deb-swift/swift/common/db_replicator.py
Lisak, Peter b6b7578190 node_timeout as float in configs
It is more convenient to use float node_timeout for fine tunning latency.

Change-Id: I7c57bba053711a27d3802efe6f2a0bf53483a54f
2015-10-19 21:14:34 +02:00

833 lines
36 KiB
Python

# Copyright (c) 2010-2012 OpenStack Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import os
import random
import math
import time
import shutil
import uuid
import errno
import re
from contextlib import contextmanager
from swift import gettext_ as _
from eventlet import GreenPool, sleep, Timeout
from eventlet.green import subprocess
import swift.common.db
from swift.common.direct_client import quote
from swift.common.utils import get_logger, whataremyips, storage_directory, \
renamer, mkdirs, lock_parent_directory, config_true_value, \
unlink_older_than, dump_recon_cache, rsync_module_interpolation, ismount, \
json, Timestamp
from swift.common import ring
from swift.common.ring.utils import is_local_device
from swift.common.http import HTTP_NOT_FOUND, HTTP_INSUFFICIENT_STORAGE
from swift.common.bufferedhttp import BufferedHTTPConnection
from swift.common.exceptions import DriveNotMounted
from swift.common.daemon import Daemon
from swift.common.swob import Response, HTTPNotFound, HTTPNoContent, \
HTTPAccepted, HTTPBadRequest
DEBUG_TIMINGS_THRESHOLD = 10
def quarantine_db(object_file, server_type):
"""
In the case that a corrupt file is found, move it to a quarantined area to
allow replication to fix it.
:param object_file: path to corrupt file
:param server_type: type of file that is corrupt
('container' or 'account')
"""
object_dir = os.path.dirname(object_file)
quarantine_dir = os.path.abspath(
os.path.join(object_dir, '..', '..', '..', '..', 'quarantined',
server_type + 's', os.path.basename(object_dir)))
try:
renamer(object_dir, quarantine_dir, fsync=False)
except OSError as e:
if e.errno not in (errno.EEXIST, errno.ENOTEMPTY):
raise
quarantine_dir = "%s-%s" % (quarantine_dir, uuid.uuid4().hex)
renamer(object_dir, quarantine_dir, fsync=False)
def roundrobin_datadirs(datadirs):
"""
Generator to walk the data dirs in a round robin manner, evenly
hitting each device on the system, and yielding any .db files
found (in their proper places). The partitions within each data
dir are walked randomly, however.
:param datadirs: a list of (path, node_id) to walk
:returns: A generator of (partition, path_to_db_file, node_id)
"""
def walk_datadir(datadir, node_id):
partitions = os.listdir(datadir)
random.shuffle(partitions)
for partition in partitions:
part_dir = os.path.join(datadir, partition)
if not os.path.isdir(part_dir):
continue
suffixes = os.listdir(part_dir)
if not suffixes:
os.rmdir(part_dir)
for suffix in suffixes:
suff_dir = os.path.join(part_dir, suffix)
if not os.path.isdir(suff_dir):
continue
hashes = os.listdir(suff_dir)
for hsh in hashes:
hash_dir = os.path.join(suff_dir, hsh)
if not os.path.isdir(hash_dir):
continue
object_file = os.path.join(hash_dir, hsh + '.db')
if os.path.exists(object_file):
yield (partition, object_file, node_id)
its = [walk_datadir(datadir, node_id) for datadir, node_id in datadirs]
while its:
for it in its:
try:
yield next(it)
except StopIteration:
its.remove(it)
class ReplConnection(BufferedHTTPConnection):
"""
Helper to simplify REPLICATEing to a remote server.
"""
def __init__(self, node, partition, hash_, logger):
""
self.logger = logger
self.node = node
host = "%s:%s" % (node['replication_ip'], node['replication_port'])
BufferedHTTPConnection.__init__(self, host)
self.path = '/%s/%s/%s' % (node['device'], partition, hash_)
def replicate(self, *args):
"""
Make an HTTP REPLICATE request
:param args: list of json-encodable objects
:returns: bufferedhttp response object
"""
try:
body = json.dumps(args)
self.request('REPLICATE', self.path, body,
{'Content-Type': 'application/json'})
response = self.getresponse()
response.data = response.read()
return response
except (Exception, Timeout):
self.logger.exception(
_('ERROR reading HTTP response from %s'), self.node)
return None
class Replicator(Daemon):
"""
Implements the logic for directing db replication.
