cache

Documentation

Index

• Variables
• type Cache
  • func New(maxSize int, opts *Options) Cache
  • func NewLRU(maxSize int) Cache
  • func NewLRUWithInitialCapacity(initialCapacity, maxSize int) Cache
  • func NewSimple(opts *SimpleOptions) Cache
• type Entry
• type Iterator
• type Options
• type RemovedFunc
• type SimpleOptions

Variables

var (
	// DummyCreateTime is the create time used by all entries in the cache.
	DummyCreateTime = time.Time{}
)

var (
	// ErrCacheFull is returned if Put fails due to cache being filled with pinned elements
	ErrCacheFull = errors.New("Cache capacity is fully occupied with pinned elements")
)

Types

type Cache

type Cache interface {
	// Get retrieves an element based on a key, returning nil if the element
	// does not exist
	Get(key interface{}) interface{}

	// Put adds an element to the cache, returning the previous element
	Put(key interface{}, value interface{}) interface{}

	// PutIfNotExist puts a value associated with a given key if it does not exist
	PutIfNotExist(key interface{}, value interface{}) (interface{}, error)

	// Delete deletes an element in the cache
	Delete(key interface{})

	// Release decrements the ref count of a pinned element. If the ref count
	// drops to 0, the element can be evicted from the cache.
	Release(key interface{})

	// Iterator returns the iterator of the cache
	Iterator() Iterator

	// Size returns the number of entries currently stored in the Cache
	Size() int
}

A Cache is a generalized interface to a cache. See cache.LRU for a specific implementation (bounded cache with LRU eviction)

func New

func New(maxSize int, opts *Options) Cache

New creates a new cache with the given options

func NewLRU

func NewLRU(maxSize int) Cache

NewLRU creates a new LRU cache of the given size, setting initial capacity to the max size

func NewLRUWithInitialCapacity

func NewLRUWithInitialCapacity(initialCapacity, maxSize int) Cache

NewLRUWithInitialCapacity creates a new LRU cache with an initial capacity and a max size

func NewSimple

func NewSimple(opts *SimpleOptions) Cache

NewSimple creates a new simple cache with given options. Simple cache will never evict entries and it will never reorder the elements. Simple cache also does not have the concept of pinning that LRU cache has. Internally simple cache uses a RWMutex instead of the exclusive Mutex that LRU cache uses. The RWMutex makes simple cache readable by many threads without introducing lock contention.

type Entry

type Entry interface {
	// Key represents the key
	Key() interface{}
	// Value represents the value
	Value() interface{}
	// CreateTime represents the time when the entry is created
	CreateTime() time.Time
}

Entry represents a key-value entry within the map

type Iterator

type Iterator interface {
	// Close closes the iterator
	// and releases any allocated resources
	Close()
	// HasNext return true if there is more items to be returned
	HasNext() bool
	// Next return the next item
	Next() Entry
}

Iterator represents the interface for cache iterators

type Options

type Options struct {
	// TTL controls the time-to-live for a given cache entry.  Cache entries that
	// are older than the TTL will not be returned.
	TTL time.Duration

	// InitialCapacity controls the initial capacity of the cache
	InitialCapacity int

	// Pin prevents in-use objects from getting evicted.
	Pin bool

	// RemovedFunc is an optional function called when an element
	// is scheduled for deletion
	RemovedFunc RemovedFunc
}

Options control the behavior of the cache

type RemovedFunc

type RemovedFunc func(interface{})

RemovedFunc is a type for notifying applications when an item is scheduled for removal from the Cache. If f is a function with the appropriate signature and i is the interface{} scheduled for deletion, Cache calls go f(i)

type SimpleOptions

type SimpleOptions struct {
	// InitialCapacity controls the initial capacity of the cache
	InitialCapacity int

	// RemovedFunc is an optional function called when an element
	// is scheduled for deletion
	RemovedFunc RemovedFunc
}

SimpleOptions provides options that can be used to configure SimpleCache