ridata

README

lru

An LRU implementation. Accessors available for the first item, last item, list of all keys, count, fullness, membership checks, explicit drops, and popping the oldest in a loop. You can also set a callback for when items are dropped and dump the current contents of the LRU.

mimetype

Convenience function for determining a mime-type from an io.Reader.

Documentation

Index

• Constants
• Variables
• func DetectMimetype(f *os.File) (mimetype string, err error)
• func GetMimetypeFromContent(r io.Reader, fileSize int64) (mimetype string, err error)
• type Lru
  • func NewLru(maxSize int) *Lru
  • func (lru *Lru) All() []LruKey
  • func (lru *Lru) Count() int
  • func (lru *Lru) Drop(id LruKey) (found bool, err error)
  • func (lru *Lru) Dump()
  • func (lru *Lru) Exists(id LruKey) bool
  • func (lru *Lru) FindPosition(id LruKey) int
  • func (lru *Lru) Get(id LruKey) (found bool, item LruItem, err error)
  • func (lru *Lru) IsFull() bool
  • func (lru *Lru) MaxCount() int
  • func (lru *Lru) Newest() LruKey
  • func (lru *Lru) Oldest() LruKey
  • func (lru *Lru) PopOldest() (item LruItem, err error)
  • func (lru *Lru) Set(item LruItem) (added bool, droppedItem LruItem, err error)
  • func (lru *Lru) SetDropCb(cb lruEventFunc)
• type LruItem
• type LruKey

Constants

const (
	MimetypeLeadBytesCount = 512
)

Variables

var (
	// ErrLruEmpty indicates that the LRU is empty..
	ErrLruEmpty = errors.New("lru is empty")
)

Functions

func DetectMimetype

func DetectMimetype(f *os.File) (mimetype string, err error)

DetectMimetype is a wrapper for GetMimetypeFromContent which returns the mime-type for the given `File`. An empty-string is returned if it is a zero- length file.

func GetMimetypeFromContent

func GetMimetypeFromContent(r io.Reader, fileSize int64) (mimetype string, err error)

GetMimetypeFromContent uses net/http to map from magic-bytes to mime-type.

Types

type Lru

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

Lru establises an LRU of IDs of any type.

func NewLru

func NewLru(maxSize int) *Lru

NewLru returns a new instance.

func (*Lru) All

func (lru *Lru) All() []LruKey

All returns a list of all IDs.

func (*Lru) Count

func (lru *Lru) Count() int

Count returns the number of items in the LRU.

func (*Lru) Drop

func (lru *Lru) Drop(id LruKey) (found bool, err error)

Drop discards the given item.

func (*Lru) Dump

func (lru *Lru) Dump()

Dump returns a list of all IDs.

func (*Lru) Exists

func (lru *Lru) Exists(id LruKey) bool

Exists will do a membership check for the given key.

func (*Lru) FindPosition

func (lru *Lru) FindPosition(id LruKey) int

FindPosition will return the numerical position in the list. Since the LRU will never be very large, this call is not expensive, per se. But, it *is* O(n) and any call to us will compound with any loops you happen to wrap us into.

func (*Lru) Get

func (lru *Lru) Get(id LruKey) (found bool, item LruItem, err error)

Get touches the cache and returns the data.

func (*Lru) IsFull

func (lru *Lru) IsFull() bool

IsFull will return true if at capacity.

func (*Lru) MaxCount

func (lru *Lru) MaxCount() int

MaxCount returns the maximum number of items the LRU can contain.

func (*Lru) Newest

func (lru *Lru) Newest() LruKey

Newest returns the most recently used ID.

func (*Lru) Oldest

func (lru *Lru) Oldest() LruKey

Oldest returns the least recently used ID.

func (*Lru) PopOldest

func (lru *Lru) PopOldest() (item LruItem, err error)

PopOldest will pop the oldest entry out of the LRU and return it. It will return ErrLruEmpty when empty.

func (*Lru) Set

func (lru *Lru) Set(item LruItem) (added bool, droppedItem LruItem, err error)

Set bumps an item to the front of the LRU. It will be added if it doesn't already exist. If as a result of adding an item the LRU exceeds the maximum size, the least recently used item will be discarded.

If it was not previously in the LRU, `added` will be `true`.

func (*Lru) SetDropCb

func (lru *Lru) SetDropCb(cb lruEventFunc)

SetDropCb sets a callback that will be triggered whenever an item ages out or is manually dropped.

type LruItem

type LruItem interface {
	Id() LruKey
}

LruItem is the interface that any item we add to the LRU must satisfy.

type LruKey

type LruKey interface{}

LruKey is the type of an LRU key.