vitess.io/vitess@v0.16.2/go/vt/vtgate/planbuilder/fallback_planner.go (about) 1 /* 2 Copyright 2021 The Vitess Authors. 3 4 Licensed under the Apache License, Version 2.0 (the "License"); 5 you may not use this file except in compliance with the License. 6 You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 See the License for the specific language governing permissions and 14 limitations under the License. 15 */ 16 17 package planbuilder 18 19 import ( 20 "fmt" 21 22 "vitess.io/vitess/go/vt/vtgate/planbuilder/plancontext" 23 24 "vitess.io/vitess/go/vt/sqlparser" 25 ) 26 27 type fallbackPlanner struct { 28 primary, fallback stmtPlanner 29 } 30 31 var _ stmtPlanner = (*fallbackPlanner)(nil).plan 32 33 func (fp *fallbackPlanner) safePrimary(stmt sqlparser.Statement, reservedVars *sqlparser.ReservedVars, vschema plancontext.VSchema) (res *planResult, err error) { 34 defer func() { 35 // if the primary planner panics, we want to catch it here so we can fall back 36 if r := recover(); r != nil { 37 err = fmt.Errorf("%v", r) // not using vterror since this will only be used for logging 38 } 39 }() 40 res, err = fp.primary(stmt, reservedVars, vschema) 41 return 42 } 43 44 func (fp *fallbackPlanner) plan(stmt sqlparser.Statement, reservedVars *sqlparser.ReservedVars, vschema plancontext.VSchema) (*planResult, error) { 45 res, err := fp.safePrimary(sqlparser.CloneStatement(stmt), reservedVars, vschema) 46 if err != nil { 47 return fp.fallback(stmt, reservedVars, vschema) 48 } 49 return res, nil 50 }