src/allmydata/frontends/magic_folder.py

   1
   2 import sys, os
   3 import os.path
   4 from collections import deque
   5 import time
   6
   7 from twisted.internet import defer, reactor, task
   8 from twisted.python.failure import Failure
   9 from twisted.python import runtime
  10 from twisted.application import service
  11
  12 from allmydata.util import fileutil
  13 from allmydata.interfaces import IDirectoryNode
  14 from allmydata.util import log
  15 from allmydata.util.fileutil import precondition_abspath, get_pathinfo, ConflictError
  16 from allmydata.util.assertutil import precondition, _assert
  17 from allmydata.util.deferredutil import HookMixin
  18 from allmydata.util.encodingutil import listdir_filepath, to_filepath, \
  19      extend_filepath, unicode_from_filepath, unicode_segments_from, \
  20      quote_filepath, quote_local_unicode_path, quote_output, FilenameEncodingError
  21 from allmydata.immutable.upload import FileName, Data
  22 from allmydata import magicfolderdb, magicpath
  23
  24
  25 IN_EXCL_UNLINK = 0x04000000L
  26
  27 def get_inotify_module():
  28     try:
  29         if sys.platform == "win32":
  30             from allmydata.windows import inotify
  31         elif runtime.platform.supportsINotify():
  32             from twisted.internet import inotify
  33         else:
  34             raise NotImplementedError("filesystem notification needed for Magic Folder is not supported.\n"
  35                                       "This currently requires Linux or Windows.")
  36         return inotify
  37     except (ImportError, AttributeError) as e:
  38         log.msg(e)
  39         if sys.platform == "win32":
  40             raise NotImplementedError("filesystem notification needed for Magic Folder is not supported.\n"
  41                                       "Windows support requires at least Vista, and has only been tested on Windows 7.")
  42         raise
  43
  44
  45 class MagicFolder(service.MultiService):
  46     name = 'magic-folder'
  47
  48     def __init__(self, client, upload_dircap, collective_dircap, local_path_u, dbfile,
  49                  pending_delay=1.0, clock=None):
  50         precondition_abspath(local_path_u)
  51
  52         service.MultiService.__init__(self)
  53
  54         immediate = clock is not None
  55         clock = clock or reactor
  56         db = magicfolderdb.get_magicfolderdb(dbfile, create_version=(magicfolderdb.SCHEMA_v1, 1))
  57         if db is None:
  58             return Failure(Exception('ERROR: Unable to load magic folder db.'))
  59
  60         # for tests
  61         self._client = client
  62         self._db = db
  63
  64         upload_dirnode = self._client.create_node_from_uri(upload_dircap)
  65         collective_dirnode = self._client.create_node_from_uri(collective_dircap)
  66
  67         self.uploader = Uploader(client, local_path_u, db, upload_dirnode, pending_delay, clock, immediate)
  68         self.downloader = Downloader(client, local_path_u, db, collective_dirnode,
  69                                      upload_dirnode.get_readonly_uri(), clock, self.uploader.is_pending)
  70
  71     def startService(self):
  72         # TODO: why is this being called more than once?
  73         if self.running:
  74             return defer.succeed(None)
  75         print "%r.startService" % (self,)
  76         service.MultiService.startService(self)
  77         return self.uploader.start_monitoring()
  78
  79     def ready(self):
  80         """ready is used to signal us to start
  81         processing the upload and download items...
  82         """
  83         d = self.uploader.start_scanning()
  84         d2 = self.downloader.start_scanning()
  85         d.addCallback(lambda ign: d2)
  86         return d
  87
  88     def finish(self):
  89         print "finish"
  90         d = self.uploader.stop()
  91         d2 = self.downloader.stop()
  92         d.addCallback(lambda ign: d2)
  93         return d
  94
  95     def remove_service(self):
  96         return service.MultiService.disownServiceParent(self)
  97
  98
  99 class QueueMixin(HookMixin):
 100     def __init__(self, client, local_path_u, db, name, clock):
 101         self._client = client
 102         self._local_path_u = local_path_u
 103         self._local_filepath = to_filepath(local_path_u)
 104         self._db = db
 105         self._name = name
 106         self._clock = clock
 107         self._hooks = {'processed': None, 'started': None}
 108         self.started_d = self.set_hook('started')
 109
 110         if not self._local_filepath.exists():
 111             raise AssertionError("The '[magic_folder] local.directory' parameter was %s "
 112                                  "but there is no directory at that location."
