ledger

type Entries []Entry

type Entry struct {
	Operation
	DeviceID string // DeviceID is the ID of the device that made the change
	Epoch    uint64 // The monotonic ID of the ledger entry
}

type Ledger interface {
	Txn(fn func(tx LedgerTxn) error) error
}

type LedgerTxn interface {
	// Append adds a new entry to the append-only log
	Append(op Operation) error
	// Filter returns all matching entries (determined by fn) sorted by timestamp
	Filter(fn func(ent Entry) (bool, error)) (Entries, error)

	// Compact compacts the local ledger deleting all entries for each key.
	// Only the most recent N entries for each key will be kept
	Compact(n int) error
}

type OperTime uint64

type OperType byte

type Operation struct {
	Time  uint64   // Timestamp of the operation
	Type  OperType // The type of operation being recorded
	Key   []byte   // The key being modified
	Value []byte   // The new value of the modified key (if a set operation)
}