poc: context support

Author: serprex

client/conn.go

@@ -35,6 +35,8 @@ type Conn struct {
 // Connection read and write timeouts to set on the connection
 ReadTimeout time.Duration
 WriteTimeout time.Duration
+contexts chan context.Context
+closed bool
 
 // The buffer size to use in the packet connection
 BufferSize int
@@ -136,6 +138,7 @@ func ConnectWithDialer(ctx context.Context, network, addr, user, password, dbNam
 c.password = password
 c.db = dbName
 c.proto = network
+c.contexts = make(chan context.Context)
 
 // use default charset here, utf-8
 c.charset = mysql.DEFAULT_CHARSET
@@ -184,6 +187,21 @@ func ConnectWithDialer(ctx context.Context, network, addr, user, password, dbNam
 }
 }
 
+go func() {
+ctx := context.Background()
+for {
+var ok bool
+select {
+case <-ctx.Done():
+_ = c.Conn.SetDeadline(time.Unix(0, 0))
+case ctx, ok = <-c.contexts:
+if !ok {
+return
+}
+}
+}
+}()
+
 return c, nil
 }
 
@@ -208,8 +226,19 @@ func (c *Conn) handshake() error {
 return nil
 }
 
+func (c *Conn) watchCtx(ctx context.Context) func() {
+c.contexts <- ctx
+return func() {
+c.contexts <- context.Background()
+}
+}
+
 // Close directly closes the connection. Use Quit() to first send COM_QUIT to the server and then close the connection.
 func (c *Conn) Close() error {
+if !c.closed {
+close(c.contexts)
+c.closed = true
+}
 return c.Conn.Close()
 }
 
@@ -309,6 +338,11 @@ func (c *Conn) Execute(command string, args ...interface{}) (*mysql.Result, erro
 }
 }
 
+func (c *Conn) ExecuteContext(ctx context.Context, command string, args ...interface{}) (*mysql.Result, error) {
+defer c.watchCtx(ctx)
+return c.Execute(command, args...)
+}
+
 // ExecuteMultiple will call perResultCallback for every result of the multiple queries
 // that are executed.
 //
@@ -363,6 +397,11 @@ func (c *Conn) ExecuteMultiple(query string, perResultCallback ExecPerResultCall
 return mysql.NewResult(rs), nil
 }
 
+func (c *Conn) ExecuteMultipleContext(ctx context.Context, query string, perResultCallback ExecPerResultCallback) (*mysql.Result, error) {
+defer c.watchCtx(ctx)
+return c.ExecuteMultiple(query, perResultCallback)
+}
+
 // ExecuteSelectStreaming will call perRowCallback for every row in resultset
 // WITHOUT saving any row data to Result.{Values/RawPkg/RowDatas} fields.
 // When given, perResultCallback will be called once per result
@@ -376,11 +415,33 @@ func (c *Conn) ExecuteSelectStreaming(command string, result *mysql.Result, perR
 return c.readResultStreaming(false, result, perRowCallback, perResultCallback)
 }
 
+func (c *Conn) ExecuteSelectStreamingContext(ctx context.Context, command string, result *mysql.Result, perRowCallback SelectPerRowCallback, perResultCallback SelectPerResultCallback) error {
+defer c.watchCtx(ctx)
+return c.ExecuteSelectStreaming(command, result, perRowCallback, perResultCallback)
+}
+
 func (c *Conn) Begin() error {
 _, err := c.exec("BEGIN")
 return errors.Trace(err)
 }
 
+func (c *Conn) BeginTx(ctx context.Context, readOnly bool, txIsolation string) error {
+defer c.watchCtx(ctx)()
+
+if txIsolation != "" {
+if _, err := c.exec("SET TRANSACTION ISOLATION LEVEL " + txIsolation); err != nil {
+return errors.Trace(err)
+}
+}
+var err error
+if readOnly {
+_, err = c.exec("START TRANSACTION READ ONLY")
+} else {
+_, err = c.exec("START TRANSACTION")
+}
+return errors.Trace(err)
+}
+
 func (c *Conn) Commit() error {
 _, err := c.exec("COMMIT")
 return errors.Trace(err)

driver/driver.go

@@ -3,6 +3,7 @@
 package driver
 
 import (
+"context"
 "crypto/tls"
 "database/sql"
 sqldriver "database/sql/driver"
@@ -185,6 +186,9 @@ type CheckNamedValueFunc func(*sqldriver.NamedValue) error
 var (
 _ sqldriver.NamedValueChecker = &conn{}
 _ sqldriver.Validator = &conn{}
+_ sqldriver.Conn = &conn{}
+_ sqldriver.ConnBeginTx = &conn{}
+_ sqldriver.QueryerContext = &conn{}
 )
 
 type state struct {
@@ -242,6 +246,27 @@ func (c *conn) Begin() (sqldriver.Tx, error) {
 return &tx{c.Conn}, nil
 }
 
+var isolationLevelTransactionIsolation = map[sql.IsolationLevel]string{
+sql.LevelDefault: "",
+sql.LevelRepeatableRead: "REPEATABLE READ",
+sql.LevelReadCommitted: "READ COMMITTED",
+sql.LevelReadUncommitted: "READ UNCOMMITTED",
+sql.LevelSerializable: "SERIALIZABLE",
+}
+
+func (c *conn) BeginTx(ctx context.Context, opts sqldriver.TxOptions) (sqldriver.Tx, error) {
+isolation := sql.IsolationLevel(opts.Isolation)
+txIsolation, ok := isolationLevelTransactionIsolation[isolation]
+if !ok {
+return nil, fmt.Errorf("invalid mysql transaction isolation level %s", isolation)
+}
+err := c.Conn.BeginTx(ctx, opts.ReadOnly, txIsolation)
+if err != nil {
+return nil, errors.Trace(err)
+}
+return &tx{c.Conn}, nil
+}
+
 func buildArgs(args []sqldriver.Value) []interface{} {
 a := make([]interface{}, len(args))
 
@@ -252,6 +277,17 @@ func buildArgs(args []sqldriver.Value) []interface{} {
 return a
 }
 
+func buildNamedArgs(args []sqldriver.NamedValue) []interface{} {
+a := make([]interface{}, len(args))
+
+for i, arg := range args {
+// TODO named parameter support
+a[i] = arg.Value
+}
+
+return a
+}
+
 func (st *state) replyError(err error) error {
 isBadConnection := mysql.ErrorEqual(err, mysql.ErrBadConn)
 
@@ -284,6 +320,15 @@ func (c *conn) Query(query string, args []sqldriver.Value) (sqldriver.Rows, erro
 return newRows(r.Resultset)
 }
 
+func (c *conn) QueryContext(ctx context.Context, query string, args []sqldriver.NamedValue) (sqldriver.Rows, error) {
+a := buildNamedArgs(args)
+r, err := c.Conn.ExecuteContext(ctx, query, a...)
+if err != nil {
+return nil, c.state.replyError(err)
+}
+return newRows(r.Resultset)
+}
+
 type stmt struct {
 *client.Stmt
 connectionState *state

packet/conn.go

@@ -31,7 +31,6 @@ type Conn struct {
 
 readTimeout time.Duration
 writeTimeout time.Duration
-ctx context.Context
 
 // Buffered reader for net.Conn in Non-TLS connection only to address replication performance issue.
 // See https://github.com/go-mysql-org/go-mysql/pull/422 for more details.