sdk/python/arvados/keep.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 import copy
   8 from future import standard_library
   9 from future.utils import native_str
  10 standard_library.install_aliases()
  11 from builtins import next
  12 from builtins import str
  13 from builtins import range
  14 from builtins import object
  15 import collections
  16 import datetime
  17 import hashlib
  18 import io
  19 import logging
  20 import math
  21 import os
  22 import pycurl
  23 import queue
  24 import re
  25 import socket
  26 import ssl
  27 import sys
  28 import threading
  29 from . import timer
  30 import urllib.parse
  31
  32 if sys.version_info >= (3, 0):
  33     from io import BytesIO
  34 else:
  35     from cStringIO import StringIO as BytesIO
  36
  37 import arvados
  38 import arvados.config as config
  39 import arvados.errors
  40 import arvados.retry as retry
  41 import arvados.util
  42
  43 _logger = logging.getLogger('arvados.keep')
  44 global_client_object = None
  45
  46
  47 # Monkey patch TCP constants when not available (apple). Values sourced from:
  48 # http://www.opensource.apple.com/source/xnu/xnu-2422.115.4/bsd/netinet/tcp.h
  49 if sys.platform == 'darwin':
  50     if not hasattr(socket, 'TCP_KEEPALIVE'):
  51         socket.TCP_KEEPALIVE = 0x010
  52     if not hasattr(socket, 'TCP_KEEPINTVL'):
  53         socket.TCP_KEEPINTVL = 0x101
  54     if not hasattr(socket, 'TCP_KEEPCNT'):
  55         socket.TCP_KEEPCNT = 0x102
  56
  57
  58 class KeepLocator(object):
  59     EPOCH_DATETIME = datetime.datetime.utcfromtimestamp(0)
  60     HINT_RE = re.compile(r'^[A-Z][A-Za-z0-9@_-]+$')
  61
  62     def __init__(self, locator_str):
  63         self.hints = []
  64         self._perm_sig = None
  65         self._perm_expiry = None
  66         pieces = iter(locator_str.split('+'))
  67         self.md5sum = next(pieces)
  68         try:
  69             self.size = int(next(pieces))
  70         except StopIteration:
  71             self.size = None
  72         for hint in pieces:
  73             if self.HINT_RE.match(hint) is None:
  74                 raise ValueError("invalid hint format: {}".format(hint))
  75             elif hint.startswith('A'):
  76                 self.parse_permission_hint(hint)
  77             else:
  78                 self.hints.append(hint)
  79
  80     def __str__(self):
  81         return '+'.join(
  82             native_str(s)
  83             for s in [self.md5sum, self.size,
  84                       self.permission_hint()] + self.hints
  85             if s is not None)
  86
  87     def stripped(self):
  88         if self.size is not None:
  89             return "%s+%i" % (self.md5sum, self.size)
  90         else:
  91             return self.md5sum
  92
  93     def _make_hex_prop(name, length):
  94         # Build and return a new property with the given name that
  95         # must be a hex string of the given length.
  96         data_name = '_{}'.format(name)
  97         def getter(self):
  98             return getattr(self, data_name)
  99         def setter(self, hex_str):
 100             if not arvados.util.is_hex(hex_str, length):
 101                 raise ValueError("{} is not a {}-digit hex string: {!r}".
 102                                  format(name, length, hex_str))
 103             setattr(self, data_name, hex_str)
 104         return property(getter, setter)
 105
 106     md5sum = _make_hex_prop('md5sum', 32)
 107     perm_sig = _make_hex_prop('perm_sig', 40)
 108
 109     @property
 110     def perm_expiry(self):
 111         return self._perm_expiry
 112
 113     @perm_expiry.setter
 114     def perm_expiry(self, value):
 115         if not arvados.util.is_hex(value, 1, 8):
 116             raise ValueError(
 117                 "permission timestamp must be a hex Unix timestamp: {}".
 118                 format(value))
 119         self._perm_expiry = datetime.datetime.utcfromtimestamp(int(value, 16))
 120
 121     def permission_hint(self):
 122         data = [self.perm_sig, self.perm_expiry]
 123         if None in data:
 124             return None
 125         data[1] = int((data[1] - self.EPOCH_DATETIME).total_seconds())
 126         return "A{}@{:08x}".format(*data)
 127
 128     def parse_permission_hint(self, s):
 129         try:
 130             self.perm_sig, self.perm_expiry = s[1:].split('@', 1)
 131         except IndexError:
 132             raise ValueError("bad permission hint {}".format(s))
 133
 134     def permission_expired(self, as_of_dt=None):
 135         if self.perm_expiry is None:
 136             return False
 137         elif as_of_dt is None:
 138             as_of_dt = datetime.datetime.now()
 139         return self.perm_expiry <= as_of_dt
 140
 141
 142 class Keep(object):
 143     """Simple interface to a global KeepClient object.
 144
 145     THIS CLASS IS DEPRECATED.  Please instantiate your own KeepClient with your
 146     own API client.  The global KeepClient will build an API client from the
 147     current Arvados configuration, which may not match the one you built.
 148     """
 149     _last_key = None
 150
 151     @classmethod
 152     def global_client_object(cls):
 153         global global_client_object
 154         # Previously, KeepClient would change its behavior at runtime based
 155         # on these configuration settings.  We simulate that behavior here
 156         # by checking the values and returning a new KeepClient if any of
 157         # them have changed.
 158         key = (config.get('ARVADOS_API_HOST'),
 159                config.get('ARVADOS_API_TOKEN'),
 160                config.flag_is_true('ARVADOS_API_HOST_INSECURE'),
 161                config.get('ARVADOS_KEEP_PROXY'),
 162                config.get('ARVADOS_EXTERNAL_CLIENT') == 'true',
 163                os.environ.get('KEEP_LOCAL_STORE'))
 164         if (global_client_object is None) or (cls._last_key != key):
 165             global_client_object = KeepClient()
 166             cls._last_key = key
 167         return global_client_object
 168
 169     @staticmethod
 170     def get(locator, **kwargs):
 171         return Keep.global_client_object().get(locator, **kwargs)
 172
 173     @staticmethod
 174     def put(data, **kwargs):
 175         return Keep.global_client_object().put(data, **kwargs)
 176
 177 class KeepBlockCache(object):
 178     # Default RAM cache is 256MiB
 179     def __init__(self, cache_max=(256 * 1024 * 1024)):
 180         self.cache_max = cache_max
 181         self._cache = []
 182         self._cache_lock = threading.Lock()
 183
 184     class CacheSlot(object):
 185         __slots__ = ("locator", "ready", "content")
 186
 187         def __init__(self, locator):
 188             self.locator = locator
 189             self.ready = threading.Event()
 190             self.content = None
 191
 192         def get(self):
 193             self.ready.wait()
 194             return self.content
 195
 196         def set(self, value):
 197             self.content = value
 198             self.ready.set()
 199
 200         def size(self):
 201             if self.content is None:
 202                 return 0
 203             else:
 204                 return len(self.content)
 205
 206     def cap_cache(self):
 207         '''Cap the cache size to self.cache_max'''
 208         with self._cache_lock:
 209             # Select all slots except those where ready.is_set() and content is
 210             # None (that means there was an error reading the block).
