index

type Index interface {
	// Put stores a given key and its value in the index
	//
	// It may replaces the old value if the given already exists
	//
	// It returns the old value if the given key already exists and nil otherwise
	Put([]byte, *data.LogRecordPosition) *data.LogRecordPosition

	// Get returns the value of the given key from the index
	//
	// It returns a value if the given key already exists and nil otherwise
	Get([]byte) *data.LogRecordPosition

	// Delete deletes the value of the given key in the index
	//
	// It returns the deleted value and a boolean value true if the key exists
	// Otherwise, it returns nil and a boolean value false
	Delete([]byte) (*data.LogRecordPosition, bool)

	// Size returns how many key/value pairs in the index
	Size() int

	// Iterator creates an iterator of the index
	//
	// The iterator supports reversed iteration if the given boolean value is true
	Iterator(bool) Iterator

	// Close closes the index
	Close() error
}

type IndexType = int8

type Iterator interface {
	Rewind() // Rewind resets the iteration

	Seek([]byte)

	Next()

	Valid() bool

	Key() []byte

	Value() *data.LogRecordPosition

	Close() // Close closes the iterator
}

type IteratorOptions struct {
	Prefix  []byte // Traverses an iterator's keys with a specified non-nil prefix
	Reverse bool   // Traverses an iterator reversely if true
}