 113                                  % quote_local_unicode_path(self._local_path_u))
 114         if not self._local_filepath.isdir():
 115             raise AssertionError("The '[magic_folder] local.directory' parameter was %s "
 116                                  "but the thing at that location is not a directory."
 117                                  % quote_local_unicode_path(self._local_path_u))
 118
 119         self._deque = deque()
 120         self._lazy_tail = defer.succeed(None)
 121         self._stopped = False
 122         self._turn_delay = 0
 123
 124     def _get_filepath(self, relpath_u):
 125         self._log("_get_filepath(%r)" % (relpath_u,))
 126         return extend_filepath(self._local_filepath, relpath_u.split(u"/"))
 127
 128     def _get_relpath(self, filepath):
 129         self._log("_get_relpath(%r)" % (filepath,))
 130         segments = unicode_segments_from(filepath, self._local_filepath)
 131         self._log("segments = %r" % (segments,))
 132         return u"/".join(segments)
 133
 134     def _count(self, counter_name, delta=1):
 135         ctr = 'magic_folder.%s.%s' % (self._name, counter_name)
 136         self._log("%s += %r" % (counter_name, delta))
 137         self._client.stats_provider.count(ctr, delta)
 138
 139     def _logcb(self, res, msg):
 140         self._log("%s: %r" % (msg, res))
 141         return res
 142
 143     def _log(self, msg):
 144         s = "Magic Folder %s %s: %s" % (quote_output(self._client.nickname), self._name, msg)
 145         self._client.log(s)
 146         print s
 147         #open("events", "ab+").write(msg)
 148
 149     def _turn_deque(self):
 150         self._log("_turn_deque")
 151         if self._stopped:
 152             self._log("stopped")
 153             return
 154         try:
 155             item = self._deque.pop()
 156             self._log("popped %r" % (item,))
 157             self._count('objects_queued', -1)
 158         except IndexError:
 159             self._log("deque is now empty")
 160             self._lazy_tail.addCallback(lambda ign: self._when_queue_is_empty())
 161         else:
 162             self._lazy_tail.addCallback(lambda ign: self._process(item))
 163             self._lazy_tail.addBoth(self._call_hook, 'processed')
 164             self._lazy_tail.addErrback(log.err)
 165             self._lazy_tail.addCallback(lambda ign: task.deferLater(self._clock, self._turn_delay, self._turn_deque))
 166
 167
 168 class Uploader(QueueMixin):
 169     def __init__(self, client, local_path_u, db, upload_dirnode, pending_delay, clock,
 170                  immediate=False):
 171         QueueMixin.__init__(self, client, local_path_u, db, 'uploader', clock)
 172
 173         self.is_ready = False
 174         self._immediate = immediate
 175
 176         if not IDirectoryNode.providedBy(upload_dirnode):
 177             raise AssertionError("The URI in '%s' does not refer to a directory."
 178                                  % os.path.join('private', 'magic_folder_dircap'))
 179         if upload_dirnode.is_unknown() or upload_dirnode.is_readonly():
 180             raise AssertionError("The URI in '%s' is not a writecap to a directory."
 181                                  % os.path.join('private', 'magic_folder_dircap'))
 182
 183         self._upload_dirnode = upload_dirnode
 184         self._inotify = get_inotify_module()
 185         self._notifier = self._inotify.INotify()
 186         self._pending = set()
 187
 188         if hasattr(self._notifier, 'set_pending_delay'):
 189             self._notifier.set_pending_delay(pending_delay)
 190
 191         # TODO: what about IN_MOVE_SELF and IN_UNMOUNT?