 211             self._cache = [c for c in self._cache if not (c.ready.is_set() and c.content is None)]
 212             sm = sum([slot.size() for slot in self._cache])
 213             while len(self._cache) > 0 and sm > self.cache_max:
 214                 for i in range(len(self._cache)-1, -1, -1):
 215                     if self._cache[i].ready.is_set():
 216                         del self._cache[i]
 217                         break
 218                 sm = sum([slot.size() for slot in self._cache])
 219
 220     def _get(self, locator):
 221         # Test if the locator is already in the cache
 222         for i in range(0, len(self._cache)):
 223             if self._cache[i].locator == locator:
 224                 n = self._cache[i]
 225                 if i != 0:
 226                     # move it to the front
 227                     del self._cache[i]
 228                     self._cache.insert(0, n)
 229                 return n
 230         return None
 231
 232     def get(self, locator):
 233         with self._cache_lock:
 234             return self._get(locator)
 235
 236     def reserve_cache(self, locator):
 237         '''Reserve a cache slot for the specified locator,
 238         or return the existing slot.'''
 239         with self._cache_lock:
 240             n = self._get(locator)
 241             if n:
 242                 return n, False
 243             else:
 244                 # Add a new cache slot for the locator
 245                 n = KeepBlockCache.CacheSlot(locator)
 246                 self._cache.insert(0, n)
 247                 return n, True
 248
 249 class Counter(object):
 250     def __init__(self, v=0):
 251         self._lk = threading.Lock()
 252         self._val = v
 253
 254     def add(self, v):
 255         with self._lk:
 256             self._val += v
 257
 258     def get(self):
 259         with self._lk:
 260             return self._val
 261
 262
 263 class KeepClient(object):
 264
 265     # Default Keep server connection timeout:  2 seconds
 266     # Default Keep server read timeout:       256 seconds
 267     # Default Keep server bandwidth minimum:  32768 bytes per second
 268     # Default Keep proxy connection timeout:  20 seconds
 269     # Default Keep proxy read timeout:        256 seconds
 270     # Default Keep proxy bandwidth minimum:   32768 bytes per second
 271     DEFAULT_TIMEOUT = (2, 256, 32768)
 272     DEFAULT_PROXY_TIMEOUT = (20, 256, 32768)
 273
 274
 275     class KeepService(object):
 276         """Make requests to a single Keep service, and track results.
 277
 278         A KeepService is intended to last long enough to perform one
 279         transaction (GET or PUT) against one Keep service. This can
 280         involve calling either get() or put() multiple times in order
 281         to retry after transient failures. However, calling both get()
 282         and put() on a single instance -- or using the same instance
 283         to access two different Keep services -- will not produce
 284         sensible behavior.
 285         """
 286
 287         HTTP_ERRORS = (
 288             socket.error,
 289             ssl.SSLError,
 290             arvados.errors.HttpError,
 291         )
 292
 293         def __init__(self, root, user_agent_pool=queue.LifoQueue(),
 294                      upload_counter=None,
 295                      download_counter=None,
 296                      headers={},
 297                      insecure=False):
 298             self.root = root
 299             self._user_agent_pool = user_agent_pool
 300             self._result = {'error': None}
 301             self._usable = True
 302             self._session = None
 303             self._socket = None
 304             self.get_headers = {'Accept': 'application/octet-stream'}
 305             self.get_headers.update(headers)
 306             self.put_headers = headers
 307             self.upload_counter = upload_counter
 308             self.download_counter = download_counter
 309             self.insecure = insecure
 310
 311         def usable(self):
 312             """Is it worth attempting a request?"""
 313             return self._usable
 314
 315         def finished(self):
 316             """Did the request succeed or encounter permanent failure?"""
 317             return self._result['error'] == False or not self._usable
 318
 319         def last_result(self):
 320             return self._result
 321
 322         def _get_user_agent(self):
 323             try:
 324                 return self._user_agent_pool.get(block=False)
 325             except queue.Empty:
 326                 return pycurl.Curl()
 327
 328         def _put_user_agent(self, ua):
 329             try:
 330                 ua.reset()
 331                 self._user_agent_pool.put(ua, block=False)
 332             except:
 333                 ua.close()
 334
 335         def _socket_open(self, *args, **kwargs):
 336             if len(args) + len(kwargs) == 2:
 337                 return self._socket_open_pycurl_7_21_5(*args, **kwargs)
 338             else:
 339                 return self._socket_open_pycurl_7_19_3(*args, **kwargs)
 340
 341         def _socket_open_pycurl_7_19_3(self, family, socktype, protocol, address=None):
 342             return self._socket_open_pycurl_7_21_5(
 343                 purpose=None,
 344                 address=collections.namedtuple(
 345                     'Address', ['family', 'socktype', 'protocol', 'addr'],
 346                 )(family, socktype, protocol, address))
 347
 348         def _socket_open_pycurl_7_21_5(self, purpose, address):
 349             """Because pycurl doesn't have CURLOPT_TCP_KEEPALIVE"""
 350             s = socket.socket(address.family, address.socktype, address.protocol)
 351             s.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
 352             # Will throw invalid protocol error on mac. This test prevents that.
 353             if hasattr(socket, 'TCP_KEEPIDLE'):
 354                 s.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 75)
 355             s.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPINTVL, 75)
 356             self._socket = s
 357             return s
 358
 359         def get(self, locator, method="GET", timeout=None):
 360             # locator is a KeepLocator object.
