// 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 stmtctx

import (
	"math"
	"sort"
	"strconv"
	"sync"
	"sync/atomic"
	"time"

	"github.com/pingcap/parser"
	"github.com/pingcap/parser/model"
	"github.com/pingcap/parser/mysql"
	"github.com/pingcap/tidb/util/disk"
	"github.com/pingcap/tidb/util/execdetails"
	"github.com/pingcap/tidb/util/memory"
	"go.uber.org/zap"
)

const (
	// WarnLevelError represents level "Error" for 'SHOW WARNINGS' syntax.
	WarnLevelError = "Error"
	// WarnLevelWarning represents level "Warning" for 'SHOW WARNINGS' syntax.
	WarnLevelWarning = "Warning"
	// WarnLevelNote represents level "Note" for 'SHOW WARNINGS' syntax.
	WarnLevelNote = "Note"
)

var taskIDAlloc uint64

// AllocateTaskID allocates a new unique ID for a statement execution
func AllocateTaskID() uint64 {
	return atomic.AddUint64(&taskIDAlloc, 1)
}

// SQLWarn relates a sql warning and it's level.
type SQLWarn struct {
	Level string
	Err   error
}

// StatementContext contains variables for a statement.
// It should be reset before executing a statement.
type StatementContext struct {
	// Set the following variables before execution
	StmtHints

	// IsDDLJobInQueue is used to mark whether the DDL job is put into the queue.
	// If IsDDLJobInQueue is true, it means the DDL job is in the queue of storage, and it can be handled by the DDL worker.
	IsDDLJobInQueue           bool
	InInsertStmt              bool
	InUpdateStmt              bool
	InDeleteStmt              bool
	InSelectStmt              bool
	InLoadDataStmt            bool
	InExplainStmt             bool
	IgnoreTruncate            bool
	IgnoreZeroInDate          bool
	DupKeyAsWarning           bool
	BadNullAsWarning          bool
	DividedByZeroAsWarning    bool
	TruncateAsWarning         bool
	OverflowAsWarning         bool
	InShowWarning             bool
	UseCache                  bool
	BatchCheck                bool
	InNullRejectCheck         bool
	AllowInvalidDate          bool
	OptimDependOnMutableConst bool
	IgnoreNoPartition         bool

	// mu struct holds variables that change during execution.
	mu struct {
		sync.Mutex

		affectedRows uint64
		foundRows    uint64

		/*
			following variables are ported from 'COPY_INFO' struct of MySQL server source,
			they are used to count rows for INSERT/REPLACE/UPDATE queries:
			  If a row is inserted then the copied variable is incremented.
			  If a row is updated by the INSERT ... ON DUPLICATE KEY UPDATE and the
			     new data differs from the old one then the copied and the updated
			     variables are incremented.
			  The touched variable is incremented if a row was touched by the update part
			     of the INSERT ... ON DUPLICATE KEY UPDATE no matter whether the row
			     was actually changed or not.

			see https://github.com/mysql/mysql-server/blob/d2029238d6d9f648077664e4cdd611e231a6dc14/sql/sql_data_change.h#L60 for more details
		*/
		records uint64
		updated uint64
		copied  uint64
		touched uint64

		message           string
		warnings          []SQLWarn
		errorCount        uint16
		histogramsNotLoad bool
		execDetails       execdetails.ExecDetails
		allExecDetails    []*execdetails.ExecDetails
	}
	// PrevAffectedRows is the affected-rows value(DDL is 0, DML is the number of affected rows).
	PrevAffectedRows int64
	// PrevLastInsertID is the last insert ID of previous statement.
	PrevLastInsertID uint64
	// LastInsertID is the auto-generated ID in the current statement.
	LastInsertID uint64
	// InsertID is the given insert ID of an auto_increment column.
	InsertID uint64

