simplelru

Documentation

Overview

Package simplelru provides simple LRU implementation based on build-in container/list.

Index

• type EvictCallback
• type ExpirableLRU
  • func NewExpirableLRU(size int, onEvict EvictCallback, ttl, purgeEvery time.Duration) *ExpirableLRU
  • func (c *ExpirableLRU) Add(key, value interface{}) (evicted bool)
  • func (c *ExpirableLRU) Close()
  • func (c *ExpirableLRU) Contains(key interface{}) (ok bool)
  • func (c *ExpirableLRU) DeleteExpired()
  • func (c *ExpirableLRU) Get(key interface{}) (interface{}, bool)
  • func (c *ExpirableLRU) GetOldest() (key, value interface{}, ok bool)
  • func (c *ExpirableLRU) Keys() []interface{}
  • func (c *ExpirableLRU) Len() int
  • func (c *ExpirableLRU) Peek(key interface{}) (interface{}, bool)
  • func (c *ExpirableLRU) Purge()
  • func (c *ExpirableLRU) Remove(key interface{}) bool
  • func (c *ExpirableLRU) RemoveOldest() (key, value interface{}, ok bool)
  • func (c *ExpirableLRU) Resize(size int) (evicted int)
• type LRU
  • func NewLRU(size int, onEvict EvictCallback) (*LRU, error)
  • func (c *LRU) Add(key, value interface{}) (evicted bool)
  • func (c *LRU) Close()
  • func (c *LRU) Contains(key interface{}) (ok bool)
  • func (c *LRU) Get(key interface{}) (value interface{}, ok bool)
  • func (c *LRU) GetOldest() (key, value interface{}, ok bool)
  • func (c *LRU) Keys() []interface{}
  • func (c *LRU) Len() int
  • func (c *LRU) Peek(key interface{}) (value interface{}, ok bool)
  • func (c *LRU) Purge()
  • func (c *LRU) Remove(key interface{}) (present bool)
  • func (c *LRU) RemoveOldest() (key, value interface{}, ok bool)
  • func (c *LRU) Resize(size int) (evicted int)
• type LRUCache

Examples

• ExpirableLRU

Types

type EvictCallback

type EvictCallback func(key interface{}, value interface{})

EvictCallback is used to get a callback when a cache entry is evicted

type ExpirableLRU

type ExpirableLRU struct {
	sync.Mutex
	// contains filtered or unexported fields
}

ExpirableLRU implements a thread safe LRU with expirable entries.

Example

// make cache with short TTL and 3 max keys, purgeEvery time.Millisecond * 10
cache := NewExpirableLRU(3, nil, time.Millisecond*5, time.Millisecond*10)
// expirable cache need to be closed after used
defer cache.Close()

// set value under key1.
cache.Add("key1", "val1")

// get value under key1
r, ok := cache.Get("key1")

// check for OK value, because otherwise return would be nil and
// type conversion will panic
if ok {
	rstr := r.(string) // convert cached value from interface{} to real type
	fmt.Printf("value before expiration is found: %v, value: %v\n", ok, rstr)
}

time.Sleep(time.Millisecond * 11)

// get value under key1 after key expiration
r, ok = cache.Get("key1")
// don't convert to string as with ok == false value would be nil
fmt.Printf("value after expiration is found: %v, value: %v\n", ok, r)

// set value under key2, would evict old entry because it is already expired.
cache.Add("key2", "val2")

fmt.Printf("Cache len: %d", cache.Len())

Output:

value before expiration is found: true, value: val1
value after expiration is found: false, value: <nil>
Cache len: 1

func NewExpirableLRU

func NewExpirableLRU(size int, onEvict EvictCallback, ttl, purgeEvery time.Duration) *ExpirableLRU

NewExpirableLRU returns a new cache with expirable entries.

Size parameter set to 0 makes cache of unlimited size.

Providing 0 TTL turns expiring off.

