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memory.go
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memory.go
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// Copyright 2017 Google 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
//
// https://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 persistence
import (
"encoding/json"
"sync"
)
// Type memoryPersistence is a Persistence implementation that stores values and queues json-encoded
// data in an in-memory map. This implementations does not offer persistence across restarts.
type memoryPersistence struct {
items map[string][]byte
mutex sync.RWMutex
}
// NewMemoryPersistence constructs a new Persistence that stores objects in memory.
func NewMemoryPersistence() Persistence {
return newMemoryPersistence()
}
func newMemoryPersistence() *memoryPersistence {
var mp memoryPersistence
mp.items = make(map[string][]byte)
return &mp
}
func (p *memoryPersistence) Value(name string) Value {
return &lockingValue{p.value(name)}
}
func (p *memoryPersistence) Queue(name string) Queue {
return &valueQueue{p.value(name)}
}
func (p *memoryPersistence) value(name string) *memoryValue {
return &memoryValue{p: p, name: name}
}
type memoryValue struct {
p *memoryPersistence
name string
}
func (v *memoryValue) mutex() *sync.RWMutex {
return &v.p.mutex
}
func (v *memoryValue) load(obj interface{}) error {
data, exists := v.p.items[v.name]
if !exists {
return ErrNotFound
}
if err := json.Unmarshal(data, obj); err != nil {
return err
}
return nil
}
func (v *memoryValue) store(obj interface{}) error {
if buff, err := json.Marshal(obj); err != nil {
return err
} else {
v.p.items[v.name] = buff
}
return nil
}
func (v *memoryValue) remove() error {
if _, ok := v.p.items[v.name]; !ok {
return ErrNotFound
}
delete(v.p.items, v.name)
return nil
}