 361             url = self.root + str(locator)
 362             _logger.debug("Request: %s %s", method, url)
 363             curl = self._get_user_agent()
 364             ok = None
 365             try:
 366                 with timer.Timer() as t:
 367                     self._headers = {}
 368                     response_body = BytesIO()
 369                     curl.setopt(pycurl.NOSIGNAL, 1)
 370                     curl.setopt(pycurl.OPENSOCKETFUNCTION,
 371                                 lambda *args, **kwargs: self._socket_open(*args, **kwargs))
 372                     curl.setopt(pycurl.URL, url.encode('utf-8'))
 373                     curl.setopt(pycurl.HTTPHEADER, [
 374                         '{}: {}'.format(k,v) for k,v in self.get_headers.items()])
 375                     curl.setopt(pycurl.WRITEFUNCTION, response_body.write)
 376                     curl.setopt(pycurl.HEADERFUNCTION, self._headerfunction)
 377                     if self.insecure:
 378                         curl.setopt(pycurl.SSL_VERIFYPEER, 0)
 379                     else:
 380                         curl.setopt(pycurl.CAINFO, arvados.util.ca_certs_path())
 381                     if method == "HEAD":
 382                         curl.setopt(pycurl.NOBODY, True)
 383                     self._setcurltimeouts(curl, timeout, method=="HEAD")
 384
 385                     try:
 386                         curl.perform()
 387                     except Exception as e:
 388                         raise arvados.errors.HttpError(0, str(e))
 389                     finally:
 390                         if self._socket:
 391                             self._socket.close()
 392                             self._socket = None
 393                     self._result = {
 394                         'status_code': curl.getinfo(pycurl.RESPONSE_CODE),
 395                         'body': response_body.getvalue(),
 396                         'headers': self._headers,
 397                         'error': False,
 398                     }
 399
 400                 ok = retry.check_http_response_success(self._result['status_code'])
 401                 if not ok:
 402                     self._result['error'] = arvados.errors.HttpError(
 403                         self._result['status_code'],
 404                         self._headers.get('x-status-line', 'Error'))
 405             except self.HTTP_ERRORS as e:
 406                 self._result = {
 407                     'error': e,
 408                 }
 409             self._usable = ok != False
 410             if self._result.get('status_code', None):
 411                 # The client worked well enough to get an HTTP status
 412                 # code, so presumably any problems are just on the
 413                 # server side and it's OK to reuse the client.
 414                 self._put_user_agent(curl)
 415             else:
 416                 # Don't return this client to the pool, in case it's
 417                 # broken.
 418                 curl.close()
 419             if not ok:
 420                 _logger.debug("Request fail: GET %s => %s: %s",
 421                               url, type(self._result['error']), str(self._result['error']))
 422                 return None
 423             if method == "HEAD":
 424                 _logger.info("HEAD %s: %s bytes",
 425                          self._result['status_code'],
 426                          self._result.get('content-length'))
 427                 if self._result['headers'].get('x-keep-locator'):
 428                     # This is a response to a remote block copy request, return
 429                     # the local copy block locator.
 430                     return self._result['headers'].get('x-keep-locator')
 431                 return True
 432
 433             _logger.info("GET %s: %s bytes in %s msec (%.3f MiB/sec)",
 434                          self._result['status_code'],
 435                          len(self._result['body']),
 436                          t.msecs,
 437                          1.0*len(self._result['body'])/2**20/t.secs if t.secs > 0 else 0)
 438
 439             if self.download_counter:
 440                 self.download_counter.add(len(self._result['body']))
 441             resp_md5 = hashlib.md5(self._result['body']).hexdigest()
 442             if resp_md5 != locator.md5sum:
 443                 _logger.warning("Checksum fail: md5(%s) = %s",
 444                                 url, resp_md5)
 445                 self._result['error'] = arvados.errors.HttpError(
 446                     0, 'Checksum fail')
 447                 return None
 448             return self._result['body']
 449
 450         def put(self, hash_s, body, timeout=None, headers={}):
 451             put_headers = copy.copy(self.put_headers)
 452             put_headers.update(headers)
 453             url = self.root + hash_s
 454             _logger.debug("Request: PUT %s", url)
 455             curl = self._get_user_agent()
 456             ok = None
 457             try:
 458                 with timer.Timer() as t:
 459                     self._headers = {}
 460                     body_reader = BytesIO(body)
 461                     response_body = BytesIO()
 462                     curl.setopt(pycurl.NOSIGNAL, 1)
 463                     curl.setopt(pycurl.OPENSOCKETFUNCTION,
 464                                 lambda *args, **kwargs: self._socket_open(*args, **kwargs))
 465                     curl.setopt(pycurl.URL, url.encode('utf-8'))
 466                     # Using UPLOAD tells cURL to wait for a "go ahead" from the
 467                     # Keep server (in the form of a HTTP/1.1 "100 Continue"
 468                     # response) instead of sending the request body immediately.
 469                     # This allows the server to reject the request if the request
 470                     # is invalid or the server is read-only, without waiting for
 471                     # the client to send the entire block.
 472                     curl.setopt(pycurl.UPLOAD, True)
 473                     curl.setopt(pycurl.INFILESIZE, len(body))
 474                     curl.setopt(pycurl.READFUNCTION, body_reader.read)
 475                     curl.setopt(pycurl.HTTPHEADER, [
 476                         '{}: {}'.format(k,v) for k,v in put_headers.items()])
 477                     curl.setopt(pycurl.WRITEFUNCTION, response_body.write)
 478                     curl.setopt(pycurl.HEADERFUNCTION, self._headerfunction)
 479                     if self.insecure:
 480                         curl.setopt(pycurl.SSL_VERIFYPEER, 0)
 481                     else:
 482                         curl.setopt(pycurl.CAINFO, arvados.util.ca_certs_path())
 483                     self._setcurltimeouts(curl, timeout)
 484                     try:
 485                         curl.perform()
 486                     except Exception as e:
 487                         raise arvados.errors.HttpError(0, str(e))
 488                     finally:
 489                         if self._socket:
 490                             self._socket.close()
 491                             self._socket = None
 492                     self._result = {
 493                         'status_code': curl.getinfo(pycurl.RESPONSE_CODE),
 494                         'body': response_body.getvalue().decode('utf-8'),
 495                         'headers': self._headers,
 496                         'error': False,
 497                     }
 498                 ok = retry.check_http_response_success(self._result['status_code'])
 499                 if not ok:
 500                     self._result['error'] = arvados.errors.HttpError(
 501                         self._result['status_code'],
 502                         self._headers.get('x-status-line', 'Error'))
 503             except self.HTTP_ERRORS as e:
 504                 self._result = {
 505                     'error': e,
 506                 }
 507             self._usable = ok != False # still usable if ok is True or None
 508             if self._result.get('status_code', None):
 509                 # Client is functional. See comment in get().