	BaseRowID int64
	MaxRowID  int64

	// Copied from SessionVars.TimeZone.
	TimeZone         *time.Location
	Priority         mysql.PriorityEnum
	NotFillCache     bool
	MemTracker       *memory.Tracker
	DiskTracker      *disk.Tracker
	RuntimeStatsColl *execdetails.RuntimeStatsColl
	TableIDs         []int64
	IndexNames       []string
	nowTs            time.Time // use this variable for now/current_timestamp calculation/cache for one stmt
	stmtTimeCached   bool
	StmtType         string
	OriginalSQL      string
	digestMemo       struct {
		sync.Once
		normalized string
		digest     string
	}
	// planNormalized use for cache the normalized plan, avoid duplicate builds.
	planNormalized        string
	planDigest            string
	encodedPlan           string
	planHint              string
	planHintSet           bool
	Tables                []TableEntry
	PointExec             bool  // for point update cached execution, Constant expression need to set "paramMarker"
	lockWaitStartTime     int64 // LockWaitStartTime stores the pessimistic lock wait start time
	PessimisticLockWaited int32
	LockKeysDuration      int64
	LockKeysCount         int32
	TblInfo2UnionScan     map[*model.TableInfo]bool
	TaskID                uint64              // unique ID for an execution of a statement
	CheckKeyExists        map[string]struct{} // mark the keys needs to check for existence for pessimistic locks.
}

// StmtHints are SessionVars related sql hints.
type StmtHints struct {
	// Hint Information
	MemQuotaQuery           int64
	MaxExecutionTime        uint64
	ReplicaRead             byte
	AllowInSubqToJoinAndAgg bool
	NoIndexMergeHint        bool
	// EnableCascadesPlanner is use cascades planner for a single query only.
	EnableCascadesPlanner bool

	// Hint flags
	HasAllowInSubqToJoinAndAggHint bool
	HasMemQuotaHint                bool
	HasReplicaReadHint             bool
	HasMaxExecutionTime            bool
	HasEnableCascadesPlannerHint   bool
}

// GetNowTsCached getter for nowTs, if not set get now time and cache it
func (sc *StatementContext) GetNowTsCached() time.Time {
	if !sc.stmtTimeCached {
		now := time.Now()
		sc.nowTs = now
		sc.stmtTimeCached = true
	}
	return sc.nowTs
}

// ResetNowTs resetter for nowTs, clear cached time flag
func (sc *StatementContext) ResetNowTs() {
	sc.stmtTimeCached = false
}

// SQLDigest gets normalized and digest for provided sql.
// it will cache result after first calling.
func (sc *StatementContext) SQLDigest() (normalized, sqlDigest string) {
	sc.digestMemo.Do(func() {
		sc.digestMemo.normalized, sc.digestMemo.digest = parser.NormalizeDigest(sc.OriginalSQL)
	})
	return sc.digestMemo.normalized, sc.digestMemo.digest
}

// InitSQLDigest sets the normalized and digest for sql.
func (sc *StatementContext) InitSQLDigest(normalized, digest string) {
	sc.digestMemo.Do(func() {
		sc.digestMemo.normalized, sc.digestMemo.digest = normalized, digest
	})
}

// GetPlanDigest gets the normalized plan and plan digest.
func (sc *StatementContext) GetPlanDigest() (normalized, planDigest string) {
	return sc.planNormalized, sc.planDigest
}

// SetPlanDigest sets the normalized plan and plan digest.
func (sc *StatementContext) SetPlanDigest(normalized, planDigest string) {
	sc.planNormalized, sc.planDigest = normalized, planDigest
}

// GetEncodedPlan gets the encoded plan, it is used to avoid repeated encode.
func (sc *StatementContext) GetEncodedPlan() string {
	return sc.encodedPlan
}

// SetEncodedPlan sets the encoded plan, it is used to avoid repeated encode.
func (sc *StatementContext) SetEncodedPlan(encodedPlan string) {
	sc.encodedPlan = encodedPlan
}

// GetPlanHint gets the hint string generated from the plan.
func (sc *StatementContext) GetPlanHint() (string, bool) {
	return sc.planHint, sc.planHintSet
}

