github.com/whtcorpsinc/milevadb-prod@v0.0.0-20211104133533-f57f4be3b597/schemareplicant/perfschema/init.go (about)

     1  // Copyright 2020 WHTCORPS INC, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package perfschema
    15  
    16  import (
    17  	"fmt"
    18  	"sync"
    19  
    20  	"github.com/whtcorpsinc/BerolinaSQL"
    21  	"github.com/whtcorpsinc/BerolinaSQL/allegrosql"
    22  	"github.com/whtcorpsinc/BerolinaSQL/ast"
    23  	"github.com/whtcorpsinc/BerolinaSQL/perceptron"
    24  	"github.com/whtcorpsinc/milevadb/dbs"
    25  	"github.com/whtcorpsinc/milevadb/memex"
    26  	"github.com/whtcorpsinc/milevadb/schemareplicant"
    27  	"github.com/whtcorpsinc/milevadb/soliton"
    28  	"github.com/whtcorpsinc/milevadb/spacetime/autoid"
    29  )
    30  
    31  var once sync.Once
    32  
    33  // Init register the PERFORMANCE_SCHEMA virtual blocks.
    34  // It should be init(), and the ideal usage should be:
    35  //
    36  // import _ "github.com/whtcorpsinc/milevadb/perfschema"
    37  //
    38  // This function depends on plan/embedded.init(), which initialize the memex.EvalAstExpr function.
    39  // The initialize order is a problem if init() is used as the function name.
    40  func Init() {
    41  	initOnce := func() {
    42  		p := BerolinaSQL.New()
    43  		tbls := make([]*perceptron.BlockInfo, 0)
    44  		dbID := autoid.PerformanceSchemaDBID
    45  		for _, allegrosql := range perfSchemaBlocks {
    46  			stmt, err := p.ParseOneStmt(allegrosql, "", "")
    47  			if err != nil {
    48  				panic(err)
    49  			}
    50  			spacetime, err := dbs.BuildBlockInfoFromAST(stmt.(*ast.CreateBlockStmt))
    51  			if err != nil {
    52  				panic(err)
    53  			}
    54  			tbls = append(tbls, spacetime)
    55  			var ok bool
    56  			spacetime.ID, ok = blockIDMap[spacetime.Name.O]
    57  			if !ok {
    58  				panic(fmt.Sprintf("get performance_schema causet id failed, unknown system causet `%v`", spacetime.Name.O))
    59  			}
    60  			for i, c := range spacetime.DeferredCausets {
    61  				c.ID = int64(i) + 1
    62  			}
    63  		}
    64  		dbInfo := &perceptron.DBInfo{
    65  			ID:          dbID,
    66  			Name:        soliton.PerformanceSchemaName,
    67  			Charset:     allegrosql.DefaultCharset,
    68  			DefCauslate: allegrosql.DefaultDefCauslationName,
    69  			Blocks:      tbls,
    70  		}
    71  		schemareplicant.RegisterVirtualBlock(dbInfo, blockFromMeta)
    72  	}
    73  	if memex.EvalAstExpr != nil {
    74  		once.Do(initOnce)
    75  	}
    76  }