/usr/share/pyshared/londiste/syncer.py is in skytools 2.1.12-6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 | """Catch moment when tables are in sync on master and slave.
"""
import sys, time, skytools
class Syncer(skytools.DBScript):
"""Walks tables in primary key order and checks if data matches."""
def __init__(self, args):
skytools.DBScript.__init__(self, 'londiste', args)
self.set_single_loop(1)
self.pgq_queue_name = self.cf.get("pgq_queue_name")
self.pgq_consumer_id = self.cf.get('pgq_consumer_id', self.job_name)
self.lock_timeout = self.cf.getfloat('lock_timeout', 10)
if self.pidfile:
self.pidfile += ".repair"
def set_lock_timeout(self, curs):
ms = int(1000 * self.lock_timeout)
if ms > 0:
q = "SET LOCAL statement_timeout = %d" % ms
self.log.debug(q)
curs.execute(q)
def init_optparse(self, p=None):
p = skytools.DBScript.init_optparse(self, p)
p.add_option("--force", action="store_true", help="ignore lag")
return p
def check_consumer(self, setup_curs):
# before locking anything check if consumer is working ok
q = "select extract(epoch from ticker_lag) from pgq.get_queue_info(%s)"
setup_curs.execute(q, [self.pgq_queue_name])
ticker_lag = setup_curs.fetchone()[0]
q = "select extract(epoch from lag)"\
" from pgq.get_consumer_info(%s, %s)"
setup_curs.execute(q, [self.pgq_queue_name, self.pgq_consumer_id])
res = setup_curs.fetchall()
if len(res) == 0:
self.log.error('No such consumer')
sys.exit(1)
consumer_lag = res[0][0]
if consumer_lag > ticker_lag + 10 and not self.options.force:
self.log.error('Consumer lagging too much, cannot proceed')
sys.exit(1)
def get_subscriber_table_state(self, dst_db):
dst_curs = dst_db.cursor()
q = "select * from londiste.subscriber_get_table_list(%s)"
dst_curs.execute(q, [self.pgq_queue_name])
res = dst_curs.dictfetchall()
dst_db.commit()
return res
def work(self):
src_loc = self.cf.get('provider_db')
lock_db = self.get_database('provider_db', cache='lock_db')
setup_db = self.get_database('provider_db', cache='setup_db', autocommit = 1)
src_db = self.get_database('provider_db',
isolation_level = skytools.I_SERIALIZABLE)
dst_db = self.get_database('subscriber_db',
isolation_level = skytools.I_SERIALIZABLE)
setup_curs = setup_db.cursor()
self.check_consumer(setup_curs)
state_list = self.get_subscriber_table_state(dst_db)
state_map = {}
full_list = []
for ts in state_list:
name = ts['table_name']
full_list.append(name)
state_map[name] = ts
if len(self.args) > 2:
tlist = self.args[2:]
else:
tlist = full_list
for tbl in tlist:
tbl = skytools.fq_name(tbl)
if not tbl in state_map:
self.log.warning('Table not subscribed: %s' % tbl)
continue
st = state_map[tbl]
if st['merge_state'] != 'ok':
self.log.info('Table %s not synced yet, no point' % tbl)
continue
self.check_table(tbl, lock_db, src_db, dst_db, setup_curs)
lock_db.commit()
src_db.commit()
dst_db.commit()
def force_tick(self, setup_curs):
q = "select pgq.force_tick(%s)"
setup_curs.execute(q, [self.pgq_queue_name])
res = setup_curs.fetchone()
cur_pos = res[0]
start = time.time()
while 1:
time.sleep(0.5)
setup_curs.execute(q, [self.pgq_queue_name])
res = setup_curs.fetchone()
if res[0] != cur_pos:
# new pos
return res[0]
# dont loop more than 10 secs
dur = time.time() - start
if dur > 10 and not self.options.force:
raise Exception("Ticker seems dead")
def check_table(self, tbl, lock_db, src_db, dst_db, setup_curs):
"""Get transaction to same state, then process."""
lock_curs = lock_db.cursor()
src_curs = src_db.cursor()
dst_curs = dst_db.cursor()
if not skytools.exists_table(src_curs, tbl):
self.log.warning("Table %s does not exist on provider side" % tbl)
return
if not skytools.exists_table(dst_curs, tbl):
self.log.warning("Table %s does not exist on subscriber side" % tbl)
return
# lock table in separate connection
self.log.info('Locking %s' % tbl)
lock_db.commit()
self.set_lock_timeout(lock_curs)
lock_time = time.time()
lock_curs.execute("LOCK TABLE %s IN SHARE MODE" % skytools.quote_fqident(tbl))
# now wait until consumer has updated target table until locking
self.log.info('Syncing %s' % tbl)
# consumer must get futher than this tick
tick_id = self.force_tick(setup_curs)
# try to force second tick also
self.force_tick(setup_curs)
# take server time
setup_curs.execute("select to_char(now(), 'YYYY-MM-DD HH24:MI:SS.MS')")
tpos = setup_curs.fetchone()[0]
# now wait
while 1:
time.sleep(0.5)
q = "select now() - lag > timestamp %s, now(), lag"\
" from pgq.get_consumer_info(%s, %s)"
setup_curs.execute(q, [tpos, self.pgq_queue_name, self.pgq_consumer_id])
res = setup_curs.fetchall()
if len(res) == 0:
raise Exception('No such consumer')
row = res[0]
self.log.debug("tpos=%s now=%s lag=%s ok=%s" % (tpos, row[1], row[2], row[0]))
if row[0]:
break
# limit lock time
if time.time() > lock_time + self.lock_timeout and not self.options.force:
self.log.error('Consumer lagging too much, exiting')
lock_db.rollback()
sys.exit(1)
# take snapshot on provider side
src_db.commit()
src_curs.execute("SELECT 1")
# take snapshot on subscriber side
dst_db.commit()
dst_curs.execute("SELECT 1")
# release lock
lock_db.commit()
# do work
self.process_sync(tbl, src_db, dst_db)
# done
src_db.commit()
dst_db.commit()
def process_sync(self, tbl, src_db, dst_db):
"""It gets 2 connections in state where tbl should be in same state.
"""
raise Exception('process_sync not implemented')
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