path: root/core/test/block-revealer.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 test

import (
    "errors"
    "sort"

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

// Errors returns from block-revealer.
var (
    ErrNotValidCompactionChain = errors.New("not valid compaction chain")
)

// loadAllBlocks is a helper to load all blocks from db.BlockIterator.
func loadAllBlocks(iter db.BlockIterator) (
    blocks map[common.Hash]*types.Block, err error) {

    blocks = make(map[common.Hash]*types.Block)
    for {
        block, err := iter.NextBlock()
        if err != nil {
            if err == db.ErrIterationFinished {
                // It's safe to ignore iteraion-finished error.
                err = nil
            }
            break
        }
        blocks[block.Hash] = &block
    }
    return
}

// BlockRevealerByPosition implements BlockRevealer interface, which would
// load all blocks from db, reveal them in the order of compaction chain,
// from the genesis block to the latest one.
type BlockRevealerByPosition struct {
    blocks          types.BlocksByPosition
    nextRevealIndex int
}

// NewBlockRevealerByPosition constructs a block revealer in the order of
// compaction chain.
func NewBlockRevealerByPosition(iter db.BlockIterator, startHeight uint64) (
    r *BlockRevealerByPosition, err error) {
    blocksByHash, err := loadAllBlocks(iter)
    if err != nil {
        return
    }
    blocks := types.BlocksByPosition{}
    for _, b := range blocksByHash {
        if b.Position.Height < startHeight {
            continue
        }
        blocks = append(blocks, b)
    }
    sort.Sort(types.BlocksByPosition(blocks))
    // Make sure the height of blocks are incremental with step 1.
    for idx, b := range blocks {
        if idx == 0 {
            continue
        }
        if b.Position.Height != blocks[idx-1].Position.Height+1 {
            err = ErrNotValidCompactionChain
            return
        }
    }
    r = &BlockRevealerByPosition{blocks: blocks}
    r.Reset()
    return
}

// NextBlock implements Revealer.Next method, which would reveal blocks in the
// order of compaction chain.
func (r *BlockRevealerByPosition) NextBlock() (types.Block, error) {
    if r.nextRevealIndex == len(r.blocks) {
        return types.Block{}, db.ErrIterationFinished
    }
    b := r.blocks[r.nextRevealIndex]
    r.nextRevealIndex++
    return *b, nil
}

// Reset implement Revealer.Reset method, which would reset revealing.
func (r *BlockRevealerByPosition) Reset() {
    r.nextRevealIndex = 0
}