"""
def __init__(self, conf, logger=None):
self.conf = conf
self.logger = logger or get_logger(conf, log_route='replicator')
self.root = conf.get('devices', '/srv/node')
self.mount_check = config_true_value(conf.get('mount_check', 'true'))
self.bind_ip = conf.get('bind_ip', '0.0.0.0')
self.port = int(conf.get('bind_port', self.default_port))
concurrency = int(conf.get('concurrency', 8))
self.cpool = GreenPool(size=concurrency)
swift_dir = conf.get('swift_dir', '/etc/swift')
self.ring = ring.Ring(swift_dir, ring_name=self.server_type)
self._local_device_ids = set()
self.per_diff = int(conf.get('per_diff', 1000))
self.max_diffs = int(conf.get('max_diffs') or 100)
self.interval = int(conf.get('interval') or
conf.get('run_pause') or 30)
self.node_timeout = float(conf.get('node_timeout', 10))
self.conn_timeout = float(conf.get('conn_timeout', 0.5))
self.rsync_compress = config_true_value(
conf.get('rsync_compress', 'no'))
self.rsync_module = conf.get('rsync_module', '').rstrip('/')
if not self.rsync_module:
self.rsync_module = '{replication_ip}::%s' % self.server_type
if config_true_value(conf.get('vm_test_mode', 'no')):
self.logger.warn('Option %(type)s-replicator/vm_test_mode is '
'deprecated and will be removed in a future '
'version. Update your configuration to use '
'option %(type)s-replicator/rsync_module.'
% {'type': self.server_type})
self.rsync_module += '{replication_port}'
self.reclaim_age = float(conf.get('reclaim_age', 86400 * 7))
swift.common.db.DB_PREALLOCATION = \
config_true_value(conf.get('db_preallocation', 'f'))
self._zero_stats()
self.recon_cache_path = conf.get('recon_cache_path',
'/var/cache/swift')
self.recon_replicator = '%s.recon' % self.server_type
self.rcache = os.path.join(self.recon_cache_path,
self.recon_replicator)
self.extract_device_re = re.compile('%s%s([^%s]+)' % (
self.root, os.path.sep, os.path.sep))
def _zero_stats(self):
"""Zero out the stats."""
self.stats = {'attempted': 0, 'success': 0, 'failure': 0, 'ts_repl': 0,
'no_change': 0, 'hashmatch': 0, 'rsync': 0, 'diff': 0,
'remove': 0, 'empty': 0, 'remote_merge': 0,
'start': time.time(), 'diff_capped': 0,
'failure_nodes': {}}
def _report_stats(self):
"""Report the current stats to the logs."""
now = time.time()
self.logger.info(
_('Attempted to replicate %(count)d dbs in %(time).5f seconds '
'(%(rate).5f/s)'),
{'count': self.stats['attempted'],
'time': now - self.stats['start'],
'rate': self.stats['attempted'] /
(now - self.stats['start'] + 0.0000001)})
self.logger.info(_('Removed %(remove)d dbs') % self.stats)
self.logger.info(_('%(success)s successes, %(failure)s failures')
% self.stats)
dump_recon_cache(
{'replication_stats': self.stats,
'replication_time': now - self.stats['start'],
'replication_last': now},
self.rcache, self.logger)
self.logger.info(' '.join(['%s:%s' % item for item in
self.stats.items() if item[0] in
('no_change', 'hashmatch', 'rsync', 'diff', 'ts_repl',
'empty', 'diff_capped')]))
def _add_failure_stats(self, failure_devs_info):
for node, dev in failure_devs_info:
self.stats['failure'] += 1
failure_devs = self.stats['failure_nodes'].setdefault(node, {})
failure_devs.setdefault(dev, 0)
failure_devs[dev] += 1
def _rsync_file(self, db_file, remote_file, whole_file=True,
different_region=False):
"""
Sync a single file using rsync. Used by _rsync_db to handle syncing.