 192         #
 193         self.mask = ( self._inotify.IN_CREATE
 194                     | self._inotify.IN_CLOSE_WRITE
 195                     | self._inotify.IN_MOVED_TO
 196                     | self._inotify.IN_MOVED_FROM
 197                     | self._inotify.IN_DELETE
 198                     | self._inotify.IN_ONLYDIR
 199                     | IN_EXCL_UNLINK
 200                     )
 201         self._notifier.watch(self._local_filepath, mask=self.mask, callbacks=[self._notify],
 202                              recursive=True)
 203
 204     def start_monitoring(self):
 205         self._log("start_monitoring")
 206         d = defer.succeed(None)
 207         d.addCallback(lambda ign: self._notifier.startReading())
 208         d.addCallback(lambda ign: self._count('dirs_monitored'))
 209         d.addBoth(self._call_hook, 'started')
 210         return d
 211
 212     def stop(self):
 213         self._log("stop")
 214         self._notifier.stopReading()
 215         self._count('dirs_monitored', -1)
 216         if hasattr(self._notifier, 'wait_until_stopped'):
 217             d = self._notifier.wait_until_stopped()
 218         else:
 219             d = defer.succeed(None)
 220         d.addCallback(lambda ign: self._lazy_tail)
 221         return d
 222
 223     def start_scanning(self):
 224         self._log("start_scanning")
 225         self.is_ready = True
 226         self._pending = self._db.get_all_relpaths()
 227         self._log("all_files %r" % (self._pending))
 228         d = self._scan(u"")
 229         def _add_pending(ign):
 230             # This adds all of the files that were in the db but not already processed
 231             # (normally because they have been deleted on disk).
 232             self._log("adding %r" % (self._pending))
 233             self._deque.extend(self._pending)
 234         d.addCallback(_add_pending)
 235         d.addCallback(lambda ign: self._turn_deque())
 236         return d
 237
 238     def _scan(self, reldir_u):
 239         self._log("scan %r" % (reldir_u,))
 240         fp = self._get_filepath(reldir_u)
 241         try:
 242             children = listdir_filepath(fp)
 243         except EnvironmentError:
 244             raise Exception("WARNING: magic folder: permission denied on directory %s"
 245                             % quote_filepath(fp))
 246         except FilenameEncodingError:
 247             raise Exception("WARNING: magic folder: could not list directory %s due to a filename encoding error"
 248                             % quote_filepath(fp))
 249
 250         d = defer.succeed(None)
 251         for child in children:
 252             _assert(isinstance(child, unicode), child=child)
 253             d.addCallback(lambda ign, child=child:
 254                           ("%s/%s" % (reldir_u, child) if reldir_u else child))
 255             def _add_pending(relpath_u):
 256                 if magicpath.should_ignore_file(relpath_u):
 257                     return None
 258
 259                 self._pending.add(relpath_u)
 260                 return relpath_u
 261             d.addCallback(_add_pending)
 262             # This call to _process doesn't go through the deque, and probably should.
 263             d.addCallback(self._process)
 264             d.addBoth(self._call_hook, 'processed')
 265             d.addErrback(log.err)
 266
 267         return d
 268
 269     def is_pending(self, relpath_u):
 270         return relpath_u in self._pending
 271
 272     def _notify(self, opaque, path, events_mask):
 273         self._log("inotify event %r, %r, %r\n" % (opaque, path, ', '.join(self._inotify.humanReadableMask(events_mask))))
 274         relpath_u = self._get_relpath(path)
 275
 276         # We filter out IN_CREATE events not associated with a directory.
 277         # Acting on IN_CREATE for files could cause us to read and upload
 278         # a possibly-incomplete file before the application has closed it.
 279         # There should always be an IN_CLOSE_WRITE after an IN_CREATE, I think.
 280         # It isn't possible to avoid watching for IN_CREATE at all, because
 281         # it is the only event notified for a directory creation.
