src/allmydata/immutable/offloaded.py

   1
   2 import os, stat, time, weakref
   3 from zope.interface import implements
   4 from twisted.internet import defer
   5 from foolscap.api import Referenceable, DeadReferenceError, eventually
   6 import allmydata # for __full_version__
   7 from allmydata import interfaces, uri
   8 from allmydata.storage.server import si_b2a
   9 from allmydata.immutable import upload
  10 from allmydata.immutable.layout import ReadBucketProxy
  11 from allmydata.util.assertutil import precondition
  12 from allmydata.util import log, observer, fileutil, hashutil, dictutil
  13
  14
  15 class NotEnoughWritersError(Exception):
  16     pass
  17
  18
  19 class CHKCheckerAndUEBFetcher:
  20     """I check to see if a file is already present in the grid. I also fetch
  21     the URI Extension Block, which is useful for an uploading client who
  22     wants to avoid the work of encryption and encoding.
  23
  24     I return False if the file is not completely healthy: i.e. if there are
  25     less than 'N' shares present.
  26
  27     If the file is completely healthy, I return a tuple of (sharemap,
  28     UEB_data, UEB_hash).
  29     """
  30
  31     def __init__(self, peer_getter, storage_index, logparent=None):
  32         self._peer_getter = peer_getter
  33         self._found_shares = set()
  34         self._storage_index = storage_index
  35         self._sharemap = dictutil.DictOfSets()
  36         self._readers = set()
  37         self._ueb_hash = None
  38         self._ueb_data = None
  39         self._logparent = logparent
  40
  41     def log(self, *args, **kwargs):
  42         if 'facility' not in kwargs:
  43             kwargs['facility'] = "tahoe.helper.chk.checkandUEBfetch"
  44         if 'parent' not in kwargs:
  45             kwargs['parent'] = self._logparent
  46         return log.msg(*args, **kwargs)
  47
  48     def check(self):
  49         d = self._get_all_shareholders(self._storage_index)
  50         d.addCallback(self._get_uri_extension)
  51         d.addCallback(self._done)
  52         return d
  53
  54     def _get_all_shareholders(self, storage_index):
  55         dl = []
  56         for s in self._peer_getter(storage_index):
  57             d = s.get_rref().callRemote("get_buckets", storage_index)
  58             d.addCallbacks(self._got_response, self._got_error,
  59                            callbackArgs=(s,))
  60             dl.append(d)
  61         return defer.DeferredList(dl)
  62
  63     def _got_response(self, buckets, server):
  64         # buckets is a dict: maps shum to an rref of the server who holds it
  65         shnums_s = ",".join([str(shnum) for shnum in buckets])
  66         self.log("got_response: [%s] has %d shares (%s)" %
  67                  (server.get_name(), len(buckets), shnums_s),
  68                  level=log.NOISY)
  69         self._found_shares.update(buckets.keys())
  70         for k in buckets:
  71             self._sharemap.add(k, server.get_serverid())
  72         self._readers.update( [ (bucket, server)
  73                                 for bucket in buckets.values() ] )
  74
  75     def _got_error(self, f):
  76         if f.check(DeadReferenceError):
  77             return
  78         log.err(f, parent=self._logparent)
  79         pass
  80
  81     def _get_uri_extension(self, res):
  82         # assume that we can pull the UEB from any share. If we get an error,
  83         # declare the whole file unavailable.
  84         if not self._readers:
  85             self.log("no readers, so no UEB", level=log.NOISY)
  86             return
  87         b,server = self._readers.pop()
  88         rbp = ReadBucketProxy(b, server, si_b2a(self._storage_index))
  89         d = rbp.get_uri_extension()
  90         d.addCallback(self._got_uri_extension)
  91         d.addErrback(self._ueb_error)
  92         return d
  93
  94     def _got_uri_extension(self, ueb):
  95         self.log("_got_uri_extension", level=log.NOISY)
  96         self._ueb_hash = hashutil.uri_extension_hash(ueb)
  97         self._ueb_data = uri.unpack_extension(ueb)
  98
  99     def _ueb_error(self, f):
 100         # an error means the file is unavailable, but the overall check
 101         # shouldn't fail.