:param db_file: file to be synced
:param remote_file: remote location to sync the DB file to
:param whole-file: if True, uses rsync's --whole-file flag
:param different_region: if True, the destination node is in a
different region
:returns: True if the sync was successful, False otherwise
"""
popen_args = ['rsync', '--quiet', '--no-motd',
'--timeout=%s' % int(math.ceil(self.node_timeout)),
'--contimeout=%s' % int(math.ceil(self.conn_timeout))]
if whole_file:
popen_args.append('--whole-file')
if self.rsync_compress and different_region:
# Allow for compression, but only if the remote node is in
# a different region than the local one.
popen_args.append('--compress')
popen_args.extend([db_file, remote_file])
proc = subprocess.Popen(popen_args)
proc.communicate()
if proc.returncode != 0:
self.logger.error(_('ERROR rsync failed with %(code)s: %(args)s'),
{'code': proc.returncode, 'args': popen_args})
return proc.returncode == 0
def _rsync_db(self, broker, device, http, local_id,
replicate_method='complete_rsync', replicate_timeout=None,
different_region=False):
"""
Sync a whole db using rsync.
:param broker: DB broker object of DB to be synced
:param device: device to sync to
:param http: ReplConnection object
:param local_id: unique ID of the local database replica
:param replicate_method: remote operation to perform after rsync
:param replicate_timeout: timeout to wait in seconds
:param different_region: if True, the destination node is in a
different region
"""
rsync_module = rsync_module_interpolation(self.rsync_module, device)
rsync_path = '%s/tmp/%s' % (device['device'], local_id)
remote_file = '%s/%s' % (rsync_module, rsync_path)
mtime = os.path.getmtime(broker.db_file)
if not self._rsync_file(broker.db_file, remote_file,
different_region=different_region):
return False
# perform block-level sync if the db was modified during the first sync
if os.path.exists(broker.db_file + '-journal') or \
os.path.getmtime(broker.db_file) > mtime:
# grab a lock so nobody else can modify it
with broker.lock():
if not self._rsync_file(broker.db_file, remote_file,
whole_file=False,
different_region=different_region):
return False
with Timeout(replicate_timeout or self.node_timeout):
response = http.replicate(replicate_method, local_id)
return response and response.status >= 200 and response.status < 300
def _usync_db(self, point, broker, http, remote_id, local_id):
"""
Sync a db by sending all records since the last sync.
:param point: synchronization high water mark between the replicas
:param broker: database broker object
:param http: ReplConnection object for the remote server
:param remote_id: database id for the remote replica
:param local_id: database id for the local replica
:returns: boolean indicating completion and success
"""
self.stats['diff'] += 1
self.logger.increment('diffs')
self.logger.debug('Syncing chunks with %s, starting at %s',
http.host, point)
sync_table = broker.get_syncs()
objects = broker.get_items_since(point, self.per_diff)
diffs = 0
while len(objects) and diffs < self.max_diffs:
diffs += 1
with Timeout(self.node_timeout):
response = http.replicate('merge_items', objects, local_id)
if not response or response.status >= 300 or response.status < 200:
if response:
self.logger.error(_('ERROR Bad response %(status)s from '
'%(host)s'),
{'status': response.status,
'host': http.host})
return False
# replication relies on db order to send the next merge batch in
# order with no gaps
point = objects[-1]['ROWID']
objects = broker.get_items_since(point, self.per_diff)
if objects:
self.logger.debug(
'Synchronization for %s has fallen more than '
'%s rows behind; moving on and will try again next pass.',
broker, self.max_diffs * self.per_diff)
self.stats['diff_capped'] += 1
self.logger.increment('diff_caps')
else:
with Timeout(self.node_timeout):
response = http.replicate('merge_syncs', sync_table)
if response and response.status >= 200 and response.status < 300:
broker.merge_syncs([{'remote_id': remote_id,
'sync_point': point}],
incoming=False)
return True
return False
def _in_sync(self, rinfo, info, broker, local_sync):
"""
Determine whether or not two replicas of a databases are considered
to be in sync.