// SetPlanHint sets the hint for the plan.
func (sc *StatementContext) SetPlanHint(hint string) {
	sc.planHintSet = true
	sc.planHint = hint
}

// TableEntry presents table in db.
type TableEntry struct {
	DB    string
	Table string
}

// AddAffectedRows adds affected rows.
func (sc *StatementContext) AddAffectedRows(rows uint64) {
	sc.mu.Lock()
	sc.mu.affectedRows += rows
	sc.mu.Unlock()
}

// AffectedRows gets affected rows.
func (sc *StatementContext) AffectedRows() uint64 {
	sc.mu.Lock()
	rows := sc.mu.affectedRows
	sc.mu.Unlock()
	return rows
}

// FoundRows gets found rows.
func (sc *StatementContext) FoundRows() uint64 {
	sc.mu.Lock()
	rows := sc.mu.foundRows
	sc.mu.Unlock()
	return rows
}

// AddFoundRows adds found rows.
func (sc *StatementContext) AddFoundRows(rows uint64) {
	sc.mu.Lock()
	sc.mu.foundRows += rows
	sc.mu.Unlock()
}

// RecordRows is used to generate info message
func (sc *StatementContext) RecordRows() uint64 {
	sc.mu.Lock()
	rows := sc.mu.records
	sc.mu.Unlock()
	return rows
}

// AddRecordRows adds record rows.
func (sc *StatementContext) AddRecordRows(rows uint64) {
	sc.mu.Lock()
	sc.mu.records += rows
	sc.mu.Unlock()
}

// UpdatedRows is used to generate info message
func (sc *StatementContext) UpdatedRows() uint64 {
	sc.mu.Lock()
	rows := sc.mu.updated
	sc.mu.Unlock()
	return rows
}

// AddUpdatedRows adds updated rows.
func (sc *StatementContext) AddUpdatedRows(rows uint64) {
	sc.mu.Lock()
	sc.mu.updated += rows
	sc.mu.Unlock()
}

// CopiedRows is used to generate info message
func (sc *StatementContext) CopiedRows() uint64 {
	sc.mu.Lock()
	rows := sc.mu.copied
	sc.mu.Unlock()
	return rows
}

// AddCopiedRows adds copied rows.
func (sc *StatementContext) AddCopiedRows(rows uint64) {
	sc.mu.Lock()
	sc.mu.copied += rows
	sc.mu.Unlock()
}

// TouchedRows is used to generate info message
func (sc *StatementContext) TouchedRows() uint64 {
	sc.mu.Lock()
	rows := sc.mu.touched
	sc.mu.Unlock()
	return rows
}

// AddTouchedRows adds touched rows.
func (sc *StatementContext) AddTouchedRows(rows uint64) {
	sc.mu.Lock()
	sc.mu.touched += rows
	sc.mu.Unlock()
}

// GetMessage returns the extra message of the last executed command, if there is no message, it returns empty string
func (sc *StatementContext) GetMessage() string {
	sc.mu.Lock()
	msg := sc.mu.message
	sc.mu.Unlock()
	return msg
}

// SetMessage sets the info message generated by some commands
func (sc *StatementContext) SetMessage(msg string) {
	sc.mu.Lock()
	sc.mu.message = msg
	sc.mu.Unlock()
}

// GetWarnings gets warnings.
func (sc *StatementContext) GetWarnings() []SQLWarn {
	sc.mu.Lock()
	warns := make([]SQLWarn, len(sc.mu.warnings))
	copy(warns, sc.mu.warnings)
	sc.mu.Unlock()
	return warns
}

// WarningCount gets warning count.
func (sc *StatementContext) WarningCount() uint16 {
	if sc.InShowWarning {
		return 0
	}
	sc.mu.Lock()
	wc := uint16(len(sc.mu.warnings))
	sc.mu.Unlock()
	return wc
}

// NumErrorWarnings gets warning and error count.
func (sc *StatementContext) NumErrorWarnings() (ec uint16, wc int) {
	sc.mu.Lock()
	ec = sc.mu.errorCount
	wc = len(sc.mu.warnings)
	sc.mu.Unlock()
	return
}

