gitee.com/go-spring2/spring-base@v1.1.3/cache/cache.go (about)

     1  /*
     2   * Copyright 2012-2019 the original author or authors.
     3   *
     4   * Licensed under the Apache License, Version 2.0 (the "License");
     5   * you may not use this file except in compliance with the License.
     6   * You may obtain a copy of the License at
     7   *
     8   *      https://www.apache.org/licenses/LICENSE-2.0
     9   *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16  
    17  // Package cache provides object caching in memory.
    18  package cache
    19  
    20  import (
    21  	"context"
    22  	"sync"
    23  	"time"
    24  )
    25  
    26  var (
    27  	Cache  Shardable
    28  	Engine Driver
    29  )
    30  
    31  func init() {
    32  	Cache = NewStorage(1, SimpleHash)
    33  	Engine = &engine{}
    34  }
    35  
    36  // A Shardable cache can improve the performance of concurrency.
    37  type Shardable interface {
    38  	Sharding(key string) *sync.Map
    39  }
    40  
    41  type LoadType int
    42  
    43  const (
    44  	LoadNone LoadType = iota
    45  	LoadOnCtx
    46  	LoadCache
    47  	LoadSource
    48  )
    49  
    50  // ResultLoader returns a wrapper for the source value of the key.
    51  type ResultLoader func(ctx context.Context, key string) (Result, error)
    52  
    53  // Driver loads value from m, if there is no cached value, call the loader
    54  // to get value, and then stores it into m.
    55  type Driver interface {
    56  	Load(ctx context.Context, m *sync.Map, key string, loader ResultLoader, arg OptionArg) (loadType LoadType, result Result, err error)
    57  }
    58  
    59  // Has returns whether the key exists.
    60  func Has(key string) bool {
    61  	v, ok := Cache.Sharding(key).Load(key)
    62  	if ok && v != nil {
    63  		return !v.(*cacheItem).expired()
    64  	}
    65  	return false
    66  }
    67  
    68  type OptionArg struct {
    69  	ExpireAfterWrite time.Duration
    70  }
    71  
    72  type Option func(*OptionArg)
    73  
    74  // ExpireAfterWrite sets the expiration time of the cache value after write.
    75  func ExpireAfterWrite(v time.Duration) Option {
    76  	return func(arg *OptionArg) {
    77  		arg.ExpireAfterWrite = v
    78  	}
    79  }
    80  
    81  // Loader gets value from a background, such as Redis, MySQL, etc.
    82  type Loader func(ctx context.Context, key string) (interface{}, error)
    83  
    84  // Load loads value from cache, if there is no cached value, call the loader
    85  // to get value, and then stores it.
    86  func Load(ctx context.Context, key string, loader Loader, opts ...Option) (loadType LoadType, result Result, _ error) {
    87  	arg := OptionArg{}
    88  	for _, opt := range opts {
    89  		opt(&arg)
    90  	}
    91  	l := func(ctx context.Context, key string) (Result, error) {
    92  		v, err := loader(ctx, key)
    93  		if err != nil {
    94  			return nil, err
    95  		}
    96  		return NewValueResult(v), nil
    97  	}
    98  	m := Cache.Sharding(key)
    99  	return Engine.Load(ctx, m, key, l, arg)
   100  }