622 lines
23 KiB
Python
622 lines
23 KiB
Python
# Copyright (c) 2010-2012 OpenStack Foundation
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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# implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import array
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import six.moves.cPickle as pickle
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import json
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from collections import defaultdict
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from gzip import GzipFile
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from os.path import getmtime
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import struct
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from time import time
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import os
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from hashlib import md5
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from itertools import chain, count
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from tempfile import NamedTemporaryFile
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import sys
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import zlib
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from six.moves import range
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from swift.common.exceptions import RingLoadError
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from swift.common.utils import hash_path, validate_configuration
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from swift.common.ring.utils import tiers_for_dev
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def calc_replica_count(replica2part2dev_id):
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base = len(replica2part2dev_id) - 1
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extra = 1.0 * len(replica2part2dev_id[-1]) / len(replica2part2dev_id[0])
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return base + extra
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class RingReader(object):
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chunk_size = 2 ** 16
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def __init__(self, filename):
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self.fp = open(filename, 'rb')
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self._reset()
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def _reset(self):
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self._buffer = b''
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self.size = 0
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self.raw_size = 0
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self._md5 = md5()
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self._decomp = zlib.decompressobj(32 + zlib.MAX_WBITS)
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@property
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def close(self):
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return self.fp.close
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def seek(self, pos, ref=0):
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if (pos, ref) != (0, 0):
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raise NotImplementedError
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self._reset()
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return self.fp.seek(pos, ref)
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def _buffer_chunk(self):
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chunk = self.fp.read(self.chunk_size)
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if not chunk:
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return False
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self.size += len(chunk)
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self._md5.update(chunk)
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chunk = self._decomp.decompress(chunk)
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self.raw_size += len(chunk)
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self._buffer += chunk
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return True
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def read(self, amount=-1):
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if amount < 0:
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raise IOError("don't be greedy")
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while amount > len(self._buffer):
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if not self._buffer_chunk():
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break
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result, self._buffer = self._buffer[:amount], self._buffer[amount:]
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return result
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def readline(self):
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# apparently pickle needs this?
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while b'\n' not in self._buffer:
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if not self._buffer_chunk():
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break
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line, sep, self._buffer = self._buffer.partition(b'\n')
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return line + sep
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@property
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def md5(self):
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return self._md5.hexdigest()
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class RingData(object):
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"""Partitioned consistent hashing ring data (used for serialization)."""
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def __init__(self, replica2part2dev_id, devs, part_shift,
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next_part_power=None, version=None):
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self.devs = devs
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self._replica2part2dev_id = replica2part2dev_id
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self._part_shift = part_shift
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self.next_part_power = next_part_power
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self.version = version
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self.md5 = self.size = self.raw_size = None
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for dev in self.devs:
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if dev is not None:
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dev.setdefault("region", 1)
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@property
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def replica_count(self):
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"""Number of replicas (full or partial) used in the ring."""
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return calc_replica_count(self._replica2part2dev_id)
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@classmethod
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def deserialize_v1(cls, gz_file, metadata_only=False):
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"""
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Deserialize a v1 ring file into a dictionary with `devs`, `part_shift`,
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and `replica2part2dev_id` keys.
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If the optional kwarg `metadata_only` is True, then the
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`replica2part2dev_id` is not loaded and that key in the returned
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dictionary just has the value `[]`.
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:param file gz_file: An opened file-like object which has already
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consumed the 6 bytes of magic and version.
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:param bool metadata_only: If True, only load `devs` and `part_shift`
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:returns: A dict containing `devs`, `part_shift`, and
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`replica2part2dev_id`
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"""
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json_len, = struct.unpack('!I', gz_file.read(4))
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ring_dict = json.loads(gz_file.read(json_len))
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ring_dict['replica2part2dev_id'] = []
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if metadata_only:
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return ring_dict
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byteswap = (ring_dict.get('byteorder', sys.byteorder) != sys.byteorder)
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partition_count = 1 << (32 - ring_dict['part_shift'])
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for x in range(ring_dict['replica_count']):
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part2dev = array.array('H', gz_file.read(2 * partition_count))
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if byteswap:
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part2dev.byteswap()
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ring_dict['replica2part2dev_id'].append(part2dev)
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return ring_dict
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@classmethod
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def load(cls, filename, metadata_only=False):
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"""
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Load ring data from a file.