// SetWarnings sets warnings.
func (sc *StatementContext) SetWarnings(warns []SQLWarn) {
	sc.mu.Lock()
	sc.mu.warnings = warns
	for _, w := range warns {
		if w.Level == WarnLevelError {
			sc.mu.errorCount++
		}
	}
	sc.mu.Unlock()
}

// TruncateWarnings truncates wanrings begin from start and returns the truncated warnings.
func (sc *StatementContext) TruncateWarnings(start int) []SQLWarn {
	sc.mu.Lock()
	defer sc.mu.Unlock()
	sz := len(sc.mu.warnings) - start
	if sz <= 0 {
		return nil
	}
	ret := make([]SQLWarn, sz)
	copy(ret, sc.mu.warnings[start:])
	sc.mu.warnings = sc.mu.warnings[:start]
	return ret
}

// AppendWarning appends a warning with level 'Warning'.
func (sc *StatementContext) AppendWarning(warn error) {
	sc.mu.Lock()
	if len(sc.mu.warnings) < math.MaxUint16 {
		sc.mu.warnings = append(sc.mu.warnings, SQLWarn{WarnLevelWarning, warn})
	}
	sc.mu.Unlock()
}

// AppendWarnings appends some warnings.
func (sc *StatementContext) AppendWarnings(warns []SQLWarn) {
	sc.mu.Lock()
	if len(sc.mu.warnings) < math.MaxUint16 {
		sc.mu.warnings = append(sc.mu.warnings, warns...)
	}
	sc.mu.Unlock()
}

// AppendNote appends a warning with level 'Note'.
func (sc *StatementContext) AppendNote(warn error) {
	sc.mu.Lock()
	if len(sc.mu.warnings) < math.MaxUint16 {
		sc.mu.warnings = append(sc.mu.warnings, SQLWarn{WarnLevelNote, warn})
	}
	sc.mu.Unlock()
}

// AppendError appends a warning with level 'Error'.
func (sc *StatementContext) AppendError(warn error) {
	sc.mu.Lock()
	if len(sc.mu.warnings) < math.MaxUint16 {
		sc.mu.warnings = append(sc.mu.warnings, SQLWarn{WarnLevelError, warn})
		sc.mu.errorCount++
	}
	sc.mu.Unlock()
}

// SetHistogramsNotLoad sets histogramsNotLoad.
func (sc *StatementContext) SetHistogramsNotLoad() {
	sc.mu.Lock()
	sc.mu.histogramsNotLoad = true
	sc.mu.Unlock()
}

// HandleTruncate ignores or returns the error based on the StatementContext state.
func (sc *StatementContext) HandleTruncate(err error) error {
	// TODO: At present we have not checked whether the error can be ignored or treated as warning.
	// We will do that later, and then append WarnDataTruncated instead of the error itself.
	if err == nil {
		return nil
	}
	if sc.IgnoreTruncate {
		return nil
	}
	if sc.TruncateAsWarning {
		sc.AppendWarning(err)
		return nil
	}
	return err
}

// HandleOverflow treats ErrOverflow as warnings or returns the error based on the StmtCtx.OverflowAsWarning state.
func (sc *StatementContext) HandleOverflow(err error, warnErr error) error {
	if err == nil {
		return nil
	}

	if sc.OverflowAsWarning {
		sc.AppendWarning(warnErr)
		return nil
	}
	return err
}

// ResetForRetry resets the changed states during execution.
func (sc *StatementContext) ResetForRetry() {
	sc.mu.Lock()
	sc.mu.affectedRows = 0
	sc.mu.foundRows = 0
	sc.mu.records = 0
	sc.mu.updated = 0
	sc.mu.copied = 0
	sc.mu.touched = 0
	sc.mu.message = ""
	sc.mu.errorCount = 0
	sc.mu.warnings = nil
	sc.mu.execDetails = execdetails.ExecDetails{}
	sc.mu.allExecDetails = make([]*execdetails.ExecDetails, 0, 4)
	sc.mu.Unlock()
	sc.MaxRowID = 0
	sc.BaseRowID = 0
	sc.TableIDs = sc.TableIDs[:0]
	sc.IndexNames = sc.IndexNames[:0]
	sc.TaskID = AllocateTaskID()
	sc.CheckKeyExists = make(map[string]struct{})
}

