Documentation

Overview

Package cache implements both in-memory and on-disk caching.

Index

Constants

This section is empty.

Variables

var ErrInvalidHash = errors.New("invalid hash")

Functions

This section is empty.

Types

type Cache

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

Cache is a cache of objects holding content in disk.

All implementations must be thread-safe.

func New

func New(policies Policies, path string, h crypto.Hash) (*Cache, error)

New creates a disk based cache.

It may return both a valid Cache and an error if it failed to load the previous cache metadata. It is safe to ignore this error. This creates cache directory if it doesn't exist.

func (*Cache) Add

func (d *Cache) Add(digest isolated.HexDigest, src io.Reader) error

Add reads data from src and stores it in cache.

func (*Cache) AddFileWithoutValidation

func (d *Cache) AddFileWithoutValidation(digest isolated.HexDigest, src string) error

AddFileWithoutValidation adds src as cache entry with hardlink. But this doesn't do any content validation.

TODO(tikuta): make one function and control the behavior by option?

func (d *Cache) AddWithHardlink(digest isolated.HexDigest, src io.Reader, dest string, perm os.FileMode) error

AddWithHardlink reads data from src and stores it in cache and hardlink file. This is to avoid file removal by shrink in Add().

func (*Cache) Close

func (d *Cache) Close() error

func (*Cache) Evict

func (d *Cache) Evict(digest isolated.HexDigest)

Evict removes item from cache if it's there.

func (*Cache) GetAdded

func (d *Cache) GetAdded() []int64

GetAdded returns a list of file size added to cache.

func (*Cache) GetUsed

func (d *Cache) GetUsed() []int64

GetUsed returns a list of file size used from cache.

func (d *Cache) Hardlink(digest isolated.HexDigest, dest string, perm os.FileMode) error

Hardlink ensures file at |dest| has the same content as cached |digest|.

Note that the behavior when dest already exists is undefined. It will work on all POSIX and may or may not fail on Windows depending on the implementation used. Do not rely on this behavior.

func (*Cache) Keys

func (d *Cache) Keys() isolated.HexDigests

Keys returns the list of all cached digests in LRU order.

func (*Cache) Read

func (d *Cache) Read(digest isolated.HexDigest) (io.ReadCloser, error)

Read returns contents of the cached item.

func (*Cache) Touch

func (d *Cache) Touch(digest isolated.HexDigest) bool

Touch updates the LRU position of an item to ensure it is kept in the cache.

Returns true if item is in cache.

type Policies

type Policies struct {
	// MaxSize trims if the cache gets larger than this value. If 0, the cache is
	// effectively a leak.
	MaxSize units.Size
	// MaxItems is the maximum number of items to keep in the cache. If 0, do not
	// enforce a limit.
	MaxItems int
	// MinFreeSpace trims if disk free space becomes lower than this value.
	// Only makes sense when using disk based cache.
	MinFreeSpace units.Size
}

Policies is the policies to use on a cache to limit it's footprint.

It's a cache, not a leak.

func (*Policies) AddFlags

func (p *Policies) AddFlags(f *flag.FlagSet)

AddFlags adds flags for cache policy parameters.

func (*Policies) IsDefault

func (p *Policies) IsDefault() bool

IsDefault returns whether some flags are set or not.