cache

Documentation

Overview

Package cache provides a cached interface to the xkcd server.

Index

• Variables
• func CheckForNewestComicInfo(freshnessThreshold time.Duration) (*xkcd.Comic, error)
• func Close() error
• func ComicImagePath(n int) string
• func ComicInfo(n int) (*xkcd.Comic, error)
• func DownloadAllComicImages(cacheWindow ViewRefreshWitherGetter)
• func DownloadAllComicMetadata(cacheWindow ViewRefreshWitherGetter)
• func DownloadComicImage(n int, cacheWindow ViewRefresherGetter) error
• func Init(index func(comic *xkcd.Comic) error) error
• func NewestComicInfoFromCache() (*xkcd.Comic, error)
• type Stat
  • func StatImages() (Stat, error)
  • func StatMetadata() (Stat, error)
  • func (s Stat) Complete() bool
  • func (s Stat) Fraction() (float64, error)
  • func (s Stat) String() string
• type ViewRefreshWither
• type ViewRefreshWitherGetter
• type ViewRefresher
• type ViewRefresherGetter

Variables

var (
	// ErrMiss means that value we are looking for wasn't in the cache.
	ErrMiss = errors.New("cache miss")
	// ErrLocalFailure means that there was an error while trying to access the
	// local cache.
	ErrLocalFailure = errors.New("error accessing local xkcd cache")
	// ErrOffline means that there was an error trying to access the xkcd
	// server.
	ErrOffline = errors.New("error accessing xkcd server")
	// ErrNoComicsFound is returned when a function can not find any comics.
	ErrNoComicsFound = errors.New("no comics found")
)

Functions

func CheckForNewestComicInfo

func CheckForNewestComicInfo(freshnessThreshold time.Duration) (*xkcd.Comic, error)

CheckForNewestComicInfo returns the latest xkcd.Comic. May query xkcd API if latest comic in the cache has not been updated since freshnessThreshold. The returned error can be safely ignored. Should not be called directly in the UI event loop.

func Close

func Close() error

Close closes the comic cache.

func ComicImagePath

func ComicImagePath(n int) string

ComicImagePath returns the path to the specified comic image within the cache. The file at the returned path may or may not exist. If it does not exist, call DownloadComicImage to fetch the file from the internet.

func ComicInfo

func ComicInfo(n int) (*xkcd.Comic, error)

ComicInfo always returns a valid *xkcd.Comic that can be used, and err will be set if any errors were encountered, however these errors can be ignored safely.

func DownloadAllComicImages

func DownloadAllComicImages(cacheWindow ViewRefreshWitherGetter)

DownloadAllComicImages tries to add all comic images to our local cache. If successful, the images can be found at the path returned by ComicImagePath.

func DownloadAllComicMetadata

func DownloadAllComicMetadata(cacheWindow ViewRefreshWitherGetter)

DownloadAllComicMetadata asynchronously fills the comic metadata cache and search index via the internet. Status can be checked with Stat(). Should not be called directly in the UI event loop.

func DownloadComicImage

func DownloadComicImage(n int, cacheWindow ViewRefresherGetter) error

DownloadComicImage tries to add a comic image to our local cache. If successful, the image can be found at the path returned by ComicImagePath.

func Init

func Init(index func(comic *xkcd.Comic) error) error

Init initializes the comic cache. Function index is called each time a comic is inserted into the comic cache.

func NewestComicInfoFromCache

func NewestComicInfoFromCache() (*xkcd.Comic, error)

NewestComicInfoFromCache returns the newest comic info available in the cache. The function will not use the internet. The returned error can be safely ignored. Can be used on UI event loop.

Types

type Stat

type Stat struct {
	LatestComicNumber int
	CachedCount       int
}

func StatImages

func StatImages() (Stat, error)

func StatMetadata

func StatMetadata() (Stat, error)

func (Stat) Complete

func (s Stat) Complete() bool

func (Stat) Fraction

func (s Stat) Fraction() (float64, error)

func (Stat) String

func (s Stat) String() string

type ViewRefreshWither

type ViewRefreshWither interface {
	RefreshMetadataWith(Stat)
	RefreshImagesWith(Stat)
}

ViewRefreshWither provides methods for refreshing a view of cache statistics with the provided stat. All methods must silently accept a nil receiver.

type ViewRefreshWitherGetter

type ViewRefreshWitherGetter func() ViewRefreshWither

ViewRefreshWitherGetter returns a ViewRefreshWither. Useful for lazily passing the ViewRefreshWither as an argument.

type ViewRefresher

type ViewRefresher interface {
	ViewRefreshWither
	// RefreshMetadata queries StatMetadata then calls RefreshMetadataWith.
	RefreshMetadata()
	// RefreshImages queries StatImages then calls RefreshImagesWith.
	RefreshImages()
}

ViewRefresher provides methods for refreshing a view of cache statistics. All methods must silently accept a nil receiver.

type ViewRefresherGetter

type ViewRefresherGetter func() ViewRefresher

ViewRefresherGetter returns a ViewRefresher. Useful for lazily passing the ViewRefresher as an argument.