:param rinfo: remote database info
:param info: local database info
:param broker: database broker object
:param local_sync: cached last sync point between replicas
:returns: boolean indicating whether or not the replicas are in sync
"""
if max(rinfo['point'], local_sync) >= info['max_row']:
self.stats['no_change'] += 1
self.logger.increment('no_changes')
return True
if rinfo['hash'] == info['hash']:
self.stats['hashmatch'] += 1
self.logger.increment('hashmatches')
broker.merge_syncs([{'remote_id': rinfo['id'],
'sync_point': rinfo['point']}],
incoming=False)
return True
def _http_connect(self, node, partition, db_file):
"""
Make an http_connection using ReplConnection
:param node: node dictionary from the ring
:param partition: partition partition to send in the url
:param db_file: DB file
:returns: ReplConnection object
"""
return ReplConnection(node, partition,
os.path.basename(db_file).split('.', 1)[0],
self.logger)
def _gather_sync_args(self, info):
"""
Convert local replication_info to sync args tuple.
"""
sync_args_order = ('max_row', 'hash', 'id', 'created_at',
'put_timestamp', 'delete_timestamp', 'metadata')
return tuple(info[key] for key in sync_args_order)
def _repl_to_node(self, node, broker, partition, info,
different_region=False):
"""
Replicate a database to a node.
:param node: node dictionary from the ring to be replicated to
:param broker: DB broker for the DB to be replication
:param partition: partition on the node to replicate to
:param info: DB info as a dictionary of {'max_row', 'hash', 'id',
'created_at', 'put_timestamp', 'delete_timestamp',
'metadata'}
:param different_region: if True, the destination node is in a
different region
:returns: True if successful, False otherwise
"""
http = self._http_connect(node, partition, broker.db_file)
sync_args = self._gather_sync_args(info)
with Timeout(self.node_timeout):
response = http.replicate('sync', *sync_args)
if not response:
return False
return self._handle_sync_response(node, response, info, broker, http,
different_region=different_region)
def _handle_sync_response(self, node, response, info, broker, http,
different_region=False):
if response.status == HTTP_NOT_FOUND: # completely missing, rsync
self.stats['rsync'] += 1
self.logger.increment('rsyncs')
return self._rsync_db(broker, node, http, info['id'],
different_region=different_region)
elif response.status == HTTP_INSUFFICIENT_STORAGE:
raise DriveNotMounted()
elif response.status >= 200 and response.status < 300:
rinfo = json.loads(response.data)
local_sync = broker.get_sync(rinfo['id'], incoming=False)
if self._in_sync(rinfo, info, broker, local_sync):
return True
# if the difference in rowids between the two differs by
# more than 50% and the difference is greater than per_diff,
# rsync then do a remote merge.
# NOTE: difference > per_diff stops us from dropping to rsync
# on smaller containers, who have only a few rows to sync.
if rinfo['max_row'] / float(info['max_row']) < 0.5 and \
info['max_row'] - rinfo['max_row'] > self.per_diff:
self.stats['remote_merge'] += 1
self.logger.increment('remote_merges')
return self._rsync_db(broker, node, http, info['id'],
replicate_method='rsync_then_merge',
replicate_timeout=(info['count'] / 2000),
different_region=different_region)
# else send diffs over to the remote server
return self._usync_db(max(rinfo['point'], local_sync),
broker, http, rinfo['id'], info['id'])
def _post_replicate_hook(self, broker, info, responses):
"""
:param broker: the container that just replicated
:param info: pre-replication full info dict
:param responses: a list of bools indicating success from nodes
"""
pass
def _replicate_object(self, partition, object_file, node_id):
"""
Replicate the db, choosing method based on whether or not it
already exists on peers.
