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         assert interfaces.IUploadResults.providedBy(ur), ur
 205         vcapstr = ur.get_verifycapstr()
 206         precondition(isinstance(vcapstr, str), vcapstr)
 207         v = uri.from_string(vcapstr)
 208         f_times = self._fetcher.get_times()
 209
 210         hur = upload.HelperUploadResults()
 211         hur.timings = {"cumulative_fetch": f_times["cumulative_fetch"],
 212                        "total_fetch": f_times["total"],
 213                        }
 214         for key,val in ur.get_timings().items():
 215             hur.timings[key] = val
 216         hur.uri_extension_hash = v.uri_extension_hash
 217         hur.ciphertext_fetched = self._fetcher.get_ciphertext_fetched()
 218         hur.preexisting_shares = ur.get_preexisting_shares()
 219         # hur.sharemap needs to be {shnum: set(serverid)}
 220         hur.sharemap = {}
 221         for shnum, servers in ur.get_sharemap().items():
 222             hur.sharemap[shnum] = set([s.get_serverid() for s in servers])
 223         # and hur.servermap needs to be {serverid: set(shnum)}
 224         hur.servermap = {}
 225         for server, shnums in ur.get_servermap().items():
 226             hur.servermap[server.get_serverid()] = set(shnums)
 227         hur.pushed_shares = ur.get_pushed_shares()
 228         hur.file_size = ur.get_file_size()
 229         hur.uri_extension_data = ur.get_uri_extension_data()
 230         hur.verifycapstr = vcapstr
 231
 232         self._reader.close()
 233         os.unlink(self._encoding_file)
 234         self._finished_observers.fire(hur)
 235         self._helper.upload_finished(self._storage_index, v.size)
 236         del self._reader
 237
 238     def _failed(self, f):
 239         self.log(format="CHKUploadHelper(%(si)s) failed",
 240                  si=si_b2a(self._storage_index)[:5],
 241                  failure=f,
 242                  level=log.UNUSUAL)
 243         self._finished_observers.fire(f)
 244         self._helper.upload_finished(self._storage_index, 0)
 245         del self._reader
 246
 247 class AskUntilSuccessMixin:
 248     # create me with a _reader array
 249     _last_failure = None
 250
 251     def add_reader(self, reader):
 252         self._readers.append(reader)
 253
 254     def call(self, *args, **kwargs):
 255         if not self._readers:
 256             raise NotEnoughWritersError("ran out of assisted uploaders, last failure was %s" % self._last_failure)
 257         rr = self._readers[0]
 258         d = rr.callRemote(*args, **kwargs)
 259         def _err(f):
 260             self._last_failure = f
 261             if rr in self._readers:
 262                 self._readers.remove(rr)
 263             self._upload_helper.log("call to assisted uploader %s failed" % rr,
 264                                     failure=f, level=log.UNUSUAL)
 265             # we can try again with someone else who's left
 266             return self.call(*args, **kwargs)
 267         d.addErrback(_err)
 268         return d
 269
 270 class CHKCiphertextFetcher(AskUntilSuccessMixin):
 271     """I use one or more remote RIEncryptedUploadable instances to gather
 272     ciphertext on disk. When I'm done, the file I create can be used by a
 273     LocalCiphertextReader to satisfy the ciphertext needs of a CHK upload
 274     process.
 275
 276     I begin pulling ciphertext as soon as a reader is added. I remove readers
 277     when they have any sort of error. If the last reader is removed, I fire
 278     my when_done() Deferred with a failure.
 279
 280     I fire my when_done() Deferred (with None) immediately after I have moved
 281     the ciphertext to 'encoded_file'.
