mirror of https://github.com/k3s-io/k3s
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
75 lines
1.9 KiB
75 lines
1.9 KiB
/*
|
|
Copyright 2014 The Kubernetes Authors.
|
|
|
|
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 volume
|
|
|
|
import (
|
|
"sync"
|
|
"sync/atomic"
|
|
)
|
|
|
|
var _ MetricsProvider = &cachedMetrics{}
|
|
|
|
// cachedMetrics represents a MetricsProvider that wraps another provider and
|
|
// caches the result.
|
|
type cachedMetrics struct {
|
|
wrapped MetricsProvider
|
|
resultError error
|
|
resultMetrics *Metrics
|
|
once cacheOnce
|
|
}
|
|
|
|
// NewCachedMetrics creates a new cachedMetrics wrapping another
|
|
// MetricsProvider and caching the results.
|
|
func NewCachedMetrics(provider MetricsProvider) MetricsProvider {
|
|
return &cachedMetrics{wrapped: provider}
|
|
}
|
|
|
|
// GetMetrics runs the wrapped metrics provider's GetMetrics methd once and
|
|
// caches the result. Will not cache result if there is an error.
|
|
// See MetricsProvider.GetMetrics
|
|
func (md *cachedMetrics) GetMetrics() (*Metrics, error) {
|
|
md.once.cache(func() error {
|
|
md.resultMetrics, md.resultError = md.wrapped.GetMetrics()
|
|
return md.resultError
|
|
})
|
|
return md.resultMetrics, md.resultError
|
|
}
|
|
|
|
// Copied from sync.Once but we don't want to cache the results if there is an
|
|
// error
|
|
type cacheOnce struct {
|
|
m sync.Mutex
|
|
done uint32
|
|
}
|
|
|
|
// Copied from sync.Once but we don't want to cache the results if there is an
|
|
// error
|
|
func (o *cacheOnce) cache(f func() error) {
|
|
if atomic.LoadUint32(&o.done) == 1 {
|
|
return
|
|
}
|
|
// Slow-path.
|
|
o.m.Lock()
|
|
defer o.m.Unlock()
|
|
if o.done == 0 {
|
|
err := f()
|
|
if err == nil {
|
|
atomic.StoreUint32(&o.done, 1)
|
|
}
|
|
}
|
|
}
|