Add context support

README.md

@@ -418,6 +418,10 @@ Version 1.0 of the driver recommended adding `&charset=utf8` (alias for `SET NAM
 
 See http://dev.mysql.com/doc/refman/5.7/en/charset-unicode.html for more details on MySQL's Unicode support.
 
+## Context Support
+Go 1.8 added some `database/sql` methods that accept a `context.Context` parameter for better control over timeout and cancellation.
+See more details on [context support to database/sql package](https://golang.org/doc/go1.8#database_sql, "sql").
+Go-MySQL-Driver supports context deadlines, but not cancellation.
 
 ## Testing / Development
 To run the driver tests you may need to adjust the configuration. See the [Testing Wiki-Page](https://github.com/go-sql-driver/mysql/wiki/Testing "Testing") for details.

buffer.go

@@ -38,7 +38,7 @@ func newBuffer(nc net.Conn) buffer {
 }
 
 // fill reads into the buffer until at least _need_ bytes are in it
-func (b *buffer) fill(need int) error {
+func (b *buffer) fill(ctx mysqlContext, need int) error {
 	n := b.length
 
 	// move existing data to the beginning
@@ -59,8 +59,14 @@ func (b *buffer) fill(need int) error {
 	b.idx = 0
 
 	for {
-		if b.timeout > 0 {
-			if err := b.nc.SetReadDeadline(time.Now().Add(b.timeout)); err != nil {
+		var deadline time.Time
+		if ctxDeadline, ok := ctx.Deadline(); ok {
+			deadline = ctxDeadline
+		} else if b.timeout > 0 {
+			deadline = time.Now().Add(b.timeout)
+		}
+		if !deadline.IsZero() {
+			if err := b.nc.SetReadDeadline(deadline); err != nil {
 				return err
 			}
 		}
@@ -91,10 +97,10 @@ func (b *buffer) fill(need int) error {
 
 // returns next N bytes from buffer.
 // The returned slice is only guaranteed to be valid until the next read
-func (b *buffer) readNext(need int) ([]byte, error) {
+func (b *buffer) readNext(ctx mysqlContext, need int) ([]byte, error) {
 	if b.length < need {
 		// refill
-		if err := b.fill(need); err != nil {
+		if err := b.fill(ctx, need); err != nil {
 			return nil, err
 		}
 	}

connection.go

@@ -42,7 +42,7 @@ func (mc *mysqlConn) handleParams() (err error) {
 			charsets := strings.Split(val, ",")
 			for i := range charsets {
 				// ignore errors here - a charset may not exist
-				err = mc.exec("SET NAMES " + charsets[i])
+				err = mc.exec(backgroundCtx(), "SET NAMES "+charsets[i])
 				if err == nil {
 					break
 				}
@@ -53,7 +53,7 @@ func (mc *mysqlConn) handleParams() (err error) {
 
 		// System Vars
 		default:
-			err = mc.exec("SET " + param + "=" + val + "")
+			err = mc.exec(backgroundCtx(), "SET "+param+"="+val+"")
 			if err != nil {
 				return
 			}
@@ -63,12 +63,17 @@ func (mc *mysqlConn) handleParams() (err error) {
 	return
 }
 
+// Begin implements driver.Conn interface
 func (mc *mysqlConn) Begin() (driver.Tx, error) {
+	return mc.beginTx(backgroundCtx(), txOptions{})
+}
+
+func (mc *mysqlConn) beginTx(ctx mysqlContext, opts txOptions) (driver.Tx, error) {
 	if mc.netConn == nil {
 		errLog.Print(ErrInvalidConn)
 		return nil, driver.ErrBadConn
 	}
-	err := mc.exec("START TRANSACTION")
+	err := mc.exec(ctx, "START TRANSACTION")
 	if err == nil {
 		return &mysqlTx{mc}, err
 	}
@@ -79,7 +84,7 @@ func (mc *mysqlConn) Begin() (driver.Tx, error) {
 func (mc *mysqlConn) Close() (err error) {
 	// Makes Close idempotent
 	if mc.netConn != nil {
-		err = mc.writeCommandPacket(comQuit)
+		err = mc.writeCommandPacket(backgroundCtx(), comQuit)
 	}
 
 	mc.cleanup()
@@ -104,12 +109,16 @@ func (mc *mysqlConn) cleanup() {
 }
 
 func (mc *mysqlConn) Prepare(query string) (driver.Stmt, error) {
+	return mc.prepareContext(backgroundCtx(), query)
+}
+
+func (mc *mysqlConn) prepareContext(ctx mysqlContext, query string) (driver.Stmt, error) {
 	if mc.netConn == nil {
 		errLog.Print(ErrInvalidConn)
 		return nil, driver.ErrBadConn
 	}
 	// Send command
-	err := mc.writeCommandPacketStr(comStmtPrepare, query)
+	err := mc.writeCommandPacketStr(ctx, comStmtPrepare, query)
 	if err != nil {
 		return nil, err
 	}
@@ -119,16 +128,16 @@ func (mc *mysqlConn) Prepare(query string) (driver.Stmt, error) {
 	}
 
