tidb init 源码
tidb init 代码
文件路径：/infoschema/perfschema/init.go
// Copyright 2016 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,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package perfschema
import (
"fmt"
"sync"
"github.com/pingcap/tidb/ddl"
"github.com/pingcap/tidb/expression"
"github.com/pingcap/tidb/infoschema"
"github.com/pingcap/tidb/meta/autoid"
"github.com/pingcap/tidb/parser"
"github.com/pingcap/tidb/parser/ast"
"github.com/pingcap/tidb/parser/model"
"github.com/pingcap/tidb/parser/mysql"
"github.com/pingcap/tidb/util"
)
var once sync.Once
// Init register the PERFORMANCE_SCHEMA virtual tables.
// It should be init(), and the ideal usage should be:
//
// import _ "github.com/pingcap/tidb/perfschema"
//
// This function depends on plan/core.init(), which initialize the expression.EvalAstExpr function.
// The initialize order is a problem if init() is used as the function name.
func Init() {
initOnce := func() {
p := parser.New()
tbls := make([]*model.TableInfo, 0)
dbID := autoid.PerformanceSchemaDBID
for _, sql := range perfSchemaTables {
stmt, err := p.ParseOneStmt(sql, "", "")
if err != nil {
panic(err)
}
meta, err := ddl.BuildTableInfoFromAST(stmt.(*ast.CreateTableStmt))
if err != nil {
panic(err)
}
tbls = append(tbls, meta)
var ok bool
meta.ID, ok = tableIDMap[meta.Name.O]
if !ok {
panic(fmt.Sprintf("get performance_schema table id failed, unknown system table `%v`", meta.Name.O))
}
for i, c := range meta.Columns {
c.ID = int64(i) + 1
}
}
dbInfo := &model.DBInfo{
ID: dbID,
Name: util.PerformanceSchemaName,
Charset: mysql.DefaultCharset,
Collate: mysql.DefaultCollationName,
Tables: tbls,
}
infoschema.RegisterVirtualTable(dbInfo, tableFromMeta)
}
if expression.EvalAstExpr != nil {
once.Do(initOnce)
}
}
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