sdk/python/arvados/arvfile.py

   1 # Copyright (C) The Arvados Authors. All rights reserved.
   2 #
   3 # SPDX-License-Identifier: Apache-2.0
   4
   5 from __future__ import absolute_import
   6 from __future__ import division
   7 from future import standard_library
   8 from future.utils import listitems, listvalues
   9 standard_library.install_aliases()
  10 from builtins import range
  11 from builtins import object
  12 import bz2
  13 import collections
  14 import copy
  15 import errno
  16 import functools
  17 import hashlib
  18 import logging
  19 import os
  20 import queue
  21 import re
  22 import sys
  23 import threading
  24 import uuid
  25 import zlib
  26
  27 from . import config
  28 from .errors import KeepWriteError, AssertionError, ArgumentError
  29 from .keep import KeepLocator
  30 from ._normalize_stream import normalize_stream
  31 from ._ranges import locators_and_ranges, replace_range, Range, LocatorAndRange
  32 from .retry import retry_method
  33
  34 MOD = "mod"
  35 WRITE = "write"
  36
  37 _logger = logging.getLogger('arvados.arvfile')
  38
  39 def split(path):
  40     """split(path) -> streamname, filename
  41
  42     Separate the stream name and file name in a /-separated stream path and
  43     return a tuple (stream_name, file_name).  If no stream name is available,
  44     assume '.'.
  45
  46     """
  47     try:
  48         stream_name, file_name = path.rsplit('/', 1)
  49     except ValueError:  # No / in string
  50         stream_name, file_name = '.', path
  51     return stream_name, file_name
  52
  53
  54 class UnownedBlockError(Exception):
  55     """Raised when there's an writable block without an owner on the BlockManager."""
  56     pass
  57
  58
  59 class _FileLikeObjectBase(object):
  60     def __init__(self, name, mode):
  61         self.name = name
  62         self.mode = mode
  63         self.closed = False
  64
  65     @staticmethod
  66     def _before_close(orig_func):
  67         @functools.wraps(orig_func)
  68         def before_close_wrapper(self, *args, **kwargs):
  69             if self.closed:
  70                 raise ValueError("I/O operation on closed stream file")
  71             return orig_func(self, *args, **kwargs)
  72         return before_close_wrapper
  73
  74     def __enter__(self):
  75         return self
  76
  77     def __exit__(self, exc_type, exc_value, traceback):
  78         try:
  79             self.close()
  80         except Exception:
  81             if exc_type is None:
  82                 raise
  83
  84     def close(self):
  85         self.closed = True
  86
  87
  88 class ArvadosFileReaderBase(_FileLikeObjectBase):
  89     def __init__(self, name, mode, num_retries=None):
  90         super(ArvadosFileReaderBase, self).__init__(name, mode)
  91         self._filepos = 0
  92         self.num_retries = num_retries
  93         self._readline_cache = (None, None)
  94
  95     def __iter__(self):
  96         while True:
  97             data = self.readline()
  98             if not data:
  99                 break
 100             yield data
 101
 102     def decompressed_name(self):
 103         return re.sub('\.(bz2|gz)$', '', self.name)
 104
 105     @_FileLikeObjectBase._before_close
 106     def seek(self, pos, whence=os.SEEK_SET):
 107         if whence == os.SEEK_CUR:
 108             pos += self._filepos
 109         elif whence == os.SEEK_END:
 110             pos += self.size()
 111         if pos < 0:
 112             raise IOError(errno.EINVAL, "Tried to seek to negative file offset.")
 113         self._filepos = pos
 114         return self._filepos
 115
 116     def tell(self):
 117         return self._filepos
 118
 119     def readable(self):
 120         return True
 121
 122     def writable(self):
 123         return False
 124
 125     def seekable(self):
 126         return True
 127
 128     @_FileLikeObjectBase._before_close
 129     @retry_method
 130     def readall(self, size=2**20, num_retries=None):
 131         while True:
 132             data = self.read(size, num_retries=num_retries)
 133             if len(data) == 0:
 134                 break
 135             yield data
 136
 137     @_FileLikeObjectBase._before_close
 138     @retry_method
 139     def readline(self, size=float('inf'), num_retries=None):
 140         cache_pos, cache_data = self._readline_cache
 141         if self.tell() == cache_pos:
 142             data = [cache_data]
 143             self._filepos += len(cache_data)
 144         else:
 145             data = [b'']
 146         data_size = len(data[-1])
 147         while (data_size < size) and (b'\n' not in data[-1]):
 148             next_read = self.read(2 ** 20, num_retries=num_retries)
 149             if not next_read:
 150                 break
 151             data.append(next_read)
 152             data_size += len(next_read)
 153         data = b''.join(data)
 154         try:
 155             nextline_index = data.index(b'\n') + 1
 156         except ValueError:
 157             nextline_index = len(data)
 158         nextline_index = min(nextline_index, size)
 159         self._filepos -= len(data) - nextline_index
 160         self._readline_cache = (self.tell(), data[nextline_index:])
 161         return data[:nextline_index].decode()
 162
 163     @_FileLikeObjectBase._before_close
 164     @retry_method
 165     def decompress(self, decompress, size, num_retries=None):
 166         for segment in self.readall(size, num_retries=num_retries):
 167             data = decompress(segment)
 168             if data:
 169                 yield data
 170
 171     @_FileLikeObjectBase._before_close
 172     @retry_method
 173     def readall_decompressed(self, size=2**20, num_retries=None):
 174         self.seek(0)
 175         if self.name.endswith('.bz2'):
 176             dc = bz2.BZ2Decompressor()
 177             return self.decompress(dc.decompress, size,
 178                                    num_retries=num_retries)
 179         elif self.name.endswith('.gz'):
 180             dc = zlib.decompressobj(16+zlib.MAX_WBITS)
 181             return self.decompress(lambda segment: dc.decompress(dc.unconsumed_tail + segment),
 182                                    size, num_retries=num_retries)
 183         else:
 184             return self.readall(size, num_retries=num_retries)
 185
 186     @_FileLikeObjectBase._before_close
 187     @retry_method
 188     def readlines(self, sizehint=float('inf'), num_retries=None):
 189         data = []
 190         data_size = 0
 191         for s in self.readall(num_retries=num_retries):
 192             data.append(s)
 193             data_size += len(s)
 194             if data_size >= sizehint:
 195                 break
 196         return b''.join(data).decode().splitlines(True)
 197
 198     def size(self):
 199         raise IOError(errno.ENOSYS, "Not implemented")
 200
 201     def read(self, size, num_retries=None):
 202         raise IOError(errno.ENOSYS, "Not implemented")
 203
 204     def readfrom(self, start, size, num_retries=None):
 205         raise IOError(errno.ENOSYS, "Not implemented")
 206
 207
 208 class StreamFileReader(ArvadosFileReaderBase):
 209     class _NameAttribute(str):
 210         # The Python file API provides a plain .name attribute.