:param partition: partition to be replicated to
:param object_file: DB file name to be replicated
:param node_id: node id of the node to be replicated to
"""
start_time = now = time.time()
self.logger.debug('Replicating db %s', object_file)
self.stats['attempted'] += 1
self.logger.increment('attempts')
shouldbehere = True
try:
broker = self.brokerclass(object_file, pending_timeout=30)
broker.reclaim(now - self.reclaim_age,
now - (self.reclaim_age * 2))
info = broker.get_replication_info()
bpart = self.ring.get_part(
info['account'], info.get('container'))
if bpart != int(partition):
partition = bpart
# Important to set this false here since the later check only
# checks if it's on the proper device, not partition.
shouldbehere = False
name = '/' + quote(info['account'])
if 'container' in info:
name += '/' + quote(info['container'])
self.logger.error(
'Found %s for %s when it should be on partition %s; will '
'replicate out and remove.' % (object_file, name, bpart))
except (Exception, Timeout) as e:
if 'no such table' in str(e):
self.logger.error(_('Quarantining DB %s'), object_file)
quarantine_db(broker.db_file, broker.db_type)
else:
self.logger.exception(_('ERROR reading db %s'), object_file)
nodes = self.ring.get_part_nodes(int(partition))
self._add_failure_stats([(failure_dev['replication_ip'],
failure_dev['device'])
for failure_dev in nodes])
self.logger.increment('failures')
return
# The db is considered deleted if the delete_timestamp value is greater
# than the put_timestamp, and there are no objects.
delete_timestamp = Timestamp(info.get('delete_timestamp') or 0)
put_timestamp = Timestamp(info.get('put_timestamp') or 0)
if delete_timestamp < (now - self.reclaim_age) and \
delete_timestamp > put_timestamp and \
info['count'] in (None, '', 0, '0'):
if self.report_up_to_date(info):
self.delete_db(broker)
self.logger.timing_since('timing', start_time)
return
responses = []
failure_devs_info = set()
nodes = self.ring.get_part_nodes(int(partition))
local_dev = None
for node in nodes:
if node['id'] == node_id:
local_dev = node
break
if shouldbehere:
shouldbehere = bool([n for n in nodes if n['id'] == node_id])
# See Footnote [1] for an explanation of the repl_nodes assignment.
i = 0
while i < len(nodes) and nodes[i]['id'] != node_id:
i += 1
repl_nodes = nodes[i + 1:] + nodes[:i]
more_nodes = self.ring.get_more_nodes(int(partition))
if not local_dev:
# Check further if local device is a handoff node
for node in more_nodes:
if node['id'] == node_id:
local_dev = node
break
for node in repl_nodes:
different_region = False
if local_dev and local_dev['region'] != node['region']:
# This additional information will help later if we
# want to handle syncing to a node in different
# region with some optimizations.
different_region = True
success = False
try:
success = self._repl_to_node(node, broker, partition, info,
different_region)
except DriveNotMounted:
repl_nodes.append(next(more_nodes))
self.logger.error(_('ERROR Remote drive not mounted %s'), node)
except (Exception, Timeout):
self.logger.exception(_('ERROR syncing %(file)s with node'
' %(node)s'),
{'file': object_file, 'node': node})
if not success:
failure_devs_info.add((node['replication_ip'], node['device']))
self.logger.increment('successes' if success else 'failures')
responses.append(success)
try:
self._post_replicate_hook(broker, info, responses)
except (Exception, Timeout):
self.logger.exception('UNHANDLED EXCEPTION: in post replicate '
'hook for %s', broker.db_file)
if not shouldbehere and all(responses):
# If the db shouldn't be on this node and has been successfully
# synced to all of its peers, it can be removed.
if not self.delete_db(broker):
failure_devs_info.update(
[(failure_dev['replication_ip'], failure_dev['device'])
for failure_dev in repl_nodes])
target_devs_info = set([(target_dev['replication_ip'],
target_dev['device'])
for target_dev in repl_nodes])
self.stats['success'] += len(target_devs_info - failure_devs_info)
self._add_failure_stats(failure_devs_info)
self.logger.timing_since('timing', start_time)
def delete_db(self, broker):
object_file = broker.db_file
hash_dir = os.path.dirname(object_file)
suf_dir = os.path.dirname(hash_dir)
with lock_parent_directory(object_file):
shutil.rmtree(hash_dir, True)
try:
os.rmdir(suf_dir)
except OSError as err:
if err.errno not in (errno.ENOENT, errno.ENOTEMPTY):
self.logger.exception(
_('ERROR while trying to clean up %s') % suf_dir)
return False
self.stats['remove'] += 1
device_name = self.extract_device(object_file)
self.logger.increment('removes.' + device_name)
return True
def extract_device(self, object_file):
"""
Extract the device name from an object path. Returns "UNKNOWN" if the
path could not be extracted successfully for some reason.