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:param filename: Path to a file serialized by the save() method.
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:param bool metadata_only: If True, only load `devs` and `part_shift`.
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:returns: A RingData instance containing the loaded data.
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"""
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gz_file = RingReader(filename)
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# See if the file is in the new format
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magic = gz_file.read(4)
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if magic == b'R1NG':
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format_version, = struct.unpack('!H', gz_file.read(2))
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if format_version == 1:
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ring_data = cls.deserialize_v1(
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gz_file, metadata_only=metadata_only)
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else:
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raise Exception('Unknown ring format version %d' %
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format_version)
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else:
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# Assume old-style pickled ring
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gz_file.seek(0)
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ring_data = pickle.load(gz_file)
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if not hasattr(ring_data, 'devs'):
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ring_data = RingData(ring_data['replica2part2dev_id'],
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ring_data['devs'], ring_data['part_shift'],
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ring_data.get('next_part_power'),
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ring_data.get('version'))
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for attr in ('md5', 'size', 'raw_size'):
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setattr(ring_data, attr, getattr(gz_file, attr))
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return ring_data
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def serialize_v1(self, file_obj):
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# Write out new-style serialization magic and version:
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file_obj.write(struct.pack('!4sH', b'R1NG', 1))
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ring = self.to_dict()
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# Only include next_part_power if it is set in the
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# builder, otherwise just ignore it
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_text = {'devs': ring['devs'], 'part_shift': ring['part_shift'],
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'replica_count': len(ring['replica2part2dev_id']),
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'byteorder': sys.byteorder}
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if ring['version'] is not None:
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_text['version'] = ring['version']
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next_part_power = ring.get('next_part_power')
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if next_part_power is not None:
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_text['next_part_power'] = next_part_power
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json_text = json.dumps(_text, sort_keys=True,
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ensure_ascii=True).encode('ascii')
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json_len = len(json_text)
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file_obj.write(struct.pack('!I', json_len))
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file_obj.write(json_text)
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for part2dev_id in ring['replica2part2dev_id']:
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file_obj.write(part2dev_id.tostring())
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def save(self, filename, mtime=1300507380.0):
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"""
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Serialize this RingData instance to disk.
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:param filename: File into which this instance should be serialized.
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:param mtime: time used to override mtime for gzip, default or None
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if the caller wants to include time
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"""
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# Override the timestamp so that the same ring data creates
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# the same bytes on disk. This makes a checksum comparison a
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# good way to see if two rings are identical.
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tempf = NamedTemporaryFile(dir=".", prefix=filename, delete=False)
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gz_file = GzipFile(filename, mode='wb', fileobj=tempf, mtime=mtime)
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self.serialize_v1(gz_file)
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gz_file.close()
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tempf.flush()
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os.fsync(tempf.fileno())
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tempf.close()
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os.chmod(tempf.name, 0o644)
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os.rename(tempf.name, filename)
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def to_dict(self):
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return {'devs': self.devs,
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'replica2part2dev_id': self._replica2part2dev_id,
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'part_shift': self._part_shift,
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'next_part_power': self.next_part_power,
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'version': self.version}
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class Ring(object):
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"""
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Partitioned consistent hashing ring.
