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pool_cache.go
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pool_cache.go
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// Copyright 2016 The Serviced 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 facade
import (
"sync"
"github.com/control-center/serviced/domain/pool"
)
// poolCache is a simple in-memory cache for storing ReadPools.
// The dirty flag should be set when changes are made that affect a ReadPool.
type poolCache struct {
mutex sync.RWMutex
dirty bool
pools []pool.ReadPool
}
// GetPoolsFunc should return an up-to-date slice of ReadPools.
type GetPoolsFunc func() ([]pool.ReadPool, error)
// NewPoolCache creates a new poolCache, which is dirty and empty by default
func NewPoolCache() *poolCache {
return &poolCache{
mutex: sync.RWMutex{},
dirty: true,
pools: make([]pool.ReadPool, 0),
}
}
// GetPools caches the result of getPoolsFunc if the cache is dirty
// then returns the cached ReadPools.
func (pc *poolCache) GetPools(getPoolsFunc GetPoolsFunc) ([]pool.ReadPool, error) {
pc.mutex.Lock()
defer pc.mutex.Unlock()
var err error
if pc.dirty {
pc.pools, err = getPoolsFunc()
if err == nil {
pc.dirty = false
}
}
return pc.pools, err
}
// SetDirty sets poolCache.dirty to true, meaning it will call a GetPoolsFunc
// next time GetPools is called.
func (pc *poolCache) SetDirty() {
pc.mutex.Lock()
defer pc.mutex.Unlock()
pc.dirty = true
}