 102         self.log("UEB fetch failed", failure=f, level=log.WEIRD, umid="sJLKVg")
 103         return None
 104
 105     def _done(self, res):
 106         if self._ueb_data:
 107             found = len(self._found_shares)
 108             total = self._ueb_data['total_shares']
 109             self.log(format="got %(found)d shares of %(total)d",
 110                      found=found, total=total, level=log.NOISY)
 111             if found < total:
 112                 # not all shares are present in the grid
 113                 self.log("not enough to qualify, file not found in grid",
 114                          level=log.NOISY)
 115                 return False
 116             # all shares are present
 117             self.log("all shares present, file is found in grid",
 118                      level=log.NOISY)
 119             return (self._sharemap, self._ueb_data, self._ueb_hash)
 120         # no shares are present
 121         self.log("unable to find UEB data, file not found in grid",
 122                  level=log.NOISY)
 123         return False
 124
 125
 126 class CHKUploadHelper(Referenceable, upload.CHKUploader):
 127     """I am the helper-server -side counterpart to AssistedUploader. I handle
 128     peer selection, encoding, and share pushing. I read ciphertext from the
 129     remote AssistedUploader.
 130     """
 131     implements(interfaces.RICHKUploadHelper)
 132     VERSION = { "http://allmydata.org/tahoe/protocols/helper/chk-upload/v1" :
 133                  { },
 134                 "application-version": str(allmydata.__full_version__),
 135                 }
 136
 137     def __init__(self, storage_index,
 138                  helper, storage_broker, secret_holder,
 139                  incoming_file, encoding_file,
 140                  log_number):
 141         self._storage_index = storage_index
 142         self._helper = helper
 143         self._incoming_file = incoming_file
 144         self._encoding_file = encoding_file
 145         self._upload_id = si_b2a(storage_index)[:5]
 146         self._log_number = log_number
 147         self._upload_status = upload.UploadStatus()
 148         self._upload_status.set_helper(False)
 149         self._upload_status.set_storage_index(storage_index)
 150         self._upload_status.set_status("fetching ciphertext")
 151         self._upload_status.set_progress(0, 1.0)
 152         self._helper.log("CHKUploadHelper starting for SI %s" % self._upload_id,
 153                          parent=log_number)
 154
 155         self._storage_broker = storage_broker
 156         self._secret_holder = secret_holder
 157         self._fetcher = CHKCiphertextFetcher(self, incoming_file, encoding_file,
 158                                              self._log_number)
 159         self._reader = LocalCiphertextReader(self, storage_index, encoding_file)
 160         self._finished_observers = observer.OneShotObserverList()
 161
 162         self._started = time.time()
 163         d = self._fetcher.when_done()
 164         d.addCallback(lambda res: self._reader.start())
 165         d.addCallback(lambda res: self.start_encrypted(self._reader))
 166         d.addCallback(self._finished)
 167         d.addErrback(self._failed)
 168
 169     def log(self, *args, **kwargs):
 170         if 'facility' not in kwargs:
 171             kwargs['facility'] = "tahoe.helper.chk"
 172         return upload.CHKUploader.log(self, *args, **kwargs)
 173
 174     def remote_get_version(self):
 175         return self.VERSION
 176
 177     def remote_upload(self, reader):
 178         # reader is an RIEncryptedUploadable. I am specified to return an
 179         # UploadResults dictionary.
 180
 181         # Log how much ciphertext we need to get.
 182         self.log("deciding whether to upload the file or not", level=log.NOISY)
 183         if os.path.exists(self._encoding_file):
 184             # we have the whole file, and we might be encoding it (or the
 185             # encode/upload might have failed, and we need to restart it).
 186             self.log("ciphertext already in place", level=log.UNUSUAL)
 187         elif os.path.exists(self._incoming_file):
 188             # we have some of the file, but not all of it (otherwise we'd be
 189             # encoding). The caller might be useful.