 282     """
 283
 284     def __init__(self, helper, incoming_file, encoded_file, logparent):
 285         self._upload_helper = helper
 286         self._incoming_file = incoming_file
 287         self._encoding_file = encoded_file
 288         self._upload_id = helper._upload_id
 289         self._log_parent = logparent
 290         self._done_observers = observer.OneShotObserverList()
 291         self._readers = []
 292         self._started = False
 293         self._f = None
 294         self._times = {
 295             "cumulative_fetch": 0.0,
 296             "total": 0.0,
 297             }
 298         self._ciphertext_fetched = 0
 299
 300     def log(self, *args, **kwargs):
 301         if "facility" not in kwargs:
 302             kwargs["facility"] = "tahoe.helper.chkupload.fetch"
 303         if "parent" not in kwargs:
 304             kwargs["parent"] = self._log_parent
 305         return log.msg(*args, **kwargs)
 306
 307     def add_reader(self, reader):
 308         AskUntilSuccessMixin.add_reader(self, reader)
 309         eventually(self._start)
 310
 311     def _start(self):
 312         if self._started:
 313             return
 314         self._started = True
 315         started = time.time()
 316
 317         if os.path.exists(self._encoding_file):
 318             self.log("ciphertext already present, bypassing fetch",
 319                      level=log.UNUSUAL)
 320             # we'll still need the plaintext hashes (when
 321             # LocalCiphertextReader.get_plaintext_hashtree_leaves() is
 322             # called), and currently the easiest way to get them is to ask
 323             # the sender for the last byte of ciphertext. That will provoke
 324             # them into reading and hashing (but not sending) everything
 325             # else.
 326             have = os.stat(self._encoding_file)[stat.ST_SIZE]
 327             d = self.call("read_encrypted", have-1, 1)
 328             d.addCallback(self._done2, started)
 329             return
 330
 331         # first, find out how large the file is going to be
 332         d = self.call("get_size")
 333         d.addCallback(self._got_size)
 334         d.addCallback(self._start_reading)
 335         d.addCallback(self._done)
 336         d.addCallback(self._done2, started)
 337         d.addErrback(self._failed)
 338
 339     def _got_size(self, size):
 340         self.log("total size is %d bytes" % size, level=log.NOISY)
 341         self._upload_helper._upload_status.set_size(size)
 342         self._expected_size = size
 343
 344     def _start_reading(self, res):
 345         # then find out how much crypttext we have on disk
 346         if os.path.exists(self._incoming_file):
 347             self._have = os.stat(self._incoming_file)[stat.ST_SIZE]
 348             self._upload_helper._helper.count("chk_upload_helper.resumes")
 349             self.log("we already have %d bytes" % self._have, level=log.NOISY)
 350         else:
 351             self._have = 0
 352             self.log("we do not have any ciphertext yet", level=log.NOISY)
 353         self.log("starting ciphertext fetch", level=log.NOISY)
 354         self._f = open(self._incoming_file, "ab")
 355
 356         # now loop to pull the data from the readers
 357         d = defer.Deferred()
 358         self._loop(d)
 359         # this Deferred will be fired once the last byte has been written to
 360         # self._f
 361         return d
 362
 363     # read data in 50kB chunks. We should choose a more considered number
 364     # here, possibly letting the client specify it. The goal should be to
 365     # keep the RTT*bandwidth to be less than 10% of the chunk size, to reduce
 366     # the upload bandwidth lost because this protocol is non-windowing. Too
 367     # large, however, means more memory consumption for both ends. Something
 368     # that can be transferred in, say, 10 seconds sounds about right. On my
 369     # home DSL line (50kBps upstream), that suggests 500kB. Most lines are
 370     # slower, maybe 10kBps, which suggests 100kB, and that's a bit more
 371     # memory than I want to hang on to, so I'm going to go with 50kB and see
 372     # how that works.
 373     CHUNK_SIZE = 50*1024
 374
 375     def _loop(self, fire_when_done):
 376         # this slightly weird structure is needed because Deferreds don't do
 377         # tail-recursion, so it is important to let each one retire promptly.
 378         # Simply chaining them will cause a stack overflow at the end of a
 379         # transfer that involves more than a few hundred chunks.
 380         # 'fire_when_done' lives a long time, but the Deferreds returned by
 381         # the inner _fetch() call do not.