 282
 283         if ((events_mask & self._inotify.IN_CREATE) != 0 and
 284             (events_mask & self._inotify.IN_ISDIR) == 0):
 285             self._log("ignoring event for %r (creation of non-directory)\n" % (relpath_u,))
 286             return
 287         if relpath_u in self._pending:
 288             self._log("ignoring event for %r (already pending)" % (relpath_u,))
 289             return
 290         if magicpath.should_ignore_file(relpath_u):
 291             self._log("ignoring event for %r (ignorable path)" % (relpath_u,))
 292             return
 293
 294         self._log("appending %r to deque" % (relpath_u,))
 295         self._deque.append(relpath_u)
 296         self._pending.add(relpath_u)
 297         self._count('objects_queued')
 298         if self.is_ready:
 299             if self._immediate:  # for tests
 300                 self._turn_deque()
 301             else:
 302                 self._clock.callLater(0, self._turn_deque)
 303
 304     def _when_queue_is_empty(self):
 305         return defer.succeed(None)
 306
 307     def _process(self, relpath_u):
 308         # Uploader
 309         self._log("_process(%r)" % (relpath_u,))
 310         if relpath_u is None:
 311             return
 312         precondition(isinstance(relpath_u, unicode), relpath_u)
 313         precondition(not relpath_u.endswith(u'/'), relpath_u)
 314
 315         d = defer.succeed(None)
 316
 317         def _maybe_upload(val, now=None):
 318             if now is None:
 319                 now = time.time()
 320             fp = self._get_filepath(relpath_u)
 321             pathinfo = get_pathinfo(unicode_from_filepath(fp))
 322
 323             self._log("about to remove %r from pending set %r" %
 324                       (relpath_u, self._pending))
 325             self._pending.remove(relpath_u)
 326             encoded_path_u = magicpath.path2magic(relpath_u)
 327
 328             if not pathinfo.exists:
 329                 # FIXME merge this with the 'isfile' case.
 330                 self._log("notified object %s disappeared (this is normal)" % quote_filepath(fp))
 331                 self._count('objects_disappeared')
 332
 333                 db_entry = self._db.get_db_entry(relpath_u)
 334                 if db_entry is None:
 335                     return None
 336
 337                 last_downloaded_timestamp = now  # is this correct?
 338
 339                 if self._db.is_new_file(pathinfo, relpath_u):
 340                     new_version = db_entry.version + 1
 341                 else:
 342                     self._log("Not uploading %r" % (relpath_u,))
 343                     self._count('objects_not_uploaded')
 344                     return
 345
 346                 metadata = { 'version': new_version,
 347                              'deleted': True,
 348                              'last_downloaded_timestamp': last_downloaded_timestamp }
 349                 if db_entry.last_downloaded_uri is not None:
 350                     metadata['last_downloaded_uri'] = db_entry.last_downloaded_uri
 351
 352                 empty_uploadable = Data("", self._client.convergence)
 353                 d2 = self._upload_dirnode.add_file(encoded_path_u, empty_uploadable,
 354                                                    metadata=metadata, overwrite=True)
 355
 356                 def _add_db_entry(filenode):
 357                     filecap = filenode.get_uri()
 358                     last_downloaded_uri = metadata.get('last_downloaded_uri', None)
 359                     self._db.did_upload_version(relpath_u, new_version, filecap,
 360                                                 last_downloaded_uri, last_downloaded_timestamp,
 361                                                 pathinfo)
 362                     self._count('files_uploaded')
 363                 d2.addCallback(_add_db_entry)
 364                 return d2
 365             elif pathinfo.islink:
 366                 self.warn("WARNING: cannot upload symlink %s" % quote_filepath(fp))
 367                 return None
 368             elif pathinfo.isdir:
 369                 if not getattr(self._notifier, 'recursive_includes_new_subdirectories', False):
 370                     self._notifier.watch(fp, mask=self.mask, callbacks=[self._notify], recursive=True)
 371
 372                 uploadable = Data("", self._client.convergence)
 373                 encoded_path_u += magicpath.path2magic(u"/")