 190             self.log("partial ciphertext already present", level=log.UNUSUAL)
 191         else:
 192             # we don't remember uploading this file
 193             self.log("no ciphertext yet", level=log.NOISY)
 194
 195         # let our fetcher pull ciphertext from the reader.
 196         self._fetcher.add_reader(reader)
 197         # and also hashes
 198         self._reader.add_reader(reader)
 199
 200         # and inform the client when the upload has finished
 201         return self._finished_observers.when_fired()
 202
 203     def _finished(self, ur):
 204         precondition(isinstance(ur.verifycapstr, str), ur.verifycapstr)
 205         assert interfaces.IUploadResults.providedBy(ur), ur
 206         v = uri.from_string(ur.verifycapstr)
 207         f_times = self._fetcher.get_times()
 208
 209         hur = upload.HelperUploadResults()
 210         hur.timings = {"cumulative_fetch": f_times["cumulative_fetch"],
 211                        "total_fetch": f_times["total"],
 212                        }
 213         for k in ur.timings:
 214             hur.timings[k] = ur.timings[k]
 215         hur.uri_extension_hash = v.uri_extension_hash
 216         hur.ciphertext_fetched = self._fetcher.get_ciphertext_fetched()
 217         hur.preexisting_shares = ur.preexisting_shares
 218         hur.sharemap = ur.sharemap
 219         hur.servermap = ur.servermap
 220         hur.pushed_shares = ur.pushed_shares
 221         hur.file_size = ur.file_size
 222         hur.uri_extension_data = ur.uri_extension_data
 223         hur.verifycapstr = ur.verifycapstr
 224
 225         self._reader.close()
 226         os.unlink(self._encoding_file)
 227         self._finished_observers.fire(hur)
 228         self._helper.upload_finished(self._storage_index, v.size)
 229         del self._reader
 230
 231     def _failed(self, f):
 232         self.log(format="CHKUploadHelper(%(si)s) failed",
 233                  si=si_b2a(self._storage_index)[:5],
 234                  failure=f,
 235                  level=log.UNUSUAL)
 236         self._finished_observers.fire(f)
 237         self._helper.upload_finished(self._storage_index, 0)
 238         del self._reader
 239
 240 class AskUntilSuccessMixin:
 241     # create me with a _reader array
 242     _last_failure = None
 243
 244     def add_reader(self, reader):
 245         self._readers.append(reader)
 246
 247     def call(self, *args, **kwargs):
 248         if not self._readers:
 249             raise NotEnoughWritersError("ran out of assisted uploaders, last failure was %s" % self._last_failure)
 250         rr = self._readers[0]
 251         d = rr.callRemote(*args, **kwargs)
 252         def _err(f):
 253             self._last_failure = f
 254             if rr in self._readers:
 255                 self._readers.remove(rr)
 256             self._upload_helper.log("call to assisted uploader %s failed" % rr,
 257                                     failure=f, level=log.UNUSUAL)
 258             # we can try again with someone else who's left
 259             return self.call(*args, **kwargs)
 260         d.addErrback(_err)
 261         return d
 262
 263 class CHKCiphertextFetcher(AskUntilSuccessMixin):
 264     """I use one or more remote RIEncryptedUploadable instances to gather
 265     ciphertext on disk. When I'm done, the file I create can be used by a
 266     LocalCiphertextReader to satisfy the ciphertext needs of a CHK upload
 267     process.
 268
 269     I begin pulling ciphertext as soon as a reader is added. I remove readers
 270     when they have any sort of error. If the last reader is removed, I fire
 271     my when_done() Deferred with a failure.
 272
 273     I fire my when_done() Deferred (with None) immediately after I have moved
 274     the ciphertext to 'encoded_file'.