 510                 self._put_user_agent(curl)
 511             else:
 512                 curl.close()
 513             if not ok:
 514                 _logger.debug("Request fail: PUT %s => %s: %s",
 515                               url, type(self._result['error']), str(self._result['error']))
 516                 return False
 517             _logger.info("PUT %s: %s bytes in %s msec (%.3f MiB/sec)",
 518                          self._result['status_code'],
 519                          len(body),
 520                          t.msecs,
 521                          1.0*len(body)/2**20/t.secs if t.secs > 0 else 0)
 522             if self.upload_counter:
 523                 self.upload_counter.add(len(body))
 524             return True
 525
 526         def _setcurltimeouts(self, curl, timeouts, ignore_bandwidth=False):
 527             if not timeouts:
 528                 return
 529             elif isinstance(timeouts, tuple):
 530                 if len(timeouts) == 2:
 531                     conn_t, xfer_t = timeouts
 532                     bandwidth_bps = KeepClient.DEFAULT_TIMEOUT[2]
 533                 else:
 534                     conn_t, xfer_t, bandwidth_bps = timeouts
 535             else:
 536                 conn_t, xfer_t = (timeouts, timeouts)
 537                 bandwidth_bps = KeepClient.DEFAULT_TIMEOUT[2]
 538             curl.setopt(pycurl.CONNECTTIMEOUT_MS, int(conn_t*1000))
 539             if not ignore_bandwidth:
 540                 curl.setopt(pycurl.LOW_SPEED_TIME, int(math.ceil(xfer_t)))
 541                 curl.setopt(pycurl.LOW_SPEED_LIMIT, int(math.ceil(bandwidth_bps)))
 542
 543         def _headerfunction(self, header_line):
 544             if isinstance(header_line, bytes):
 545                 header_line = header_line.decode('iso-8859-1')
 546             if ':' in header_line:
 547                 name, value = header_line.split(':', 1)
 548                 name = name.strip().lower()
 549                 value = value.strip()
 550             elif self._headers:
 551                 name = self._lastheadername
 552                 value = self._headers[name] + ' ' + header_line.strip()
 553             elif header_line.startswith('HTTP/'):
 554                 name = 'x-status-line'
 555                 value = header_line
 556             else:
 557                 _logger.error("Unexpected header line: %s", header_line)
 558                 return
 559             self._lastheadername = name
 560             self._headers[name] = value
 561             # Returning None implies all bytes were written
 562
 563
 564     class KeepWriterQueue(queue.Queue):
 565         def __init__(self, copies, classes=[]):
 566             queue.Queue.__init__(self) # Old-style superclass
 567             self.wanted_copies = copies
 568             self.wanted_storage_classes = classes
 569             self.successful_copies = 0
 570             self.confirmed_storage_classes = {}
 571             self.response = None
 572             self.storage_classes_tracking = True
 573             self.queue_data_lock = threading.RLock()
 574             self.pending_tries = max(copies, len(classes))
 575             self.pending_tries_notification = threading.Condition()
 576
 577         def write_success(self, response, replicas_nr, classes_confirmed):
 578             with self.queue_data_lock:
 579                 self.successful_copies += replicas_nr
 580                 if classes_confirmed is None:
 581                     self.storage_classes_tracking = False
 582                 elif self.storage_classes_tracking:
 583                     for st_class, st_copies in classes_confirmed.items():
 584                         try:
 585                             self.confirmed_storage_classes[st_class] += st_copies
 586                         except KeyError:
 587                             self.confirmed_storage_classes[st_class] = st_copies
 588                     self.pending_tries = max(self.wanted_copies - self.successful_copies, len(self.pending_classes()))
 589                 self.response = response
 590             with self.pending_tries_notification:
 591                 self.pending_tries_notification.notify_all()
 592
 593         def write_fail(self, ks):
 594             with self.pending_tries_notification:
 595                 self.pending_tries += 1
 596                 self.pending_tries_notification.notify()
 597
 598         def pending_copies(self):
 599             with self.queue_data_lock:
 600                 return self.wanted_copies - self.successful_copies
 601
 602         def satisfied_classes(self):
 603             with self.queue_data_lock:
 604                 if not self.storage_classes_tracking:
 605                     # Notifies disabled storage classes expectation to
 606                     # the outer loop.
 607                     return None
 608             return list(set(self.wanted_storage_classes) - set(self.pending_classes()))
 609
 610         def pending_classes(self):
 611             with self.queue_data_lock:
 612                 if (not self.storage_classes_tracking) or (self.wanted_storage_classes is None):
 613                     return []
 614                 unsatisfied_classes = copy.copy(self.wanted_storage_classes)
 615                 for st_class, st_copies in self.confirmed_storage_classes.items():
 616                     if st_class in unsatisfied_classes and st_copies >= self.wanted_copies:
 617                         unsatisfied_classes.remove(st_class)
 618                 return unsatisfied_classes
 619
 620         def get_next_task(self):
 621             with self.pending_tries_notification:
 622                 while True:
 623                     if self.pending_copies() < 1 and len(self.pending_classes()) == 0:
 624                         # This notify_all() is unnecessary --
 625                         # write_success() already called notify_all()
 626                         # when pending<1 became true, so it's not
 627                         # possible for any other thread to be in
 628                         # wait() now -- but it's cheap insurance
 629                         # against deadlock so we do it anyway:
 630                         self.pending_tries_notification.notify_all()
 631                         # Drain the queue and then raise Queue.Empty
 632                         while True:
 633                             self.get_nowait()
 634                             self.task_done()
 635                     elif self.pending_tries > 0:
 636                         service, service_root = self.get_nowait()
 637                         if service.finished():
 638                             self.task_done()
 639                             continue
 640                         self.pending_tries -= 1
 641                         return service, service_root
 642                     elif self.empty():
 643                         self.pending_tries_notification.notify_all()
 644                         raise queue.Empty
 645                     else:
 646                         self.pending_tries_notification.wait()
 647
 648
 649     class KeepWriterThreadPool(object):
 650         def __init__(self, data, data_hash, copies, max_service_replicas, timeout=None, classes=[]):
 651             self.total_task_nr = 0
 652             if (not max_service_replicas) or (max_service_replicas >= copies):
 653                 num_threads = 1
 654             else:
 655                 num_threads = int(math.ceil(1.0*copies/max_service_replicas))
 656             _logger.debug("Pool max threads is %d", num_threads)
 657             self.workers = []
 658             self.queue = KeepClient.KeepWriterQueue(copies, classes)
 659             # Create workers
 660             for _ in range(num_threads):
 661                 w = KeepClient.KeepWriterThread(self.queue, data, data_hash, timeout)
 662                 self.workers.append(w)
 663
 664         def add_task(self, ks, service_root):
 665             self.queue.put((ks, service_root))
 666             self.total_task_nr += 1
 667
 668         def done(self):
 669             return self.queue.successful_copies, self.queue.satisfied_classes()
 670
 671         def join(self):
 672             # Start workers
 673             for worker in self.workers:
 674                 worker.start()
 675             # Wait for finished work
 676             self.queue.join()
 677
 678         def response(self):
 679             return self.queue.response
 680
 681
 682     class KeepWriterThread(threading.Thread):
 683         class TaskFailed(RuntimeError): pass
 684
 685         def __init__(self, queue, data, data_hash, timeout=None):
 686             super(KeepClient.KeepWriterThread, self).__init__()
 687             self.timeout = timeout
 688             self.queue = queue
 689             self.data = data
 690             self.data_hash = data_hash
 691             self.daemon = True
 692
 693         def run(self):
