maker/access.go

// Copyright (C) 2015 The Android Open Source Project
//
// 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.

package maker

import (
	"sort"
	"sync"
)

type lock struct {
	name string
	mu   sync.Mutex
}

var locks = map[string]*lock{}

func addLock(name string) {
	_, ok := locks[name]
	if !ok {
		locks[name] = &lock{name: name}
	}
}

func withLocks(accesses []string, do func()) {
	// sort the names for consistent aquire order
	sort.Strings(accesses)
	// aquire all the mutexes in order
	for _, name := range accesses {
		locks[name].mu.Lock()
	}
	do()
	// unlock order does not matter
	for _, name := range accesses {
		locks[name].mu.Unlock()
	}
}