Activates deleteExpired by purgeEvery duration. If MaxKeys and TTL are defined and PurgeEvery is zero, PurgeEvery will be set to 5 minutes.

func (*ExpirableLRU) Add

func (c *ExpirableLRU) Add(key, value interface{}) (evicted bool)

Add key

func (*ExpirableLRU) Close

func (c *ExpirableLRU) Close()

Close cleans the cache and destroys running goroutines

func (*ExpirableLRU) Contains

func (c *ExpirableLRU) Contains(key interface{}) (ok bool)

Contains checks if a key is in the cache, without updating the recent-ness or deleting it for being stale.

func (*ExpirableLRU) DeleteExpired

func (c *ExpirableLRU) DeleteExpired()

DeleteExpired clears cache of expired items

func (*ExpirableLRU) Get

func (c *ExpirableLRU) Get(key interface{}) (interface{}, bool)

Get returns the key value

func (*ExpirableLRU) GetOldest

func (c *ExpirableLRU) GetOldest() (key, value interface{}, ok bool)

GetOldest returns the oldest entry

func (*ExpirableLRU) Keys

func (c *ExpirableLRU) Keys() []interface{}

Keys returns a slice of the keys in the cache, from oldest to newest.

func (*ExpirableLRU) Len

func (c *ExpirableLRU) Len() int

Len return count of items in cache

func (*ExpirableLRU) Peek

func (c *ExpirableLRU) Peek(key interface{}) (interface{}, bool)

Peek returns the key value (or undefined if not found) without updating the "recently used"-ness of the key.

func (*ExpirableLRU) Purge

func (c *ExpirableLRU) Purge()

Purge clears the cache completely.

func (*ExpirableLRU) Remove

func (c *ExpirableLRU) Remove(key interface{}) bool

Remove key from the cache

func (*ExpirableLRU) RemoveOldest

func (c *ExpirableLRU) RemoveOldest() (key, value interface{}, ok bool)

RemoveOldest removes the oldest item from the cache.

func (*ExpirableLRU) Resize

func (c *ExpirableLRU) Resize(size int) (evicted int)

Resize changes the cache size. size 0 doesn't resize the cache, as it means unlimited.

type LRU

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

LRU implements a non-thread safe fixed size LRU cache

func NewLRU

func NewLRU(size int, onEvict EvictCallback) (*LRU, error)

NewLRU constructs an LRU of the given size

func (*LRU) Add

func (c *LRU) Add(key, value interface{}) (evicted bool)

Add adds a value to the cache. Returns true if an eviction occurred.

func (*LRU) Close

func (c *LRU) Close()

Close does nothing for this type of cache.

func (*LRU) Contains

func (c *LRU) Contains(key interface{}) (ok bool)

Contains checks if a key is in the cache, without updating the recent-ness or deleting it for being stale.

func (*LRU) Get

func (c *LRU) Get(key interface{}) (value interface{}, ok bool)

Get looks up a key's value from the cache.

func (*LRU) GetOldest

func (c *LRU) GetOldest() (key, value interface{}, ok bool)

GetOldest returns the oldest entry

func (*LRU) Keys

func (c *LRU) Keys() []interface{}

Keys returns a slice of the keys in the cache, from oldest to newest.

func (*LRU) Len

func (c *LRU) Len() int

Len returns the number of items in the cache.

func (*LRU) Peek

func (c *LRU) Peek(key interface{}) (value interface{}, ok bool)

Peek returns the key value (or undefined if not found) without updating the "recently used"-ness of the key.

func (*LRU) Purge

func (c *LRU) Purge()

Purge is used to completely clear the cache.

func (*LRU) Remove

func (c *LRU) Remove(key interface{}) (present bool)

Remove removes the provided key from the cache, returning if the key was contained.

func (*LRU) RemoveOldest

func (c *LRU) RemoveOldest() (key, value interface{}, ok bool)

RemoveOldest removes the oldest item from the cache.

func (*LRU) Resize

func (c *LRU) Resize(size int) (evicted int)

Resize changes the cache size.

type LRUCache

type LRUCache interface {
	// Adds a value to the cache, returns true if an eviction occurred and
	// updates the "recently used"-ness of the key.
	Add(key, value interface{}) bool

	// Returns key's value from the cache and
	// updates the "recently used"-ness of the key. #value, isFound
	Get(key interface{}) (value interface{}, ok bool)

	// Checks if a key exists in cache without updating the recent-ness.
	Contains(key interface{}) (ok bool)

	// Returns key's value without updating the "recently used"-ness of the key.
	Peek(key interface{}) (value interface{}, ok bool)

	// Removes a key from the cache.
	Remove(key interface{}) bool

	// Removes the oldest entry from cache.
	RemoveOldest() (interface{}, interface{}, bool)

	// Returns the oldest entry from the cache. #key, value, isFound
	GetOldest() (interface{}, interface{}, bool)

	// Returns a slice of the keys in the cache, from oldest to newest.
	Keys() []interface{}

	// Returns the number of items in the cache.
	Len() int

	// Clears all cache entries.
	Purge()

	// Closes all hanging goroutines.
	Close()

	// Resizes cache, returning number evicted
	Resize(int) int
}

LRUCache is the interface for simple LRU cache.