 694             while True:
 695                 try:
 696                     service, service_root = self.queue.get_next_task()
 697                 except queue.Empty:
 698                     return
 699                 try:
 700                     locator, copies, classes = self.do_task(service, service_root)
 701                 except Exception as e:
 702                     if not isinstance(e, self.TaskFailed):
 703                         _logger.exception("Exception in KeepWriterThread")
 704                     self.queue.write_fail(service)
 705                 else:
 706                     self.queue.write_success(locator, copies, classes)
 707                 finally:
 708                     self.queue.task_done()
 709
 710         def do_task(self, service, service_root):
 711             classes = self.queue.pending_classes()
 712             headers = {}
 713             if len(classes) > 0:
 714                 classes.sort()
 715                 headers['X-Keep-Storage-Classes'] = ', '.join(classes)
 716             success = bool(service.put(self.data_hash,
 717                                         self.data,
 718                                         timeout=self.timeout,
 719                                         headers=headers))
 720             result = service.last_result()
 721
 722             if not success:
 723                 if result.get('status_code', None):
 724                     _logger.debug("Request fail: PUT %s => %s %s",
 725                                   self.data_hash,
 726                                   result['status_code'],
 727                                   result['body'])
 728                 raise self.TaskFailed()
 729
 730             _logger.debug("KeepWriterThread %s succeeded %s+%i %s",
 731                           str(threading.current_thread()),
 732                           self.data_hash,
 733                           len(self.data),
 734                           service_root)
 735             try:
 736                 replicas_stored = int(result['headers']['x-keep-replicas-stored'])
 737             except (KeyError, ValueError):
 738                 replicas_stored = 1
 739
 740             classes_confirmed = {}
 741             try:
 742                 scch = result['headers']['x-keep-storage-classes-confirmed']
 743                 for confirmation in scch.replace(' ', '').split(','):
 744                     if '=' in confirmation:
 745                         stored_class, stored_copies = confirmation.split('=')[:2]
 746                         classes_confirmed[stored_class] = int(stored_copies)
 747             except (KeyError, ValueError):
 748                 # Storage classes confirmed header missing or corrupt
 749                 classes_confirmed = None
 750
 751             return result['body'].strip(), replicas_stored, classes_confirmed
 752
 753
 754     def __init__(self, api_client=None, proxy=None,
 755                  timeout=DEFAULT_TIMEOUT, proxy_timeout=DEFAULT_PROXY_TIMEOUT,
 756                  api_token=None, local_store=None, block_cache=None,
 757                  num_retries=0, session=None):
 758         """Initialize a new KeepClient.
 759
 760         Arguments:
 761         :api_client:
 762           The API client to use to find Keep services.  If not
 763           provided, KeepClient will build one from available Arvados
 764           configuration.
 765
 766         :proxy:
 767           If specified, this KeepClient will send requests to this Keep
 768           proxy.  Otherwise, KeepClient will fall back to the setting of the
 769           ARVADOS_KEEP_SERVICES or ARVADOS_KEEP_PROXY configuration settings.
 770           If you want to KeepClient does not use a proxy, pass in an empty
 771           string.
 772
 773         :timeout:
 774           The initial timeout (in seconds) for HTTP requests to Keep
 775           non-proxy servers.  A tuple of three floats is interpreted as
 776           (connection_timeout, read_timeout, minimum_bandwidth). A connection
 777           will be aborted if the average traffic rate falls below
 778           minimum_bandwidth bytes per second over an interval of read_timeout
 779           seconds. Because timeouts are often a result of transient server
 780           load, the actual connection timeout will be increased by a factor
 781           of two on each retry.
 782           Default: (2, 256, 32768).
 783
 784         :proxy_timeout:
 785           The initial timeout (in seconds) for HTTP requests to
 786           Keep proxies. A tuple of three floats is interpreted as
 787           (connection_timeout, read_timeout, minimum_bandwidth). The behavior
 788           described above for adjusting connection timeouts on retry also
 789           applies.
 790           Default: (20, 256, 32768).
 791
 792         :api_token:
 793           If you're not using an API client, but only talking
 794           directly to a Keep proxy, this parameter specifies an API token
 795           to authenticate Keep requests.  It is an error to specify both
 796           api_client and api_token.  If you specify neither, KeepClient
 797           will use one available from the Arvados configuration.
 798
 799         :local_store:
 800           If specified, this KeepClient will bypass Keep
 801           services, and save data to the named directory.  If unspecified,
 802           KeepClient will fall back to the setting of the $KEEP_LOCAL_STORE
 803           environment variable.  If you want to ensure KeepClient does not
 804           use local storage, pass in an empty string.  This is primarily
 805           intended to mock a server for testing.
 806
 807         :num_retries:
 808           The default number of times to retry failed requests.
 809           This will be used as the default num_retries value when get() and
 810           put() are called.  Default 0.
 811         """
 812         self.lock = threading.Lock()
 813         if proxy is None:
 814             if config.get('ARVADOS_KEEP_SERVICES'):
 815                 proxy = config.get('ARVADOS_KEEP_SERVICES')
 816             else:
 817                 proxy = config.get('ARVADOS_KEEP_PROXY')
 818         if api_token is None:
 819             if api_client is None:
 820                 api_token = config.get('ARVADOS_API_TOKEN')
 821             else:
 822                 api_token = api_client.api_token
 823         elif api_client is not None:
 824             raise ValueError(
 825                 "can't build KeepClient with both API client and token")
 826         if local_store is None:
 827             local_store = os.environ.get('KEEP_LOCAL_STORE')
 828
 829         if api_client is None:
 830             self.insecure = config.flag_is_true('ARVADOS_API_HOST_INSECURE')
 831         else:
 832             self.insecure = api_client.insecure
 833
 834         self.block_cache = block_cache if block_cache else KeepBlockCache()
 835         self.timeout = timeout
 836         self.proxy_timeout = proxy_timeout
 837         self._user_agent_pool = queue.LifoQueue()
 838         self.upload_counter = Counter()
 839         self.download_counter = Counter()
 840         self.put_counter = Counter()
 841         self.get_counter = Counter()
 842         self.hits_counter = Counter()
 843         self.misses_counter = Counter()
 844         self._storage_classes_unsupported_warning = False
 845
 846         if local_store:
 847             self.local_store = local_store
 848             self.head = self.local_store_head
 849             self.get = self.local_store_get
 850             self.put = self.local_store_put
 851         else:
 852             self.num_retries = num_retries
 853             self.max_replicas_per_service = None
 854             if proxy:
 855                 proxy_uris = proxy.split()
 856                 for i in range(len(proxy_uris)):
 857                     if not proxy_uris[i].endswith('/'):
 858                         proxy_uris[i] += '/'
 859                     # URL validation
 860                     url = urllib.parse.urlparse(proxy_uris[i])
 861                     if not (url.scheme and url.netloc):
 862                         raise arvados.errors.ArgumentError("Invalid proxy URI: {}".format(proxy_uris[i]))
 863                 self.api_token = api_token
 864                 self._gateway_services = {}
 865                 self._keep_services = [{
 866                     'uuid': "00000-bi6l4-%015d" % idx,
 867                     'service_type': 'proxy',
 868                     '_service_root': uri,
 869                     } for idx, uri in enumerate(proxy_uris)]
 870                 self._writable_services = self._keep_services
 871                 self.using_proxy = True
 872                 self._static_services_list = True
 873             else:
 874                 # It's important to avoid instantiating an API client
 875                 # unless we actually need one, for testing's sake.