 211         # Older SDK provided a name() method.
 212         # This class provides both, for maximum compatibility.
 213         def __call__(self):
 214             return self
 215
 216     def __init__(self, stream, segments, name):
 217         super(StreamFileReader, self).__init__(self._NameAttribute(name), 'rb', num_retries=stream.num_retries)
 218         self._stream = stream
 219         self.segments = segments
 220
 221     def stream_name(self):
 222         return self._stream.name()
 223
 224     def size(self):
 225         n = self.segments[-1]
 226         return n.range_start + n.range_size
 227
 228     @_FileLikeObjectBase._before_close
 229     @retry_method
 230     def read(self, size, num_retries=None):
 231         """Read up to 'size' bytes from the stream, starting at the current file position"""
 232         if size == 0:
 233             return b''
 234
 235         data = b''
 236         available_chunks = locators_and_ranges(self.segments, self._filepos, size)
 237         if available_chunks:
 238             lr = available_chunks[0]
 239             data = self._stream.readfrom(lr.locator+lr.segment_offset,
 240                                          lr.segment_size,
 241                                          num_retries=num_retries)
 242
 243         self._filepos += len(data)
 244         return data
 245
 246     @_FileLikeObjectBase._before_close
 247     @retry_method
 248     def readfrom(self, start, size, num_retries=None):
 249         """Read up to 'size' bytes from the stream, starting at 'start'"""
 250         if size == 0:
 251             return b''
 252
 253         data = []
 254         for lr in locators_and_ranges(self.segments, start, size):
 255             data.append(self._stream.readfrom(lr.locator+lr.segment_offset, lr.segment_size,
 256                                               num_retries=num_retries))
 257         return b''.join(data)
 258
 259     def as_manifest(self):
 260         segs = []
 261         for r in self.segments:
 262             segs.extend(self._stream.locators_and_ranges(r.locator, r.range_size))
 263         return " ".join(normalize_stream(".", {self.name: segs})) + "\n"
 264
 265
 266 def synchronized(orig_func):
 267     @functools.wraps(orig_func)
 268     def synchronized_wrapper(self, *args, **kwargs):
 269         with self.lock:
 270             return orig_func(self, *args, **kwargs)
 271     return synchronized_wrapper
 272
 273
 274 class StateChangeError(Exception):
 275     def __init__(self, message, state, nextstate):
 276         super(StateChangeError, self).__init__(message)
 277         self.state = state
 278         self.nextstate = nextstate
 279
 280 class _BufferBlock(object):
 281     """A stand-in for a Keep block that is in the process of being written.
 282
 283     Writers can append to it, get the size, and compute the Keep locator.
 284     There are three valid states:
 285
 286     WRITABLE
 287       Can append to block.
 288
 289     PENDING
 290       Block is in the process of being uploaded to Keep, append is an error.
 291
 292     COMMITTED
 293       The block has been written to Keep, its internal buffer has been
 294       released, fetching the block will fetch it via keep client (since we
 295       discarded the internal copy), and identifiers referring to the BufferBlock
 296       can be replaced with the block locator.
 297
 298     """
 299
 300     WRITABLE = 0
 301     PENDING = 1
 302     COMMITTED = 2
 303     ERROR = 3
 304     DELETED = 4
 305
 306     def __init__(self, blockid, starting_capacity, owner):
 307         """
 308         :blockid:
 309           the identifier for this block
 310
 311         :starting_capacity:
 312           the initial buffer capacity
 313
 314         :owner:
 315           ArvadosFile that owns this block
 316
 317         """
 318         self.blockid = blockid
 319         self.buffer_block = bytearray(starting_capacity)
 320         self.buffer_view = memoryview(self.buffer_block)
 321         self.write_pointer = 0
 322         self._state = _BufferBlock.WRITABLE
 323         self._locator = None
 324         self.owner = owner
 325         self.lock = threading.Lock()
 326         self.wait_for_commit = threading.Event()
 327         self.error = None
 328
 329     @synchronized
 330     def append(self, data):
 331         """Append some data to the buffer.
 332
 333         Only valid if the block is in WRITABLE state.  Implements an expanding
 334         buffer, doubling capacity as needed to accomdate all the data.
 335
 336         """
 337         if self._state == _BufferBlock.WRITABLE:
 338             if not isinstance(data, bytes) and not isinstance(data, memoryview):
 339                 data = data.encode()
 340             while (self.write_pointer+len(data)) > len(self.buffer_block):
 341                 new_buffer_block = bytearray(len(self.buffer_block) * 2)
 342                 new_buffer_block[0:self.write_pointer] = self.buffer_block[0:self.write_pointer]
 343                 self.buffer_block = new_buffer_block
 344                 self.buffer_view = memoryview(self.buffer_block)
 345             self.buffer_view[self.write_pointer:self.write_pointer+len(data)] = data
 346             self.write_pointer += len(data)
 347             self._locator = None
 348         else:
 349             raise AssertionError("Buffer block is not writable")
 350
 351     STATE_TRANSITIONS = frozenset([
 352             (WRITABLE, PENDING),
 353             (PENDING, COMMITTED),
 354             (PENDING, ERROR),
 355             (ERROR, PENDING)])
 356
 357     @synchronized
 358     def set_state(self, nextstate, val=None):
 359         if (self._state, nextstate) not in self.STATE_TRANSITIONS:
 360             raise StateChangeError("Invalid state change from %s to %s" % (self._state, nextstate), self._state, nextstate)
 361         self._state = nextstate
 362
 363         if self._state == _BufferBlock.PENDING:
 364             self.wait_for_commit.clear()
 365
 366         if self._state == _BufferBlock.COMMITTED:
 367             self._locator = val
 368             self.buffer_view = None
 369             self.buffer_block = None
 370             self.wait_for_commit.set()
 371
 372         if self._state == _BufferBlock.ERROR:
 373             self.error = val
 374             self.wait_for_commit.set()
 375
 376     @synchronized
 377     def state(self):
 378         return self._state
 379
 380     def size(self):
 381         """The amount of data written to the buffer."""
