// Copyright 2016 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package perfschema
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import (
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"github.com/pingcap/tidb/kv"
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"github.com/pingcap/tidb/model"
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"github.com/pingcap/tidb/table"
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)
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// StatementInstrument defines the methods for statement instrumentation points
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type StatementInstrument interface {
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RegisterStatement(category, name string, elem interface{})
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StartStatement(sql string, connID uint64, callerName EnumCallerName, elem interface{}) *StatementState
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EndStatement(state *StatementState)
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}
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// PerfSchema defines the methods to be invoked by the executor
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type PerfSchema interface {
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// For statement instrumentation only.
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StatementInstrument
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// GetDBMeta returns db info for PerformanceSchema.
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GetDBMeta() *model.DBInfo
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// GetTable returns table instance for name.
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GetTable(name string) (table.Table, bool)
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}
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type perfSchema struct {
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store kv.Storage
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dbInfo *model.DBInfo
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tables map[string]*model.TableInfo
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mTables map[string]table.Table // MemoryTables for perfSchema
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// Used for TableStmtsHistory
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historyHandles []int64
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historyCursor int
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}
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var _ PerfSchema = (*perfSchema)(nil)
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// PerfHandle is the only access point for the in-memory performance schema information
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var (
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PerfHandle PerfSchema
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)
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// NewPerfHandle creates a new perfSchema on store.
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func NewPerfHandle(store kv.Storage) PerfSchema {
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schema := PerfHandle.(*perfSchema)
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schema.store = store
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schema.historyHandles = make([]int64, 0, stmtsHistoryElemMax)
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_ = schema.initialize()
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registerStatements()
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return PerfHandle
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}
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func init() {
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schema := &perfSchema{}
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PerfHandle = schema
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}
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