 876                 if api_client is None:
 877                     api_client = arvados.api('v1')
 878                 self.api_client = api_client
 879                 self.api_token = api_client.api_token
 880                 self._gateway_services = {}
 881                 self._keep_services = None
 882                 self._writable_services = None
 883                 self.using_proxy = None
 884                 self._static_services_list = False
 885
 886     def current_timeout(self, attempt_number):
 887         """Return the appropriate timeout to use for this client.
 888
 889         The proxy timeout setting if the backend service is currently a proxy,
 890         the regular timeout setting otherwise.  The `attempt_number` indicates
 891         how many times the operation has been tried already (starting from 0
 892         for the first try), and scales the connection timeout portion of the
 893         return value accordingly.
 894
 895         """
 896         # TODO(twp): the timeout should be a property of a
 897         # KeepService, not a KeepClient. See #4488.
 898         t = self.proxy_timeout if self.using_proxy else self.timeout
 899         if len(t) == 2:
 900             return (t[0] * (1 << attempt_number), t[1])
 901         else:
 902             return (t[0] * (1 << attempt_number), t[1], t[2])
 903     def _any_nondisk_services(self, service_list):
 904         return any(ks.get('service_type', 'disk') != 'disk'
 905                    for ks in service_list)
 906
 907     def build_services_list(self, force_rebuild=False):
 908         if (self._static_services_list or
 909               (self._keep_services and not force_rebuild)):
 910             return
 911         with self.lock:
 912             try:
 913                 keep_services = self.api_client.keep_services().accessible()
 914             except Exception:  # API server predates Keep services.
 915                 keep_services = self.api_client.keep_disks().list()
 916
 917             # Gateway services are only used when specified by UUID,
 918             # so there's nothing to gain by filtering them by
 919             # service_type.
 920             self._gateway_services = {ks['uuid']: ks for ks in
 921                                       keep_services.execute()['items']}
 922             if not self._gateway_services:
 923                 raise arvados.errors.NoKeepServersError()
 924
 925             # Precompute the base URI for each service.
 926             for r in self._gateway_services.values():
 927                 host = r['service_host']
 928                 if not host.startswith('[') and host.find(':') >= 0:
 929                     # IPv6 URIs must be formatted like http://[::1]:80/...
 930                     host = '[' + host + ']'
 931                 r['_service_root'] = "{}://{}:{:d}/".format(
 932                     'https' if r['service_ssl_flag'] else 'http',
 933                     host,
 934                     r['service_port'])
 935
 936             _logger.debug(str(self._gateway_services))
 937             self._keep_services = [
 938                 ks for ks in self._gateway_services.values()
 939                 if not ks.get('service_type', '').startswith('gateway:')]
 940             self._writable_services = [ks for ks in self._keep_services
 941                                        if not ks.get('read_only')]
 942
 943             # For disk type services, max_replicas_per_service is 1
 944             # It is unknown (unlimited) for other service types.
 945             if self._any_nondisk_services(self._writable_services):
 946                 self.max_replicas_per_service = None
 947             else:
 948                 self.max_replicas_per_service = 1
 949
 950     def _service_weight(self, data_hash, service_uuid):
 951         """Compute the weight of a Keep service endpoint for a data
 952         block with a known hash.
 953
 954         The weight is md5(h + u) where u is the last 15 characters of
 955         the service endpoint's UUID.
 956         """
 957         return hashlib.md5((data_hash + service_uuid[-15:]).encode()).hexdigest()
 958
 959     def weighted_service_roots(self, locator, force_rebuild=False, need_writable=False):
 960         """Return an array of Keep service endpoints, in the order in
 961         which they should be probed when reading or writing data with
 962         the given hash+hints.
 963         """
 964         self.build_services_list(force_rebuild)
 965
 966         sorted_roots = []
 967         # Use the services indicated by the given +K@... remote
 968         # service hints, if any are present and can be resolved to a
 969         # URI.
 970         for hint in locator.hints:
 971             if hint.startswith('K@'):
 972                 if len(hint) == 7:
 973                     sorted_roots.append(
 974                         "https://keep.{}.arvadosapi.com/".format(hint[2:]))
 975                 elif len(hint) == 29:
 976                     svc = self._gateway_services.get(hint[2:])
 977                     if svc:
 978                         sorted_roots.append(svc['_service_root'])
 979
 980         # Sort the available local services by weight (heaviest first)
 981         # for this locator, and return their service_roots (base URIs)
 982         # in that order.
 983         use_services = self._keep_services
 984         if need_writable:
 985             use_services = self._writable_services
 986         self.using_proxy = self._any_nondisk_services(use_services)
 987         sorted_roots.extend([
 988             svc['_service_root'] for svc in sorted(
 989                 use_services,
 990                 reverse=True,
 991                 key=lambda svc: self._service_weight(locator.md5sum, svc['uuid']))])
 992         _logger.debug("{}: {}".format(locator, sorted_roots))
 993         return sorted_roots
 994
 995     def map_new_services(self, roots_map, locator, force_rebuild, need_writable, headers):
 996         # roots_map is a dictionary, mapping Keep service root strings
 997         # to KeepService objects.  Poll for Keep services, and add any
 998         # new ones to roots_map.  Return the current list of local
 999         # root strings.