 382         return self.write_pointer
 383
 384     @synchronized
 385     def locator(self):
 386         """The Keep locator for this buffer's contents."""
 387         if self._locator is None:
 388             self._locator = "%s+%i" % (hashlib.md5(self.buffer_view[0:self.write_pointer]).hexdigest(), self.size())
 389         return self._locator
 390
 391     @synchronized
 392     def clone(self, new_blockid, owner):
 393         if self._state == _BufferBlock.COMMITTED:
 394             raise AssertionError("Cannot duplicate committed buffer block")
 395         bufferblock = _BufferBlock(new_blockid, self.size(), owner)
 396         bufferblock.append(self.buffer_view[0:self.size()])
 397         return bufferblock
 398
 399     @synchronized
 400     def clear(self):
 401         self._state = _BufferBlock.DELETED
 402         self.owner = None
 403         self.buffer_block = None
 404         self.buffer_view = None
 405
 406     @synchronized
 407     def repack_writes(self):
 408         """Optimize buffer block by repacking segments in file sequence.
 409
 410         When the client makes random writes, they appear in the buffer block in
 411         the sequence they were written rather than the sequence they appear in
 412         the file.  This makes for inefficient, fragmented manifests.  Attempt
 413         to optimize by repacking writes in file sequence.
 414
 415         """
 416         if self._state != _BufferBlock.WRITABLE:
 417             raise AssertionError("Cannot repack non-writable block")
 418
 419         segs = self.owner.segments()
 420
 421         # Collect the segments that reference the buffer block.
 422         bufferblock_segs = [s for s in segs if s.locator == self.blockid]
 423
 424         # Collect total data referenced by segments (could be smaller than
 425         # bufferblock size if a portion of the file was written and
 426         # then overwritten).
 427         write_total = sum([s.range_size for s in bufferblock_segs])
 428
 429         if write_total < self.size() or len(bufferblock_segs) > 1:
 430             # If there's more than one segment referencing this block, it is
 431             # due to out-of-order writes and will produce a fragmented
 432             # manifest, so try to optimize by re-packing into a new buffer.
 433             contents = self.buffer_view[0:self.write_pointer].tobytes()
 434             new_bb = _BufferBlock(None, write_total, None)
 435             for t in bufferblock_segs:
 436                 new_bb.append(contents[t.segment_offset:t.segment_offset+t.range_size])
 437                 t.segment_offset = new_bb.size() - t.range_size
 438
 439             self.buffer_block = new_bb.buffer_block
 440             self.buffer_view = new_bb.buffer_view
 441             self.write_pointer = new_bb.write_pointer
 442             self._locator = None
 443             new_bb.clear()
 444             self.owner.set_segments(segs)
 445
 446     def __repr__(self):
 447         return "<BufferBlock %s>" % (self.blockid)
 448
 449
 450 class NoopLock(object):
 451     def __enter__(self):
 452         return self
 453
 454     def __exit__(self, exc_type, exc_value, traceback):
 455         pass
 456
 457     def acquire(self, blocking=False):
 458         pass
 459
 460     def release(self):
 461         pass
 462
 463
 464 def must_be_writable(orig_func):
 465     @functools.wraps(orig_func)
 466     def must_be_writable_wrapper(self, *args, **kwargs):
 467         if not self.writable():
 468             raise IOError(errno.EROFS, "Collection is read-only.")
 469         return orig_func(self, *args, **kwargs)
 470     return must_be_writable_wrapper
 471
 472
 473 class _BlockManager(object):
 474     """BlockManager handles buffer blocks.
 475
 476     Also handles background block uploads, and background block prefetch for a
 477     Collection of ArvadosFiles.
 478
 479     """
 480
 481     DEFAULT_PUT_THREADS = 2
 482     DEFAULT_GET_THREADS = 2
 483
 484     def __init__(self, keep, copies=None, put_threads=None, num_retries=None, storage_classes_func=None):
 485         """keep: KeepClient object to use"""
 486         self._keep = keep
 487         self._bufferblocks = collections.OrderedDict()
 488         self._put_queue = None
 489         self._put_threads = None
 490         self._prefetch_queue = None
 491         self._prefetch_threads = None
 492         self.lock = threading.Lock()
 493         self.prefetch_enabled = True
 494         self.num_put_threads = put_threads or _BlockManager.DEFAULT_PUT_THREADS
 495         self.num_get_threads = _BlockManager.DEFAULT_GET_THREADS
 496         self.copies = copies
 497         self.storage_classes = storage_classes_func or (lambda: [])
 498         self._pending_write_size = 0
 499         self.threads_lock = threading.Lock()
 500         self.padding_block = None
 501         self.num_retries = num_retries
 502
 503     @synchronized
 504     def alloc_bufferblock(self, blockid=None, starting_capacity=2**14, owner=None):
 505         """Allocate a new, empty bufferblock in WRITABLE state and return it.
 506
 507         :blockid:
 508           optional block identifier, otherwise one will be automatically assigned
 509
 510         :starting_capacity:
 511           optional capacity, otherwise will use default capacity
 512
 513         :owner:
 514           ArvadosFile that owns this block
 515
 516         """
 517         return self._alloc_bufferblock(blockid, starting_capacity, owner)
 518
 519     def _alloc_bufferblock(self, blockid=None, starting_capacity=2**14, owner=None):
 520         if blockid is None:
 521             blockid = str(uuid.uuid4())
 522         bufferblock = _BufferBlock(blockid, starting_capacity=starting_capacity, owner=owner)
 523         self._bufferblocks[bufferblock.blockid] = bufferblock
 524         return bufferblock
 525
 526     @synchronized
 527     def dup_block(self, block, owner):
 528         """Create a new bufferblock initialized with the content of an existing bufferblock.
 529
 530         :block:
 531           the buffer block to copy.
 532
 533         :owner:
 534           ArvadosFile that owns the new block
 535
 536         """
 537         new_blockid = str(uuid.uuid4())
 538         bufferblock = block.clone(new_blockid, owner)
 539         self._bufferblocks[bufferblock.blockid] = bufferblock
 540         return bufferblock
 541
 542     @synchronized
 543     def is_bufferblock(self, locator):
 544         return locator in self._bufferblocks
 545
 546     def _commit_bufferblock_worker(self):
 547         """Background uploader thread."""
