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144 lines
4.3 KiB
144 lines
4.3 KiB
// Copyright 2015 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 variable
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import (
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"github.com/pingcap/tidb/context"
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)
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// SessionVars is to handle user-defined or global variables in current session.
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type SessionVars struct {
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// user-defined variables
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Users map[string]string
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// system variables
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Systems map[string]string
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// prepared statement
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PreparedStmts map[uint32]interface{}
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PreparedStmtNameToID map[string]uint32
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// prepared statement auto increment id
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preparedStmtID uint32
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// following variables are special for current session
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Status uint16
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LastInsertID uint64
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AffectedRows uint64
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// Client capability
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ClientCapability uint32
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// Connection ID
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ConnectionID uint64
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// Found rows
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FoundRows uint64
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// Current user
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User string
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}
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// sessionVarsKeyType is a dummy type to avoid naming collision in context.
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type sessionVarsKeyType int
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// String defines a Stringer function for debugging and pretty printing.
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func (k sessionVarsKeyType) String() string {
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return "session_vars"
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}
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const sessionVarsKey sessionVarsKeyType = 0
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// BindSessionVars creates a session vars object and binds it to context.
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func BindSessionVars(ctx context.Context) {
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v := &SessionVars{
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Users: make(map[string]string),
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Systems: make(map[string]string),
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PreparedStmts: make(map[uint32]interface{}),
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PreparedStmtNameToID: make(map[string]uint32),
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}
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ctx.SetValue(sessionVarsKey, v)
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}
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// GetSessionVars gets the session vars from context.
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func GetSessionVars(ctx context.Context) *SessionVars {
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v, ok := ctx.Value(sessionVarsKey).(*SessionVars)
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if !ok {
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return nil
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}
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return v
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}
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const (
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characterSetConnection = "character_set_connection"
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collationConnection = "collation_connection"
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)
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// GetCharsetInfo gets charset and collation for current context.
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// What character set should the server translate a statement to after receiving it?
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// For this, the server uses the character_set_connection and collation_connection system variables.
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// It converts statements sent by the client from character_set_client to character_set_connection
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// (except for string literals that have an introducer such as _latin1 or _utf8).
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// collation_connection is important for comparisons of literal strings.
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// For comparisons of strings with column values, collation_connection does not matter because columns
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// have their own collation, which has a higher collation precedence.
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// See: https://dev.mysql.com/doc/refman/5.7/en/charset-connection.html
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func GetCharsetInfo(ctx context.Context) (charset, collation string) {
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sessionVars := GetSessionVars(ctx)
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charset = sessionVars.Systems[characterSetConnection]
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collation = sessionVars.Systems[collationConnection]
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return
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}
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// SetLastInsertID saves the last insert id to the session context.
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// TODO: we may store the result for last_insert_id sys var later.
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func (s *SessionVars) SetLastInsertID(insertID uint64) {
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s.LastInsertID = insertID
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}
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// SetAffectedRows saves the affected rows to the session context.
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func (s *SessionVars) SetAffectedRows(affectedRows uint64) {
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s.AffectedRows = affectedRows
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}
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// AddAffectedRows adds affected rows with the argument rows.
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func (s *SessionVars) AddAffectedRows(rows uint64) {
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s.AffectedRows += rows
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}
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// AddFoundRows adds found rows with the argument rows.
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func (s *SessionVars) AddFoundRows(rows uint64) {
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s.FoundRows += rows
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}
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// SetStatusFlag sets the session server status variable.
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// If on is ture sets the flag in session status,
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// otherwise removes the flag.
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func (s *SessionVars) SetStatusFlag(flag uint16, on bool) {
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if on {
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s.Status |= flag
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return
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}
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s.Status &= (^flag)
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}
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// GetNextPreparedStmtID generates and returns the next session scope prepared statement id.
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func (s *SessionVars) GetNextPreparedStmtID() uint32 {
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s.preparedStmtID++
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return s.preparedStmtID
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}
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// SetCurrentUser saves the current user to the session context.
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func (s *SessionVars) SetCurrentUser(user string) {
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s.User = user
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}
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