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/*
* Copyright 2015 Manish R Jain <manishrjain@gmail.com>
*
* 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 posting
import (
"sync"
"github.com/dgryski/go-farm"
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)
var lmutex sync.RWMutex
var lcache map[uint64]*List
var pstore *store.Store
var mstore *store.Store
func Init(posting *store.Store, mutation *store.Store) {
lmutex.Lock()
defer lmutex.Unlock()
lcache = make(map[uint64]*List)
pstore = posting
mstore = mutation
}
func Get(key []byte) *List {
// Acquire read lock and check if list is available.
lmutex.RLock()
uid := farm.Fingerprint64(key)
if list, ok := lcache[uid]; ok {
lmutex.RUnlock()
return list
}
lmutex.RUnlock()
// Couldn't find it. Acquire write lock.
lmutex.Lock()
defer lmutex.Unlock()
// Check again after acquiring write lock.
if list, ok := lcache[uid]; ok {
return list
}
list := new(List)
list.init(key, pstore, mstore)
lcache[uid] = list
return list
}