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// Package database provides KV database for meta-information
package database
import "errors"
// Errors for Storage
var (
ErrNotFound = errors.New("key not found")
)
// StorageProcessor is a function to process one single storage entry
type StorageProcessor func(key []byte, value []byte) error
// Reader provides KV read calls
type Reader interface {
Get(key []byte) ([]byte, error)
}
// PrefixReader provides prefixed operations
type PrefixReader interface {
HasPrefix(prefix []byte) bool
ProcessByPrefix(prefix []byte, proc StorageProcessor) error
KeysByPrefix(prefix []byte) [][]byte
FetchByPrefix(prefix []byte) [][]byte
}
// Writer provides KV update/delete calls
type Writer interface {
Put(key []byte, value []byte) error
Delete(key []byte) error
}
// ReaderWriter combines Reader and Writer
type ReaderWriter interface {
Reader
Writer
}
// Storage is an interface to KV storage
type Storage interface {
Reader
Writer
PrefixReader
CreateBatch() Batch
OpenTransaction() (Transaction, error)
CreateTemporary() (Storage, error)
Open() error
Close() error
CompactDB() error
Drop() error
}
// Batch provides a way to pack many writes.
type Batch interface {
Writer
// Write closes batch and send accumulated writes to the database
Write() error
}
// Transaction provides isolated atomic way to perform updates.
//
// Transactions might be expensive.
// Transaction should always finish with either Discard() or Commit()
type Transaction interface {
Reader
Writer
Commit() error
Discard()
}
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