1000         headers.setdefault('Authorization', "OAuth2 %s" % (self.api_token,))
1001         local_roots = self.weighted_service_roots(locator, force_rebuild, need_writable)
1002         for root in local_roots:
1003             if root not in roots_map:
1004                 roots_map[root] = self.KeepService(
1005                     root, self._user_agent_pool,
1006                     upload_counter=self.upload_counter,
1007                     download_counter=self.download_counter,
1008                     headers=headers,
1009                     insecure=self.insecure)
1010         return local_roots
1011
1012     @staticmethod
1013     def _check_loop_result(result):
1014         # KeepClient RetryLoops should save results as a 2-tuple: the
1015         # actual result of the request, and the number of servers available
1016         # to receive the request this round.
1017         # This method returns True if there's a real result, False if
1018         # there are no more servers available, otherwise None.
1019         if isinstance(result, Exception):
1020             return None
1021         result, tried_server_count = result
1022         if (result is not None) and (result is not False):
1023             return True
1024         elif tried_server_count < 1:
1025             _logger.info("No more Keep services to try; giving up")
1026             return False
1027         else:
1028             return None
1029
1030     def get_from_cache(self, loc):
1031         """Fetch a block only if is in the cache, otherwise return None."""
1032         slot = self.block_cache.get(loc)
1033         if slot is not None and slot.ready.is_set():
1034             return slot.get()
1035         else:
1036             return None
1037
1038     def refresh_signature(self, loc):
1039         """Ask Keep to get the remote block and return its local signature"""
1040         now = datetime.datetime.utcnow().isoformat("T") + 'Z'
1041         return self.head(loc, headers={'X-Keep-Signature': 'local, {}'.format(now)})
1042
1043     @retry.retry_method
1044     def head(self, loc_s, **kwargs):
1045         return self._get_or_head(loc_s, method="HEAD", **kwargs)
1046
1047     @retry.retry_method
1048     def get(self, loc_s, **kwargs):
1049         return self._get_or_head(loc_s, method="GET", **kwargs)
1050
1051     def _get_or_head(self, loc_s, method="GET", num_retries=None, request_id=None, headers=None):
1052         """Get data from Keep.
1053
1054         This method fetches one or more blocks of data from Keep.  It
1055         sends a request each Keep service registered with the API
1056         server (or the proxy provided when this client was
1057         instantiated), then each service named in location hints, in
1058         sequence.  As soon as one service provides the data, it's
1059         returned.
1060
1061         Arguments:
1062         * loc_s: A string of one or more comma-separated locators to fetch.
1063           This method returns the concatenation of these blocks.
1064         * num_retries: The number of times to retry GET requests to
1065           *each* Keep server if it returns temporary failures, with
1066           exponential backoff.  Note that, in each loop, the method may try
1067           to fetch data from every available Keep service, along with any
1068           that are named in location hints in the locator.  The default value
1069           is set when the KeepClient is initialized.
1070         """
1071         if ',' in loc_s:
1072             return ''.join(self.get(x) for x in loc_s.split(','))
1073
1074         self.get_counter.add(1)
1075
1076         slot = None
1077         blob = None
1078         try:
1079             locator = KeepLocator(loc_s)
1080             if method == "GET":
1081                 slot, first = self.block_cache.reserve_cache(locator.md5sum)
1082                 if not first:
1083                     self.hits_counter.add(1)
1084                     blob = slot.get()
1085                     if blob is None:
1086                         raise arvados.errors.KeepReadError(
1087                             "failed to read {}".format(loc_s))
1088                     return blob
1089
1090             self.misses_counter.add(1)
1091
1092             if headers is None:
1093                 headers = {}
1094             headers['X-Request-Id'] = (request_id or
1095                                         (hasattr(self, 'api_client') and self.api_client.request_id) or
1096                                         arvados.util.new_request_id())
1097
1098             # If the locator has hints specifying a prefix (indicating a
1099             # remote keepproxy) or the UUID of a local gateway service,
1100             # read data from the indicated service(s) instead of the usual
1101             # list of local disk services.
1102             hint_roots = ['http://keep.{}.arvadosapi.com/'.format(hint[2:])
1103                           for hint in locator.hints if hint.startswith('K@') and len(hint) == 7]
1104             hint_roots.extend([self._gateway_services[hint[2:]]['_service_root']
1105                                for hint in locator.hints if (
1106                                        hint.startswith('K@') and
1107                                        len(hint) == 29 and
1108                                        self._gateway_services.get(hint[2:])
1109                                        )])
1110             # Map root URLs to their KeepService objects.
1111             roots_map = {
1112                 root: self.KeepService(root, self._user_agent_pool,
1113                                        upload_counter=self.upload_counter,
1114                                        download_counter=self.download_counter,
1115                                        headers=headers,
1116                                        insecure=self.insecure)
1117                 for root in hint_roots
1118             }
1119
1120             # See #3147 for a discussion of the loop implementation.  Highlights:
1121             # * Refresh the list of Keep services after each failure, in case
1122             #   it's being updated.
1123             # * Retry until we succeed, we're out of retries, or every available
1124             #   service has returned permanent failure.
1125             sorted_roots = []
1126             roots_map = {}
1127             loop = retry.RetryLoop(num_retries, self._check_loop_result,
1128                                    backoff_start=2)
1129             for tries_left in loop:
1130                 try:
1131                     sorted_roots = self.map_new_services(
1132                         roots_map, locator,
1133                         force_rebuild=(tries_left < num_retries),
1134                         need_writable=False,
1135                         headers=headers)
1136                 except Exception as error:
1137                     loop.save_result(error)
1138                     continue
1139
1140                 # Query KeepService objects that haven't returned
1141                 # permanent failure, in our specified shuffle order.
1142                 services_to_try = [roots_map[root]
1143                                    for root in sorted_roots
1144                                    if roots_map[root].usable()]
1145                 for keep_service in services_to_try:
1146                     blob = keep_service.get(locator, method=method, timeout=self.current_timeout(num_retries-tries_left))
1147                     if blob is not None:
1148                         break
1149                 loop.save_result((blob, len(services_to_try)))
1150
1151             # Always cache the result, then return it if we succeeded.
1152             if loop.success():
1153                 return blob
1154         finally:
1155             if slot is not None:
1156                 slot.set(blob)
1157                 self.block_cache.cap_cache()
1158
1159         # Q: Including 403 is necessary for the Keep tests to continue
1160         # passing, but maybe they should expect KeepReadError instead?