 275     """
 276
 277     def __init__(self, helper, incoming_file, encoded_file, logparent):
 278         self._upload_helper = helper
 279         self._incoming_file = incoming_file
 280         self._encoding_file = encoded_file
 281         self._upload_id = helper._upload_id
 282         self._log_parent = logparent
 283         self._done_observers = observer.OneShotObserverList()
 284         self._readers = []
 285         self._started = False
 286         self._f = None
 287         self._times = {
 288             "cumulative_fetch": 0.0,
 289             "total": 0.0,
 290             }
 291         self._ciphertext_fetched = 0
 292
 293     def log(self, *args, **kwargs):
 294         if "facility" not in kwargs:
 295             kwargs["facility"] = "tahoe.helper.chkupload.fetch"
 296         if "parent" not in kwargs:
 297             kwargs["parent"] = self._log_parent
 298         return log.msg(*args, **kwargs)
 299
 300     def add_reader(self, reader):
 301         AskUntilSuccessMixin.add_reader(self, reader)
 302         eventually(self._start)
 303
 304     def _start(self):
 305         if self._started:
 306             return
 307         self._started = True
 308         started = time.time()
 309
 310         if os.path.exists(self._encoding_file):
 311             self.log("ciphertext already present, bypassing fetch",
 312                      level=log.UNUSUAL)
 313             # we'll still need the plaintext hashes (when
 314             # LocalCiphertextReader.get_plaintext_hashtree_leaves() is
 315             # called), and currently the easiest way to get them is to ask
 316             # the sender for the last byte of ciphertext. That will provoke
 317             # them into reading and hashing (but not sending) everything
 318             # else.
 319             have = os.stat(self._encoding_file)[stat.ST_SIZE]
 320             d = self.call("read_encrypted", have-1, 1)
 321             d.addCallback(self._done2, started)
 322             return
 323
 324         # first, find out how large the file is going to be
 325         d = self.call("get_size")
 326         d.addCallback(self._got_size)
 327         d.addCallback(self._start_reading)
 328         d.addCallback(self._done)
 329         d.addCallback(self._done2, started)
 330         d.addErrback(self._failed)
 331
 332     def _got_size(self, size):
 333         self.log("total size is %d bytes" % size, level=log.NOISY)
 334         self._upload_helper._upload_status.set_size(size)
 335         self._expected_size = size
 336
 337     def _start_reading(self, res):
 338         # then find out how much crypttext we have on disk
 339         if os.path.exists(self._incoming_file):
 340             self._have = os.stat(self._incoming_file)[stat.ST_SIZE]
 341             self._upload_helper._helper.count("chk_upload_helper.resumes")
 342             self.log("we already have %d bytes" % self._have, level=log.NOISY)
 343         else:
 344             self._have = 0
 345             self.log("we do not have any ciphertext yet", level=log.NOISY)
 346         self.log("starting ciphertext fetch", level=log.NOISY)
 347         self._f = open(self._incoming_file, "ab")
 348
 349         # now loop to pull the data from the readers
 350         d = defer.Deferred()
 351         self._loop(d)
 352         # this Deferred will be fired once the last byte has been written to
 353         # self._f
 354         return d
 355
 356     # read data in 50kB chunks. We should choose a more considered number
 357     # here, possibly letting the client specify it. The goal should be to
 358     # keep the RTT*bandwidth to be less than 10% of the chunk size, to reduce
 359     # the upload bandwidth lost because this protocol is non-windowing. Too
 360     # large, however, means more memory consumption for both ends. Something
 361     # that can be transferred in, say, 10 seconds sounds about right. On my
 362     # home DSL line (50kBps upstream), that suggests 500kB. Most lines are
 363     # slower, maybe 10kBps, which suggests 100kB, and that's a bit more
 364     # memory than I want to hang on to, so I'm going to go with 50kB and see
 365     # how that works.
 366     CHUNK_SIZE = 50*1024
 367
 368     def _loop(self, fire_when_done):
 369         # this slightly weird structure is needed because Deferreds don't do
 370         # tail-recursion, so it is important to let each one retire promptly.
 371         # Simply chaining them will cause a stack overflow at the end of a
 372         # transfer that involves more than a few hundred chunks.
