journal

type ChnksController interface {
	// JournalName returns the jounal name it controls
	JournalName() string

	// GetChunkForWrite returns chunk for write operaion, the call could
	// be cancelled via ctx. The excludeCid could contain the chunk.Id which should
	// not be returned. Providing excludeCid the client indicates that it already
	// tries to write to the chunk and the operation was not successful, so it should not
	// be repeated.
	// ctx == nil is acceptable
	GetChunkForWrite(ctx context.Context, excludeCid chunk.Id) (chunk.Chunk, error)

	// Chunks returns a sorted list of chunks. ctx can cancel the call. ctx
	// could be nil.
	Chunks(ctx context.Context) (chunk.Chunks, error)

	// WaitForNewData waits till new data appears in the journal, or the
	// ctx is closed. Will return an error if any. or indicates the new
	// data is added to the journal
	WaitForNewData(ctx context.Context, pos Pos) error

	// DeleteChunk marks the journal's chunk with Id <= lastCid as deleted. The cdf will be called as soon as a chunk
	// will be marked as deleted. The DeleteChunk doesn't delete the chunk data physically, but it gets the chunk out from
	// the service loop. The callback function could either delete the data or archive it.
	// The function returns number of chunks makred as deleted or an error, if any
	DeleteChunks(ctx context.Context, lastCid chunk.Id, cdf OnChunkDeleteF) (int, error)

	// LocalFolder returns the folder on the FS where all the chunks are stored
	LocalFolder() string
}

type Controller interface {
	// Visit iterate over all known journals and it calls the cv for every journal found. Iteration is
	// stopped when all journals are visited or cv returns false
	Visit(ctx context.Context, cv ControllerVisitorF)

	// GetOrCreate creates new, or gives an access to existing journal
	GetOrCreate(ctx context.Context, jname string) (Journal, error)

	// Delete removes the internal record, but doesn't touch the journal data.
	// an error could be returned if there are alive chunks registered. The journal could be
	// re-created following up calls by GetOrCreate
	Delete(ctx context.Context, jname string) error
}

type ControllerVisitorF func(j Journal) bool

type Iterator interface {
	io.Closer
	records.Iterator

	Pos() Pos

	// SetPos allows to change the JIterator position
	SetPos(pos Pos)
}

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

type Journal interface {

	// Name returns the journal name
	Name() string

	// Write - writes records received from the JIterator to the journal.
	// It returns number of records written, next record write position and an error if any
	Write(ctx context.Context, rit records.Iterator) (int, Pos, error)

	// Size returns the summarized chunks' size
	Size() uint64

	// Count returns number of records in the journal
	Count() uint64

	// Sync could be called after a write to sync the written data with the
	// storage to be sure the read will be able to read the new added
	// data
	Sync()

	// ChnksController returns ChnksController for the journal
	Chunks() ChnksController
}

type OnChunkDeleteF func(cid chunk.Id, filename string, err error)

type Pos struct {
	CId chunk.Id
	Idx uint32
}