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