 	// Read Result
-	columnCount, err := stmt.readPrepareResultPacket()
+	columnCount, err := stmt.readPrepareResultPacket(ctx)
 	if err == nil {
 		if stmt.paramCount > 0 {
-			if err = mc.readUntilEOF(); err != nil {
+			if err = mc.readUntilEOF(ctx); err != nil {
 				return nil, err
 			}
 		}
 
 		if columnCount > 0 {
-			err = mc.readUntilEOF()
+			err = mc.readUntilEOF(ctx)
 		}
 	}
 
@@ -258,6 +267,10 @@ func (mc *mysqlConn) interpolateParams(query string, args []driver.Value) (strin
 }
 
 func (mc *mysqlConn) Exec(query string, args []driver.Value) (driver.Result, error) {
+	return mc.ExecContext(backgroundCtx(), query, args)
+}
+
+func (mc *mysqlConn) ExecContext(ctx mysqlContext, query string, args []driver.Value) (driver.Result, error) {
 	if mc.netConn == nil {
 		errLog.Print(ErrInvalidConn)
 		return nil, driver.ErrBadConn
@@ -276,7 +289,7 @@ func (mc *mysqlConn) Exec(query string, args []driver.Value) (driver.Result, err
 	mc.affectedRows = 0
 	mc.insertId = 0
 
-	err := mc.exec(query)
+	err := mc.exec(ctx, query)
 	if err == nil {
 		return &mysqlResult{
 			affectedRows: int64(mc.affectedRows),
@@ -287,34 +300,39 @@ func (mc *mysqlConn) Exec(query string, args []driver.Value) (driver.Result, err
 }
 
 // Internal function to execute commands
-func (mc *mysqlConn) exec(query string) error {
+func (mc *mysqlConn) exec(ctx mysqlContext, query string) error {
 	// Send command
-	if err := mc.writeCommandPacketStr(comQuery, query); err != nil {
+	if err := mc.writeCommandPacketStr(ctx, comQuery, query); err != nil {
 		return err
 	}
 
 	// Read Result
-	resLen, err := mc.readResultSetHeaderPacket()
+	resLen, err := mc.readResultSetHeaderPacket(ctx)
 	if err != nil {
 		return err
 	}
 
 	if resLen > 0 {
 		// columns
-		if err := mc.readUntilEOF(); err != nil {
+		if err := mc.readUntilEOF(ctx); err != nil {
 			return err
 		}
 
 		// rows
-		if err := mc.readUntilEOF(); err != nil {
+		if err := mc.readUntilEOF(ctx); err != nil {
 			return err
 		}
 	}
 
-	return mc.discardResults()
+	return mc.discardResults(ctx)
 }
 
+// Query implements driver.Queryer interface
 func (mc *mysqlConn) Query(query string, args []driver.Value) (driver.Rows, error) {
+	return mc.queryContext(backgroundCtx(), query, args)
+}
+
+func (mc *mysqlConn) queryContext(ctx mysqlContext, query string, args []driver.Value) (driver.Rows, error) {
 	if mc.netConn == nil {
 		errLog.Print(ErrInvalidConn)
 		return nil, driver.ErrBadConn
@@ -331,11 +349,11 @@ func (mc *mysqlConn) Query(query string, args []driver.Value) (driver.Rows, erro
 		query = prepared
 	}
 	// Send command
-	err := mc.writeCommandPacketStr(comQuery, query)
+	err := mc.writeCommandPacketStr(ctx, comQuery, query)
 	if err == nil {
 		// Read Result
 		var resLen int
-		resLen, err = mc.readResultSetHeaderPacket()
+		resLen, err = mc.readResultSetHeaderPacket(ctx)
 		if err == nil {
 			rows := new(textRows)
 			rows.mc = mc
@@ -351,7 +369,7 @@ func (mc *mysqlConn) Query(query string, args []driver.Value) (driver.Rows, erro
 				}
 			}
 			// Columns
-			rows.rs.columns, err = mc.readColumns(resLen)
+			rows.rs.columns, err = mc.readColumns(ctx, resLen)
 			return rows, err
 		}
 	}
@@ -360,29 +378,29 @@ func (mc *mysqlConn) Query(query string, args []driver.Value) (driver.Rows, erro
 
