lazycache

package
Version: v1.0.0-alpha4 Latest Latest
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Published: Jun 13, 2018 License: Apache-2.0 Imports: 6 Imported by: 0

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Examples

Constants

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Variables

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Functions

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Types

type Cache

type Cache struct {
	// contains filtered or unexported fields
}

Cache implements a lazy initializing cache. A cache entry is created the first time a value is accessed (via Get or MustGet) by invoking the provided Initializer. If the Initializer returns an error then the entry will not be added.

func New

func New(name string, initializer EntryInitializer) *Cache

New creates a new lazy cache with the given name (Note that the name is only used for debugging purpose)

func (*Cache) Close

func (c *Cache) Close()

Close does the following: - calls Close on all values that implement a Close() function - deletes all entries from the cache - prevents further calls to the cache

func (*Cache) Get

func (c *Cache) Get(key Key) (interface{}, error)

Get returns the value for the given key. If the key doesn't exist then the initializer is invoked to create the value, and the key is inserted. If the initializer returns an error then the key is removed from the cache.

Example
cache := New("Example_Cache", func(key Key) (interface{}, error) {
	if key.String() == "error" {
		return nil, fmt.Errorf("some error")
	}
	return fmt.Sprintf("Value_for_key_%s", key), nil
})
defer cache.Close()

value, err := cache.Get(NewStringKey("Key1"))
if err != nil {
	fmt.Printf("Error returned: %s\n", err)
}
fmt.Println(value)

value, err = cache.Get(NewStringKey("error"))
if err != nil {
	fmt.Printf("Error returned: %s\n", err)
}
fmt.Println(value)
Output:

func (*Cache) MustGet

func (c *Cache) MustGet(key Key) interface{}

MustGet returns the value for the given key. If the key doesn't exist then the initializer is invoked to create the value and the key is inserted. If an error is returned during initialization of the value then this function will panic.

Example
cache := New("Example_Cache", func(key Key) (interface{}, error) {
	return fmt.Sprintf("Value_for_key_%s", key), nil
})
defer cache.Close()

key := NewStringKey("Key1")

fmt.Println(cache.MustGet(key))
Output:

Value_for_key_Key1

func (*Cache) Name

func (c *Cache) Name() string

Name returns the name of the cache (useful for debugging)

type EntryInitializer

type EntryInitializer func(key Key) (interface{}, error)

EntryInitializer creates a cache value for the given key

type Key

type Key interface {
	String() string
}

Key holds the string key for the cache entry

type StringKey

type StringKey struct {
	// contains filtered or unexported fields
}

StringKey is a simple string cache key

func NewStringKey

func NewStringKey(key string) *StringKey

NewStringKey returns a new StringKey

func (*StringKey) String

func (k *StringKey) String() string

String returns the key as a string

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