:param object_file: the path to a database file.
"""
match = self.extract_device_re.match(object_file)
if match:
return match.groups()[0]
return "UNKNOWN"
def report_up_to_date(self, full_info):
return True
def run_once(self, *args, **kwargs):
"""Run a replication pass once."""
self._zero_stats()
dirs = []
ips = whataremyips(self.bind_ip)
if not ips:
self.logger.error(_('ERROR Failed to get my own IPs?'))
return
self._local_device_ids = set()
for node in self.ring.devs:
if node and is_local_device(ips, self.port,
node['replication_ip'],
node['replication_port']):
if self.mount_check and not ismount(
os.path.join(self.root, node['device'])):
self._add_failure_stats(
[(failure_dev['replication_ip'],
failure_dev['device'])
for failure_dev in self.ring.devs if failure_dev])
self.logger.warn(
_('Skipping %(device)s as it is not mounted') % node)
continue
unlink_older_than(
os.path.join(self.root, node['device'], 'tmp'),
time.time() - self.reclaim_age)
datadir = os.path.join(self.root, node['device'], self.datadir)
if os.path.isdir(datadir):
self._local_device_ids.add(node['id'])
dirs.append((datadir, node['id']))
self.logger.info(_('Beginning replication run'))
for part, object_file, node_id in roundrobin_datadirs(dirs):
self.cpool.spawn_n(
self._replicate_object, part, object_file, node_id)
self.cpool.waitall()
self.logger.info(_('Replication run OVER'))
self._report_stats()
def run_forever(self, *args, **kwargs):
"""
Replicate dbs under the given root in an infinite loop.
"""
sleep(random.random() * self.interval)
while True:
begin = time.time()
try:
self.run_once()
except (Exception, Timeout):
self.logger.exception(_('ERROR trying to replicate'))
elapsed = time.time() - begin
if elapsed < self.interval:
sleep(self.interval - elapsed)
class ReplicatorRpc(object):
"""Handle Replication RPC calls. TODO(redbo): document please :)"""
def __init__(self, root, datadir, broker_class, mount_check=True,
logger=None):
self.root = root
self.datadir = datadir
self.broker_class = broker_class
self.mount_check = mount_check
self.logger = logger or get_logger({}, log_route='replicator-rpc')
def dispatch(self, replicate_args, args):
if not hasattr(args, 'pop'):
return HTTPBadRequest(body='Invalid object type')
op = args.pop(0)
drive, partition, hsh = replicate_args
if self.mount_check and not ismount(os.path.join(self.root, drive)):
return Response(status='507 %s is not mounted' % drive)
db_file = os.path.join(self.root, drive,
storage_directory(self.datadir, partition, hsh),
hsh + '.db')
if op == 'rsync_then_merge':
return self.rsync_then_merge(drive, db_file, args)
if op == 'complete_rsync':
return self.complete_rsync(drive, db_file, args)
else:
# someone might be about to rsync a db to us,
# make sure there's a tmp dir to receive it.
mkdirs(os.path.join(self.root, drive, 'tmp'))
if not os.path.exists(db_file):
return HTTPNotFound()
return getattr(self, op)(self.broker_class(db_file), args)
@contextmanager
def debug_timing(self, name):
timemark = time.time()
yield
timespan = time.time() - timemark
if timespan > DEBUG_TIMINGS_THRESHOLD:
self.logger.debug(
'replicator-rpc-sync time for %s: %.02fs' % (
name, timespan))
def _parse_sync_args(self, args):
"""
Convert remote sync args to remote_info dictionary.
