Fix connection handling (#30)

Co-authored-by: Lesovsky Aleksey <[email protected]>

internal/collector/collector_common.go

@@ -267,11 +267,9 @@ func updateFromMultipleDatabases(config Config, descSets []typedDescSet, ch chan
 			err = updateSingleDescSet(conn, s, ch, true)
 			if err != nil {
 				log.Errorf("collect failed: %s; skip", err)
-				conn.Close()
-				continue
 			}
 
-			// Close connection.
+			// Close connection and go next database.
 			conn.Close()
 		}
 	}

internal/collector/config.go

@@ -198,6 +198,7 @@ func discoverPgStatStatements(connStr string) (bool, string, string, error) {
 	var setting string
 	err = conn.Conn().QueryRow(context.Background(), "SELECT setting FROM pg_settings WHERE name = 'shared_preload_libraries'").Scan(&setting)
 	if err != nil {
+		conn.Close()
 		return false, "", "", err
 	}
 
@@ -238,10 +239,11 @@ func discoverPgStatStatements(connStr string) (bool, string, string, error) {
 
 		// If pg_stat_statements found, update source and return connection.
 		if schema := extensionInstalledSchema(conn, "pg_stat_statements"); schema != "" {
+			conn.Close()
 			return true, conn.Conn().Config().Database, schema, nil
 		}
 
-		// Otherwise close connection and go to next database in the list.
+		// Otherwise, close connection and go to next database in the list.
 		conn.Close()
 	}
 

internal/collector/postgres_statements.go

@@ -196,14 +196,14 @@ func (c *postgresStatementsCollector) Update(config Config, ch chan<- prometheus
 		return err
 	}
 
+	defer conn.Close()
+
 	// get pg_stat_statements stats
 	res, err := conn.Query(selectStatementsQuery(config.serverVersionNum, config.pgStatStatementsSchema))
 	if err != nil {
 		return err
 	}
 
-	conn.Close()
-
 	// parse pg_stat_statements stats
 	stats := parsePostgresStatementsStats(res, []string{"user", "database", "queryid", "query"})