 374                 self._log("encoded_path_u =  %r" % (encoded_path_u,))
 375                 upload_d = self._upload_dirnode.add_file(encoded_path_u, uploadable, metadata={"version":0}, overwrite=True)
 376                 def _succeeded(ign):
 377                     self._log("created subdirectory %r" % (relpath_u,))
 378                     self._count('directories_created')
 379                 def _failed(f):
 380                     self._log("failed to create subdirectory %r" % (relpath_u,))
 381                     return f
 382                 upload_d.addCallbacks(_succeeded, _failed)
 383                 upload_d.addCallback(lambda ign: self._scan(relpath_u))
 384                 return upload_d
 385             elif pathinfo.isfile:
 386                 db_entry = self._db.get_db_entry(relpath_u)
 387
 388                 last_downloaded_timestamp = now
 389
 390                 if db_entry is None:
 391                     new_version = 0
 392                 elif self._db.is_new_file(pathinfo, relpath_u):
 393                     new_version = db_entry.version + 1
 394                 else:
 395                     self._log("Not uploading %r" % (relpath_u,))
 396                     self._count('objects_not_uploaded')
 397                     return None
 398
 399                 metadata = { 'version': new_version,
 400                              'last_downloaded_timestamp': last_downloaded_timestamp }
 401                 if db_entry is not None and db_entry.last_downloaded_uri is not None:
 402                     metadata['last_downloaded_uri'] = db_entry.last_downloaded_uri
 403
 404                 uploadable = FileName(unicode_from_filepath(fp), self._client.convergence)
 405                 d2 = self._upload_dirnode.add_file(encoded_path_u, uploadable,
 406                                                    metadata=metadata, overwrite=True)
 407
 408                 def _add_db_entry(filenode):
 409                     filecap = filenode.get_uri()
 410                     last_downloaded_uri = metadata.get('last_downloaded_uri', None)
 411                     self._db.did_upload_version(relpath_u, new_version, filecap,
 412                                                 last_downloaded_uri, last_downloaded_timestamp,
 413                                                 pathinfo)
 414                     self._count('files_uploaded')
 415                 d2.addCallback(_add_db_entry)
 416                 return d2
 417             else:
 418                 self.warn("WARNING: cannot process special file %s" % quote_filepath(fp))
 419                 return None
 420
 421         d.addCallback(_maybe_upload)
 422
 423         def _succeeded(res):
 424             self._count('objects_succeeded')
 425             return res
 426         def _failed(f):
 427             self._count('objects_failed')
 428             self._log("%s while processing %r" % (f, relpath_u))
 429             return f
 430         d.addCallbacks(_succeeded, _failed)
 431         return d
 432
 433     def _get_metadata(self, encoded_path_u):
 434         try:
 435             d = self._upload_dirnode.get_metadata_for(encoded_path_u)
 436         except KeyError:
 437             return Failure()
 438         return d
 439
 440     def _get_filenode(self, encoded_path_u):
 441         try:
 442             d = self._upload_dirnode.get(encoded_path_u)
 443         except KeyError:
 444             return Failure()
 445         return d
 446
 447
 448 class WriteFileMixin(object):
 449     FUDGE_SECONDS = 10.0
 450
 451     def _get_conflicted_filename(self, abspath_u):
 452         return abspath_u + u".conflict"
 453
 454     def _write_downloaded_file(self, abspath_u, file_contents, is_conflict=False, now=None):
 455         self._log("_write_downloaded_file(%r, <%d bytes>, is_conflict=%r, now=%r)"
 456                   % (abspath_u, len(file_contents), is_conflict, now))
 457
 458         # 1. Write a temporary file, say .foo.tmp.
 459         # 2. is_conflict determines whether this is an overwrite or a conflict.
 460         # 3. Set the mtime of the replacement file to be T seconds before the
 461         #    current local time.
 462         # 4. Perform a file replacement with backup filename foo.backup,
 463         #    replaced file foo, and replacement file .foo.tmp. If any step of
 464         #    this operation fails, reclassify as a conflict and stop.
 465         #
 466         # Returns the path of the destination file.