"""
(remote_sync, hash_, id_, created_at, put_timestamp,
delete_timestamp, metadata) = args[:7]
remote_metadata = {}
if metadata:
try:
remote_metadata = json.loads(metadata)
except ValueError:
self.logger.error("Unable to decode remote metadata %r",
metadata)
remote_info = {
'point': remote_sync,
'hash': hash_,
'id': id_,
'created_at': created_at,
'put_timestamp': put_timestamp,
'delete_timestamp': delete_timestamp,
'metadata': remote_metadata,
}
return remote_info
def sync(self, broker, args):
remote_info = self._parse_sync_args(args)
return self._handle_sync_request(broker, remote_info)
def _get_synced_replication_info(self, broker, remote_info):
"""
Apply any changes to the broker based on remote_info and return the
current replication info.
:param broker: the database broker
:param remote_info: the remote replication info
:returns: local broker replication info
"""
return broker.get_replication_info()
def _handle_sync_request(self, broker, remote_info):
"""
Update metadata, timestamps, sync points.
"""
with self.debug_timing('info'):
try:
info = self._get_synced_replication_info(broker, remote_info)
except (Exception, Timeout) as e:
if 'no such table' in str(e):
self.logger.error(_("Quarantining DB %s"), broker)
quarantine_db(broker.db_file, broker.db_type)
return HTTPNotFound()
raise
if remote_info['metadata']:
with self.debug_timing('update_metadata'):
broker.update_metadata(remote_info['metadata'])
sync_timestamps = ('created_at', 'put_timestamp', 'delete_timestamp')
if any(info[ts] != remote_info[ts] for ts in sync_timestamps):
with self.debug_timing('merge_timestamps'):
broker.merge_timestamps(*(remote_info[ts] for ts in
sync_timestamps))
with self.debug_timing('get_sync'):
info['point'] = broker.get_sync(remote_info['id'])
if remote_info['hash'] == info['hash'] and \
info['point'] < remote_info['point']:
with self.debug_timing('merge_syncs'):
translate = {
'remote_id': 'id',
'sync_point': 'point',
}
data = dict((k, remote_info[v]) for k, v in translate.items())
broker.merge_syncs([data])
info['point'] = remote_info['point']
return Response(json.dumps(info))
def merge_syncs(self, broker, args):
broker.merge_syncs(args[0])
return HTTPAccepted()
def merge_items(self, broker, args):
broker.merge_items(args[0], args[1])
return HTTPAccepted()
def complete_rsync(self, drive, db_file, args):
old_filename = os.path.join(self.root, drive, 'tmp', args[0])
if os.path.exists(db_file):
return HTTPNotFound()
if not os.path.exists(old_filename):
return HTTPNotFound()
broker = self.broker_class(old_filename)
broker.newid(args[0])
renamer(old_filename, db_file)
return HTTPNoContent()
def rsync_then_merge(self, drive, db_file, args):
old_filename = os.path.join(self.root, drive, 'tmp', args[0])
if not os.path.exists(db_file) or not os.path.exists(old_filename):
return HTTPNotFound()
new_broker = self.broker_class(old_filename)
existing_broker = self.broker_class(db_file)
point = -1
objects = existing_broker.get_items_since(point, 1000)
while len(objects):
new_broker.merge_items(objects)
point = objects[-1]['ROWID']
objects = existing_broker.get_items_since(point, 1000)
sleep()
new_broker.newid(args[0])
renamer(old_filename, db_file)
return HTTPNoContent()
# Footnote [1]:
# This orders the nodes so that, given nodes a b c, a will contact b then c,
# b will contact c then a, and c will contact a then b -- in other words, each
# node will always contact the next node in the list first.
# This helps in the case where databases are all way out of sync, so each
# node is likely to be sending to a different node than it's receiving from,
# rather than two nodes talking to each other, starving out the third.
# If the third didn't even have a copy and the first two nodes were way out
# of sync, such starvation would mean the third node wouldn't get any copy
# until the first two nodes finally got in sync, which could take a while.
# This new ordering ensures such starvation doesn't occur, making the data
# more durable.