path: root/pow/ezp/pow.go

// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package ezp

import (
    "encoding/binary"
    "math/big"
    "math/rand"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/crypto/sha3"
    "github.com/ethereum/go-ethereum/logger"
    "github.com/ethereum/go-ethereum/pow"
)

var powlogger = logger.NewLogger("POW")

type EasyPow struct {
    hash     *big.Int
    HashRate int64
    turbo    bool
}

func New() *EasyPow {
    return &EasyPow{turbo: false}
}

func (pow *EasyPow) GetHashrate() int64 {
    return pow.HashRate
}

func (pow *EasyPow) Turbo(on bool) {
    pow.turbo = on
}

func (pow *EasyPow) Search(block pow.Block, stop <-chan struct{}) (uint64, []byte) {
    r := rand.New(rand.NewSource(time.Now().UnixNano()))
    hash := block.HashNoNonce()
    diff := block.Difficulty()
    //i := int64(0)
    // TODO fix offset
    i := rand.Int63()
    starti := i
    start := time.Now().UnixNano()

    defer func() { pow.HashRate = 0 }()

    // Make sure stop is empty
empty:
    for {
        select {
        case <-stop:
        default:
            break empty
        }
    }

    for {
        select {
        case <-stop:
            return 0, nil
        default:
            i++

            elapsed := time.Now().UnixNano() - start
            hashes := ((float64(1e9) / float64(elapsed)) * float64(i-starti)) / 1000
            pow.HashRate = int64(hashes)

            sha := uint64(r.Int63())
            if verify(hash, diff, sha) {
                return sha, nil
            }
        }

        if !pow.turbo {
            time.Sleep(20 * time.Microsecond)
        }
    }

    return 0, nil
}

func (pow *EasyPow) Verify(block pow.Block) bool {
    return Verify(block)
}

func verify(hash common.Hash, diff *big.Int, nonce uint64) bool {
    sha := sha3.NewKeccak256()
    n := make([]byte, 8)
    binary.PutUvarint(n, nonce)
    sha.Write(n)
    sha.Write(hash[:])
    verification := new(big.Int).Div(common.BigPow(2, 256), diff)
    res := common.BigD(sha.Sum(nil))
    return res.Cmp(verification) <= 0
}

func Verify(block pow.Block) bool {
    return verify(block.HashNoNonce(), block.Difficulty(), block.Nonce())
}