 // Gets the value of the given MySQL System Variable
 // The returned byte slice is only valid until the next read
-func (mc *mysqlConn) getSystemVar(name string) ([]byte, error) {
+func (mc *mysqlConn) getSystemVar(ctx mysqlContext, name string) ([]byte, error) {
 	// Send command
-	if err := mc.writeCommandPacketStr(comQuery, "SELECT @@"+name); err != nil {
+	if err := mc.writeCommandPacketStr(ctx, comQuery, "SELECT @@"+name); err != nil {
 		return nil, err
 	}
 
 	// Read Result
-	resLen, err := mc.readResultSetHeaderPacket()
+	resLen, err := mc.readResultSetHeaderPacket(ctx)
 	if err == nil {
 		rows := new(textRows)
 		rows.mc = mc
 		rows.rs.columns = []mysqlField{{fieldType: fieldTypeVarChar}}
 
 		if resLen > 0 {
 			// Columns
-			if err := mc.readUntilEOF(); err != nil {
+			if err := mc.readUntilEOF(ctx); err != nil {
 				return nil, err
 			}
 		}
 
 		dest := make([]driver.Value, resLen)
-		if err = rows.readRow(dest); err == nil {
-			return dest[0].([]byte), mc.readUntilEOF()
+		if err = rows.readRow(ctx, dest); err == nil {
+			return dest[0].([]byte), mc.readUntilEOF(ctx)
 		}
 	}
 	return nil, err

connection_ctx.go

@@ -0,0 +1,48 @@
+// +build go1.8
+
+// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
+//
+// Copyright 2012 The Go-MySQL-Driver Authors. All rights reserved.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package mysql
+
+import (
+	"context"
+	"database/sql/driver"
+)
+
+// Ping implements driver.Pinger interface
+func (mc *mysqlConn) Ping(ctx context.Context) error {
+	if mc.netConn == nil {
+		errLog.Print(ErrInvalidConn)
+		return driver.ErrBadConn
+	}
+	if err := mc.writeCommandPacket(ctx, comPing); err != nil {
+		errLog.Print(err)
+		return err
+	}
+
+	if _, err := mc.readResultOK(ctx); err != nil {
+		errLog.Print(err)
+		return err
+	}
+	return nil
+}
+
+// BeginTx implements driver.ConnBeginTx interface
+func (mc *mysqlConn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, error) {
+	return mc.beginTx(ctx, txOptions(opts))
+}
+
+func (mc *mysqlConn) PrepareContext(ctx context.Context, query string) (driver.Stmt, error) {
+	return mc.prepareContext(ctx, query)
+}
+
+// QueryContext implements driver.QueryerContext interface
+func (mc *mysqlConn) QueryContext(ctx context.Context, query string, args []driver.Value) (driver.Rows, error) {
+	return mc.queryContext(ctx, query, args)
+}

ctx_backport.go

@@ -0,0 +1,70 @@
+// +build !go1.8
+
+// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
+//
+// Copyright 2012 The Go-MySQL-Driver Authors. All rights reserved.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package mysql
+
+import (
+	"time"
+)
+
+// txOptions is defined for compatibility with Go 1.8's driver.TxOptions struct.
+type txOptions struct {
+	Isolation int
+	ReadOnly  bool
+}
+
+// mysqlContext is a copy of context.Context from Go 1.7 and later.
+type mysqlContext interface {
+	Deadline() (deadline time.Time, ok bool)
+
+	Done() <-chan struct{}
+
+	Err() error
+
+	Value(key interface{}) interface{}
+}
+
+// emptyCtx is copied from Go 1.7's context package.
+type emptyCtx int
+
+func (*emptyCtx) Deadline() (deadline time.Time, ok bool) {
+	return
+}
+
+func (*emptyCtx) Done() <-chan struct{} {
+	return nil
+}
+
+func (*emptyCtx) Err() error {
+	return nil
+}
+
+func (*emptyCtx) Value(key interface{}) interface{} {
+	return nil
+}
+
+func (e *emptyCtx) String() string {
+	return "context.Background"
+}
+
+var background = new(emptyCtx)
+
+func backgroundCtx() mysqlContext {
+	return background
+}
+
+var deadlineExceeded = deadlineExceededError{}
+
+// deadlineExceededError is copied from Go 1.7's context package.
+type deadlineExceededError struct{}
+
+func (deadlineExceededError) Error() string   { return "context deadline exceeded" }
+func (deadlineExceededError) Timeout() bool   { return true }
+func (deadlineExceededError) Temporary() bool { return true }