 548
 549         while True:
 550             try:
 551                 bufferblock = self._put_queue.get()
 552                 if bufferblock is None:
 553                     return
 554
 555                 if self.copies is None:
 556                     loc = self._keep.put(bufferblock.buffer_view[0:bufferblock.write_pointer].tobytes(), num_retries=self.num_retries, classes=self.storage_classes())
 557                 else:
 558                     loc = self._keep.put(bufferblock.buffer_view[0:bufferblock.write_pointer].tobytes(), num_retries=self.num_retries, copies=self.copies, classes=self.storage_classes())
 559                 bufferblock.set_state(_BufferBlock.COMMITTED, loc)
 560             except Exception as e:
 561                 bufferblock.set_state(_BufferBlock.ERROR, e)
 562             finally:
 563                 if self._put_queue is not None:
 564                     self._put_queue.task_done()
 565
 566     def start_put_threads(self):
 567         with self.threads_lock:
 568             if self._put_threads is None:
 569                 # Start uploader threads.
 570
 571                 # If we don't limit the Queue size, the upload queue can quickly
 572                 # grow to take up gigabytes of RAM if the writing process is
 573                 # generating data more quickly than it can be sent to the Keep
 574                 # servers.
 575                 #
 576                 # With two upload threads and a queue size of 2, this means up to 4
 577                 # blocks pending.  If they are full 64 MiB blocks, that means up to
 578                 # 256 MiB of internal buffering, which is the same size as the
 579                 # default download block cache in KeepClient.
 580                 self._put_queue = queue.Queue(maxsize=2)
 581
 582                 self._put_threads = []
 583                 for i in range(0, self.num_put_threads):
 584                     thread = threading.Thread(target=self._commit_bufferblock_worker)
 585                     self._put_threads.append(thread)
 586                     thread.daemon = True
 587                     thread.start()
 588
 589     def _block_prefetch_worker(self):
 590         """The background downloader thread."""
 591         while True:
 592             try:
 593                 b = self._prefetch_queue.get()
 594                 if b is None:
 595                     return
 596                 self._keep.get(b)
 597             except Exception:
 598                 _logger.exception("Exception doing block prefetch")
 599
 600     @synchronized
 601     def start_get_threads(self):
 602         if self._prefetch_threads is None:
 603             self._prefetch_queue = queue.Queue()
 604             self._prefetch_threads = []
 605             for i in range(0, self.num_get_threads):
 606                 thread = threading.Thread(target=self._block_prefetch_worker)
 607                 self._prefetch_threads.append(thread)
 608                 thread.daemon = True
 609                 thread.start()
 610
 611
 612     @synchronized
 613     def stop_threads(self):
 614         """Shut down and wait for background upload and download threads to finish."""
 615
 616         if self._put_threads is not None:
 617             for t in self._put_threads:
 618                 self._put_queue.put(None)
 619             for t in self._put_threads:
 620                 t.join()
 621         self._put_threads = None
 622         self._put_queue = None
 623
 624         if self._prefetch_threads is not None:
 625             for t in self._prefetch_threads:
 626                 self._prefetch_queue.put(None)
 627             for t in self._prefetch_threads:
 628                 t.join()
 629         self._prefetch_threads = None
 630         self._prefetch_queue = None
 631
 632     def __enter__(self):
 633         return self
 634
 635     def __exit__(self, exc_type, exc_value, traceback):
 636         self.stop_threads()
 637
 638     @synchronized
 639     def repack_small_blocks(self, force=False, sync=False, closed_file_size=0):
 640         """Packs small blocks together before uploading"""
 641
 642         self._pending_write_size += closed_file_size
 643
 644         # Check if there are enough small blocks for filling up one in full
 645         if not (force or (self._pending_write_size >= config.KEEP_BLOCK_SIZE)):
 646             return
 647
 648         # Search blocks ready for getting packed together before being
 649         # committed to Keep.
 650         # A WRITABLE block always has an owner.
 651         # A WRITABLE block with its owner.closed() implies that its
 652         # size is <= KEEP_BLOCK_SIZE/2.
 653         try:
 654             small_blocks = [b for b in listvalues(self._bufferblocks)
 655                             if b.state() == _BufferBlock.WRITABLE and b.owner.closed()]
 656         except AttributeError:
 657             # Writable blocks without owner shouldn't exist.
 658             raise UnownedBlockError()
 659
 660         if len(small_blocks) <= 1:
 661             # Not enough small blocks for repacking
 662             return
 663
 664         for bb in small_blocks:
 665             bb.repack_writes()
 666
 667         # Update the pending write size count with its true value, just in case
 668         # some small file was opened, written and closed several times.
 669         self._pending_write_size = sum([b.size() for b in small_blocks])
 670
 671         if self._pending_write_size < config.KEEP_BLOCK_SIZE and not force:
 672             return
 673
 674         new_bb = self._alloc_bufferblock()
 675         new_bb.owner = []
 676         files = []
 677         while len(small_blocks) > 0 and (new_bb.write_pointer + small_blocks[0].size()) <= config.KEEP_BLOCK_SIZE:
 678             bb = small_blocks.pop(0)
 679             new_bb.owner.append(bb.owner)
 680             self._pending_write_size -= bb.size()
 681             new_bb.append(bb.buffer_view[0:bb.write_pointer].tobytes())
 682             files.append((bb, new_bb.write_pointer - bb.size()))
 683
 684         self.commit_bufferblock(new_bb, sync=sync)
 685
 686         for bb, new_bb_segment_offset in files:
 687             newsegs = bb.owner.segments()
 688             for s in newsegs:
 689                 if s.locator == bb.blockid:
 690                     s.locator = new_bb.blockid
 691                     s.segment_offset = new_bb_segment_offset+s.segment_offset
 692             bb.owner.set_segments(newsegs)
 693             self._delete_bufferblock(bb.blockid)
 694
 695     def commit_bufferblock(self, block, sync):
 696         """Initiate a background upload of a bufferblock.