 467
 468         precondition_abspath(abspath_u)
 469         replacement_path_u = abspath_u + u".tmp"  # FIXME more unique
 470         backup_path_u = abspath_u + u".backup"
 471         if now is None:
 472             now = time.time()
 473
 474         # ensure parent directory exists
 475         head, tail = os.path.split(abspath_u)
 476         mode = 0777 # XXX
 477         fileutil.make_dirs(head, mode)
 478
 479         fileutil.write(replacement_path_u, file_contents)
 480         os.utime(replacement_path_u, (now, now - self.FUDGE_SECONDS))
 481         if is_conflict:
 482             print "0x00 ------------ <><> is conflict; calling _rename_conflicted_file... %r %r" % (abspath_u, replacement_path_u)
 483             return self._rename_conflicted_file(abspath_u, replacement_path_u)
 484         else:
 485             try:
 486                 fileutil.replace_file(abspath_u, replacement_path_u, backup_path_u)
 487                 return abspath_u
 488             except fileutil.ConflictError:
 489                 return self._rename_conflicted_file(abspath_u, replacement_path_u)
 490
 491     def _rename_conflicted_file(self, abspath_u, replacement_path_u):
 492         self._log("_rename_conflicted_file(%r, %r)" % (abspath_u, replacement_path_u))
 493
 494         conflict_path_u = self._get_conflicted_filename(abspath_u)
 495         print "XXX rename %r %r" % (replacement_path_u, conflict_path_u)
 496         if os.path.isfile(replacement_path_u):
 497             print "%r exists" % (replacement_path_u,)
 498         if os.path.isfile(conflict_path_u):
 499             print "%r exists" % (conflict_path_u,)
 500
 501         fileutil.rename_no_overwrite(replacement_path_u, conflict_path_u)
 502         return conflict_path_u
 503
 504     def _rename_deleted_file(self, abspath_u):
 505         self._log('renaming deleted file to backup: %s' % (abspath_u,))
 506         try:
 507             fileutil.rename_no_overwrite(abspath_u, abspath_u + u'.backup')
 508         except OSError:
 509             self._log("Already gone: '%s'" % (abspath_u,))
 510         return abspath_u
 511
 512
 513 class Downloader(QueueMixin, WriteFileMixin):
 514     REMOTE_SCAN_INTERVAL = 3  # facilitates tests
 515
 516     def __init__(self, client, local_path_u, db, collective_dirnode,
 517                  upload_readonly_dircap, clock, is_upload_pending):
 518         QueueMixin.__init__(self, client, local_path_u, db, 'downloader', clock)
 519
 520         if not IDirectoryNode.providedBy(collective_dirnode):
 521             raise AssertionError("The URI in '%s' does not refer to a directory."
 522                                  % os.path.join('private', 'collective_dircap'))
 523         if collective_dirnode.is_unknown() or not collective_dirnode.is_readonly():
 524             raise AssertionError("The URI in '%s' is not a readonly cap to a directory."
 525                                  % os.path.join('private', 'collective_dircap'))
 526
 527         self._collective_dirnode = collective_dirnode
 528         self._upload_readonly_dircap = upload_readonly_dircap
 529         self._is_upload_pending = is_upload_pending
 530
 531         self._turn_delay = self.REMOTE_SCAN_INTERVAL
 532
 533     def start_scanning(self):
 534         self._log("start_scanning")
 535         files = self._db.get_all_relpaths()
 536         self._log("all files %s" % files)
 537
 538         d = self._scan_remote_collective(scan_self=True)
 539         d.addBoth(self._logcb, "after _scan_remote_collective 0")
 540         self._turn_deque()
 541         return d
 542
 543     def stop(self):
 544         self._stopped = True
 545         d = defer.succeed(None)
 546         d.addCallback(lambda ign: self._lazy_tail)
 547         return d
 548
 549     def _should_download(self, relpath_u, remote_version):
 550         """
 551         _should_download returns a bool indicating whether or not a remote object should be downloaded.
 552         We check the remote metadata version against our magic-folder db version number;
 553         latest version wins.
 554         """
 555         self._log("_should_download(%r, %r)" % (relpath_u, remote_version))
 556         if magicpath.should_ignore_file(relpath_u):
 557             self._log("nope")
 558             return False
 559         self._log("yep")
 560         db_entry = self._db.get_db_entry(relpath_u)
 561         if db_entry is None:
 562             return True
 563         self._log("version %r" % (db_entry.version,))
 564         return (db_entry.version < remote_version)
 565
 566     def _get_local_latest(self, relpath_u):
 567         """
 568         _get_local_latest takes a unicode path string checks to see if this file object
 569         exists in our magic-folder db; if not then return None
 570         else check for an entry in our magic-folder db and return the version number.
