ENH: Add cache for database getBansMerged

This is avoids duplicate queries when using the ip(jail)matches and
ip(jail)failures in actions

fail2ban/server/database.py

@@ -64,6 +64,8 @@ class Fail2BanDb(object):
 			self._dbFilename = filename
 			self._purgeAge = purgeAge
 
+			self._bansMergedCache = {}
+
 			logSys.info(
 				"Connected to fail2ban persistent database '%s'", filename)
 		except sqlite3.OperationalError, e:
@@ -219,6 +221,7 @@ class Fail2BanDb(object):
 
 	@commitandrollback
 	def addBan(self, cur, jail, ticket):
+		self._bansMergedCache = {}
 		#TODO: Implement data parts once arbitrary match keys completed
 		cur.execute(
 			"INSERT INTO bans(jail, ip, timeofban, data) VALUES(?, ?, ?, ?)",
@@ -253,6 +256,9 @@ class Fail2BanDb(object):
 		return tickets
 
 	def getBansMerged(self, ip, jail=None, **kwargs):
+		cacheKey = ip if jail is None else "%s|%s" % (ip, jail.getName())
+		if cacheKey in self._bansMergedCache:
+			return self._bansMergedCache[cacheKey]
 		matches = []
 		failures = 0
 		for ip, timeofban, data in self._getBans(ip=ip, jail=jail, **kwargs):
@@ -261,10 +267,12 @@ class Fail2BanDb(object):
 			failures += data['failures']
 		ticket = FailTicket(ip, timeofban, matches)
 		ticket.setAttempt(failures)
+		self._bansMergedCache[cacheKey] = ticket
 		return ticket
 
 	@commitandrollback
 	def purge(self, cur):
+		self._bansMergedCache = {}
 		cur.execute(
 			"DELETE FROM bans WHERE timeofban < ?",
 			(MyTime.time() - self._purgeAge, ))

fail2ban/tests/databasetestcase.py

@@ -162,6 +162,20 @@ class DatabaseTest(unittest.TestCase):
 		self.assertEqual(ticket.getAttempt(), 30)
 		self.assertEqual(ticket.getMatches(), ["abc\n", "123\n"])
 
+		# Should cache result if no extra bans added
+		ticketID = id(ticket)
+		self.assertEqual(
+			ticketID,
+			id(self.db.getBansMerged("127.0.0.1", jail=self.jail)))
+
+		ticket = FailTicket("127.0.0.1", 40, ["ABC\n"])
+		ticket.setAttempt(40)
+		self.db.addBan(jail2, ticket)
+		# Added ticket, so cache should have been cleared
+		self.assertNotEqual(
+			ticketID,
+			id(self.db.getBansMerged("127.0.0.1", jail=self.jail)))
+
 	def testPurge(self):
 		self.testAddJail() # Add jail