100 lines
2.5 KiB
Go
100 lines
2.5 KiB
Go
// Copyright 2017-present The Hugo Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package cache
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import (
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"sync"
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)
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// Partition represents a cache partition where Load is the callback
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// for when the partition is needed.
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type Partition struct {
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Key string
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Load func() (map[string]interface{}, error)
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}
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// Lazy represents a lazily loaded cache.
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type Lazy struct {
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initSync sync.Once
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initErr error
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cache map[string]interface{}
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load func() (map[string]interface{}, error)
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}
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// NewLazy creates a lazy cache with the given load func.
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func NewLazy(load func() (map[string]interface{}, error)) *Lazy {
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return &Lazy{load: load}
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}
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func (l *Lazy) init() error {
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l.initSync.Do(func() {
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c, err := l.load()
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l.cache = c
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l.initErr = err
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})
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return l.initErr
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}
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// Get initializes the cache if not already initialized, then looks up the
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// given key.
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func (l *Lazy) Get(key string) (interface{}, bool, error) {
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l.init()
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if l.initErr != nil {
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return nil, false, l.initErr
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}
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v, found := l.cache[key]
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return v, found, nil
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}
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// PartitionedLazyCache is a lazily loaded cache paritioned by a supplied string key.
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type PartitionedLazyCache struct {
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partitions map[string]*Lazy
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}
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// NewPartitionedLazyCache creates a new NewPartitionedLazyCache with the supplied
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// partitions.
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func NewPartitionedLazyCache(partitions ...Partition) *PartitionedLazyCache {
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lazyPartitions := make(map[string]*Lazy, len(partitions))
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for _, partition := range partitions {
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lazyPartitions[partition.Key] = NewLazy(partition.Load)
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}
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cache := &PartitionedLazyCache{partitions: lazyPartitions}
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return cache
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}
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// Get initializes the partition if not already done so, then looks up the given
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// key in the given partition, returns nil if no value found.
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func (c *PartitionedLazyCache) Get(partition, key string) (interface{}, error) {
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p, found := c.partitions[partition]
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if !found {
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return nil, nil
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}
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v, found, err := p.Get(key)
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if err != nil {
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return nil, err
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}
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if found {
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return v, nil
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}
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return nil, nil
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}
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