// MergeExecDetails merges a single region execution details into self, used to print
// the information in slow query log.
func (sc *StatementContext) MergeExecDetails(details *execdetails.ExecDetails, commitDetails *execdetails.CommitDetails) {
	sc.mu.Lock()
	if details != nil {
		sc.mu.execDetails.CopTime += details.CopTime
		sc.mu.execDetails.BackoffTime += details.BackoffTime
		sc.mu.execDetails.RequestCount++
		sc.MergeScanDetail(details.ScanDetail)
		sc.MergeTimeDetail(details.TimeDetail)
		sc.mu.allExecDetails = append(sc.mu.allExecDetails, details)
	}
	if commitDetails != nil {
		if sc.mu.execDetails.CommitDetail == nil {
			sc.mu.execDetails.CommitDetail = commitDetails
		} else {
			sc.mu.execDetails.CommitDetail.Merge(commitDetails)
		}
	}
	sc.mu.Unlock()
}

// MergeScanDetail merges scan details into self.
func (sc *StatementContext) MergeScanDetail(scanDetail *execdetails.ScanDetail) {
	// Currently TiFlash cop task does not fill scanDetail, so need to skip it if scanDetail is nil
	if scanDetail == nil {
		return
	}
	if sc.mu.execDetails.ScanDetail == nil {
		sc.mu.execDetails.ScanDetail = &execdetails.ScanDetail{}
	}
	sc.mu.execDetails.ScanDetail.Merge(scanDetail)
}

// MergeTimeDetail merges time details into self.
func (sc *StatementContext) MergeTimeDetail(timeDetail execdetails.TimeDetail) {
	sc.mu.execDetails.TimeDetail.ProcessTime += timeDetail.ProcessTime
	sc.mu.execDetails.TimeDetail.WaitTime += timeDetail.WaitTime
}

// MergeLockKeysExecDetails merges lock keys execution details into self.
func (sc *StatementContext) MergeLockKeysExecDetails(lockKeys *execdetails.LockKeysDetails) {
	sc.mu.Lock()
	if sc.mu.execDetails.LockKeysDetail == nil {
		sc.mu.execDetails.LockKeysDetail = lockKeys
	} else {
		sc.mu.execDetails.LockKeysDetail.Merge(lockKeys)
	}
	sc.mu.Unlock()
}

// GetExecDetails gets the execution details for the statement.
func (sc *StatementContext) GetExecDetails() execdetails.ExecDetails {
	var details execdetails.ExecDetails
	sc.mu.Lock()
	details = sc.mu.execDetails
	details.LockKeysDuration = time.Duration(atomic.LoadInt64(&sc.LockKeysDuration))
	sc.mu.Unlock()
	return details
}

// ShouldClipToZero indicates whether values less than 0 should be clipped to 0 for unsigned integer types.
// This is the case for `insert`, `update`, `alter table` and `load data infile` statements, when not in strict SQL mode.
// see https://dev.mysql.com/doc/refman/5.7/en/out-of-range-and-overflow.html
func (sc *StatementContext) ShouldClipToZero() bool {
	// TODO: Currently altering column of integer to unsigned integer is not supported.
	// If it is supported one day, that case should be added here.
	return sc.InInsertStmt || sc.InLoadDataStmt || sc.InUpdateStmt
}

// ShouldIgnoreOverflowError indicates whether we should ignore the error when type conversion overflows,
// so we can leave it for further processing like clipping values less than 0 to 0 for unsigned integer types.
func (sc *StatementContext) ShouldIgnoreOverflowError() bool {
	if (sc.InInsertStmt && sc.TruncateAsWarning) || sc.InLoadDataStmt {
		return true
	}
	return false
}

