...
Run Format

Source file src/runtime/lfstack.go

Documentation: runtime

  // 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)
  		}
  	}
  }
  

View as plain text