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runtime: delay marking maps as writing until after first alg call

Fixes #19359

Change-Id: I196b47cf0471915b6dc63785e8542aa1876ff695
Reviewed-on: https://go-review.googlesource.com/37665
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Josh Bleecher Snyder 2017-03-02 06:30:26 -08:00
parent 0ee9c46cb1
commit 04fc887761
2 changed files with 46 additions and 3 deletions

View File

@ -498,11 +498,13 @@ func mapassign(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
if h.flags&hashWriting != 0 {
throw("concurrent map writes")
}
h.flags |= hashWriting
alg := t.key.alg
hash := alg.hash(key, uintptr(h.hash0))
// Set hashWriting after calling alg.hash, since alg.hash may panic,
// in which case we have not actually done a write.
h.flags |= hashWriting
if h.buckets == nil {
h.buckets = newarray(t.bucket, 1)
}
@ -611,10 +613,14 @@ func mapdelete(t *maptype, h *hmap, key unsafe.Pointer) {
if h.flags&hashWriting != 0 {
throw("concurrent map writes")
}
h.flags |= hashWriting
alg := t.key.alg
hash := alg.hash(key, uintptr(h.hash0))
// Set hashWriting after calling alg.hash, since alg.hash may panic,
// in which case we have not actually done a write (delete).
h.flags |= hashWriting
bucket := hash & (uintptr(1)<<h.B - 1)
if h.growing() {
growWork(t, h, bucket)

View File

@ -0,0 +1,37 @@
// run
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import "fmt"
func set(m map[interface{}]interface{}, key interface{}) (err error) {
defer func() {
if r := recover(); r != nil {
err = fmt.Errorf("set failed: %v", r)
}
}()
m[key] = nil
return nil
}
func del(m map[interface{}]interface{}, key interface{}) (err error) {
defer func() {
if r := recover(); r != nil {
err = fmt.Errorf("del failed: %v", r)
}
}()
delete(m, key)
return nil
}
func main() {
m := make(map[interface{}]interface{})
set(m, []int{1, 2, 3})
set(m, "abc") // used to throw
del(m, []int{1, 2, 3})
del(m, "abc") // used to throw
}