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#!/usr/bin/env python3
#
# varnish_queue.py - handle varnish purging queues
#
# Spawns a worker for each of the varnish servers, each will drain
# it's own queue as quickly as it can when told to do so by a notify.
#
import time
import sys
import select
import requests
import multiprocessing
import logging
import psycopg2
from setproctitle import setproctitle
def do_purge(consumername, extraheaders):
try:
headers = {'Host': 'www.postgresql.org'}
headers.update(extraheaders)
r = requests.get("https://{}.postgresql.org/varnish-purge-url".format(consumername),
headers=headers,
timeout=10)
if r.status_code == 200:
return True
logging.warning("Varnish purge on %s returned status %s (%s)" % (consumername, r.status_code, r.reason))
return False
except Exception as ex:
logging.error("Exception purging on %s: %s" % (consumername, ex))
return False
return True
def worker(consumerid, consumername, dsn):
logging.info("Starting worker for %s" % consumername)
setproctitle("varnish_queue - worker for %s" % consumername)
conn = psycopg2.connect(dsn)
curs = conn.cursor()
curs.execute("LISTEN varnishqueue")
conn.commit()
while True:
# See if there is something to pick up off the queue
curs.execute("SELECT id, mode, expr FROM varnishqueue.queue WHERE consumerid=%(consumerid)s AND completed IS NULL FOR UPDATE", {
'consumerid': consumerid,
})
res = curs.fetchall()
failed = False
if len(res):
idlist = []
for r in res:
# Do something with this entry...
if r[1] == 'P':
logging.info("Purging url %s on %s" % (r[2], consumername))
if not do_purge(consumername, {'X-Purge-URL': r[2]}):
# Failed, but we will try again, so don't add to list of removals
failed = True
continue
elif r[1] == 'X':
logging.info("Purging expression %s on %s" % (r[2], consumername))
if not do_purge(consumername, {'X-Purge-Expr': r[2]}):
failed = True
continue
elif r[1] == 'K':
logging.info("Purging xkey %s on %s" % (r[2], consumername))
if not do_purge(consumername, {'X-Purge-Xkey': r[2]}):
failed = True
continue
else:
logging.warning("Unknown purge type %s on %s, ignoring." % (r[1], consumername))
# Schedule for removal
idlist.append(r[0])
# Then remove from queue
curs.execute("UPDATE varnishqueue.queue SET completed=CURRENT_TIMESTAMP WHERE id=ANY(%(idlist)s)", {
'idlist': idlist
})
conn.commit()
if failed:
time.sleep(5)
else:
# Nothing, so roll back the transaction and wait
conn.rollback()
select.select([conn], [], [], 5 * 60)
conn.poll()
while conn.notifies:
conn.notifies.pop()
# Loop back up and process the full queue
def housekeeper(dsn):
logging.info("Starting housekeeper")
setproctitle("varnish_queue - housekeeper")
conn = psycopg2.connect(dsn)
curs = conn.cursor()
while True:
curs.execute("DELETE FROM varnishqueue.queue WHERE completed IS NOT NULL")
if curs.rowcount > 0:
conn.commit()
else:
conn.rollback()
time.sleep(5 * 60)
if __name__ == "__main__":
if len(sys.argv) != 2:
print("Usage: varnish_queue.py <dsn>")
sys.exit(1)
logging.basicConfig(format='%(asctime)s:%(levelname)s:%(message)s', level=logging.INFO)
conn = psycopg2.connect(sys.argv[1])
curs = conn.cursor()
curs.execute("SELECT consumerid, consumer FROM varnishqueue.consumers")
consumers = curs.fetchall()
conn.close()
# Now spawn a worker for each
processes = []
for consumerid, consumername in consumers:
p = multiprocessing.Process(target=worker, args=(consumerid, consumername, sys.argv[1]))
p.start()
processes.append(p)
# Start a housekeeping process as well
p = multiprocessing.Process(target=housekeeper, args=(sys.argv[1],))
p.start()
processes.append(p)
# They should never die, but if they do, commit suicide and
# restart everything.
while True:
processes[0].join(timeout=120)
for p in processes:
if not p.is_alive():
logging.warning("Child process died, killing all and existing")
for p2 in processes:
try:
p2.terminate()
except Exception as e:
pass
logging.error("Children killed, existing")
sys.exit(1)
# If all processes are alive, loop back up and try again
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