/usr/share/go-1.8/src/runtime/lfstack.go is in golang-1.8-src 1.8.3-2ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 | // 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"
)
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)
}
}
}
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