Revert "database/sql: prevent race in driver by locking dc in Next"

This reverts commit 897080d5cbb1793f8ad3ef5fb7c6fafba2e97d42.

Reason for revert: Fails to fix all the locking issues.

Updates #21117

Change-Id: I6fc9cb7897244d6e1af78c089a2bf383258ec049
Reviewed-on: https://go-review.googlesource.com/71450
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/database/sql/fakedb_test.go b/src/database/sql/fakedb_test.go
index 8e77df4ace8aa43dd8a41e9a74a74faf515ea615..4dcd096ca4d20db0e4fa4d8dc0f3a37ff32f3a50 100644 (file)
--- a/src/database/sql/fakedb_test.go
+++ b/src/database/sql/fakedb_test.go
@@ -943,7 +943,6 @@ type rowsCursor struct {
 }
 
 func (rc *rowsCursor) touchMem() {
-       rc.parentMem.touchMem()
        rc.line++
 }
 

diff --git a/src/database/sql/sql.go b/src/database/sql/sql.go
index 9a3957b267fc836645ffd04ddbf7727062703a3e..17910904f62eed5a90d7f469759f228c877c0f13 100644 (file)
--- a/src/database/sql/sql.go
+++ b/src/database/sql/sql.go
@@ -2491,12 +2491,6 @@ func (rs *Rows) nextLocked() (doClose, ok bool) {
        if rs.lastcols == nil {
                rs.lastcols = make([]driver.Value, len(rs.rowsi.Columns()))
        }
-
-       // Lock the driver connection before calling the driver interface
-       // rowsi to prevent a Tx from rolling back the connection at the same time.
-       rs.dc.Lock()
-       defer rs.dc.Unlock()
-
        rs.lasterr = rs.rowsi.Next(rs.lastcols)
        if rs.lasterr != nil {
                // Close the connection if there is a driver error.
@@ -2546,12 +2540,6 @@ func (rs *Rows) NextResultSet() bool {
                doClose = true
                return false
        }
-
-       // Lock the driver connection before calling the driver interface
-       // rowsi to prevent a Tx from rolling back the connection at the same time.
-       rs.dc.Lock()
-       defer rs.dc.Unlock()
-
        rs.lasterr = nextResultSet.NextResultSet()
        if rs.lasterr != nil {
                doClose = true

diff --git a/src/database/sql/sql_test.go b/src/database/sql/sql_test.go
index 760159a9acd6c0443361b9bffbbe0c979b30af20..046d95aff47bb9231756bc6b77c6fec1eaef20e6 100644 (file)
--- a/src/database/sql/sql_test.go
+++ b/src/database/sql/sql_test.go
@@ -3127,9 +3127,6 @@ func TestIssue6081(t *testing.T) {
 // In the test, a context is canceled while the query is in process so
 // the internal rollback will run concurrently with the explicitly called
 // Tx.Rollback.
-//
-// The addition of calling rows.Next also tests
-// Issue 21117.
 func TestIssue18429(t *testing.T) {
        db := newTestDB(t, "people")
        defer closeDB(t, db)
@@ -3140,7 +3137,7 @@ func TestIssue18429(t *testing.T) {
 
        const milliWait = 30
 
-       for i := 0; i < 1000; i++ {
+       for i := 0; i < 100; i++ {
                sem <- true
                wg.Add(1)
                go func() {
@@ -3162,9 +3159,6 @@ func TestIssue18429(t *testing.T) {
                        // reported.
                        rows, _ := tx.QueryContext(ctx, "WAIT|"+qwait+"|SELECT|people|name|")
                        if rows != nil {
-                               // Call Next to test Issue 21117 and check for races.
-                               for rows.Next() {
-                               }
                                rows.Close()
                        }
                        // This call will race with the context cancel rollback to complete