 373         # 'fire_when_done' lives a long time, but the Deferreds returned by
 374         # the inner _fetch() call do not.
 375         start = time.time()
 376         d = defer.maybeDeferred(self._fetch)
 377         def _done(finished):
 378             elapsed = time.time() - start
 379             self._times["cumulative_fetch"] += elapsed
 380             if finished:
 381                 self.log("finished reading ciphertext", level=log.NOISY)
 382                 fire_when_done.callback(None)
 383             else:
 384                 self._loop(fire_when_done)
 385         def _err(f):
 386             self.log(format="[%(si)s] ciphertext read failed",
 387                      si=self._upload_id, failure=f, level=log.UNUSUAL)
 388             fire_when_done.errback(f)
 389         d.addCallbacks(_done, _err)
 390         return None
 391
 392     def _fetch(self):
 393         needed = self._expected_size - self._have
 394         fetch_size = min(needed, self.CHUNK_SIZE)
 395         if fetch_size == 0:
 396             self._upload_helper._upload_status.set_progress(1, 1.0)
 397             return True # all done
 398         percent = 0.0
 399         if self._expected_size:
 400             percent = 1.0 * (self._have+fetch_size) / self._expected_size
 401         self.log(format="fetching [%(si)s] %(start)d-%(end)d of %(total)d (%(percent)d%%)",
 402                  si=self._upload_id,
 403                  start=self._have,
 404                  end=self._have+fetch_size,
 405                  total=self._expected_size,
 406                  percent=int(100.0*percent),
 407                  level=log.NOISY)
 408         d = self.call("read_encrypted", self._have, fetch_size)
 409         def _got_data(ciphertext_v):
 410             for data in ciphertext_v:
 411                 self._f.write(data)
 412                 self._have += len(data)
 413                 self._ciphertext_fetched += len(data)
 414                 self._upload_helper._helper.count("chk_upload_helper.fetched_bytes", len(data))
 415                 self._upload_helper._upload_status.set_progress(1, percent)
 416             return False # not done
 417         d.addCallback(_got_data)
 418         return d
 419
 420     def _done(self, res):
 421         self._f.close()
 422         self._f = None
 423         self.log(format="done fetching ciphertext, size=%(size)d",
 424                  size=os.stat(self._incoming_file)[stat.ST_SIZE],
 425                  level=log.NOISY)
 426         os.rename(self._incoming_file, self._encoding_file)
 427
 428     def _done2(self, _ignored, started):
 429         self.log("done2", level=log.NOISY)
 430         elapsed = time.time() - started
 431         self._times["total"] = elapsed
 432         self._readers = []
 433         self._done_observers.fire(None)
 434
 435     def _failed(self, f):
 436         if self._f:
 437             self._f.close()
 438         self._readers = []
 439         self._done_observers.fire(f)
 440
 441     def when_done(self):
 442         return self._done_observers.when_fired()
 443
 444     def get_times(self):
 445         return self._times
 446
 447     def get_ciphertext_fetched(self):
 448         return self._ciphertext_fetched
 449
 450
 451 class LocalCiphertextReader(AskUntilSuccessMixin):
 452     implements(interfaces.IEncryptedUploadable)
 453
 454     def __init__(self, upload_helper, storage_index, encoding_file):
 455         self._readers = []
 456         self._upload_helper = upload_helper
 457         self._storage_index = storage_index
 458         self._encoding_file = encoding_file
 459         self._status = None
 460
 461     def start(self):
 462         self._upload_helper._upload_status.set_status("pushing")
 463         self._size = os.stat(self._encoding_file)[stat.ST_SIZE]
 464         self.f = open(self._encoding_file, "rb")
 465
 466     def get_size(self):
 467         return defer.succeed(self._size)
 468
 469     def get_all_encoding_parameters(self):
 470         return self.call("get_all_encoding_parameters")
 471
 472     def get_storage_index(self):
 473         return defer.succeed(self._storage_index)
 474
 475     def read_encrypted(self, length, hash_only):
 476         assert hash_only is False
 477         d = defer.maybeDeferred(self.f.read, length)
 478         d.addCallback(lambda data: [data])
 479         return d
 480
 481     def close(self):
 482         self.f.close()
 483         # ??. I'm not sure if it makes sense to forward the close message.
