// Copyright © SAS Institute 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. package closeonce import ( "sync" "sync/atomic" ) type Closed struct { done uintptr mu sync.Mutex err error } func (o *Closed) Closed() bool { return atomic.LoadUintptr(&o.done) != 0 } func (o *Closed) Close(f func() error) error { o.mu.Lock() defer o.mu.Unlock() if o.Closed() { return o.err } o.err = f() atomic.StoreUintptr(&o.done, 1) o.done = 1 return o.err }