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server: fixed a bug that params description will be sent when no params in handleStmtDescription #61

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merged 1 commit into from
Sep 8, 2021
Merged

server: fixed a bug that params description will be sent when no params in handleStmtDescription #61

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1 change: 1 addition & 0 deletions server/conn.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1025,6 +1025,7 @@ func (cc *clientConn) dispatch(ctx context.Context, data []byte) error {
}
return cc.handleStmtDescription(ctx, desc)
case 'H': /* flush */
return cc.flush(ctx)
case 'S': /* sync */
return cc.writeReadyForQuery(ctx, cc.ctx.Status())
case 'X':
Expand Down
75 changes: 42 additions & 33 deletions server/conn_stmt.go
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Original file line number Diff line number Diff line change
Expand Up @@ -66,7 +66,7 @@ import (
"github.com/pingcap/tidb/util/hack"
)

// handleStmtPrepare 预处理语句
// handleStmtPrepare handle prepare message in pgsql's extended query.
// PgSQL Modified
func (cc *clientConn) handleStmtPrepare(ctx context.Context, parser pgproto3.Parse) error {
//stmt, columns, params, err := cc.ctx.Prepare(parser.Query)
Expand All @@ -78,7 +78,7 @@ func (cc *clientConn) handleStmtPrepare(ctx context.Context, parser pgproto3.Par

vars := cc.ctx.GetSessionVars()

// 将在 Prepare 阶段解析传来的参数类型在这里获取，并保留在 stmt 中
// Get param types in sqllan, and save it in `stmt`.
var paramTypes []byte
if cachedStmt, ok := vars.PreparedStmts[uint32(stmt.ID())].(*plannercore.CachedPrepareStmt); ok {
cachedParams := cachedStmt.PreparedAst.Params
Expand All @@ -96,17 +96,17 @@ func (cc *clientConn) handleStmtPrepare(ctx context.Context, parser pgproto3.Par
return cc.flush(ctx)
}

// handleStmtBind 处理pgsql拓展查询协议过程中的bind过程
// handleStmtBind handle bind messages in pgsql's extended query.
// PGSQL Modified
func (cc *clientConn) handleStmtBind(ctx context.Context, bind pgproto3.Bind) (err error) {
vars := cc.ctx.GetSessionVars()

// 当为临时预处理查询，默认设置 Name 为 0
// When it is a temporary prepared stmt, the default name setting is 0
if bind.PreparedStatement == "" {
bind.PreparedStatement = "0"
}

// 获取stmtID 通过ID获取到预处理语句
// Get stmtID through stmt name.
stmtID, ok := vars.PreparedStmtNameToID[bind.PreparedStatement]
if !ok {
return mysql.NewErr(mysql.ErrUnknownStmtHandler,
Expand Down Expand Up @@ -137,19 +137,20 @@ func (cc *clientConn) handleStmtBind(ctx context.Context, bind pgproto3.Bind) (e
stmt.SetArgs(args)
}

// 当ResultFormatCode长度为1时，表示一次设定整行数据格式，如果长度大于1小于column，代表客户端传参存在问题
// When the length of `ResultFormatCodes` equ that the data format of the whole row is set at one time.
// If the length is greater than 1 and less than column length,
// it means that there is a problem in the parameter transfer of the client.
if len(bind.ResultFormatCodes) > 1 && len(bind.ResultFormatCodes) < len(stmt.GetColumnInfo()) {
return errors.New("the result format code parameter in the bind message is wrong")
}

// 对返回数据的格式进行设置, 由Bind信息中获取
// 当resultFormat 为空代表默认为Text
// 当resultFormat 只有一个值代表指定一整行的格式

stmt.SetResultFormat(bind.ResultFormatCodes)

// Bind 完成后创建 Portal，Portal Name 由客户端传送过来
// 果如 Portal Name 为空则表示为临时门户，用"0"作为默认 Name
// 这个位置没有进行真正的 Portal 生成，只是绑定 StmtID 在后面的阶段可以通过 Portal Name 找到 Statement ID
// When create `Portal`, clients will send the portal name.
// If portal name is empty, it will be set to "0" by default.
// Notice: there is not a real portal by created,
// we just put portal name and stmtID in map, then you can get stmtID.
if bind.DestinationPortal != "" {
vars.Portal[bind.DestinationPortal] = stmtID
} else {
Expand All @@ -163,24 +164,27 @@ func (cc *clientConn) handleStmtBind(ctx context.Context, bind pgproto3.Bind) (e
return cc.flush(ctx)
}

