1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
|
// Copyright 2012 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.
// Lock-free stack.
// Initialize head to 0, compare with 0 to test for emptiness.
// The stack does not keep pointers to nodes,
// so they can be garbage collected if there are no other pointers to nodes.
// The following code runs only in non-preemptible contexts.
package runtime
import (
"runtime/internal/atomic"
"unsafe"
)
// Temporary for C code to call:
//go:linkname lfstackpush runtime.lfstackpush
//go:linkname lfstackpop runtime.lfstackpop
func lfstackpush(head *uint64, node *lfnode) {
node.pushcnt++
new := lfstackPack(node, node.pushcnt)
if node1 := lfstackUnpack(new); node1 != node {
print("runtime: lfstackpush invalid packing: node=", node, " cnt=", hex(node.pushcnt), " packed=", hex(new), " -> node=", node1, "\n")
throw("lfstackpush")
}
for {
old := atomic.Load64(head)
node.next = old
if atomic.Cas64(head, old, new) {
break
}
}
}
func lfstackpop(head *uint64) unsafe.Pointer {
for {
old := atomic.Load64(head)
if old == 0 {
return nil
}
node := lfstackUnpack(old)
next := atomic.Load64(&node.next)
if atomic.Cas64(head, old, next) {
return unsafe.Pointer(node)
}
}
}
|