 382         start = time.time()
 383         d = defer.maybeDeferred(self._fetch)
 384         def _done(finished):
 385             elapsed = time.time() - start
 386             self._times["cumulative_fetch"] += elapsed
 387             if finished:
 388                 self.log("finished reading ciphertext", level=log.NOISY)
 389                 fire_when_done.callback(None)
 390             else:
 391                 self._loop(fire_when_done)
 392         def _err(f):
 393             self.log(format="[%(si)s] ciphertext read failed",
 394                      si=self._upload_id, failure=f, level=log.UNUSUAL)
 395             fire_when_done.errback(f)
 396         d.addCallbacks(_done, _err)
 397         return None
 398
 399     def _fetch(self):
 400         needed = self._expected_size - self._have
 401         fetch_size = min(needed, self.CHUNK_SIZE)
 402         if fetch_size == 0:
 403             self._upload_helper._upload_status.set_progress(1, 1.0)
 404             return True # all done
 405         percent = 0.0
 406         if self._expected_size:
 407             percent = 1.0 * (self._have+fetch_size) / self._expected_size
 408         self.log(format="fetching [%(si)s] %(start)d-%(end)d of %(total)d (%(percent)d%%)",
 409                  si=self._upload_id,
 410                  start=self._have,
 411                  end=self._have+fetch_size,
 412                  total=self._expected_size,
 413                  percent=int(100.0*percent),
 414                  level=log.NOISY)
 415         d = self.call("read_encrypted", self._have, fetch_size)
 416         def _got_data(ciphertext_v):
 417             for data in ciphertext_v:
 418                 self._f.write(data)
 419                 self._have += len(data)
 420                 self._ciphertext_fetched += len(data)
 421                 self._upload_helper._helper.count("chk_upload_helper.fetched_bytes", len(data))
 422                 self._upload_helper._upload_status.set_progress(1, percent)
 423             return False # not done
 424         d.addCallback(_got_data)
 425         return d
 426
 427     def _done(self, res):
 428         self._f.close()
 429         self._f = None
 430         self.log(format="done fetching ciphertext, size=%(size)d",
 431                  size=os.stat(self._incoming_file)[stat.ST_SIZE],
 432                  level=log.NOISY)
 433         os.rename(self._incoming_file, self._encoding_file)
 434
 435     def _done2(self, _ignored, started):
 436         self.log("done2", level=log.NOISY)
 437         elapsed = time.time() - started
 438         self._times["total"] = elapsed
 439         self._readers = []
 440         self._done_observers.fire(None)
 441
 442     def _failed(self, f):
 443         if self._f:
 444             self._f.close()
 445         self._readers = []
 446         self._done_observers.fire(f)
 447
 448     def when_done(self):
 449         return self._done_observers.when_fired()
 450
 451     def get_times(self):
 452         return self._times
 453
 454     def get_ciphertext_fetched(self):
 455         return self._ciphertext_fetched
 456
 457
 458 class LocalCiphertextReader(AskUntilSuccessMixin):
 459     implements(interfaces.IEncryptedUploadable)
 460
 461     def __init__(self, upload_helper, storage_index, encoding_file):
 462         self._readers = []
 463         self._upload_helper = upload_helper
 464         self._storage_index = storage_index
 465         self._encoding_file = encoding_file
 466         self._status = None
 467
 468     def start(self):
 469         self._upload_helper._upload_status.set_status("pushing")
 470         self._size = os.stat(self._encoding_file)[stat.ST_SIZE]
 471         self.f = open(self._encoding_file, "rb")
 472
 473     def get_size(self):
 474         return defer.succeed(self._size)
 475
 476     def get_all_encoding_parameters(self):
 477         return self.call("get_all_encoding_parameters")
 478
 479     def get_storage_index(self):
 480         return defer.succeed(self._storage_index)
 481
 482     def read_encrypted(self, length, hash_only):
 483         assert hash_only is False
 484         d = defer.maybeDeferred(self.f.read, length)
 485         d.addCallback(lambda data: [data])
 486         return d
 487
 488     def close(self):
 489         self.f.close()
 490         # ??. I'm not sure if it makes sense to forward the close message.