 571         """
 572         if not self._get_filepath(relpath_u).exists():
 573             return None
 574         db_entry = self._db.get_db_entry(relpath_u)
 575         return None if db_entry is None else db_entry.version
 576
 577     def _get_collective_latest_file(self, filename):
 578         """
 579         _get_collective_latest_file takes a file path pointing to a file managed by
 580         magic-folder and returns a deferred that fires with the two tuple containing a
 581         file node and metadata for the latest version of the file located in the
 582         magic-folder collective directory.
 583         """
 584         collective_dirmap_d = self._collective_dirnode.list()
 585         def scan_collective(result):
 586             list_of_deferreds = []
 587             for dir_name in result.keys():
 588                 # XXX make sure it's a directory
 589                 d = defer.succeed(None)
 590                 d.addCallback(lambda x, dir_name=dir_name: result[dir_name][0].get_child_and_metadata(filename))
 591                 list_of_deferreds.append(d)
 592             deferList = defer.DeferredList(list_of_deferreds, consumeErrors=True)
 593             return deferList
 594         collective_dirmap_d.addCallback(scan_collective)
 595         def highest_version(deferredList):
 596             max_version = 0
 597             metadata = None
 598             node = None
 599             for success, result in deferredList:
 600                 if success:
 601                     if result[1]['version'] > max_version:
 602                         node, metadata = result
 603                         max_version = result[1]['version']
 604             return node, metadata
 605         collective_dirmap_d.addCallback(highest_version)
 606         return collective_dirmap_d
 607
 608     def _scan_remote_dmd(self, nickname, dirnode, scan_batch):
 609         self._log("_scan_remote_dmd nickname %r" % (nickname,))
 610         d = dirnode.list()
 611         def scan_listing(listing_map):
 612             for encoded_relpath_u in listing_map.keys():
 613                 relpath_u = magicpath.magic2path(encoded_relpath_u)
 614                 self._log("found %r" % (relpath_u,))
 615
 616                 file_node, metadata = listing_map[encoded_relpath_u]
 617                 local_version = self._get_local_latest(relpath_u)
 618                 remote_version = metadata.get('version', None)
 619                 self._log("%r has local version %r, remote version %r" % (relpath_u, local_version, remote_version))
 620
 621                 if local_version is None or remote_version is None or local_version < remote_version:
 622                     self._log("%r added to download queue" % (relpath_u,))
 623                     if scan_batch.has_key(relpath_u):
 624                         scan_batch[relpath_u] += [(file_node, metadata)]
 625                     else:
 626                         scan_batch[relpath_u] = [(file_node, metadata)]
 627
 628         d.addCallback(scan_listing)
 629         d.addBoth(self._logcb, "end of _scan_remote_dmd")
 630         return d
 631
 632     def _scan_remote_collective(self, scan_self=False):
 633         self._log("_scan_remote_collective")
 634         scan_batch = {}  # path -> [(filenode, metadata)]
 635
 636         d = self._collective_dirnode.list()
 637         def scan_collective(dirmap):
 638             d2 = defer.succeed(None)
 639             for dir_name in dirmap:
 640                 (dirnode, metadata) = dirmap[dir_name]
 641                 if scan_self or dirnode.get_readonly_uri() != self._upload_readonly_dircap:
 642                     d2.addCallback(lambda ign, dir_name=dir_name, dirnode=dirnode:
 643                                    self._scan_remote_dmd(dir_name, dirnode, scan_batch))
 644                     def _err(f, dir_name=dir_name):
 645                         self._log("failed to scan DMD for client %r: %s" % (dir_name, f))
 646                         # XXX what should we do to make this failure more visible to users?