 484         return self.call("close")
 485
 486
 487
 488 class Helper(Referenceable):
 489     implements(interfaces.RIHelper, interfaces.IStatsProducer)
 490     # this is the non-distributed version. When we need to have multiple
 491     # helpers, this object will become the HelperCoordinator, and will query
 492     # the farm of Helpers to see if anyone has the storage_index of interest,
 493     # and send the request off to them. If nobody has it, we'll choose a
 494     # helper at random.
 495
 496     name = "helper"
 497     VERSION = { "http://allmydata.org/tahoe/protocols/helper/v1" :
 498                  { },
 499                 "application-version": str(allmydata.__full_version__),
 500                 }
 501     MAX_UPLOAD_STATUSES = 10
 502
 503     def __init__(self, basedir, storage_broker, secret_holder,
 504                  stats_provider, history):
 505         self._basedir = basedir
 506         self._storage_broker = storage_broker
 507         self._secret_holder = secret_holder
 508         self._chk_incoming = os.path.join(basedir, "CHK_incoming")
 509         self._chk_encoding = os.path.join(basedir, "CHK_encoding")
 510         fileutil.make_dirs(self._chk_incoming)
 511         fileutil.make_dirs(self._chk_encoding)
 512         self._active_uploads = {}
 513         self._all_uploads = weakref.WeakKeyDictionary() # for debugging
 514         self.stats_provider = stats_provider
 515         if stats_provider:
 516             stats_provider.register_producer(self)
 517         self._counters = {"chk_upload_helper.upload_requests": 0,
 518                           "chk_upload_helper.upload_already_present": 0,
 519                           "chk_upload_helper.upload_need_upload": 0,
 520                           "chk_upload_helper.resumes": 0,
 521                           "chk_upload_helper.fetched_bytes": 0,
 522                           "chk_upload_helper.encoded_bytes": 0,
 523                           }
 524         self._history = history
 525
 526     def log(self, *args, **kwargs):
 527         if 'facility' not in kwargs:
 528             kwargs['facility'] = "tahoe.helper"
 529         return log.msg(*args, **kwargs)
 530
 531     def count(self, key, value=1):
 532         if self.stats_provider:
 533             self.stats_provider.count(key, value)
 534         self._counters[key] += value
 535
 536     def get_stats(self):
 537         OLD = 86400*2 # 48hours
 538         now = time.time()
 539         inc_count = inc_size = inc_size_old = 0
 540         enc_count = enc_size = enc_size_old = 0
 541         inc = os.listdir(self._chk_incoming)
 542         enc = os.listdir(self._chk_encoding)
 543         for f in inc:
 544             s = os.stat(os.path.join(self._chk_incoming, f))
 545             size = s[stat.ST_SIZE]
 546             mtime = s[stat.ST_MTIME]
 547             inc_count += 1
 548             inc_size += size
 549             if now - mtime > OLD:
 550                 inc_size_old += size
 551         for f in enc:
 552             s = os.stat(os.path.join(self._chk_encoding, f))
 553             size = s[stat.ST_SIZE]
 554             mtime = s[stat.ST_MTIME]
 555             enc_count += 1
 556             enc_size += size
 557             if now - mtime > OLD:
 558                 enc_size_old += size
 559         stats = { 'chk_upload_helper.active_uploads': len(self._active_uploads),
 560                   'chk_upload_helper.incoming_count': inc_count,
 561                   'chk_upload_helper.incoming_size': inc_size,
 562                   'chk_upload_helper.incoming_size_old': inc_size_old,
 563                   'chk_upload_helper.encoding_count': enc_count,
 564                   'chk_upload_helper.encoding_size': enc_size,
 565                   'chk_upload_helper.encoding_size_old': enc_size_old,
 566                   }
 567         stats.update(self._counters)
 568         return stats
 569
 570     def remote_get_version(self):
 571         return self.VERSION
 572
 573     def remote_upload_chk(self, storage_index):
 574         self.count("chk_upload_helper.upload_requests")