 491         return self.call("close")
 492
 493
 494
 495 class Helper(Referenceable):
 496     implements(interfaces.RIHelper, interfaces.IStatsProducer)
 497     # this is the non-distributed version. When we need to have multiple
 498     # helpers, this object will become the HelperCoordinator, and will query
 499     # the farm of Helpers to see if anyone has the storage_index of interest,
 500     # and send the request off to them. If nobody has it, we'll choose a
 501     # helper at random.
 502
 503     name = "helper"
 504     VERSION = { "http://allmydata.org/tahoe/protocols/helper/v1" :
 505                  { },
 506                 "application-version": str(allmydata.__full_version__),
 507                 }
 508     MAX_UPLOAD_STATUSES = 10
 509
 510     def __init__(self, basedir, storage_broker, secret_holder,
 511                  stats_provider, history):
 512         self._basedir = basedir
 513         self._storage_broker = storage_broker
 514         self._secret_holder = secret_holder
 515         self._chk_incoming = os.path.join(basedir, "CHK_incoming")
 516         self._chk_encoding = os.path.join(basedir, "CHK_encoding")
 517         fileutil.make_dirs(self._chk_incoming)
 518         fileutil.make_dirs(self._chk_encoding)
 519         self._active_uploads = {}
 520         self._all_uploads = weakref.WeakKeyDictionary() # for debugging
 521         self.stats_provider = stats_provider
 522         if stats_provider:
 523             stats_provider.register_producer(self)
 524         self._counters = {"chk_upload_helper.upload_requests": 0,
 525                           "chk_upload_helper.upload_already_present": 0,
 526                           "chk_upload_helper.upload_need_upload": 0,
 527                           "chk_upload_helper.resumes": 0,
 528                           "chk_upload_helper.fetched_bytes": 0,
 529                           "chk_upload_helper.encoded_bytes": 0,
 530                           }
 531         self._history = history
 532
 533     def log(self, *args, **kwargs):
 534         if 'facility' not in kwargs:
 535             kwargs['facility'] = "tahoe.helper"
 536         return log.msg(*args, **kwargs)
 537
 538     def count(self, key, value=1):
 539         if self.stats_provider:
 540             self.stats_provider.count(key, value)
 541         self._counters[key] += value
 542
 543     def get_stats(self):
 544         OLD = 86400*2 # 48hours
 545         now = time.time()
 546         inc_count = inc_size = inc_size_old = 0
 547         enc_count = enc_size = enc_size_old = 0
 548         inc = os.listdir(self._chk_incoming)
 549         enc = os.listdir(self._chk_encoding)
 550         for f in inc:
 551             s = os.stat(os.path.join(self._chk_incoming, f))
 552             size = s[stat.ST_SIZE]
 553             mtime = s[stat.ST_MTIME]
 554             inc_count += 1
 555             inc_size += size
 556             if now - mtime > OLD:
 557                 inc_size_old += size
 558         for f in enc:
 559             s = os.stat(os.path.join(self._chk_encoding, f))
 560             size = s[stat.ST_SIZE]
 561             mtime = s[stat.ST_MTIME]
 562             enc_count += 1
 563             enc_size += size
 564             if now - mtime > OLD:
 565                 enc_size_old += size
 566         stats = { 'chk_upload_helper.active_uploads': len(self._active_uploads),
 567                   'chk_upload_helper.incoming_count': inc_count,
 568                   'chk_upload_helper.incoming_size': inc_size,
 569                   'chk_upload_helper.incoming_size_old': inc_size_old,
 570                   'chk_upload_helper.encoding_count': enc_count,
 571                   'chk_upload_helper.encoding_size': enc_size,
 572                   'chk_upload_helper.encoding_size_old': enc_size_old,
 573                   }
 574         stats.update(self._counters)
 575         return stats
 576
 577     def remote_get_version(self):
 578         return self.VERSION
 579
 580     def remote_upload_chk(self, storage_index):
 581         self.count("chk_upload_helper.upload_requests")
