common

Documentation

Overview

Thank elastic for these codes. Copy from github.com/beats/libbeat/common. Git: commit b48d073b84e874a182c122d8ef2bad867f714a11 (HEAD, tag: v6.5.2)

Index

• type Cache
  • func NewCache(d time.Duration, initialSize int) *Cache
  • func NewCacheWithRemovalListener(d time.Duration, initialSize int, l RemovalListener) *Cache
  • func (c *Cache) CleanUp() int
  • func (c *Cache) Delete(k Key) Value
  • func (c *Cache) Entries() map[Key]Value
  • func (c *Cache) Get(k Key) Value
  • func (c *Cache) Put(k Key, v Value) Value
  • func (c *Cache) PutIfAbsent(k Key, v Value) Value
  • func (c *Cache) PutIfAbsentWithTimeout(k Key, v Value, timeout time.Duration) Value
  • func (c *Cache) PutWithTimeout(k Key, v Value, timeout time.Duration) Value
  • func (c *Cache) Replace(k Key, v Value) Value
  • func (c *Cache) ReplaceWithTimeout(k Key, v Value, timeout time.Duration) Value
  • func (c *Cache) Size() int
  • func (c *Cache) StartJanitor(interval time.Duration)
  • func (c *Cache) StopJanitor()
• type Key
• type RemovalListener
• type Value

Types

type Cache

type Cache struct {
	sync.RWMutex
	// contains filtered or unexported fields
}

Cache is a semi-persistent mapping of keys to values. Elements added to the cache are store until they are explicitly deleted or are expired due time- based eviction based on last access time.

Expired elements are not visible through classes methods, but they do remain stored in the cache until CleanUp() is invoked. Therefore CleanUp() must be invoked periodically to prevent the cache from becoming a memory leak. If you want to start a goroutine to perform periodic clean-up then see StartJanitor().

Cache does not support storing nil values. Any attempt to put nil into the cache will cause a panic.

func NewCache

func NewCache(d time.Duration, initialSize int) *Cache

NewCache creates and returns a new Cache. d is the length of time after last access that cache elements expire. initialSize is the initial allocation size used for the Cache's underlying map.

func NewCacheWithRemovalListener

func NewCacheWithRemovalListener(d time.Duration, initialSize int, l RemovalListener) *Cache

NewCacheWithRemovalListener creates and returns a new Cache and register a RemovalListener callback function. d is the length of time after last access that cache elements expire. initialSize is the initial allocation size used for the Cache's underlying map. l is the callback function that will be invoked when cache elements are removed from the map on CleanUp.

func (*Cache) CleanUp

func (c *Cache) CleanUp() int

CleanUp performs maintenance on the cache by removing expired elements from the cache. If a RemoveListener is registered it will be invoked for each element that is removed during this clean up operation. The RemovalListener is invoked on the caller's goroutine.

func (*Cache) Delete

func (c *Cache) Delete(k Key) Value

Delete a key from the map and return the value or nil if the key does not exist. The RemovalListener is not notified for explicit deletions.

func (*Cache) Entries

func (c *Cache) Entries() map[Key]Value

Entries returns a shallow copy of the non-expired elements in the cache.

func (*Cache) Get

func (c *Cache) Get(k Key) Value

Get the current value associated with a key or nil if the key is not present. The last access time of the element is updated.

func (*Cache) Put

func (c *Cache) Put(k Key, v Value) Value

Put writes the given key and value to the map replacing any existing value if it exists. The previous value associated with the key returned or nil if the key was not present.

func (*Cache) PutIfAbsent

func (c *Cache) PutIfAbsent(k Key, v Value) Value

PutIfAbsent writes the given key and value to the cache only if the key is absent from the cache. Nil is returned if the key-value pair were written, otherwise the old value is returned.

func (*Cache) PutIfAbsentWithTimeout

func (c *Cache) PutIfAbsentWithTimeout(k Key, v Value, timeout time.Duration) Value

PutIfAbsentWithTimeout writes the given key and value to the cache only if the key is absent from the cache. Nil is returned if the key-value pair were written, otherwise the old value is returned. The cache expiration time will be overwritten by timeout of the key being inserted.

func (*Cache) PutWithTimeout

func (c *Cache) PutWithTimeout(k Key, v Value, timeout time.Duration) Value

PutWithTimeout writes the given key and value to the map replacing any existing value if it exists. The previous value associated with the key returned or nil if the key was not present. The cache expiration time will be overwritten by timeout of the key being inserted.

func (*Cache) Replace

func (c *Cache) Replace(k Key, v Value) Value

Replace overwrites the value for a key only if the key exists. The old value is returned if the value is updated, otherwise nil is returned.

func (*Cache) ReplaceWithTimeout

func (c *Cache) ReplaceWithTimeout(k Key, v Value, timeout time.Duration) Value

ReplaceWithTimeout overwrites the value for a key only if the key exists. The old value is returned if the value is updated, otherwise nil is returned. The cache expiration time will be overwritten by timeout of the key being inserted.

func (*Cache) Size

func (c *Cache) Size() int

Size returns the number of elements in the cache. The number includes both active elements and expired elements that have not been cleaned up.

func (*Cache) StartJanitor

func (c *Cache) StartJanitor(interval time.Duration)

StartJanitor starts a goroutine that will periodically invoke the cache's CleanUp() method.

func (*Cache) StopJanitor

func (c *Cache) StopJanitor()

StopJanitor stops the goroutine created by StartJanitor.

type Key

type Key interface{}

Key type used in the cache.

type RemovalListener

type RemovalListener func(k Key, v Value)

RemovalListener is the callback function type that can be registered with the cache to receive notification of the removal of expired elements.

type Value

type Value interface{}

Value type held in the cache. Cannot be nil.