rclone/vendor/github.com/spacemonkeygo/monkit/v3/cas_safe.go

// Copyright (C) 2015 Space Monkey, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// +build appengine

package monkit

import "sync"

// TODO(jeff): make this mutex smaller scoped, perhaps based on the arguments
// to compare and swap?
var bigHonkinMutex sync.Mutex

func loadFunc(addr **Func) (s *Func) {
	bigHonkinMutex.Lock()
	s = *addr
	bigHonkinMutex.Unlock()
	return s
}

func compareAndSwapFunc(addr **Func, old, new *Func) bool {
	bigHonkinMutex.Lock()
	val := *addr
	if val == old {
		*addr = new
		bigHonkinMutex.Unlock()
		return true
	}
	bigHonkinMutex.Unlock()
	return false
}

func loadTraceWatcherRef(addr **traceWatcherRef) (val *traceWatcherRef) {
	bigHonkinMutex.Lock()
	val = *addr
	bigHonkinMutex.Unlock()
	return val
}

func storeTraceWatcherRef(addr **traceWatcherRef, val *traceWatcherRef) {
	bigHonkinMutex.Lock()
	*addr = val
	bigHonkinMutex.Unlock()
}

func compareAndSwapSpanObserverTuple(addr **spanObserverTuple,
	old, new *spanObserverTuple) bool {
	bigHonkinMutex.Lock()
	val := *addr
	if val == old {
		*addr = new
		bigHonkinMutex.Unlock()
		return true
	}
	bigHonkinMutex.Unlock()
	return false
}

func loadSpanObserverTuple(addr **spanObserverTuple) (val *spanObserverTuple) {
	bigHonkinMutex.Lock()
	val = *addr
	bigHonkinMutex.Unlock()
	return val
}