cache

Documentation

Overview

Package cache provides interface and implementation of a cache algorithms.

Index

• type Cache
  • func NewEmptyCache() Cache
  • func NewLRUCache(capacity int) Cache
• type DelFin
• type Namespace
• type Object
• type PurgeFin
• type SetFin
• type SetFunc

Types

type Cache

type Cache interface {
	// SetCapacity sets cache capacity.
	SetCapacity(capacity int)

	// GetNamespace gets or creates a cache namespace for the given id.
	GetNamespace(id uint64) Namespace

	// Purge purges all cache namespaces, read Namespace.Purge method documentation.
	Purge(fin PurgeFin)

	// Zap zaps all cache namespaces, read Namespace.Zap method documentation.
	Zap(closed bool)
}

Cache is a cache tree. A cache instance must be goroutine-safe.

func NewEmptyCache

func NewEmptyCache() Cache

NewEmptyCache creates a new initialized empty cache.

func NewLRUCache

func NewLRUCache(capacity int) Cache

NewLRUCache creates a new initialized LRU cache with the given capacity.

type DelFin

type DelFin func(exist bool)

DelFin will be called when corresponding cache object are released. DelFin will be called after SetFin. The exist is true if the corresponding cache object is actually exist in the cache tree.

type Namespace

type Namespace interface {
	// Get gets cache object for the given key. The given SetFunc (if not nil) will
	// be called if the given key does not exist.
	// If the given key does not exist, SetFunc is nil or SetFunc return ok false, Get
	// will return ok false.
	Get(key uint64, setf SetFunc) (obj Object, ok bool)

	// Get deletes cache object for the given key. If exist the cache object will
	// be deleted later when all of its handles have been released (i.e. no one use
	// it anymore) and the given DelFin (if not nil) will finally be  executed. If
	// such cache object does not exist the given DelFin will be executed anyway.
	//
	// Delete returns true if such cache object exist.
	Delete(key uint64, fin DelFin) bool

	// Purge deletes all cache objects, read Delete method documentation.
	Purge(fin PurgeFin)

	// Zap detaches the namespace from the cache tree and delete all its cache
	// objects. The cache objects deletion and finalizers execution are happen
	// immediately, even if its existing handles haven't yet been released.
	// A zapped namespace can't never be filled again.
	// If closed is false then the Get function will always call the given SetFunc
	// if it is not nil, but resultant of the SetFunc will not be cached.
	Zap(closed bool)
}

Namespace is a cache namespace. A namespace instance must be goroutine-safe.

type Object

type Object interface {
	// Release releases the cache object. Other methods should not be called
	// after the cache object has been released.
	Release()

	// Value returns value of the cache object.
	Value() interface{}
}

Object is a cache object.

type PurgeFin

type PurgeFin func(ns, key uint64, delfin DelFin)

PurgeFin will be called when corresponding cache object are released. PurgeFin will be called after SetFin. If PurgeFin present DelFin will not be executed but passed to the PurgeFin, it is up to the caller to call it or not.

type SetFin

type SetFin func()

SetFin will be called when corresponding cache object are released.

type SetFunc

type SetFunc func() (ok bool, value interface{}, charge int, fin SetFin)

SetFunc used by Namespace.Get method to create a cache object. SetFunc may return ok false, in that case the cache object will not be created.