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:param serialized_path: path to serialized RingData instance
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:param reload_time: time interval in seconds to check for a ring change
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:param ring_name: ring name string (basically specified from policy)
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:param validation_hook: hook point to validate ring configuration ontime
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:raises RingLoadError: if the loaded ring data violates its constraint
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"""
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def __init__(self, serialized_path, reload_time=15, ring_name=None,
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validation_hook=lambda ring_data: None):
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# can't use the ring unless HASH_PATH_SUFFIX is set
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validate_configuration()
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if ring_name:
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self.serialized_path = os.path.join(serialized_path,
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ring_name + '.ring.gz')
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else:
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self.serialized_path = os.path.join(serialized_path)
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self.reload_time = reload_time
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self._validation_hook = validation_hook
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self._reload(force=True)
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def _reload(self, force=False):
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self._rtime = time() + self.reload_time
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if force or self.has_changed():
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ring_data = RingData.load(self.serialized_path)
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try:
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self._validation_hook(ring_data)
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except RingLoadError:
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if force:
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raise
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else:
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# In runtime reload at working server, it's ok to use old
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# ring data if the new ring data is invalid.
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return
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self._mtime = getmtime(self.serialized_path)
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self._devs = ring_data.devs
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# NOTE(akscram): Replication parameters like replication_ip
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# and replication_port are required for
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# replication process. An old replication
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# ring doesn't contain this parameters into
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# device. Old-style pickled rings won't have
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# region information.
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for dev in self._devs:
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if dev:
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dev.setdefault('region', 1)
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if 'ip' in dev:
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dev.setdefault('replication_ip', dev['ip'])
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if 'port' in dev:
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dev.setdefault('replication_port', dev['port'])
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self._replica2part2dev_id = ring_data._replica2part2dev_id
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self._part_shift = ring_data._part_shift
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self._rebuild_tier_data()
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self._update_bookkeeping()
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self._next_part_power = ring_data.next_part_power
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self._version = ring_data.version
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self._md5 = ring_data.md5
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self._size = ring_data.size
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self._raw_size = ring_data.raw_size
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def _update_bookkeeping(self):
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# Do this now, when we know the data has changed, rather than
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# doing it on every call to get_more_nodes().
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#
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# Since this is to speed up the finding of handoffs, we only
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# consider devices with at least one partition assigned. This
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# way, a region, zone, or server with no partitions assigned
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# does not count toward our totals, thereby keeping the early
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# bailouts in get_more_nodes() working.
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dev_ids_with_parts = set()
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for part2dev_id in self._replica2part2dev_id:
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for dev_id in part2dev_id:
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dev_ids_with_parts.add(dev_id)
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regions = set()
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zones = set()
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ips = set()
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self._num_devs = 0
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self._num_assigned_devs = 0
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self._num_weighted_devs = 0
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for dev in self._devs:
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if dev is None:
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continue
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self._num_devs += 1
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if dev.get('weight', 0) > 0:
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self._num_weighted_devs += 1
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if dev['id'] in dev_ids_with_parts:
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regions.add(dev['region'])
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zones.add((dev['region'], dev['zone']))
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ips.add((dev['region'], dev['zone'], dev['ip']))
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self._num_assigned_devs += 1
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self._num_regions = len(regions)
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self._num_zones = len(zones)
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self._num_ips = len(ips)
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@property
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def next_part_power(self):
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return self._next_part_power
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@property
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def part_power(self):
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return 32 - self._part_shift
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@property
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def version(self):
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return self._version
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@property
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def md5(self):
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return self._md5
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@property
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def size(self):
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return self._size
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@property
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def raw_size(self):
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return self._raw_size
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def _rebuild_tier_data(self):
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self.tier2devs = defaultdict(list)
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for dev in self._devs:
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if not dev:
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continue
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for tier in tiers_for_dev(dev):
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self.tier2devs[tier].append(dev)
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tiers_by_length = defaultdict(list)
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for tier in self.tier2devs:
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tiers_by_length[len(tier)].append(tier)
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self.tiers_by_length = sorted(tiers_by_length.values(),
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key=lambda x: len(x[0]))
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for tiers in self.tiers_by_length:
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tiers.sort()
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@property
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def replica_count(self):
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"""Number of replicas (full or partial) used in the ring."""
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return calc_replica_count(self._replica2part2dev_id)
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@property
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def partition_count(self):
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"""Number of partitions in the ring."""