 697
 698         :block:
 699           The block object to upload
 700
 701         :sync:
 702           If `sync` is True, upload the block synchronously.
 703           If `sync` is False, upload the block asynchronously.  This will
 704           return immediately unless the upload queue is at capacity, in
 705           which case it will wait on an upload queue slot.
 706
 707         """
 708         try:
 709             # Mark the block as PENDING so to disallow any more appends.
 710             block.set_state(_BufferBlock.PENDING)
 711         except StateChangeError as e:
 712             if e.state == _BufferBlock.PENDING:
 713                 if sync:
 714                     block.wait_for_commit.wait()
 715                 else:
 716                     return
 717             if block.state() == _BufferBlock.COMMITTED:
 718                 return
 719             elif block.state() == _BufferBlock.ERROR:
 720                 raise block.error
 721             else:
 722                 raise
 723
 724         if sync:
 725             try:
 726                 if self.copies is None:
 727                     loc = self._keep.put(block.buffer_view[0:block.write_pointer].tobytes(), num_retries=self.num_retries, classes=self.storage_classes())
 728                 else:
 729                     loc = self._keep.put(block.buffer_view[0:block.write_pointer].tobytes(), num_retries=self.num_retries, copies=self.copies, classes=self.storage_classes())
 730                 block.set_state(_BufferBlock.COMMITTED, loc)
 731             except Exception as e:
 732                 block.set_state(_BufferBlock.ERROR, e)
 733                 raise
 734         else:
 735             self.start_put_threads()
 736             self._put_queue.put(block)
 737
 738     @synchronized
 739     def get_bufferblock(self, locator):
 740         return self._bufferblocks.get(locator)
 741
 742     @synchronized
 743     def get_padding_block(self):
 744         """Get a bufferblock 64 MB in size consisting of all zeros, used as padding
 745         when using truncate() to extend the size of a file.
 746
 747         For reference (and possible future optimization), the md5sum of the
 748         padding block is: 7f614da9329cd3aebf59b91aadc30bf0+67108864
 749
 750         """
 751
 752         if self.padding_block is None:
 753             self.padding_block = self._alloc_bufferblock(starting_capacity=config.KEEP_BLOCK_SIZE)
 754             self.padding_block.write_pointer = config.KEEP_BLOCK_SIZE
 755             self.commit_bufferblock(self.padding_block, False)
 756         return self.padding_block
 757
 758     @synchronized
 759     def delete_bufferblock(self, locator):
 760         self._delete_bufferblock(locator)
 761
 762     def _delete_bufferblock(self, locator):
 763         if locator in self._bufferblocks:
 764             bb = self._bufferblocks[locator]
 765             bb.clear()
 766             del self._bufferblocks[locator]
 767
 768     def get_block_contents(self, locator, num_retries, cache_only=False):
 769         """Fetch a block.
 770
 771         First checks to see if the locator is a BufferBlock and return that, if
 772         not, passes the request through to KeepClient.get().
 773
 774         """
 775         with self.lock:
 776             if locator in self._bufferblocks:
 777                 bufferblock = self._bufferblocks[locator]
 778                 if bufferblock.state() != _BufferBlock.COMMITTED:
 779                     return bufferblock.buffer_view[0:bufferblock.write_pointer].tobytes()
 780                 else:
 781                     locator = bufferblock._locator
 782         if cache_only:
 783             return self._keep.get_from_cache(locator)
 784         else:
 785             return self._keep.get(locator, num_retries=num_retries)
 786
 787     def commit_all(self):
 788         """Commit all outstanding buffer blocks.
 789
 790         This is a synchronous call, and will not return until all buffer blocks
 791         are uploaded.  Raises KeepWriteError() if any blocks failed to upload.
 792
 793         """
 794         self.repack_small_blocks(force=True, sync=True)
 795
 796         with self.lock:
 797             items = listitems(self._bufferblocks)
 798
 799         for k,v in items:
 800             if v.state() != _BufferBlock.COMMITTED and v.owner:
 801                 # Ignore blocks with a list of owners, as if they're not in COMMITTED
 802                 # state, they're already being committed asynchronously.
 803                 if isinstance(v.owner, ArvadosFile):
 804                     v.owner.flush(sync=False)
 805
 806         with self.lock:
 807             if self._put_queue is not None:
 808                 self._put_queue.join()
 809
 810                 err = []
 811                 for k,v in items:
 812                     if v.state() == _BufferBlock.ERROR:
 813                         err.append((v.locator(), v.error))
 814                 if err:
 815                     raise KeepWriteError("Error writing some blocks", err, label="block")
 816
 817         for k,v in items:
 818             # flush again with sync=True to remove committed bufferblocks from
 819             # the segments.
 820             if v.owner:
 821                 if isinstance(v.owner, ArvadosFile):
 822                     v.owner.flush(sync=True)
 823                 elif isinstance(v.owner, list) and len(v.owner) > 0:
 824                     # This bufferblock is referenced by many files as a result
 825                     # of repacking small blocks, so don't delete it when flushing
 826                     # its owners, just do it after flushing them all.
 827                     for owner in v.owner:
 828                         owner.flush(sync=True)
 829                     self.delete_bufferblock(k)
 830
 831     def block_prefetch(self, locator):
 832         """Initiate a background download of a block.
 833
 834         This assumes that the underlying KeepClient implements a block cache,
 835         so repeated requests for the same block will not result in repeated
 836         downloads (unless the block is evicted from the cache.)  This method
 837         does not block.
 838
 839         """
 840
 841         if not self.prefetch_enabled:
 842             return
 843
 844         if self._keep.get_from_cache(locator) is not None:
 845             return
 846
 847         with self.lock:
 848             if locator in self._bufferblocks:
 849                 return
 850
 851         self.start_get_threads()
 852         self._prefetch_queue.put(locator)
 853
 854
 855 class ArvadosFile(object):
 856     """Represent a file in a Collection.
 857
 858     ArvadosFile manages the underlying representation of a file in Keep as a
 859     sequence of segments spanning a set of blocks, and implements random
 860     read/write access.
