = m
if offset+size <= current_size:
log.msg(format=("immutable filenode read [%(si)s] " +
"%(offset)d+%(size)d vs %(filesize)d: " +
"done"),
si=base32.b2a(self._storage_index),
offset=offset, size=size, filesize=current_size,
umid="nuedUg", level=log.NOISY)
self.milestones.discard(m)
eventually(d.callback, None)
else:
log.msg(format=("immutable filenode read [%(si)s] " +
"%(offset)d+%(size)d vs %(filesize)d: " +
"still waiting"),
si=base32.b2a(self._storage_index),
offset=offset, size=size, filesize=current_size,
umid="8PKOhg", level=log.NOISY)
def get_filesize(self):
try:
filesize = os.stat(self.cachefile.get_filename())[stat.ST_SIZE]
except OSError:
filesize = 0
return filesize
def open(self, size):
self.f = open(self.cachefile.get_filename(), "wb")
def write(self, data):
self.f.write(data)
self._check_milestones()
def close(self):
self.f.close()
self._check_milestones()
def fail(self, why):
pass
def register_canceller(self, cb):
pass
def finish(self):
return None
class FileNode(_ImmutableFileNodeBase, log.PrefixingLogMixin):
def __init__(self, uri, client, cachefile):
_ImmutableFileNodeBase.__init__(self, uri, client)
self.download_cache = DownloadCache(self, cachefile)
prefix = uri.get_verify_cap().to_string()
log.PrefixingLogMixin.__init__(self, "allmydata.immutable.filenode", prefix=prefix)
self.log("starting", level=log.OPERATIONAL)
def get_uri(self):
return self.u.to_string()
def get_size(self):
return self.u.get_size()
def get_verify_cap(self):
return self.u.get_verify_cap()
def get_storage_index(self):
return self.u.storage_index
def check_and_repair(self, monitor, verify=False):
verifycap = self.get_verify_cap()
servers = self._client.get_servers("storage")
c = Checker(client=self._client, verifycap=verifycap, servers=servers, verify=verify, monitor=monitor)
d = c.start()
def _maybe_repair(cr):
crr = CheckAndRepairResults(self.u.storage_index)
crr.pre_repair_results = cr
if cr.is_healthy():
crr.post_repair_results = cr
return defer.succeed(crr)
else:
def _gather_repair_results(rr):
crr.post_repair_results = rr
return crr
r = Repairer(client=self._client, verifycap=verifycap, servers=servers, monitor=monitor)
d = r.start()
d.addCallback(_gather_repair_results)
return d
d.addCallback(_maybe_repair)
return d
def check(self, monitor, verify=False):
v = Checker(client=self._client, verifycap=self.get_verify_cap(), servers=self._client.get_servers("storage"), verify=verify, monitor=monitor)
return v.start()
def read(self, consumer, offset=0, size=None):
if size is None:
size = self.get_size() - offset
size = min(size, self.get_size() - offset)
if offset == 0 and size == self.get_size():
# don't use the cache, just do a normal streaming download
self.log("doing normal full download", umid="VRSBwg", level=log.OPERATIONAL)
return self.download(download.ConsumerAdapter(consumer))
d = self.download_cache.when_range_available(offset, size)
d.addCallback(lambda res:
self.download_cache.read(consumer, offset, size))
return d
def download(self, target):
downloader = self._client.getServiceNamed("downloader")
return downloader.download(self.get_uri(), target, self._parentmsgid)
def download_to_data(self):
downloader = self._client.getServiceNamed("downloader")
return downloader.download_to_data(self.get_uri())
class LiteralProducer:
implements(IPushProducer)
def resumeProducing(self):
pass
def stopProducing(self):
pass
class LiteralFileNode(_ImmutableFileNodeBase):
def __init__(self, uri, client):
precondition(urimodule.IImmutableFileURI.providedBy(uri), uri)
_ImmutableFileNodeBase.__init__(self, uri, client)
def get_uri(self):
return self.u.to_string()
def get_size(self):
return len(self.u.data)
def get_verify_cap(self):
return None
def get_storage_index(self):
return None
def check(self, monitor, verify=False):
return defer.succeed(None)
def check_and_repair(self, monitor, verify=False):
return defer.succeed(None)
def read(self, consumer, offset=0, size=None):
if size is None:
data = self.u.data[offset:]
else:
data = self.u.data[offset:offset+size]
# We use twisted.protocols.basic.FileSender, which only does
# non-streaming, i.e. PullProducer, where the receiver/consumer must
# ask explicitly for each chunk of data. There are only two places in
# the Twisted codebase that can't handle streaming=False, both of
# which are in the upload path for an FTP/SFTP server
# (protocols.ftp.FileConsumer and
# vfs.adapters.ftp._FileToConsumerAdapter), neither of which is
# likely to be used as the target for a Tahoe download.
d = basic.FileSender().beginFileTransfer(StringIO(data), consumer)
d.addCallback(lambda lastSent: consumer)
return d
def download(self, target):
# note that this does not update the stats_provider
data = self.u.data
if IConsumer.providedBy(target):
target.registerProducer(LiteralProducer(), True)
target.open(len(data))
target.write(data)
if IConsumer.providedBy(target):
target.unregisterProducer()
target.close()
return defer.maybeDeferred(target.finish)
def download_to_data(self):
data = self.u.data
return defer.succeed(data)