From d1783bbbebffb91385d4d756523a8e134375311b Mon Sep 17 00:00:00 2001
From: Alain Jobart <alainjobart@google.com>
Date: Mon, 22 May 2017 14:08:36 -0700
Subject: [PATCH] Changing mysql.ComQuery parameter to []byte.

So we minimize copies.
---
 go/mysql/fakesqldb/server.go        | 3 ++-
 go/mysql/query.go                   | 4 ++--
 go/mysql/query_test.go              | 2 +-
 go/mysql/server.go                  | 4 +++-
 go/mysql/server_test.go             | 3 ++-
 go/vt/vtgate/plugin_mysql_server.go | 4 ++--
 6 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/go/mysql/fakesqldb/server.go b/go/mysql/fakesqldb/server.go
index 877d1b4c10..fb606060be 100644
--- a/go/mysql/fakesqldb/server.go
+++ b/go/mysql/fakesqldb/server.go
@@ -241,7 +241,8 @@ func (db *DB) ConnectionClosed(c *mysql.Conn) {
 }
 
 // ComQuery is part of the mysql.Handler interface.
-func (db *DB) ComQuery(c *mysql.Conn, query string) (*sqltypes.Result, error) {
+func (db *DB) ComQuery(c *mysql.Conn, q []byte) (*sqltypes.Result, error) {
+	query := string(q)
 	db.t.Logf("ComQuery(%v): client %v: %v", db.name, c.ConnectionID, query)
 
 	key := strings.ToLower(query)
diff --git a/go/mysql/query.go b/go/mysql/query.go
index 3ff6bc5b2f..23d7658995 100644
--- a/go/mysql/query.go
+++ b/go/mysql/query.go
@@ -454,8 +454,8 @@ func (c *Conn) readComQueryResponse() (uint64, uint64, int, error) {
 // Server side methods.
 //
 
-func (c *Conn) parseComQuery(data []byte) string {
-	return string(data[1:])
+func (c *Conn) parseComQuery(data []byte) []byte {
+	return data[1:]
 }
 
 func (c *Conn) parseComInitDB(data []byte) string {
diff --git a/go/mysql/query_test.go b/go/mysql/query_test.go
index f7bdf0933a..f431bcaf2c 100644
--- a/go/mysql/query_test.go
+++ b/go/mysql/query_test.go
@@ -404,7 +404,7 @@ func checkQueryInternal(t *testing.T, query string, sConn, cConn *Conn, result *
 		if comQuery[0] != ComQuery {
 			t.Fatalf("server got bad packet: %v", comQuery)
 		}
-		got := sConn.parseComQuery(comQuery)
+		got := string(sConn.parseComQuery(comQuery))
 		if got != query {
 			t.Errorf("server got query '%v' but expected '%v'", got, query)
 		}
diff --git a/go/mysql/server.go b/go/mysql/server.go
index db41bc4f60..269d406d6f 100644
--- a/go/mysql/server.go
+++ b/go/mysql/server.go
@@ -54,7 +54,9 @@ type Handler interface {
 	ConnectionClosed(c *Conn)
 
 	// ComQuery is called when a connection receives a query.
-	ComQuery(c *Conn, query string) (*sqltypes.Result, error)
+	// Note the contents of the query slice may change after this method
+	// returns, so the Handler should not hang on to the byte slice.
+	ComQuery(c *Conn, query []byte) (*sqltypes.Result, error)
 }
 
 // Listener is the MySQL server protocol listener.
diff --git a/go/mysql/server_test.go b/go/mysql/server_test.go
index 4b5f4edf1d..7669bd0066 100644
--- a/go/mysql/server_test.go
+++ b/go/mysql/server_test.go
@@ -71,7 +71,8 @@ func (th *testHandler) NewConnection(c *Conn) {
 func (th *testHandler) ConnectionClosed(c *Conn) {
 }
 
-func (th *testHandler) ComQuery(c *Conn, query string) (*sqltypes.Result, error) {
+func (th *testHandler) ComQuery(c *Conn, q []byte) (*sqltypes.Result, error) {
+	query := string(q)
 	if query == "error" {
 		return nil, NewSQLError(ERUnknownComError, SSUnknownComError, "forced query handling error for: %v", query)
 	}
diff --git a/go/vt/vtgate/plugin_mysql_server.go b/go/vt/vtgate/plugin_mysql_server.go
index ec63d0c288..48afc9980a 100644
--- a/go/vt/vtgate/plugin_mysql_server.go
+++ b/go/vt/vtgate/plugin_mysql_server.go
@@ -69,7 +69,7 @@ func (vh *vtgateHandler) ConnectionClosed(c *mysql.Conn) {
 	}
 }
 
-func (vh *vtgateHandler) ComQuery(c *mysql.Conn, query string) (*sqltypes.Result, error) {
+func (vh *vtgateHandler) ComQuery(c *mysql.Conn, query []byte) (*sqltypes.Result, error) {
 	// FIXME(alainjobart): Add some kind of timeout to the context.
 	ctx := context.Background()
 
@@ -99,7 +99,7 @@ func (vh *vtgateHandler) ComQuery(c *mysql.Conn, query string) (*sqltypes.Result
 	if c.SchemaName != "" {
 		session.TargetString = c.SchemaName
 	}
-	session, result, err := vh.vtg.Execute(ctx, session, query, make(map[string]interface{}))
+	session, result, err := vh.vtg.Execute(ctx, session, string(query), make(map[string]interface{}))
 	c.ClientData = session
 	return result, mysql.NewSQLErrorFromError(err)
 }