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caddy/caddytls/sync_locker.go
2017-11-06 09:43:41 -07:00

57 lines
1.5 KiB
Go

// Copyright 2015 Light Code Labs, LLC
//
// 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 caddytls
import (
"fmt"
"sync"
)
var _ Locker = &syncLock{}
type syncLock struct {
nameLocks map[string]*sync.WaitGroup
nameLocksMu sync.Mutex
}
// TryLock attempts to get a lock for name, otherwise it returns
// a Waiter value to wait until the other process is finished.
func (s *syncLock) TryLock(name string) (Waiter, error) {
s.nameLocksMu.Lock()
defer s.nameLocksMu.Unlock()
wg, ok := s.nameLocks[name]
if ok {
// lock already obtained, let caller wait on it
return wg, nil
}
// caller gets lock
wg = new(sync.WaitGroup)
wg.Add(1)
s.nameLocks[name] = wg
return nil, nil
}
// Unlock unlocks name.
func (s *syncLock) Unlock(name string) error {
s.nameLocksMu.Lock()
defer s.nameLocksMu.Unlock()
wg, ok := s.nameLocks[name]
if !ok {
return fmt.Errorf("FileStorage: no lock to release for %s", name)
}
wg.Done()
delete(s.nameLocks, name)
return nil
}