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return len(self._replica2part2dev_id[0])
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@property
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def device_count(self):
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"""Number of devices in the ring."""
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return self._num_devs
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@property
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def weighted_device_count(self):
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"""Number of devices with weight in the ring."""
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return self._num_weighted_devs
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@property
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def assigned_device_count(self):
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"""Number of devices with assignments in the ring."""
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return self._num_assigned_devs
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@property
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def devs(self):
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"""devices in the ring"""
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if time() > self._rtime:
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self._reload()
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return self._devs
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def has_changed(self):
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"""
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Check to see if the ring on disk is different than the current one in
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memory.
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:returns: True if the ring on disk has changed, False otherwise
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"""
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return getmtime(self.serialized_path) != self._mtime
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def _get_part_nodes(self, part):
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part_nodes = []
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seen_ids = set()
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for r2p2d in self._replica2part2dev_id:
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if part < len(r2p2d):
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dev_id = r2p2d[part]
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if dev_id not in seen_ids:
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part_nodes.append(self.devs[dev_id])
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seen_ids.add(dev_id)
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return [dict(node, index=i) for i, node in enumerate(part_nodes)]
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def get_part(self, account, container=None, obj=None):
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"""
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Get the partition for an account/container/object.
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:param account: account name
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:param container: container name
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:param obj: object name
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:returns: the partition number
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"""
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key = hash_path(account, container, obj, raw_digest=True)
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if time() > self._rtime:
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self._reload()
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part = struct.unpack_from('>I', key)[0] >> self._part_shift
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return part
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def get_part_nodes(self, part):
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"""
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Get the nodes that are responsible for the partition. If one
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node is responsible for more than one replica of the same
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partition, it will only appear in the output once.
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:param part: partition to get nodes for
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:returns: list of node dicts
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See :func:`get_nodes` for a description of the node dicts.
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"""
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if time() > self._rtime:
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self._reload()
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return self._get_part_nodes(part)
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def get_nodes(self, account, container=None, obj=None):
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"""
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Get the partition and nodes for an account/container/object.
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If a node is responsible for more than one replica, it will
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only appear in the output once.
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:param account: account name
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:param container: container name
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:param obj: object name
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:returns: a tuple of (partition, list of node dicts)
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Each node dict will have at least the following keys:
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====== ===============================================================
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id unique integer identifier amongst devices
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index offset into the primary node list for the partition
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weight a float of the relative weight of this device as compared to
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others; this indicates how many partitions the builder will try
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to assign to this device
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zone integer indicating which zone the device is in; a given
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partition will not be assigned to multiple devices within the
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same zone
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ip the ip address of the device
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port the tcp port of the device
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device the device's name on disk (sdb1, for example)
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meta general use 'extra' field; for example: the online date, the
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hardware description
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====== ===============================================================
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"""
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part = self.get_part(account, container, obj)
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return part, self._get_part_nodes(part)
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def get_more_nodes(self, part):
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"""
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Generator to get extra nodes for a partition for hinted handoff.
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The handoff nodes will try to be in zones other than the
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primary zones, will take into account the device weights, and
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will usually keep the same sequences of handoffs even with
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ring changes.
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:param part: partition to get handoff nodes for
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:returns: generator of node dicts
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See :func:`get_nodes` for a description of the node dicts.
|
|
"""
|
|
if time() > self._rtime:
|
|
self._reload()
|
|
primary_nodes = self._get_part_nodes(part)
|
|
used = set(d['id'] for d in primary_nodes)
|
|
index = count()
|
|
same_regions = set(d['region'] for d in primary_nodes)
|
|
same_zones = set((d['region'], d['zone']) for d in primary_nodes)
|
|
same_ips = set(
|
|
(d['region'], d['zone'], d['ip']) for d in primary_nodes)
|
|
|
|
parts = len(self._replica2part2dev_id[0])
|
|
part_hash = md5(str(part).encode('ascii')).digest()
|
|
start = struct.unpack_from('>I', part_hash)[0] >> self._part_shift
|
|
inc = int(parts / 65536) or 1
|
|
# Multiple loops for execution speed; the checks and bookkeeping get
|
|
# simpler as you go along
|
|
hit_all_regions = len(same_regions) == self._num_regions
|
|
for handoff_part in chain(range(start, parts, inc),
|
|
range(inc - ((parts - start) % inc),
|
|
start, inc)):
|
|
if hit_all_regions:
|
|
# At this point, there are no regions left untouched, so we
|
|
# can stop looking.
|
|
break
|
|
for part2dev_id in self._replica2part2dev_id:
|
|
if handoff_part < len(part2dev_id):
|
|
dev_id = part2dev_id[handoff_part]
|
|
dev = self._devs[dev_id]
|
|
region = dev['region']
|
|
if dev_id not in used and region not in same_regions:
|
|
yield dict(dev, handoff_index=next(index))
|
|
used.add(dev_id)
|
|
same_regions.add(region)
|
|
zone = dev['zone']
|
|
ip = (region, zone, dev['ip'])
|
|
same_zones.add((region, zone))
|
|
same_ips.add(ip)
|
|
if len(same_regions) == self._num_regions:
|
|
hit_all_regions = True
|
|
break
|
|
|
|
hit_all_zones = len(same_zones) == self._num_zones
|
|
for handoff_part in chain(range(start, parts, inc),
|
|
range(inc - ((parts - start) % inc),
|
|
start, inc)):
|
|
if hit_all_zones:
|
|
# Much like we stopped looking for fresh regions before, we
|
|
# can now stop looking for fresh zones; there are no more.
|
|
break
|
|
for part2dev_id in self._replica2part2dev_id:
|
|
if handoff_part < len(part2dev_id):
|
|
dev_id = part2dev_id[handoff_part]
|
|
dev = self._devs[dev_id]
|
|
zone = (dev['region'], dev['zone'])
|
|
if dev_id not in used and zone not in same_zones:
|
|
yield dict(dev, handoff_index=next(index))
|
|
used.add(dev_id)
|
|
same_zones.add(zone)
|
|
ip = zone + (dev['ip'],)
|
|
same_ips.add(ip)
|
|
if len(same_zones) == self._num_zones:
|
|
hit_all_zones = True
|
|
break
|
|
|
|
hit_all_ips = len(same_ips) == self._num_ips
|
|
for handoff_part in chain(range(start, parts, inc),
|
|
range(inc - ((parts - start) % inc),
|
|
start, inc)):
|
|
if hit_all_ips:
|
|
# We've exhausted the pool of unused backends, so stop
|
|
# looking.
|
|
break
|
|
for part2dev_id in self._replica2part2dev_id:
|
|
if handoff_part < len(part2dev_id):
|
|
dev_id = part2dev_id[handoff_part]
|
|
dev = self._devs[dev_id]
|
|
ip = (dev['region'], dev['zone'], dev['ip'])
|
|
if dev_id not in used and ip not in same_ips:
|
|
yield dict(dev, handoff_index=next(index))
|
|
used.add(dev_id)
|
|
same_ips.add(ip)
|
|
if len(same_ips) == self._num_ips:
|
|
hit_all_ips = True
|
|
break
|
|
|
|
hit_all_devs = len(used) == self._num_assigned_devs
|
|
for handoff_part in chain(range(start, parts, inc),
|
|
range(inc - ((parts - start) % inc),
|
|
start, inc)):
|
|
if hit_all_devs:
|
|
# We've used every device we have, so let's stop looking for
|
|
# unused devices now.
|
|
break
|
|
for part2dev_id in self._replica2part2dev_id:
|
|
if handoff_part < len(part2dev_id):
|
|
dev_id = part2dev_id[handoff_part]
|
|
if dev_id not in used:
|
|
dev = self._devs[dev_id]
|
|
yield dict(dev, handoff_index=next(index))
|
|
used.add(dev_id)
|
|
if len(used) == self._num_assigned_devs:
|
|
hit_all_devs = True
|
|
break
|