// PushDownFlags converts StatementContext to tipb.SelectRequest.Flags.
func (sc *StatementContext) PushDownFlags() uint64 {
	var flags uint64
	if sc.InInsertStmt {
		flags |= model.FlagInInsertStmt
	} else if sc.InUpdateStmt || sc.InDeleteStmt {
		flags |= model.FlagInUpdateOrDeleteStmt
	} else if sc.InSelectStmt {
		flags |= model.FlagInSelectStmt
	}
	if sc.IgnoreTruncate {
		flags |= model.FlagIgnoreTruncate
	} else if sc.TruncateAsWarning {
		flags |= model.FlagTruncateAsWarning
	}
	if sc.OverflowAsWarning {
		flags |= model.FlagOverflowAsWarning
	}
	if sc.IgnoreZeroInDate {
		flags |= model.FlagIgnoreZeroInDate
	}
	if sc.DividedByZeroAsWarning {
		flags |= model.FlagDividedByZeroAsWarning
	}
	if sc.InLoadDataStmt {
		flags |= model.FlagInLoadDataStmt
	}
	return flags
}

// CopTasksDetails returns some useful information of cop-tasks during execution.
func (sc *StatementContext) CopTasksDetails() *CopTasksDetails {
	sc.mu.Lock()
	defer sc.mu.Unlock()
	n := len(sc.mu.allExecDetails)
	d := &CopTasksDetails{
		NumCopTasks:       n,
		MaxBackoffTime:    make(map[string]time.Duration),
		AvgBackoffTime:    make(map[string]time.Duration),
		P90BackoffTime:    make(map[string]time.Duration),
		TotBackoffTime:    make(map[string]time.Duration),
		TotBackoffTimes:   make(map[string]int),
		MaxBackoffAddress: make(map[string]string),
	}
	if n == 0 {
		return d
	}
	d.AvgProcessTime = sc.mu.execDetails.TimeDetail.ProcessTime / time.Duration(n)
	d.AvgWaitTime = sc.mu.execDetails.TimeDetail.WaitTime / time.Duration(n)

	sort.Slice(sc.mu.allExecDetails, func(i, j int) bool {
		return sc.mu.allExecDetails[i].TimeDetail.ProcessTime < sc.mu.allExecDetails[j].TimeDetail.ProcessTime
	})
	d.P90ProcessTime = sc.mu.allExecDetails[n*9/10].TimeDetail.ProcessTime
	d.MaxProcessTime = sc.mu.allExecDetails[n-1].TimeDetail.ProcessTime
	d.MaxProcessAddress = sc.mu.allExecDetails[n-1].CalleeAddress

	sort.Slice(sc.mu.allExecDetails, func(i, j int) bool {
		return sc.mu.allExecDetails[i].TimeDetail.WaitTime < sc.mu.allExecDetails[j].TimeDetail.WaitTime
	})
	d.P90WaitTime = sc.mu.allExecDetails[n*9/10].TimeDetail.WaitTime
	d.MaxWaitTime = sc.mu.allExecDetails[n-1].TimeDetail.WaitTime
	d.MaxWaitAddress = sc.mu.allExecDetails[n-1].CalleeAddress

	// calculate backoff details
	type backoffItem struct {
		callee    string
		sleepTime time.Duration
		times     int
	}
	backoffInfo := make(map[string][]backoffItem)
	for _, ed := range sc.mu.allExecDetails {
		for backoff := range ed.BackoffTimes {
			backoffInfo[backoff] = append(backoffInfo[backoff], backoffItem{
				callee:    ed.CalleeAddress,
				sleepTime: ed.BackoffSleep[backoff],
				times:     ed.BackoffTimes[backoff],
			})
		}
	}
	for backoff, items := range backoffInfo {
		if len(items) == 0 {
			continue
		}
		sort.Slice(items, func(i, j int) bool {
			return items[i].sleepTime < items[j].sleepTime
		})
		n := len(items)
		d.MaxBackoffAddress[backoff] = items[n-1].callee
		d.MaxBackoffTime[backoff] = items[n-1].sleepTime
		d.P90BackoffTime[backoff] = items[n*9/10].sleepTime

		var totalTime time.Duration
		totalTimes := 0
		for _, it := range items {
			totalTime += it.sleepTime
			totalTimes += it.times
		}
		d.AvgBackoffTime[backoff] = totalTime / time.Duration(n)
		d.TotBackoffTime[backoff] = totalTime
		d.TotBackoffTimes[backoff] = totalTimes
	}
	return d
}

