ref: b69a36140f42ec99ffa2d1e029b8b86ecf8ff929
dir: /cache/partitioned_lazy_cache.go/
// Copyright 2017-present The Hugo Authors. 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 cache import ( "sync" ) // Partition represents a cache partition where Load is the callback // for when the partition is needed. type Partition struct { Key string Load func() (map[string]interface{}, error) } // Lazy represents a lazily loaded cache. type Lazy struct { initSync sync.Once initErr error cache map[string]interface{} load func() (map[string]interface{}, error) } // NewLazy creates a lazy cache with the given load func. func NewLazy(load func() (map[string]interface{}, error)) *Lazy { return &Lazy{load: load} } func (l *Lazy) init() error { l.initSync.Do(func() { c, err := l.load() l.cache = c l.initErr = err }) return l.initErr } // Get initializes the cache if not already initialized, then looks up the // given key. func (l *Lazy) Get(key string) (interface{}, bool, error) { l.init() if l.initErr != nil { return nil, false, l.initErr } v, found := l.cache[key] return v, found, nil } // PartitionedLazyCache is a lazily loaded cache paritioned by a supplied string key. type PartitionedLazyCache struct { partitions map[string]*Lazy } // NewPartitionedLazyCache creates a new NewPartitionedLazyCache with the supplied // partitions. func NewPartitionedLazyCache(partitions ...Partition) *PartitionedLazyCache { lazyPartitions := make(map[string]*Lazy, len(partitions)) for _, partition := range partitions { lazyPartitions[partition.Key] = NewLazy(partition.Load) } cache := &PartitionedLazyCache{partitions: lazyPartitions} return cache } // Get initializes the partition if not already done so, then looks up the given // key in the given partition, returns nil if no value found. func (c *PartitionedLazyCache) Get(partition, key string) (interface{}, error) { p, found := c.partitions[partition] if !found { return nil, nil } v, found, err := p.Get(key) if err != nil { return nil, err } if found { return v, nil } return nil, nil }