 861
 862     This object may be accessed from multiple threads.
 863
 864     """
 865
 866     __slots__ = ('parent', 'name', '_writers', '_committed',
 867                  '_segments', 'lock', '_current_bblock', 'fuse_entry')
 868
 869     def __init__(self, parent, name, stream=[], segments=[]):
 870         """
 871         ArvadosFile constructor.
 872
 873         :stream:
 874           a list of Range objects representing a block stream
 875
 876         :segments:
 877           a list of Range objects representing segments
 878         """
 879         self.parent = parent
 880         self.name = name
 881         self._writers = set()
 882         self._committed = False
 883         self._segments = []
 884         self.lock = parent.root_collection().lock
 885         for s in segments:
 886             self._add_segment(stream, s.locator, s.range_size)
 887         self._current_bblock = None
 888
 889     def writable(self):
 890         return self.parent.writable()
 891
 892     @synchronized
 893     def permission_expired(self, as_of_dt=None):
 894         """Returns True if any of the segment's locators is expired"""
 895         for r in self._segments:
 896             if KeepLocator(r.locator).permission_expired(as_of_dt):
 897                 return True
 898         return False
 899
 900     @synchronized
 901     def has_remote_blocks(self):
 902         """Returns True if any of the segment's locators has a +R signature"""
 903
 904         for s in self._segments:
 905             if '+R' in s.locator:
 906                 return True
 907         return False
 908
 909     @synchronized
 910     def _copy_remote_blocks(self, remote_blocks={}):
 911         """Ask Keep to copy remote blocks and point to their local copies.
 912
 913         This is called from the parent Collection.
 914
 915         :remote_blocks:
 916             Shared cache of remote to local block mappings. This is used to avoid
 917             doing extra work when blocks are shared by more than one file in
 918             different subdirectories.
 919         """
 920
 921         for s in self._segments:
 922             if '+R' in s.locator:
 923                 try:
 924                     loc = remote_blocks[s.locator]
 925                 except KeyError:
 926                     loc = self.parent._my_keep().refresh_signature(s.locator)
 927                     remote_blocks[s.locator] = loc
 928                 s.locator = loc
 929                 self.parent.set_committed(False)
 930         return remote_blocks
 931
 932     @synchronized
 933     def segments(self):
 934         return copy.copy(self._segments)
 935
 936     @synchronized
 937     def clone(self, new_parent, new_name):
 938         """Make a copy of this file."""
 939         cp = ArvadosFile(new_parent, new_name)
 940         cp.replace_contents(self)
 941         return cp
 942
 943     @must_be_writable
 944     @synchronized
 945     def replace_contents(self, other):
 946         """Replace segments of this file with segments from another `ArvadosFile` object."""
 947
 948         map_loc = {}
 949         self._segments = []
 950         for other_segment in other.segments():
 951             new_loc = other_segment.locator
 952             if other.parent._my_block_manager().is_bufferblock(other_segment.locator):
 953                 if other_segment.locator not in map_loc:
 954                     bufferblock = other.parent._my_block_manager().get_bufferblock(other_segment.locator)
 955                     if bufferblock.state() != _BufferBlock.WRITABLE:
 956                         map_loc[other_segment.locator] = bufferblock.locator()
 957                     else:
 958                         map_loc[other_segment.locator] = self.parent._my_block_manager().dup_block(bufferblock, self).blockid
 959                 new_loc = map_loc[other_segment.locator]
 960
 961             self._segments.append(Range(new_loc, other_segment.range_start, other_segment.range_size, other_segment.segment_offset))
 962
 963         self.set_committed(False)
 964
 965     def __eq__(self, other):
 966         if other is self:
 967             return True
 968         if not isinstance(other, ArvadosFile):
 969             return False
 970
 971         othersegs = other.segments()
 972         with self.lock:
 973             if len(self._segments) != len(othersegs):
 974                 return False
 975             for i in range(0, len(othersegs)):
 976                 seg1 = self._segments[i]
 977                 seg2 = othersegs[i]
 978                 loc1 = seg1.locator
 979                 loc2 = seg2.locator
 980
 981                 if self.parent._my_block_manager().is_bufferblock(loc1):
 982                     loc1 = self.parent._my_block_manager().get_bufferblock(loc1).locator()
 983
 984                 if other.parent._my_block_manager().is_bufferblock(loc2):
 985                     loc2 = other.parent._my_block_manager().get_bufferblock(loc2).locator()
 986
 987                 if (KeepLocator(loc1).stripped() != KeepLocator(loc2).stripped() or
 988                     seg1.range_start != seg2.range_start or
 989                     seg1.range_size != seg2.range_size or
 990                     seg1.segment_offset != seg2.segment_offset):
 991                     return False
 992
 993         return True
 994
 995     def __ne__(self, other):
 996         return not self.__eq__(other)
 997
 998     @synchronized
 999     def set_segments(self, segs):
1000         self._segments = segs
1001
1002     @synchronized
1003     def set_committed(self, value=True):
1004         """Set committed flag.
1005
1006         If value is True, set committed to be True.
1007
1008         If value is False, set committed to be False for this and all parents.
1009         """
1010         if value == self._committed:
1011             return
1012         self._committed = value
1013         if self._committed is False and self.parent is not None:
1014             self.parent.set_committed(False)
1015
1016     @synchronized
1017     def committed(self):
1018         """Get whether this is committed or not."""
1019         return self._committed
1020
1021     @synchronized
1022     def add_writer(self, writer):
1023         """Add an ArvadosFileWriter reference to the list of writers"""
1024         if isinstance(writer, ArvadosFileWriter):
1025             self._writers.add(writer)
1026
1027     @synchronized
1028     def remove_writer(self, writer, flush):
1029         """
1030         Called from ArvadosFileWriter.close(). Remove a writer reference from the list
1031         and do some block maintenance tasks.
1032         """
1033         self._writers.remove(writer)
1034
1035         if flush or self.size() > config.KEEP_BLOCK_SIZE // 2:
1036             # File writer closed, not small enough for repacking
1037             self.flush()
1038         elif self.closed():
1039             # All writers closed and size is adequate for repacking
1040             self.parent._my_block_manager().repack_small_blocks(closed_file_size=self.size())
1041
1042     def closed(self):
1043         """
1044         Get whether this is closed or not. When the writers list is empty, the file
1045         is supposed to be closed.
1046         """
1047         return len(self._writers) == 0
1048
1049     @must_be_writable
1050     @synchronized
1051     def truncate(self, size):
1052         """Shrink or expand the size of the file.
1053
1054         If `size` is less than the size of the file, the file contents after
1055         `size` will be discarded.  If `size` is greater than the current size
1056         of the file, it will be filled with zero bytes.