 582         lp = self.log(format="helper: upload_chk query for SI %(si)s",
 583                       si=si_b2a(storage_index))
 584         if storage_index in self._active_uploads:
 585             self.log("upload is currently active", parent=lp)
 586             uh = self._active_uploads[storage_index]
 587             return (None, uh)
 588
 589         d = self._check_chk(storage_index, lp)
 590         d.addCallback(self._did_chk_check, storage_index, lp)
 591         def _err(f):
 592             self.log("error while checking for chk-already-in-grid",
 593                      failure=f, level=log.WEIRD, parent=lp, umid="jDtxZg")
 594             return f
 595         d.addErrback(_err)
 596         return d
 597
 598     def _check_chk(self, storage_index, lp):
 599         # see if this file is already in the grid
 600         lp2 = self.log("doing a quick check+UEBfetch",
 601                        parent=lp, level=log.NOISY)
 602         sb = self._storage_broker
 603         c = CHKCheckerAndUEBFetcher(sb.get_servers_for_psi, storage_index, lp2)
 604         d = c.check()
 605         def _checked(res):
 606             if res:
 607                 (sharemap, ueb_data, ueb_hash) = res
 608                 self.log("found file in grid", level=log.NOISY, parent=lp)
 609                 hur = upload.HelperUploadResults()
 610                 hur.uri_extension_hash = ueb_hash
 611                 hur.sharemap = sharemap
 612                 hur.uri_extension_data = ueb_data
 613                 hur.preexisting_shares = len(sharemap)
 614                 hur.pushed_shares = 0
 615                 return hur
 616             return None
 617         d.addCallback(_checked)
 618         return d
 619
 620     def _did_chk_check(self, already_present, storage_index, lp):
 621         if already_present:
 622             # the necessary results are placed in the UploadResults
 623             self.count("chk_upload_helper.upload_already_present")
 624             self.log("file already found in grid", parent=lp)
 625             return (already_present, None)
 626
 627         self.count("chk_upload_helper.upload_need_upload")
 628         # the file is not present in the grid, by which we mean there are
 629         # less than 'N' shares available.
 630         self.log("unable to find file in the grid", parent=lp,
 631                  level=log.NOISY)
 632         # We need an upload helper. Check our active uploads again in
 633         # case there was a race.
 634         if storage_index in self._active_uploads:
 635             self.log("upload is currently active", parent=lp)
 636             uh = self._active_uploads[storage_index]
 637         else:
 638             self.log("creating new upload helper", parent=lp)
 639             uh = self._make_chk_upload_helper(storage_index, lp)
 640             self._active_uploads[storage_index] = uh
 641             self._add_upload(uh)
 642         return (None, uh)
 643
 644     def _make_chk_upload_helper(self, storage_index, lp):
 645         si_s = si_b2a(storage_index)
 646         incoming_file = os.path.join(self._chk_incoming, si_s)
 647         encoding_file = os.path.join(self._chk_encoding, si_s)
 648         uh = CHKUploadHelper(storage_index, self,
 649                              self._storage_broker,
 650                              self._secret_holder,
 651                              incoming_file, encoding_file,
 652                              lp)
 653         return uh
 654
 655     def _add_upload(self, uh):
 656         self._all_uploads[uh] = None
 657         if self._history:
 658             s = uh.get_upload_status()
 659             self._history.notify_helper_upload(s)
 660
 661     def upload_finished(self, storage_index, size):
 662         # this is called with size=0 if the upload failed
 663         self.count("chk_upload_helper.encoded_bytes", size)
 664         uh = self._active_uploads[storage_index]
 665         del self._active_uploads[storage_index]
 666         s = uh.get_upload_status()
 667         s.set_active(False)