path: root/miner/remote_agent.go

// Copyright 2015 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 miner

import (
    "errors"
    "math/big"
    "sync"
    "sync/atomic"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/consensus"
    "github.com/ethereum/go-ethereum/consensus/ethash"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/log"
)

type hashrate struct {
    ping time.Time
    rate uint64
}

type RemoteAgent struct {
    mu sync.Mutex

    quitCh   chan struct{}
    workCh   chan *Work
    returnCh chan<- *Result

    chain       consensus.ChainReader
    engine      consensus.Engine
    currentWork *Work
    work        map[common.Hash]*Work

    hashrateMu sync.RWMutex
    hashrate   map[common.Hash]hashrate

    running int32 // running indicates whether the agent is active. Call atomically
}

func NewRemoteAgent(chain consensus.ChainReader, engine consensus.Engine) *RemoteAgent {
    return &RemoteAgent{
        chain:    chain,
        engine:   engine,
        work:     make(map[common.Hash]*Work),
        hashrate: make(map[common.Hash]hashrate),
    }
}

func (a *RemoteAgent) SubmitHashrate(id common.Hash, rate uint64) {
    a.hashrateMu.Lock()
    defer a.hashrateMu.Unlock()

    a.hashrate[id] = hashrate{time.Now(), rate}
}

func (a *RemoteAgent) Work() chan<- *Work {
    return a.workCh
}

func (a *RemoteAgent) SetReturnCh(returnCh chan<- *Result) {
    a.returnCh = returnCh
}

func (a *RemoteAgent) Start() {
    if !atomic.CompareAndSwapInt32(&a.running, 0, 1) {
        return
    }
    a.quitCh = make(chan struct{})
    a.workCh = make(chan *Work, 1)
    go a.loop(a.workCh, a.quitCh)
}

func (a *RemoteAgent) Stop() {
    if !atomic.CompareAndSwapInt32(&a.running, 1, 0) {
        return
    }
    close(a.quitCh)
    close(a.workCh)
}

// GetHashRate returns the accumulated hashrate of all identifier combined
func (a *RemoteAgent) GetHashRate() (tot int64) {
    a.hashrateMu.RLock()
    defer a.hashrateMu.RUnlock()

    // this could overflow
    for _, hashrate := range a.hashrate {
        tot += int64(hashrate.rate)
    }
    return
}

func (a *RemoteAgent) GetWork() ([3]string, error) {
    a.mu.Lock()
    defer a.mu.Unlock()

    var res [3]string

    if a.currentWork != nil {
        block := a.currentWork.Block

        res[0] = block.HashNoNonce().Hex()
        seedHash := ethash.SeedHash(block.NumberU64())
        res[1] = common.BytesToHash(seedHash).Hex()
        // Calculate the "target" to be returned to the external miner
        n := big.NewInt(1)
        n.Lsh(n, 255)
        n.Div(n, block.Difficulty())
        n.Lsh(n, 1)
        res[2] = common.BytesToHash(n.Bytes()).Hex()

        a.work[block.HashNoNonce()] = a.currentWork
        return res, nil
    }
    return res, errors.New("No work available yet, don't panic.")
}

// SubmitWork tries to inject a pow solution into the remote agent, returning
// whether the solution was accepted or not (not can be both a bad pow as well as
// any other error, like no work pending).
func (a *RemoteAgent) SubmitWork(nonce types.BlockNonce, mixDigest, hash common.Hash) bool {
    a.mu.Lock()
    defer a.mu.Unlock()

    // Make sure the work submitted is present
    work := a.work[hash]
    if work == nil {
        log.Info("Work submitted but none pending", "hash", hash)
        return false
    }
    // Make sure the Engine solutions is indeed valid
    result := work.Block.Header()
    result.Nonce = nonce
    result.MixDigest = mixDigest

    if err := a.engine.VerifySeal(a.chain, result); err != nil {
        log.Warn("Invalid proof-of-work submitted", "hash", hash, "err", err)
        return false
    }
    block := work.Block.WithSeal(result)

    // Solutions seems to be valid, return to the miner and notify acceptance
    a.returnCh <- &Result{work, block}
    delete(a.work, hash)

    return true
}

// loop monitors mining events on the work and quit channels, updating the internal
// state of the remote miner until a termination is requested.
//
// Note, the reason the work and quit channels are passed as parameters is because
// RemoteAgent.Start() constantly recreates these channels, so the loop code cannot
// assume data stability in these member fields.
func (a *RemoteAgent) loop(workCh chan *Work, quitCh chan struct{}) {
    ticker := time.NewTicker(5 * time.Second)
    defer ticker.Stop()

    for {
        select {
        case <-quitCh:
            return
        case work := <-workCh:
            a.mu.Lock()
            a.currentWork = work
            a.mu.Unlock()
        case <-ticker.C:
            // cleanup
            a.mu.Lock()
            for hash, work := range a.work {
                if time.Since(work.createdAt) > 7*(12*time.Second) {
                    delete(a.work, hash)
                }
            }
            a.mu.Unlock()

            a.hashrateMu.Lock()
            for id, hashrate := range a.hashrate {
                if time.Since(hashrate.ping) > 10*time.Second {
                    delete(a.hashrate, id)
                }
            }
            a.hashrateMu.Unlock()
        }
    }
}