perf scripts python: call-graph-from-sql.py: Separate the database details into a class

Separate the database details into a class that can provide different
connections using the same connection information.  That paves the way
for sub-processes that require their own connection.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20181001062853.28285-7-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/scripts/python/call-graph-from-sql.py

@@ -284,41 +284,33 @@ class MainWindow(QMainWindow):
 
 		self.setCentralWidget(self.view)
 
-# Main
+# Database reference
 
-def Main():
-	if (len(sys.argv) < 2):
-		print >> sys.stderr, "Usage is: call-graph-from-sql.py <database name>"
-		raise Exception("Too few arguments")
+class DBRef():
 
-	dbname = sys.argv[1]
+	def __init__(self, is_sqlite3, dbname):
+		self.is_sqlite3 = is_sqlite3
+		self.dbname = dbname
 
-	is_sqlite3 = False
-	try:
-		f = open(dbname)
-		if f.read(15) == "SQLite format 3":
-			is_sqlite3 = True
-		f.close()
-	except:
-		pass
-
-	if is_sqlite3:
-		db = QSqlDatabase.addDatabase('QSQLITE')
+	def Open(self, connection_name):
+		dbname = self.dbname
+		if self.is_sqlite3:
+			db = QSqlDatabase.addDatabase("QSQLITE", connection_name)
 		else:
-		db = QSqlDatabase.addDatabase('QPSQL')
+			db = QSqlDatabase.addDatabase("QPSQL", connection_name)
 			opts = dbname.split()
 			for opt in opts:
-			if '=' in opt:
-				opt = opt.split('=')
-				if opt[0] == 'hostname':
+				if "=" in opt:
+					opt = opt.split("=")
+					if opt[0] == "hostname":
 						db.setHostName(opt[1])
-				elif opt[0] == 'port':
+					elif opt[0] == "port":
 						db.setPort(int(opt[1]))
-				elif opt[0] == 'username':
+					elif opt[0] == "username":
 						db.setUserName(opt[1])
-				elif opt[0] == 'password':
+					elif opt[0] == "password":
 						db.setPassword(opt[1])
-				elif opt[0] == 'dbname':
+					elif opt[0] == "dbname":
 						dbname = opt[1]
 				else:
 					dbname = opt
@@ -326,7 +318,28 @@ def Main():
 		db.setDatabaseName(dbname)
 		if not db.open():
 			raise Exception("Failed to open database " + dbname + " error: " + db.lastError().text())
+		return db, dbname
+
+# Main
+
+def Main():
+	if (len(sys.argv) < 2):
+		print >> sys.stderr, "Usage is: call-graph-from-sql.py <database name>"
+		raise Exception("Too few arguments")
+
+	dbname = sys.argv[1]
+
+	is_sqlite3 = False
+	try:
+		f = open(dbname)
+		if f.read(15) == "SQLite format 3":
+			is_sqlite3 = True
+		f.close()
+	except:
+		pass
 
+	dbref = DBRef(is_sqlite3, dbname)
+	db, dbname = dbref.Open("main")
 	app = QApplication(sys.argv)
 	window = MainWindow(db, dbname)
 	window.show()