mysql: update mysql driver to latest master

The latest master implements the ColumnType interface.

See https://github.com/go-sql-driver/mysql/issues/495

This removes the custom code in the vendor folder that
did a ColumnType mapping.

vendor/github.com/go-sql-driver/mysql/connection.go

@@ -17,6 +17,16 @@ import (
 	"time"
 )
 
+// a copy of context.Context for Go 1.7 and earlier
+type mysqlContext interface {
+	Done() <-chan struct{}
+	Err() error
+
+	// defined in context.Context, but not used in this driver:
+	// Deadline() (deadline time.Time, ok bool)
+	// Value(key interface{}) interface{}
+}
+
 type mysqlConn struct {
 	buf              buffer
 	netConn          net.Conn
@@ -30,7 +40,14 @@ type mysqlConn struct {
 	status           statusFlag
 	sequence         uint8
 	parseTime        bool
-	strict           bool
+
+	// for context support (Go 1.8+)
+	watching bool
+	watcher  chan<- mysqlContext
+	closech  chan struct{}
+	finished chan<- struct{}
+	canceled atomicError // set non-nil if conn is canceled
+	closed   atomicBool  // set when conn is closed, before closech is closed
 }
 
 // Handles parameters set in DSN after the connection is established
@@ -63,22 +80,41 @@ func (mc *mysqlConn) handleParams() (err error) {
 	return
 }
 
+func (mc *mysqlConn) markBadConn(err error) error {
+	if mc == nil {
+		return err
+	}
+	if err != errBadConnNoWrite {
+		return err
+	}
+	return driver.ErrBadConn
+}
+
 func (mc *mysqlConn) Begin() (driver.Tx, error) {
-	if mc.netConn == nil {
+	return mc.begin(false)
+}
+
+func (mc *mysqlConn) begin(readOnly bool) (driver.Tx, error) {
+	if mc.closed.IsSet() {
 		errLog.Print(ErrInvalidConn)
 		return nil, driver.ErrBadConn
 	}
-	err := mc.exec("START TRANSACTION")
+	var q string
+	if readOnly {
+		q = "START TRANSACTION READ ONLY"
+	} else {
+		q = "START TRANSACTION"
+	}
+	err := mc.exec(q)
 	if err == nil {
 		return &mysqlTx{mc}, err
 	}
-
-	return nil, err
+	return nil, mc.markBadConn(err)
 }
 
 func (mc *mysqlConn) Close() (err error) {
 	// Makes Close idempotent
-	if mc.netConn != nil {
+	if !mc.closed.IsSet() {
 		err = mc.writeCommandPacket(comQuit)
 	}
 
@@ -92,26 +128,39 @@ func (mc *mysqlConn) Close() (err error) {
 // is called before auth or on auth failure because MySQL will have already
 // closed the network connection.
 func (mc *mysqlConn) cleanup() {
-	// Makes cleanup idempotent
-	if mc.netConn != nil {
-		if err := mc.netConn.Close(); err != nil {
-			errLog.Print(err)
-		}
-		mc.netConn = nil
+	if !mc.closed.TrySet(true) {
+		return
 	}
-	mc.cfg = nil
-	mc.buf.nc = nil
+
+	// Makes cleanup idempotent
+	close(mc.closech)
+	if mc.netConn == nil {
+		return
+	}
+	if err := mc.netConn.Close(); err != nil {
+		errLog.Print(err)
+	}
+}
+
+func (mc *mysqlConn) error() error {
+	if mc.closed.IsSet() {
+		if err := mc.canceled.Value(); err != nil {
+			return err
+		}
+		return ErrInvalidConn
+	}
+	return nil
 }
 
 func (mc *mysqlConn) Prepare(query string) (driver.Stmt, error) {
-	if mc.netConn == nil {
+	if mc.closed.IsSet() {
 		errLog.Print(ErrInvalidConn)
 		return nil, driver.ErrBadConn
 	}
 	// Send command
 	err := mc.writeCommandPacketStr(comStmtPrepare, query)
 	if err != nil {
-		return nil, err
+		return nil, mc.markBadConn(err)
 	}
 
 	stmt := &mysqlStmt{
@@ -145,7 +194,7 @@ func (mc *mysqlConn) interpolateParams(query string, args []driver.Value) (strin
 	if buf == nil {
 		// can not take the buffer. Something must be wrong with the connection
 		errLog.Print(ErrBusyBuffer)
-		return "", driver.ErrBadConn
+		return "", ErrInvalidConn
 	}
 	buf = buf[:0]
 	argPos := 0
@@ -258,7 +307,7 @@ func (mc *mysqlConn) interpolateParams(query string, args []driver.Value) (strin
 }
 
 func (mc *mysqlConn) Exec(query string, args []driver.Value) (driver.Result, error) {
-	if mc.netConn == nil {
+	if mc.closed.IsSet() {
 		errLog.Print(ErrInvalidConn)
 		return nil, driver.ErrBadConn
 	}
@@ -272,7 +321,6 @@ func (mc *mysqlConn) Exec(query string, args []driver.Value) (driver.Result, err
 			return nil, err
 		}
 		query = prepared
-		args = nil
 	}
 	mc.affectedRows = 0
 	mc.insertId = 0
@@ -284,14 +332,14 @@ func (mc *mysqlConn) Exec(query string, args []driver.Value) (driver.Result, err
 			insertId:     int64(mc.insertId),
 		}, err
 	}
-	return nil, err
+	return nil, mc.markBadConn(err)
 }
 
 // Internal function to execute commands
 func (mc *mysqlConn) exec(query string) error {
 	// Send command
 	if err := mc.writeCommandPacketStr(comQuery, query); err != nil {
-		return err
+		return mc.markBadConn(err)
 	}
 
 	// Read Result
@@ -316,7 +364,11 @@ func (mc *mysqlConn) exec(query string) error {
 }
 
 func (mc *mysqlConn) Query(query string, args []driver.Value) (driver.Rows, error) {
-	if mc.netConn == nil {
+	return mc.query(query, args)
+}
+
+func (mc *mysqlConn) query(query string, args []driver.Value) (*textRows, error) {
+	if mc.closed.IsSet() {
 		errLog.Print(ErrInvalidConn)
 		return nil, driver.ErrBadConn
 	}
@@ -330,7 +382,6 @@ func (mc *mysqlConn) Query(query string, args []driver.Value) (driver.Rows, erro
 			return nil, err
 		}
 		query = prepared
-		args = nil
 	}
 	// Send command
 	err := mc.writeCommandPacketStr(comQuery, query)
@@ -352,12 +403,13 @@ func (mc *mysqlConn) Query(query string, args []driver.Value) (driver.Rows, erro
 					return nil, err
 				}
 			}
+
 			// Columns
 			rows.rs.columns, err = mc.readColumns(resLen)
 			return rows, err
 		}
 	}
-	return nil, err
+	return nil, mc.markBadConn(err)
 }
 
 // Gets the value of the given MySQL System Variable
@@ -389,3 +441,21 @@ func (mc *mysqlConn) getSystemVar(name string) ([]byte, error) {
 	}
 	return nil, err
 }
+
+// finish is called when the query has canceled.
+func (mc *mysqlConn) cancel(err error) {
+	mc.canceled.Set(err)
+	mc.cleanup()
+}
+
+// finish is called when the query has succeeded.
+func (mc *mysqlConn) finish() {
+	if !mc.watching || mc.finished == nil {
+		return
+	}
+	select {
+	case mc.finished <- struct{}{}:
+		mc.watching = false
+	case <-mc.closech:
+	}
+}