// handleStmtDescription 处理 Description 请求，通过 stmtName 找到相应的预处理语句
// 返回参数的类型信息和返回值的表结构信息，如果没有返回值，则返回 NoData
// handleStmtDescription handle Description messages in pgsql's extended query，
// find prepared stmt through `stmtName` or `portal`.
// Return `writeParameterDescription` and `WriteRowDescription` when columnInfo is not empty,
// otherwise return `writeNoData`.
func (cc *clientConn) handleStmtDescription(ctx context.Context, desc pgproto3.Describe) error {
vars := cc.ctx.GetSessionVars()

// 无论是 Stmt Name 还是 Portal Name 当为临时语句的时候，默认 Name 为 "0"
// Whether stmt name or portal name, when it is a temporary statement, the default name is "0".
if desc.Name == "" {
desc.Name = "0"
}

var stmtID uint32
var ok bool

// 如果通过 Portal 来指定运行语句，则直接通过 Portal 找到对应 StmtID 来运行即可
// If it specify the prepared statement through portal,
// here can directly find the corresponding stmtID through portal.
if desc.ObjectType == 'P' {
stmtID, ok = vars.Portal[desc.Name]
} else {
// 获取stmtID 通过ID获取到预处理语句
// Or get prepared stmtID through stmtName.
stmtID, ok = vars.PreparedStmtNameToID[desc.Name]
}

Expand All @@ -189,33 +193,38 @@ func (cc *clientConn) handleStmtDescription(ctx context.Context, desc pgproto3.D
strconv.FormatUint(uint64(stmtID), 10), "stmt_description")
}

stmt := cc.ctx.GetStatement(int(stmtID))
// Get prepared stmt through stmtID.
stmt :=cc.ctx.GetStatement(int(stmtID))
if stmt == nil {
return mysql.NewErr(mysql.ErrUnknownStmtHandler,
strconv.FormatUint(uint64(stmtID), 10), "stmt_description")
}
numParams := stmt.NumParams()

// 将解析阶段解析出的参数类型获取到，并转换为PgSQL数据类型传回到客户端
paramsType := stmt.GetParamsType()
pgType := make([]uint32, numParams)
for i := range paramsType {
pgType[i] = convertMySQLDataTypeToPgSQLDataType(paramsType[i])
}
numParams := stmt.NumParams()
if numParams > 0 {
// Get param types that analyzed in `handleStmtBind`,
// And convert it to PgSQL data type and return it to the client
paramsType := stmt.GetParamsType()
pgType := make([]uint32, numParams)
for i := range paramsType {
pgType[i] = convertMySQLDataTypeToPgSQLDataType(paramsType[i])
}

if err := cc.writeParameterDescription(pgType); err != nil {
return err
if err := cc.writeParameterDescription(pgType); err != nil {
return err
}
}

// columnInfo 有数据则返回 WriteRowDescription 没有数据则需要返回 NoData
// Return `WriteRowDescription` when columnInfo is not empty,
// otherwise return `writeNoData`.
columnInfo := stmt.GetColumnInfo()
if columnInfo == nil || len(columnInfo) > 0 {
if err := cc.WriteRowDescription(columnInfo); err != nil {
return err
}

// 如果在这个位子已经输出的行描述信息，则在后面输出结果时不再输出行描述信息

// If the row description information has been output here,
// it will not be output when `writeResultset` later.
} else {
if err := cc.writeNoData(); err != nil {
return err
Expand All @@ -224,12 +233,12 @@ func (cc *clientConn) handleStmtDescription(ctx context.Context, desc pgproto3.D
return cc.flush(ctx)
}

// handleStmtExecute 处理 Execute 请求
// handleStmtExecute handle execute messages in pgsql's extended query.
// PGSQL Modified
func (cc *clientConn) handleStmtExecute(ctx context.Context, execute pgproto3.Execute) error {
defer trace.StartRegion(ctx, "HandleStmtExecute").End()

// 当为临时预处理查询，默认设置 Name 为 0
// When it is a temporary prepared stmt, the default name setting is "0".
if execute.Portal == "" {
execute.Portal = "0"
}
Expand Down Expand Up @@ -261,7 +270,7 @@ func (cc *clientConn) handleStmtExecute(ctx context.Context, execute pgproto3.Ex
return nil
}

// handleStmtClose 处理 Close 请求
// handleStmtClose handle close messages in pgsql's extended query.
func (cc *clientConn) handleStmtClose(ctx context.Context, close pgproto3.Close) error {
vars := cc.ctx.GetSessionVars()
var stmtID uint32
Expand Down