 575         lp = self.log(format="helper: upload_chk query for SI %(si)s",
 576                       si=si_b2a(storage_index))
 577         if storage_index in self._active_uploads:
 578             self.log("upload is currently active", parent=lp)
 579             uh = self._active_uploads[storage_index]
 580             return (None, uh)
 581
 582         d = self._check_chk(storage_index, lp)
 583         d.addCallback(self._did_chk_check, storage_index, lp)
 584         def _err(f):
 585             self.log("error while checking for chk-already-in-grid",
 586                      failure=f, level=log.WEIRD, parent=lp, umid="jDtxZg")
 587             return f
 588         d.addErrback(_err)
 589         return d
 590
 591     def _check_chk(self, storage_index, lp):
 592         # see if this file is already in the grid
 593         lp2 = self.log("doing a quick check+UEBfetch",
 594                        parent=lp, level=log.NOISY)
 595         sb = self._storage_broker
 596         c = CHKCheckerAndUEBFetcher(sb.get_servers_for_psi, storage_index, lp2)
 597         d = c.check()
 598         def _checked(res):
 599             if res:
 600                 (sharemap, ueb_data, ueb_hash) = res
 601                 self.log("found file in grid", level=log.NOISY, parent=lp)
 602                 hur = upload.HelperUploadResults()
 603                 hur.uri_extension_hash = ueb_hash
 604                 hur.sharemap = sharemap
 605                 hur.uri_extension_data = ueb_data
 606                 hur.preexisting_shares = len(sharemap)
 607                 hur.pushed_shares = 0
 608                 return hur
 609             return None
 610         d.addCallback(_checked)
 611         return d
 612
 613     def _did_chk_check(self, already_present, storage_index, lp):
 614         if already_present:
 615             # the necessary results are placed in the UploadResults
 616             self.count("chk_upload_helper.upload_already_present")
 617             self.log("file already found in grid", parent=lp)
 618             return (already_present, None)
 619
 620         self.count("chk_upload_helper.upload_need_upload")
 621         # the file is not present in the grid, by which we mean there are
 622         # less than 'N' shares available.
 623         self.log("unable to find file in the grid", parent=lp,
 624                  level=log.NOISY)
 625         # We need an upload helper. Check our active uploads again in
 626         # case there was a race.
 627         if storage_index in self._active_uploads:
 628             self.log("upload is currently active", parent=lp)
 629             uh = self._active_uploads[storage_index]
 630         else:
 631             self.log("creating new upload helper", parent=lp)
 632             uh = self._make_chk_upload_helper(storage_index, lp)
 633             self._active_uploads[storage_index] = uh
 634             self._add_upload(uh)
 635         return (None, uh)
 636
 637     def _make_chk_upload_helper(self, storage_index, lp):
 638         si_s = si_b2a(storage_index)
 639         incoming_file = os.path.join(self._chk_incoming, si_s)
 640         encoding_file = os.path.join(self._chk_encoding, si_s)
 641         uh = CHKUploadHelper(storage_index, self,
 642                              self._storage_broker,
 643                              self._secret_holder,
 644                              incoming_file, encoding_file,
 645                              lp)
 646         return uh
 647
 648     def _add_upload(self, uh):
 649         self._all_uploads[uh] = None
 650         if self._history:
 651             s = uh.get_upload_status()
 652             self._history.notify_helper_upload(s)
 653
 654     def upload_finished(self, storage_index, size):
 655         # this is called with size=0 if the upload failed
 656         self.count("chk_upload_helper.encoded_bytes", size)
 657         uh = self._active_uploads[storage_index]
 658         del self._active_uploads[storage_index]
 659         s = uh.get_upload_status()
 660         s.set_active(False)