 647                     d2.addErrback(_err)
 648
 649             return d2
 650         d.addCallback(scan_collective)
 651
 652         def _filter_batch_to_deque(ign):
 653             self._log("deque = %r, scan_batch = %r" % (self._deque, scan_batch))
 654             for relpath_u in scan_batch.keys():
 655                 file_node, metadata = max(scan_batch[relpath_u], key=lambda x: x[1]['version'])
 656
 657                 if self._should_download(relpath_u, metadata['version']):
 658                     self._deque.append( (relpath_u, file_node, metadata) )
 659                 else:
 660                     self._log("Excluding %r" % (relpath_u,))
 661                     self._count('objects_excluded')
 662                     self._call_hook(None, 'processed')
 663
 664             self._log("deque after = %r" % (self._deque,))
 665         d.addCallback(_filter_batch_to_deque)
 666         return d
 667
 668     def _when_queue_is_empty(self):
 669         d = task.deferLater(self._clock, self._turn_delay, self._scan_remote_collective)
 670         d.addBoth(self._logcb, "after _scan_remote_collective 1")
 671         d.addCallback(lambda ign: self._turn_deque())
 672         return d
 673
 674     def _process(self, item, now=None):
 675         # Downloader
 676         self._log("_process(%r)" % (item,))
 677         if now is None:
 678             now = time.time()
 679         (relpath_u, file_node, metadata) = item
 680         fp = self._get_filepath(relpath_u)
 681         abspath_u = unicode_from_filepath(fp)
 682         conflict_path_u = self._get_conflicted_filename(abspath_u)
 683
 684         d = defer.succeed(None)
 685
 686         def do_update_db(written_abspath_u):
 687             filecap = file_node.get_uri()
 688             last_uploaded_uri = metadata.get('last_uploaded_uri', None)
 689             last_downloaded_uri = filecap
 690             last_downloaded_timestamp = now
 691             written_pathinfo = get_pathinfo(written_abspath_u)
 692
 693             if not written_pathinfo.exists and not metadata.get('deleted', False):
 694                 raise Exception("downloaded object %s disappeared" % quote_local_unicode_path(written_abspath_u))
 695
 696             self._db.did_upload_version(relpath_u, metadata['version'], last_uploaded_uri,
 697                                         last_downloaded_uri, last_downloaded_timestamp, written_pathinfo)
 698             self._count('objects_downloaded')
 699         def failed(f):
 700             self._log("download failed: %s" % (str(f),))
 701             self._count('objects_failed')
 702             return f
 703
 704         if os.path.isfile(conflict_path_u):
 705             def fail(res):
 706                 raise ConflictError("download failed: already conflicted: %r" % (relpath_u,))
 707             d.addCallback(fail)
 708         else:
 709             is_conflict = False
 710             db_entry = self._db.get_db_entry(relpath_u)
 711             dmd_last_downloaded_uri = metadata.get('last_downloaded_uri', None)
 712             dmd_last_uploaded_uri = metadata.get('last_uploaded_uri', None)
 713             if db_entry:
 714                 if dmd_last_downloaded_uri is not None and db_entry.last_downloaded_uri is not None:
 715                     if dmd_last_downloaded_uri != db_entry.last_downloaded_uri:
 716                         is_conflict = True
 717                         self._count('objects_conflicted')
 718                 elif dmd_last_uploaded_uri is not None and dmd_last_uploaded_uri != db_entry.last_uploaded_uri:
 719                     is_conflict = True
 720                     self._count('objects_conflicted')
 721                 elif self._is_upload_pending(relpath_u):
 722                     is_conflict = True
 723                     self._count('objects_conflicted')
 724
 725             if relpath_u.endswith(u"/"):
 726                 if metadata.get('deleted', False):
 727                     self._log("rmdir(%r) ignored" % (abspath_u,))
 728                 else:
 729                     self._log("mkdir(%r)" % (abspath_u,))
 730                     d.addCallback(lambda ign: fileutil.make_dirs(abspath_u))
 731                     d.addCallback(lambda ign: abspath_u)
 732             else:
 733                 if metadata.get('deleted', False):
 734                     d.addCallback(lambda ign: self._rename_deleted_file(abspath_u))
 735                 else:
 736                     d.addCallback(lambda ign: file_node.download_best_version())
 737                     d.addCallback(lambda contents: self._write_downloaded_file(abspath_u, contents,
 738                                                                                is_conflict=is_conflict))
 739
 740         d.addCallbacks(do_update_db, failed)
 741
 742         def trap_conflicts(f):
 743             f.trap(ConflictError)
 744             return None
 745         d.addErrback(trap_conflicts)
 746         return d