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// Copyright 2017 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package core
import (
"math"
"sync/atomic"
"time"
"github.com/pingcap/parser/ast"
"github.com/pingcap/parser/model"
"github.com/pingcap/parser/mysql"
"github.com/pingcap/tidb/kv"
"github.com/pingcap/tidb/sessionctx/variable"
"github.com/pingcap/tidb/types"
"github.com/pingcap/tidb/util/codec"
"github.com/pingcap/tidb/util/hack"
"github.com/pingcap/tidb/util/kvcache"
atomic2 "go.uber.org/atomic"
)
var (
// preparedPlanCacheEnabledValue stores the global config "prepared-plan-cache-enabled".
// If the value of "prepared-plan-cache-enabled" is true, preparedPlanCacheEnabledValue's value is 1.
// Otherwise, preparedPlanCacheEnabledValue's value is 0.
preparedPlanCacheEnabledValue int32
// PreparedPlanCacheCapacity stores the global config "prepared-plan-cache-capacity".
PreparedPlanCacheCapacity uint = 100
// PreparedPlanCacheMemoryGuardRatio stores the global config "prepared-plan-cache-memory-guard-ratio".
PreparedPlanCacheMemoryGuardRatio float64 = 0.1
// PreparedPlanCacheMaxMemory stores the max memory size defined in the global config "performance-max-memory".
PreparedPlanCacheMaxMemory atomic2.Uint64 = *atomic2.NewUint64(math.MaxUint64)
)
const (
preparedPlanCacheEnabled = 1
preparedPlanCacheUnable = 0
)
// SetPreparedPlanCache sets isEnabled to true, then prepared plan cache is enabled.
func SetPreparedPlanCache(isEnabled bool) {
if isEnabled {
atomic.StoreInt32(&preparedPlanCacheEnabledValue, preparedPlanCacheEnabled)
} else {
atomic.StoreInt32(&preparedPlanCacheEnabledValue, preparedPlanCacheUnable)
}
}
// PreparedPlanCacheEnabled returns whether the prepared plan cache is enabled.
func PreparedPlanCacheEnabled() bool {
isEnabled := atomic.LoadInt32(&preparedPlanCacheEnabledValue)
return isEnabled == preparedPlanCacheEnabled
}
type pstmtPlanCacheKey struct {
database string
connID uint64
pstmtID uint32
snapshot uint64
schemaVersion int64
sqlMode mysql.SQLMode
timezoneOffset int
selectLimit uint64
isolationReadEngines map[kv.StoreType]struct{}
hash []byte
}
// Hash implements Key interface.
func (key *pstmtPlanCacheKey) Hash() []byte {
if len(key.hash) == 0 {
var (
dbBytes = hack.Slice(key.database)
bufferSize = len(dbBytes) + 8*6 + 3*8
)
if key.hash == nil {
key.hash = make([]byte, 0, bufferSize)
}
key.hash = append(key.hash, dbBytes...)
key.hash = codec.EncodeInt(key.hash, int64(key.connID))
key.hash = codec.EncodeInt(key.hash, int64(key.pstmtID))
key.hash = codec.EncodeInt(key.hash, int64(key.snapshot))
key.hash = codec.EncodeInt(key.hash, key.schemaVersion)
key.hash = codec.EncodeInt(key.hash, int64(key.sqlMode))
key.hash = codec.EncodeInt(key.hash, int64(key.timezoneOffset))
key.hash = codec.EncodeInt(key.hash, int64(key.selectLimit))
if _, ok := key.isolationReadEngines[kv.TiDB]; ok {
key.hash = append(key.hash, kv.TiDB.Name()...)
}
if _, ok := key.isolationReadEngines[kv.TiKV]; ok {
key.hash = append(key.hash, kv.TiKV.Name()...)
}
if _, ok := key.isolationReadEngines[kv.TiFlash]; ok {
key.hash = append(key.hash, kv.TiFlash.Name()...)
}
}
return key.hash
}
// SetPstmtIDSchemaVersion implements PstmtCacheKeyMutator interface to change pstmtID and schemaVersion of cacheKey.
// so we can reuse Key instead of new every time.
func SetPstmtIDSchemaVersion(key kvcache.Key, pstmtID uint32, schemaVersion int64, isolationReadEngines map[kv.StoreType]struct{}) {
psStmtKey, isPsStmtKey := key.(*pstmtPlanCacheKey)
if !isPsStmtKey {
return
}
psStmtKey.pstmtID = pstmtID
psStmtKey.schemaVersion = schemaVersion
psStmtKey.isolationReadEngines = make(map[kv.StoreType]struct{})
for k, v := range isolationReadEngines {
psStmtKey.isolationReadEngines[k] = v
}
psStmtKey.hash = psStmtKey.hash[:0]
}
// NewPSTMTPlanCacheKey creates a new pstmtPlanCacheKey object.
func NewPSTMTPlanCacheKey(sessionVars *variable.SessionVars, pstmtID uint32, schemaVersion int64) kvcache.Key {
timezoneOffset := 0
if sessionVars.TimeZone != nil {
_, timezoneOffset = time.Now().In(sessionVars.TimeZone).Zone()
}
key := &pstmtPlanCacheKey{
database: sessionVars.CurrentDB,
connID: sessionVars.ConnectionID,
pstmtID: pstmtID,
snapshot: sessionVars.SnapshotTS,
schemaVersion: schemaVersion,
sqlMode: sessionVars.SQLMode,
timezoneOffset: timezoneOffset,
selectLimit: sessionVars.SelectLimit,
isolationReadEngines: make(map[kv.StoreType]struct{}),
}
for k, v := range sessionVars.IsolationReadEngines {
key.isolationReadEngines[k] = v
}
return key
}
// FieldSlice is the slice of the types.FieldType
type FieldSlice []types.FieldType
// Equal compares FieldSlice with []*types.FieldType
func (s FieldSlice) Equal(tps []*types.FieldType) bool {
if len(s) != len(tps) {
return false
}
for i := range tps {
if !s[i].Equal(tps[i]) {
return false
}
}
return true
}
// PSTMTPlanCacheValue stores the cached Statement and StmtNode.
type PSTMTPlanCacheValue struct {
Plan Plan
OutPutNames []*types.FieldName
TblInfo2UnionScan map[*model.TableInfo]bool
UserVarTypes FieldSlice
}
// NewPSTMTPlanCacheValue creates a SQLCacheValue.
func NewPSTMTPlanCacheValue(plan Plan, names []*types.FieldName, srcMap map[*model.TableInfo]bool, userVarTps []*types.FieldType) *PSTMTPlanCacheValue {
dstMap := make(map[*model.TableInfo]bool)
for k, v := range srcMap {
dstMap[k] = v
}
userVarTypes := make([]types.FieldType, len(userVarTps))
for i, tp := range userVarTps {
userVarTypes[i] = *tp
}
return &PSTMTPlanCacheValue{
Plan: plan,
OutPutNames: names,
TblInfo2UnionScan: dstMap,
UserVarTypes: userVarTypes,
}
}
// CachedPrepareStmt store prepared ast from PrepareExec and other related fields
type CachedPrepareStmt struct {
PreparedAst *ast.Prepared
VisitInfos []visitInfo
ColumnInfos interface{}
Executor interface{}
NormalizedSQL string
NormalizedPlan string
SQLDigest string
PlanDigest string
}