mirror of
https://github.com/ko-build/ko.git
synced 2024-12-12 08:54:09 +02:00
76 lines
1.9 KiB
Go
76 lines
1.9 KiB
Go
|
// Copyright 2018 Google LLC All Rights Reserved.
|
||
|
//
|
||
|
// 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 publish
|
||
|
|
||
|
import (
|
||
|
"sync"
|
||
|
|
||
|
"github.com/google/go-containerregistry/pkg/name"
|
||
|
)
|
||
|
|
||
|
func newFuture(work func() (name.Reference, error)) *future {
|
||
|
// Create a channel on which to send the result.
|
||
|
ch := make(chan *result)
|
||
|
// Initiate the actual work, sending its result
|
||
|
// along the above channel.
|
||
|
go func() {
|
||
|
ref, err := work()
|
||
|
ch <- &result{ref: ref, err: err}
|
||
|
}()
|
||
|
// Return a future for the above work. Callers should
|
||
|
// call .Get() on this result (as many times as needed).
|
||
|
// One of these calls will receive the result, store it,
|
||
|
// and close the channel so that the rest of the callers
|
||
|
// can consume it.
|
||
|
return &future{
|
||
|
promise: ch,
|
||
|
}
|
||
|
}
|
||
|
|
||
|
type result struct {
|
||
|
ref name.Reference
|
||
|
err error
|
||
|
}
|
||
|
|
||
|
type future struct {
|
||
|
m sync.RWMutex
|
||
|
|
||
|
result *result
|
||
|
promise chan *result
|
||
|
}
|
||
|
|
||
|
// Get blocks on the result of the future.
|
||
|
func (f *future) Get() (name.Reference, error) {
|
||
|
// Block on the promise of a result until we get one.
|
||
|
result, ok := <-f.promise
|
||
|
if ok {
|
||
|
func() {
|
||
|
f.m.Lock()
|
||
|
defer f.m.Unlock()
|
||
|
// If we got the result, then store it so that
|
||
|
// others may access it.
|
||
|
f.result = result
|
||
|
// Close the promise channel so that others
|
||
|
// are signaled that the result is available.
|
||
|
close(f.promise)
|
||
|
}()
|
||
|
}
|
||
|
|
||
|
f.m.RLock()
|
||
|
defer f.m.RUnlock()
|
||
|
|
||
|
return f.result.ref, f.result.err
|
||
|
}
|