path: root/core/db/interfaces.go

// Copyright 2018 The dexon-consensus Authors
// This file is part of the dexon-consensus library.
//
// The dexon-consensus library is free software: you can redistribute it
// and/or modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation, either version 3 of the License,
// or (at your option) any later version.
//
// The dexon-consensus library is distributed in the hope that it will be
// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
// General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the dexon-consensus library. If not, see
// <http://www.gnu.org/licenses/>.

package db

import (
    "errors"
    "fmt"

    "github.com/dexon-foundation/dexon-consensus/common"
    "github.com/dexon-foundation/dexon-consensus/core/crypto/dkg"
    "github.com/dexon-foundation/dexon-consensus/core/types"
)

var (
    // ErrBlockExists is the error when block eixsts.
    ErrBlockExists = errors.New("block exists")
    // ErrBlockDoesNotExist is the error when block does not eixst.
    ErrBlockDoesNotExist = errors.New("block does not exist")
    // ErrIterationFinished is the error to check if the iteration is finished.
    ErrIterationFinished = errors.New("iteration finished")
    // ErrEmptyPath is the error when the required path is empty.
    ErrEmptyPath = fmt.Errorf("empty path")
    // ErrClosed is the error when using DB after it's closed.
    ErrClosed = fmt.Errorf("db closed")
    // ErrNotImplemented is the error that some interface is not implemented.
    ErrNotImplemented = fmt.Errorf("not implemented")
    // ErrInvalidCompactionChainTipHeight means the newly updated height of
    // the tip of compaction chain is invalid, usually means it's smaller than
    // current cached one.
    ErrInvalidCompactionChainTipHeight = fmt.Errorf(
        "invalid compaction chain tip height")
    // ErrDKGPrivateKeyExists raised when attempting to save DKG private key
    // that already saved.
    ErrDKGPrivateKeyExists = errors.New("dkg private key exists")
    // ErrDKGPrivateKeyDoesNotExist raised when the DKG private key of the
    // requested round does not exists.
    ErrDKGPrivateKeyDoesNotExist = errors.New("dkg private key does not exists")
)

// Database is the interface for a Database.
type Database interface {
    Reader
    Writer

    // Close allows database implementation able to
    // release resource when finishing.
    Close() error
}

// Reader defines the interface for reading blocks into DB.
type Reader interface {
    HasBlock(hash common.Hash) bool
    GetBlock(hash common.Hash) (types.Block, error)
    GetAllBlocks() (BlockIterator, error)

    // GetCompactionChainTipInfo returns the block hash and finalization height
    // of the tip block of compaction chain. Empty hash and zero height means
    // the compaction chain is empty.
    GetCompactionChainTipInfo() (common.Hash, uint64)

    // DKG Private Key related methods.
    HasDKGPrivateKey(round uint64) (bool, error)
    GetDKGPrivateKey(round uint64) (dkg.PrivateKey, error)
}

// Writer defines the interface for writing blocks into DB.
type Writer interface {
    UpdateBlock(block types.Block) error
    PutBlock(block types.Block) error
    PutCompactionChainTipInfo(common.Hash, uint64) error
    PutDKGPrivateKey(uint64, dkg.PrivateKey) error
}

// BlockIterator defines an iterator on blocks hold
// in a DB.
type BlockIterator interface {
    NextBlock() (types.Block, error)
}