1057
1058         """
1059         if size < self.size():
1060             new_segs = []
1061             for r in self._segments:
1062                 range_end = r.range_start+r.range_size
1063                 if r.range_start >= size:
1064                     # segment is past the trucate size, all done
1065                     break
1066                 elif size < range_end:
1067                     nr = Range(r.locator, r.range_start, size - r.range_start, 0)
1068                     nr.segment_offset = r.segment_offset
1069                     new_segs.append(nr)
1070                     break
1071                 else:
1072                     new_segs.append(r)
1073
1074             self._segments = new_segs
1075             self.set_committed(False)
1076         elif size > self.size():
1077             padding = self.parent._my_block_manager().get_padding_block()
1078             diff = size - self.size()
1079             while diff > config.KEEP_BLOCK_SIZE:
1080                 self._segments.append(Range(padding.blockid, self.size(), config.KEEP_BLOCK_SIZE, 0))
1081                 diff -= config.KEEP_BLOCK_SIZE
1082             if diff > 0:
1083                 self._segments.append(Range(padding.blockid, self.size(), diff, 0))
1084             self.set_committed(False)
1085         else:
1086             # size == self.size()
1087             pass
1088
1089     def readfrom(self, offset, size, num_retries, exact=False):
1090         """Read up to `size` bytes from the file starting at `offset`.
1091
1092         :exact:
1093          If False (default), return less data than requested if the read
1094          crosses a block boundary and the next block isn't cached.  If True,
1095          only return less data than requested when hitting EOF.
1096         """
1097
1098         with self.lock:
1099             if size == 0 or offset >= self.size():
1100                 return b''
1101             readsegs = locators_and_ranges(self._segments, offset, size)
1102             prefetch = locators_and_ranges(self._segments, offset + size, config.KEEP_BLOCK_SIZE, limit=32)
1103
1104         locs = set()
1105         data = []
1106         for lr in readsegs:
1107             block = self.parent._my_block_manager().get_block_contents(lr.locator, num_retries=num_retries, cache_only=(bool(data) and not exact))
1108             if block:
1109                 blockview = memoryview(block)
1110                 data.append(blockview[lr.segment_offset:lr.segment_offset+lr.segment_size].tobytes())
1111                 locs.add(lr.locator)
1112             else:
1113                 break
1114
1115         for lr in prefetch:
1116             if lr.locator not in locs:
1117                 self.parent._my_block_manager().block_prefetch(lr.locator)
1118                 locs.add(lr.locator)
1119
1120         return b''.join(data)
1121
1122     @must_be_writable
1123     @synchronized
1124     def writeto(self, offset, data, num_retries):
1125         """Write `data` to the file starting at `offset`.
1126
1127         This will update existing bytes and/or extend the size of the file as
1128         necessary.
1129
1130         """
1131         if not isinstance(data, bytes) and not isinstance(data, memoryview):
1132             data = data.encode()
1133         if len(data) == 0:
1134             return
1135
1136         if offset > self.size():
1137             self.truncate(offset)
1138
1139         if len(data) > config.KEEP_BLOCK_SIZE:
1140             # Chunk it up into smaller writes
1141             n = 0
1142             dataview = memoryview(data)
1143             while n < len(data):
1144                 self.writeto(offset+n, dataview[n:n + config.KEEP_BLOCK_SIZE].tobytes(), num_retries)
1145                 n += config.KEEP_BLOCK_SIZE
1146             return
1147
1148         self.set_committed(False)
1149
1150         if self._current_bblock is None or self._current_bblock.state() != _BufferBlock.WRITABLE:
1151             self._current_bblock = self.parent._my_block_manager().alloc_bufferblock(owner=self)
1152
1153         if (self._current_bblock.size() + len(data)) > config.KEEP_BLOCK_SIZE:
1154             self._current_bblock.repack_writes()
1155             if (self._current_bblock.size() + len(data)) > config.KEEP_BLOCK_SIZE:
1156                 self.parent._my_block_manager().commit_bufferblock(self._current_bblock, sync=False)
1157                 self._current_bblock = self.parent._my_block_manager().alloc_bufferblock(owner=self)
1158
1159         self._current_bblock.append(data)
1160
1161         replace_range(self._segments, offset, len(data), self._current_bblock.blockid, self._current_bblock.write_pointer - len(data))
1162
1163         self.parent.notify(WRITE, self.parent, self.name, (self, self))
1164
1165         return len(data)
1166
1167     @synchronized
1168     def flush(self, sync=True, num_retries=0):
1169         """Flush the current bufferblock to Keep.
1170
1171         :sync:
1172           If True, commit block synchronously, wait until buffer block has been written.
1173           If False, commit block asynchronously, return immediately after putting block into
1174           the keep put queue.
1175         """
1176         if self.committed():
1177             return
1178
1179         if self._current_bblock and self._current_bblock.state() != _BufferBlock.COMMITTED:
1180             if self._current_bblock.state() == _BufferBlock.WRITABLE:
1181                 self._current_bblock.repack_writes()
1182             if self._current_bblock.state() != _BufferBlock.DELETED:
1183                 self.parent._my_block_manager().commit_bufferblock(self._current_bblock, sync=sync)
1184
1185         if sync:
1186             to_delete = set()
1187             for s in self._segments:
1188                 bb = self.parent._my_block_manager().get_bufferblock(s.locator)
1189                 if bb:
1190                     if bb.state() != _BufferBlock.COMMITTED:
1191                         self.parent._my_block_manager().commit_bufferblock(bb, sync=True)
1192                     to_delete.add(s.locator)
1193                     s.locator = bb.locator()
1194             for s in to_delete:
1195                 # Don't delete the bufferblock if it's owned by many files. It'll be
1196                 # deleted after all of its owners are flush()ed.
1197                 if self.parent._my_block_manager().get_bufferblock(s).owner is self:
1198                     self.parent._my_block_manager().delete_bufferblock(s)
1199
1200         self.parent.notify(MOD, self.parent, self.name, (self, self))
1201
1202     @must_be_writable
1203     @synchronized
1204     def add_segment(self, blocks, pos, size):
1205         """Add a segment to the end of the file.
1206
1207         `pos` and `offset` reference a section of the stream described by
1208         `blocks` (a list of Range objects)
1209
1210         """
1211         self._add_segment(blocks, pos, size)
1212
1213     def _add_segment(self, blocks, pos, size):
1214         """Internal implementation of add_segment."""