// SetFlagsFromPBFlag set the flag of StatementContext from a `tipb.SelectRequest.Flags`.
func (sc *StatementContext) SetFlagsFromPBFlag(flags uint64) {
	sc.IgnoreTruncate = (flags & model.FlagIgnoreTruncate) > 0
	sc.TruncateAsWarning = (flags & model.FlagTruncateAsWarning) > 0
	sc.InInsertStmt = (flags & model.FlagInInsertStmt) > 0
	sc.InSelectStmt = (flags & model.FlagInSelectStmt) > 0
	sc.OverflowAsWarning = (flags & model.FlagOverflowAsWarning) > 0
	sc.IgnoreZeroInDate = (flags & model.FlagIgnoreZeroInDate) > 0
	sc.DividedByZeroAsWarning = (flags & model.FlagDividedByZeroAsWarning) > 0
}

// GetLockWaitStartTime returns the statement pessimistic lock wait start time
func (sc *StatementContext) GetLockWaitStartTime() time.Time {
	startTime := atomic.LoadInt64(&sc.lockWaitStartTime)
	if startTime == 0 {
		startTime = time.Now().UnixNano()
		atomic.StoreInt64(&sc.lockWaitStartTime, startTime)
	}
	return time.Unix(0, startTime)
}

//CopTasksDetails collects some useful information of cop-tasks during execution.
type CopTasksDetails struct {
	NumCopTasks int

	AvgProcessTime    time.Duration
	P90ProcessTime    time.Duration
	MaxProcessAddress string
	MaxProcessTime    time.Duration

	AvgWaitTime    time.Duration
	P90WaitTime    time.Duration
	MaxWaitAddress string
	MaxWaitTime    time.Duration

	MaxBackoffTime    map[string]time.Duration
	MaxBackoffAddress map[string]string
	AvgBackoffTime    map[string]time.Duration
	P90BackoffTime    map[string]time.Duration
	TotBackoffTime    map[string]time.Duration
	TotBackoffTimes   map[string]int
}

// ToZapFields wraps the CopTasksDetails as zap.Fileds.
func (d *CopTasksDetails) ToZapFields() (fields []zap.Field) {
	if d.NumCopTasks == 0 {
		return
	}
	fields = make([]zap.Field, 0, 10)
	fields = append(fields, zap.Int("num_cop_tasks", d.NumCopTasks))
	fields = append(fields, zap.String("process_avg_time", strconv.FormatFloat(d.AvgProcessTime.Seconds(), 'f', -1, 64)+"s"))
	fields = append(fields, zap.String("process_p90_time", strconv.FormatFloat(d.P90ProcessTime.Seconds(), 'f', -1, 64)+"s"))
	fields = append(fields, zap.String("process_max_time", strconv.FormatFloat(d.MaxProcessTime.Seconds(), 'f', -1, 64)+"s"))
	fields = append(fields, zap.String("process_max_addr", d.MaxProcessAddress))
	fields = append(fields, zap.String("wait_avg_time", strconv.FormatFloat(d.AvgWaitTime.Seconds(), 'f', -1, 64)+"s"))
	fields = append(fields, zap.String("wait_p90_time", strconv.FormatFloat(d.P90WaitTime.Seconds(), 'f', -1, 64)+"s"))
	fields = append(fields, zap.String("wait_max_time", strconv.FormatFloat(d.MaxWaitTime.Seconds(), 'f', -1, 64)+"s"))
	fields = append(fields, zap.String("wait_max_addr", d.MaxWaitAddress))
	return fields
}