Package storage

Storage methods, modeled after the venerable INN usenet server.

NOTE: All interfaces are WIP. Expect breaking changes.

var ENotInitialized = errors.New("SM not Initialized")

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func Bzero(bs []byte)

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func RegisterHisLoader(name string, ldr CfgHisLoader)

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func RegisterOverviewLoader(name string, ldr CfgOverviewLoader)

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func RegisterStorageLoader(name string, ldr CfgStorageLoader)

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type Article_MD struct {
	Arrival time.Time
}

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type Article_R interface {
	Releaser
	io.WriterTo
}

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type Article_W interface {
	Releaser
	io.Reader
	io.WriterTo
}

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type CfgBaseInfo struct {
	Spool string `inn:"$spool"`
}

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type CfgHisLoader func(cfg *CfgMaster) (HisMethod, error)

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type CfgMaster struct {
	OvMethod	string	`inn:"$ovmethod"`
	HisMethod	string	`inn:"$hismethod"`
	Spool		string	`inn:"$pathspool"`
}

General-Config.

func (cfg *CfgMaster) BaseInfo() *CfgBaseInfo

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type CfgOverviewLoader func(cfg *CfgMaster) (OverviewMethod, error)

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type CfgStorage struct {
	Methods []*CfgStorageMethod `inn:"@method"`
}

Storage-Config.

type CfgStorageLoader func(cfg *CfgStorageMethod, bi *CfgBaseInfo) (StorageMethod, error)

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type CfgStorageMethod struct {
	Method		string	`inn:"$method"`
	Class		int	`inn:"$class"`
	Newsgroups	string	`inn:"$newsgroup"`
	Size		int64	`inn:"$size"`
	MaxSize		int64	`inn:"$max-size" json:"max-size"`
	Options		string	`inn:"$options"`
	ExactMatch	bool	`inn:"$exactmatch"`
}

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type Cursor interface {
	Releaser
	Next() bool
}

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type GroupElement struct {
	Group		[]byte
	Status		byte
	Description	[]byte
}

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type GroupMethod interface {
	FetchGroups(status, descr bool, ge *GroupElement) (cur Cursor, err error)
}

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type HisMethod interface {
	HisWrite(msgid []byte, md *Article_MD, t *TOKEN) (err error)
	HisLookup(msgid []byte, t *TOKEN) (err error)
	HisCancel(msgid []byte) (err error)
}

Inspired by INN's HIS(history) database. Maps message-ids to storage tokens.

func OpenHisMethod(cfg *CfgMaster) (HisMethod, error)

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type OverviewElement struct {
	Num					int64
	Subject, From, Date, MsgId, Refs	[]byte
	Lng, Lines				int64
}

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func (ove *OverviewElement) Debug() string

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type OverviewMethod interface {
	FetchOne(grp []byte, num int64, tk *TOKEN, ove *OverviewElement) (rel Releaser, err error)
	FetchAll(grp []byte, num, lastnum int64, tk *TOKEN, ove *OverviewElement) (cur Cursor, err error)
	SeekOne(grp []byte, num int64, back bool, tk *TOKEN, ove *OverviewElement) (rel Releaser, err error)
	GroupStat(grp []byte) (num, low, high int64, err error)

	// Writes a new Overview line into the database.
	GroupWriteOv(grp []byte, autonum bool, md *Article_MD, tk *TOKEN, ove *OverviewElement) (err error)

	// Initializes a group in the overview-database.
	InitGroup(grp []byte) (err error)
}

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func OpenOverviewMethod(cfg *CfgMaster) (OverviewMethod, error)

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type Releaser interface {
	Release()
}

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type RiElement struct {
	Group	[]byte
	Num	int64
}

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type RiHistory struct {
	// IF Group != nil THEN expire a group.
	Group	[]byte
	Num	int64

	// IF MessageID != nil THEN expire an article.
	MessageId	[]byte
}

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type RiMethod interface {
	// Called for the first group/number-pair associated to the article
	RiWrite(msgid []byte, md *Article_MD, rie *RiElement) (err error)

	// Called for the remaining group/number-pair associated to the article
	RiWriteMore(msgid []byte, md *Article_MD, rie *RiElement) (err error)

	// Performs a reverse index lookup: message-id to the first group/number pair.
	RiLookup(msgid []byte, rie *RiElement) (rel Releaser, err error)

	// Query Expired articles. SHOULD return message-ids after their group/number counterparts.
	RiQueryExpired(ow *time.Time, rih *RiHistory) (cur Cursor, err error)

	// Expires an article using the message-id.
	RiExpire(msgid []byte) (err error)
}

Reverse Index. Maps message-ids to group/number-pairs.

type SMFlags uint

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const (
	SM_Expensivestat	SMFlags	= 1 << iota
	SM_Selfexpire
)

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type SMLevel uint

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const (
	SM_Stat	SMLevel	= iota
	SM_Head
	SM_All
)

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type StorageManager struct {
	Classes	[256]StorageMethod
	Methods	[256]*CfgStorageMethod

	/*
		Used by the Posting backend.
		Will hold *fastnntp.WildMat objects.
	*/
	Wildmat	[256]interface{}
}

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func (s *StorageManager) Open(bi *CfgBaseInfo) (err error)

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func (s *StorageManager) Retrieve(t *TOKEN, sl SMLevel) (a Article_R, rs SMLevel, err error)

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func (s *StorageManager) SetMethods(cfg *CfgStorage)

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type StorageMethod interface {
	io.Closer

	Store(md *Article_MD, a Article_W, t *TOKEN) (err error)
	Retrieve(t *TOKEN, s SMLevel) (a Article_R, rs SMLevel, err error)
	Cancel(t *TOKEN) (err error)
}

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type TOKEN [34]byte

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func (t *TOKEN) Bytes() []byte

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func (t *TOKEN) Class() byte

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func (t *TOKEN) Debug() string

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