incdb

type Batch interface {
	KeyValueWriter

	// ValueSize retrieves the amount of data queued up for writing.
	ValueSize() int

	// Write flushes any accumulated data to disk.
	Write() error

	// Reset resets the batch for reuse.
	Reset()

	// Replay replays the batch contents.
	Replay(w KeyValueWriter) error
}

type BatchData struct {
	Key   []byte
	Value []byte
}

type Batcher interface {
	// NewBatch creates a write-only database that buffers changes to its host db
	// until a final write is called.
	NewBatch() Batch
}

type Compacter interface {
	// Compact flattens the underlying data store for the given key range. In essence,
	// deleted and overwritten versions are discarded, and the data is rearranged to
	// reduce the cost of operations needed to access them.
	//
	// A nil start is treated as a key before all keys in the data store; a nil limit
	// is treated as a key after all keys in the data store. If both is nil then it
	// will compact entire data store.
	Compact(start []byte, limit []byte) error
}

type Database interface {
	KeyValueReader
	KeyValueWriter
	Batcher
	Iteratee
	Stater
	Compacter
	io.Closer
	RemoveBackup(string)
	Backup(backupFolder string) error
	LatestBackup(backupFolder string) (int, string)
	PreloadBackup(backupFile string) error
	ReOpen() error
	Clear() error
}

type DbLogger struct {
	Log common.Logger
}

type Driver struct {
	DbType string
	Open   func(args ...interface{}) (Database, error)
}

type Iteratee interface {
	// NewIterator creates a binary-alphabetical iterator over the entire keyspace
	// contained within the key-value database.
	NewIterator() Iterator

	// NewIteratorWithStart creates a binary-alphabetical iterator over a subset of
	// database content starting at a particular initial key (or after, if it does
	// not exist).
	NewIteratorWithStart(start []byte) Iterator

	// NewIteratorWithPrefix creates a binary-alphabetical iterator over a subset
	// of database content with a particular key prefix.
	NewIteratorWithPrefix(prefix []byte) Iterator

	// NewIteratorWithPrefixStart creates a binary-alphabetical iterator over a subset
	// of database content with a particular key prefix, starting at a particular
	// initial key (or after, if it does not exist).
	//
	// Note: This method assumes that the prefix is NOT part of the start, so there's
	// no need for the caller to prepend the prefix to the start
	NewIteratorWithPrefixStart(prefix []byte, start []byte) Iterator
}

type Iterator interface {
	// Next moves the iterator to the next key/value pair. It returns whether the
	// iterator is exhausted.
	Next() bool

	// Error returns any accumulated error. Exhausting all the key/value pairs
	// is not considered to be an error.
	Error() error

	// Key returns the key of the current key/value pair, or nil if done. The caller
	// should not modify the contents of the returned slice, and its contents may
	// change on the next call to Next.
	Key() []byte

	// Value returns the value of the current key/value pair, or nil if done. The
	// caller should not modify the contents of the returned slice, and its contents
	// may change on the next call to Next.
	Value() []byte

	// Last moves the iterator to the last key/value pair. If the iterator
	// only contains one key/value pair then First and Last would moves
	// to the same key/value pair.
	// It returns whether such pair exist.
	Last() bool
	// Release releases associated resources. Release should always succeed and can
	// be called multiple times without causing error.
	Release()
}

type KeyValueReader interface {
	// Has retrieves if a key is present in the key-value data store.
	Has(key []byte) (bool, error)

	// Get retrieves the given key if it's present in the key-value data store.
	Get(key []byte) ([]byte, error)
}

type KeyValueWriter interface {
	// Put inserts the given value into the key-value data store.
	Put(key []byte, value []byte) error

	// Delete removes the key from the key-value data store.
	Delete(key []byte) error
}

type Stater interface {
	// Stat returns a particular internal stat of the database.
	Stat(property string) (string, error)
}