1161         not_founds = sum(1 for key in sorted_roots
1162                          if roots_map[key].last_result().get('status_code', None) in {403, 404, 410})
1163         service_errors = ((key, roots_map[key].last_result()['error'])
1164                           for key in sorted_roots)
1165         if not roots_map:
1166             raise arvados.errors.KeepReadError(
1167                 "failed to read {}: no Keep services available ({})".format(
1168                     loc_s, loop.last_result()))
1169         elif not_founds == len(sorted_roots):
1170             raise arvados.errors.NotFoundError(
1171                 "{} not found".format(loc_s), service_errors)
1172         else:
1173             raise arvados.errors.KeepReadError(
1174                 "failed to read {} after {}".format(loc_s, loop.attempts_str()), service_errors, label="service")
1175
1176     @retry.retry_method
1177     def put(self, data, copies=2, num_retries=None, request_id=None, classes=[]):
1178         """Save data in Keep.
1179
1180         This method will get a list of Keep services from the API server, and
1181         send the data to each one simultaneously in a new thread.  Once the
1182         uploads are finished, if enough copies are saved, this method returns
1183         the most recent HTTP response body.  If requests fail to upload
1184         enough copies, this method raises KeepWriteError.
1185
1186         Arguments:
1187         * data: The string of data to upload.
1188         * copies: The number of copies that the user requires be saved.
1189           Default 2.
1190         * num_retries: The number of times to retry PUT requests to
1191           *each* Keep server if it returns temporary failures, with
1192           exponential backoff.  The default value is set when the
1193           KeepClient is initialized.
1194         * classes: An optional list of storage class names where copies should
1195           be written.
1196         """
1197
1198         if not isinstance(data, bytes):
1199             data = data.encode()
1200
1201         self.put_counter.add(1)
1202
1203         data_hash = hashlib.md5(data).hexdigest()
1204         loc_s = data_hash + '+' + str(len(data))
1205         if copies < 1:
1206             return loc_s
1207         locator = KeepLocator(loc_s)
1208
1209         headers = {
1210             'X-Request-Id': (request_id or
1211                              (hasattr(self, 'api_client') and self.api_client.request_id) or
1212                              arvados.util.new_request_id()),
1213             'X-Keep-Desired-Replicas': str(copies),
1214         }
1215         roots_map = {}
1216         loop = retry.RetryLoop(num_retries, self._check_loop_result,
1217                                backoff_start=2)
1218         done_copies = 0
1219         done_classes = []
1220         for tries_left in loop:
1221             try:
1222                 sorted_roots = self.map_new_services(
1223                     roots_map, locator,
1224                     force_rebuild=(tries_left < num_retries),
1225                     need_writable=True,
1226                     headers=headers)
1227             except Exception as error:
1228                 loop.save_result(error)
1229                 continue
1230
1231             pending_classes = []
1232             if done_classes is not None:
1233                 pending_classes = list(set(classes) - set(done_classes))
1234             writer_pool = KeepClient.KeepWriterThreadPool(data=data,
1235                                                         data_hash=data_hash,
1236                                                         copies=copies - done_copies,
1237                                                         max_service_replicas=self.max_replicas_per_service,
1238                                                         timeout=self.current_timeout(num_retries - tries_left),
1239                                                         classes=pending_classes)
1240             for service_root, ks in [(root, roots_map[root])
1241                                      for root in sorted_roots]:
1242                 if ks.finished():
1243                     continue
1244                 writer_pool.add_task(ks, service_root)
1245             writer_pool.join()
1246             pool_copies, pool_classes = writer_pool.done()
1247             done_copies += pool_copies
1248             if (done_classes is not None) and (pool_classes is not None):
1249                 done_classes += pool_classes
1250                 loop.save_result(
1251                     (done_copies >= copies and set(done_classes) == set(classes),
1252                     writer_pool.total_task_nr))
1253             else:
1254                 # Old keepstore contacted without storage classes support:
1255                 # success is determined only by successful copies.
1256                 #
1257                 # Disable storage classes tracking from this point forward.
1258                 if not self._storage_classes_unsupported_warning:
1259                     self._storage_classes_unsupported_warning = True
1260                     _logger.warning("X-Keep-Storage-Classes header not supported by the cluster")
1261                 done_classes = None
1262                 loop.save_result(
1263                     (done_copies >= copies, writer_pool.total_task_nr))
1264
1265         if loop.success():
1266             return writer_pool.response()
1267         if not roots_map:
1268             raise arvados.errors.KeepWriteError(
1269                 "failed to write {}: no Keep services available ({})".format(
1270                     data_hash, loop.last_result()))
1271         else:
1272             service_errors = ((key, roots_map[key].last_result()['error'])
1273                               for key in sorted_roots
1274                               if roots_map[key].last_result()['error'])
1275             raise arvados.errors.KeepWriteError(
1276                 "failed to write {} after {} (wanted {} copies but wrote {})".format(
1277                     data_hash, loop.attempts_str(), (copies, classes), writer_pool.done()), service_errors, label="service")
1278
1279     def local_store_put(self, data, copies=1, num_retries=None, classes=[]):
1280         """A stub for put().
1281
1282         This method is used in place of the real put() method when
1283         using local storage (see constructor's local_store argument).
1284
1285         copies and num_retries arguments are ignored: they are here
1286         only for the sake of offering the same call signature as
1287         put().
1288
1289         Data stored this way can be retrieved via local_store_get().
1290         """
1291         md5 = hashlib.md5(data).hexdigest()
1292         locator = '%s+%d' % (md5, len(data))
1293         with open(os.path.join(self.local_store, md5 + '.tmp'), 'wb') as f:
1294             f.write(data)
1295         os.rename(os.path.join(self.local_store, md5 + '.tmp'),
1296                   os.path.join(self.local_store, md5))
1297         return locator
1298
1299     def local_store_get(self, loc_s, num_retries=None):
1300         """Companion to local_store_put()."""
1301         try:
1302             locator = KeepLocator(loc_s)
1303         except ValueError:
1304             raise arvados.errors.NotFoundError(
1305                 "Invalid data locator: '%s'" % loc_s)
1306         if locator.md5sum == config.EMPTY_BLOCK_LOCATOR.split('+')[0]:
1307             return b''
1308         with open(os.path.join(self.local_store, locator.md5sum), 'rb') as f:
1309             return f.read()
1310
1311     def local_store_head(self, loc_s, num_retries=None):
1312         """Companion to local_store_put()."""
1313         try:
1314             locator = KeepLocator(loc_s)
1315         except ValueError:
1316             raise arvados.errors.NotFoundError(
1317                 "Invalid data locator: '%s'" % loc_s)
1318         if locator.md5sum == config.EMPTY_BLOCK_LOCATOR.split('+')[0]:
1319             return True
1320         if os.path.exists(os.path.join(self.local_store, locator.md5sum)):
1321             return True
1322
1323     def is_cached(self, locator):
1324         return self.block_cache.reserve_cache(expect_hash)