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import os
import cherrypy
import mariadb
from cherrypy.process import plugins
from time import sleep
from threading import Event
if not mariadb.threadsafety:
print("Mariadb connector not threadsafe. Failing.")
exit(1)
class DBPoolManager(plugins.SimplePlugin):
def __init__(self, bus):
plugins.SimplePlugin.__init__(self, bus)
self.pool:mariadb.ConnectionPool=None
self.poolStartedEvent=Event()
def start(self):
# get amount of concurrent connections
conns=os.getenv("DB_CONNECTIONS",4)
self.maxconns=conns
if not type(conns)==int and not conns.isdigit():
self._log("DB_CONNECTIONS does not have a valid value:",conns,", using 4 instead.")
conns=4
conns=int(conns)
# get host/port from MYSQL_HOST
HOST=os.getenv("MYSQL_HOST","database")
if ":" in HOST:
HOST,PORT=HOST.split(":",2)
else:
PORT=3306
self._log(f"Connecting to database at {HOST}:{PORT}")
# fill connection pool
attempts=0
while True:
try:
self.pool=mariadb.ConnectionPool(
pool_name="main", pool_size=conns,
user=os.getenv("MYSQL_USER","root"),
password=os.getenv("MYSQL_PASSWORD"),
host=HOST,
port=PORT,
database=os.getenv("MYSQL_DATABASE","db")
)
self._log("Database connection pool set up in %d attempts"%attempts)
break
except mariadb.Error as e:
self._log(f"Error connecting to database: {e}")
attempts+=1
if attempts>=5:
self._log("ERROR: Limit for connecting to database reached, stopping cherrypy!")
cherrypy.engine.exit()
return
self._log("Attempt %d to connect to database failed (see above error), retrying in 10 seconds..."%attempts)
sleep(10)
cherrypy.engine.publish("db-started")
self.poolStartedEvent.set()
def stop(self):
if not self.pool:
self._log("Nothing to stop.")
return
self.pool.close()
self._log("Stopped database pool.")
def _log(self, *msg):
"""
Just a simple wrapper around cherrypy.log adding a context
"""
cherrypy.log(
context="DBCONN",
msg=" ".join(( str(i) for i in msg )),
)
def get_connection(self):
if self.pool==None:
self.poolStartedEvent.wait(cherrypy)
conn=self.pool.get_connection()
conn.rollback() # reset any previous actions and refresh
return conn
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