1215         self.set_committed(False)
1216         for lr in locators_and_ranges(blocks, pos, size):
1217             last = self._segments[-1] if self._segments else Range(0, 0, 0, 0)
1218             r = Range(lr.locator, last.range_start+last.range_size, lr.segment_size, lr.segment_offset)
1219             self._segments.append(r)
1220
1221     @synchronized
1222     def size(self):
1223         """Get the file size."""
1224         if self._segments:
1225             n = self._segments[-1]
1226             return n.range_start + n.range_size
1227         else:
1228             return 0
1229
1230     @synchronized
1231     def manifest_text(self, stream_name=".", portable_locators=False,
1232                       normalize=False, only_committed=False):
1233         buf = ""
1234         filestream = []
1235         for segment in self._segments:
1236             loc = segment.locator
1237             if self.parent._my_block_manager().is_bufferblock(loc):
1238                 if only_committed:
1239                     continue
1240                 loc = self.parent._my_block_manager().get_bufferblock(loc).locator()
1241             if portable_locators:
1242                 loc = KeepLocator(loc).stripped()
1243             filestream.append(LocatorAndRange(loc, KeepLocator(loc).size,
1244                                  segment.segment_offset, segment.range_size))
1245         buf += ' '.join(normalize_stream(stream_name, {self.name: filestream}))
1246         buf += "\n"
1247         return buf
1248
1249     @must_be_writable
1250     @synchronized
1251     def _reparent(self, newparent, newname):
1252         self.set_committed(False)
1253         self.flush(sync=True)
1254         self.parent.remove(self.name)
1255         self.parent = newparent
1256         self.name = newname
1257         self.lock = self.parent.root_collection().lock
1258
1259
1260 class ArvadosFileReader(ArvadosFileReaderBase):
1261     """Wraps ArvadosFile in a file-like object supporting reading only.
1262
1263     Be aware that this class is NOT thread safe as there is no locking around
1264     updating file pointer.
1265
1266     """
1267
1268     def __init__(self, arvadosfile, mode="r", num_retries=None):
1269         super(ArvadosFileReader, self).__init__(arvadosfile.name, mode=mode, num_retries=num_retries)
1270         self.arvadosfile = arvadosfile
1271
1272     def size(self):
1273         return self.arvadosfile.size()
1274
1275     def stream_name(self):
1276         return self.arvadosfile.parent.stream_name()
1277
1278     def readinto(self, b):
1279         data = self.read(len(b))
1280         b[:len(data)] = data
1281         return len(data)
1282
1283     @_FileLikeObjectBase._before_close
1284     @retry_method
1285     def read(self, size=None, num_retries=None):
1286         """Read up to `size` bytes from the file and return the result.
1287
1288         Starts at the current file position.  If `size` is None, read the
1289         entire remainder of the file.
1290         """
1291         if size is None:
1292             data = []
1293             rd = self.arvadosfile.readfrom(self._filepos, config.KEEP_BLOCK_SIZE, num_retries)
1294             while rd:
1295                 data.append(rd)
1296                 self._filepos += len(rd)
1297                 rd = self.arvadosfile.readfrom(self._filepos, config.KEEP_BLOCK_SIZE, num_retries)
1298             return b''.join(data)
1299         else:
1300             data = self.arvadosfile.readfrom(self._filepos, size, num_retries, exact=True)
1301             self._filepos += len(data)
1302             return data
1303
1304     @_FileLikeObjectBase._before_close
1305     @retry_method
1306     def readfrom(self, offset, size, num_retries=None):
1307         """Read up to `size` bytes from the stream, starting at the specified file offset.
1308
1309         This method does not change the file position.
1310         """
1311         return self.arvadosfile.readfrom(offset, size, num_retries)
1312
1313     def flush(self):
1314         pass
1315
1316
1317 class ArvadosFileWriter(ArvadosFileReader):
1318     """Wraps ArvadosFile in a file-like object supporting both reading and writing.
1319
1320     Be aware that this class is NOT thread safe as there is no locking around
1321     updating file pointer.
1322
1323     """
1324
1325     def __init__(self, arvadosfile, mode, num_retries=None):
1326         super(ArvadosFileWriter, self).__init__(arvadosfile, mode=mode, num_retries=num_retries)
1327         self.arvadosfile.add_writer(self)
1328
1329     def writable(self):
1330         return True
1331
1332     @_FileLikeObjectBase._before_close
1333     @retry_method
1334     def write(self, data, num_retries=None):
1335         if self.mode[0] == "a":
1336             self._filepos = self.size()
1337         self.arvadosfile.writeto(self._filepos, data, num_retries)
1338         self._filepos += len(data)
1339         return len(data)
1340
1341     @_FileLikeObjectBase._before_close
1342     @retry_method
1343     def writelines(self, seq, num_retries=None):
1344         for s in seq:
1345             self.write(s, num_retries=num_retries)
1346
1347     @_FileLikeObjectBase._before_close
1348     def truncate(self, size=None):
1349         if size is None:
1350             size = self._filepos
1351         self.arvadosfile.truncate(size)
1352
1353     @_FileLikeObjectBase._before_close
1354     def flush(self):
1355         self.arvadosfile.flush()
1356
1357     def close(self, flush=True):
1358         if not self.closed:
1359             self.arvadosfile.remove_writer(self, flush)
1360             super(ArvadosFileWriter, self).close()
1361
1362
1363 class WrappableFile(object):
1364     """An interface to an Arvados file that's compatible with io wrappers.
1365
1366     """
1367     def __init__(self, f):
1368         self.f = f
1369         self.closed = False
1370     def close(self):
1371         self.closed = True
1372         return self.f.close()
1373     def flush(self):
1374         return self.f.flush()
1375     def read(self, *args, **kwargs):
1376         return self.f.read(*args, **kwargs)
1377     def readable(self):
1378         return self.f.readable()
1379     def readinto(self, *args, **kwargs):
1380         return self.f.readinto(*args, **kwargs)
1381     def seek(self, *args, **kwargs):
1382         return self.f.seek(*args, **kwargs)
1383     def seekable(self):
1384         return self.f.seekable()
1385     def tell(self):
1386         return self.f.tell()
1387     def writable(self):
1388         return self.f.writable()
1389     def write(self, *args, **kwargs):
1390         return self.f.write(*args, **kwargs)