README
¶
store
-- import "github.com/sebcat/store"
concurrency-safe file-backed element store
- Asynchronous writes (errors reported on next action)
- Optional cache with LRU eviction on either
store insertion or store retrieval
To avoid a lot of casting from store.Element on Store#Get, you should probably write a wrapper around this element store for each type you intend to use it for.
Pull requests welcome
Usage
var (
ErrAlreadyExists = errors.New("element already exists in store")
ErrDoesNotExist = errors.New("element not present in store")
)
type Cache
type Cache interface {
// update (insert, promote) an element in the cache
Cache(Element)
// retrieve an Element from the cache, or nil if non-existant
Get(id ElementID) Element
}
type CacheMode
type CacheMode int
Tells the store when to pass an element to the cache
const (
CacheOnGet CacheMode = (1 << 0)
CacheOnPut = (1 << 1)
)
type Element
type Element interface {
// load an element from a reader
Load(io.Reader) error
// store an element to a writer
Store(io.Writer) error
// must return a file-system safe ID
// the two first letters of ID will be
// used to create directories and the
// complete ID string will be used as
// a file name
ID() ElementID
}
type ElementID
type ElementID uint64
func (*ElementID) FromString
func (id *ElementID) FromString(str string) error
func (ElementID) String
func (id ElementID) String() string
type LRUCache
type LRUCache struct {
}
cache with LRU eviction policy
func NewLRUCache
func NewLRUCache(size int) *LRUCache
create a new cache with room for 'size' elements
func (*LRUCache) Cache
func (l *LRUCache) Cache(el Element)
update (insert, promote) an element in the cache
func (*LRUCache) Get
func (l *LRUCache) Get(id ElementID) Element
retrieve an element from the cache, or nil if the element is not in cache
type Store
type Store struct {
}
func New
func New(path string) (*Store, error)
func (*Store) Get
func (s *Store) Get(element Element) (Element, error)
retrieve an Element either from cache or from disk. If retrieved from cache, the cache Element will be returned. If retrieved from disk, the Element passed to Get will be loaded with the data from disk. Therefor, this function should always be called like:
var el = SomeElement{ID: someID}
ret, err := s.Get(&el)
func (*Store) Has
func (s *Store) Has(id ElementID) bool
func (*Store) Put
func (s *Store) Put(el Element) error
func (*Store) Remove
func (s *Store) Remove() error
func (*Store) SetCache
func (s *Store) SetCache(c Cache, mode CacheMode)
func (*Store) Sync
func (s *Store) Sync()
Documentation
¶
Overview ¶
concurrency-safe file-backed element store
- Asynchronous writes (errors reported on next action)
- Optional cache with LRU eviction on either store insertion or store retrieval
To avoid a lot of casting from store.Element on Store#Get, you should probably write a wrapper around this element store for each type you intend to use it for.
Pull requests welcome
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ( ErrAlreadyExists = errors.New("element already exists in store") ErrDoesNotExist = errors.New("element not present in store") )
Functions ¶
This section is empty.
Types ¶
type CacheMode ¶
type CacheMode int
Tells the store when to pass an element to the cache
const ( CacheOnGet CacheMode = (1 << 0) CacheOnPut = (1 << 1) )
type Element ¶
type Element interface {
// load an element from a reader
Load(io.Reader) error
// store an element to a writer
Store(io.Writer) error
// must return a file-system safe ID
// the two first letters of ID will be
// used to create directories and the
// complete ID string will be used as
// a file name
ID() ElementID
}
type LRUCache ¶
type LRUCache struct {
// contains filtered or unexported fields
}
cache with LRU eviction policy
func NewLRUCache ¶
create a new cache with room for 'size' elements
type Store ¶
type Store struct {
// contains filtered or unexported fields
}
func (*Store) Get ¶
retrieve an Element either from cache or from disk. If retrieved from cache, the cache Element will be returned. If retrieved from disk, the Element passed to Get will be loaded with the data from disk. Therefor, this function should always be called like:
var el = SomeElement{ID: someID}
ret, err := s.Get(&el)
Source Files