Merge pull request #5 from ava-labs/revert-4-revert-2-plugin

Added the EVM as a plugin

1 files changed, 502 insertions, 0 deletions

diff --git a/plugin/evm/vm.go b/plugin/evm/vm.go
new file mode 100644
index 0000000..a9011ea
--- /dev/null
+++ b/plugin/evm/vm.go
@@ -0,0 +1,502 @@
+// (c) 2019-2020, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package evm
+
+import (
+	"crypto/rand"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"math/big"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/ava-labs/coreth"
+	"github.com/ava-labs/coreth/core"
+	"github.com/ava-labs/coreth/eth"
+	"github.com/ava-labs/coreth/node"
+
+	"github.com/ava-labs/go-ethereum/common"
+	"github.com/ava-labs/go-ethereum/core/types"
+	"github.com/ava-labs/go-ethereum/rlp"
+	"github.com/ava-labs/go-ethereum/rpc"
+
+	"github.com/ava-labs/gecko/cache"
+	"github.com/ava-labs/gecko/database"
+	"github.com/ava-labs/gecko/ids"
+	"github.com/ava-labs/gecko/snow"
+	"github.com/ava-labs/gecko/snow/choices"
+	"github.com/ava-labs/gecko/snow/consensus/snowman"
+	"github.com/ava-labs/gecko/utils/timer"
+
+	commonEng "github.com/ava-labs/gecko/snow/engine/common"
+)
+
+const (
+	lastAcceptedKey = "snowman_lastAccepted"
+)
+
+const (
+	minBlockTime = 250 * time.Millisecond
+	maxBlockTime = 1000 * time.Millisecond
+	batchSize    = 250
+)
+
+const (
+	bdTimerStateMin = iota
+	bdTimerStateMax
+	bdTimerStateLong
+)
+
+var (
+	errEmptyBlock     = errors.New("empty block")
+	errCreateBlock    = errors.New("couldn't create block")
+	errUnknownBlock   = errors.New("unknown block")
+	errBlockFrequency = errors.New("too frequent block issuance")
+	errUnsupportedFXs = errors.New("unsupported feature extensions")
+)
+
+func maxDuration(x, y time.Duration) time.Duration {
+	if x > y {
+		return x
+	}
+	return y
+}
+
+// VM implements the snowman.ChainVM interface
+type VM struct {
+	ctx *snow.Context
+
+	chainID           *big.Int
+	networkID         uint64
+	chain             *coreth.ETHChain
+	chaindb           Database
+	newBlockChan      chan *Block
+	networkChan       chan<- commonEng.Message
+	newTxPoolHeadChan chan core.NewTxPoolHeadEvent
+
+	txPoolStabilizedHead common.Hash
+	txPoolStabilizedOk   chan struct{}
+	txPoolStabilizedLock sync.Mutex
+
+	metalock                     sync.Mutex
+	blockCache, blockStatusCache cache.LRU
+	lastAccepted                 *Block
+	writingMetadata              uint32
+
+	bdlock          sync.Mutex
+	blockDelayTimer *timer.Timer
+	bdTimerState    int8
+	bdGenWaitFlag   bool
+	bdGenFlag       bool
+
+	genlock      sync.Mutex
+	txSubmitChan <-chan struct{}
+}
+
+/*
+ ******************************************************************************
+ ********************************* Snowman API ********************************
+ ******************************************************************************
+ */
+
+// Initialize implements the snowman.ChainVM interface
+func (vm *VM) Initialize(
+	ctx *snow.Context,
+	db database.Database,
+	b []byte,
+	toEngine chan<- commonEng.Message,
+	fxs []*commonEng.Fx,
+) error {
+	if len(fxs) > 0 {
+		return errUnsupportedFXs
+	}
+
+	vm.ctx = ctx
+	vm.chaindb = Database{db}
+	g := new(core.Genesis)
+	err := json.Unmarshal(b, g)
+	if err != nil {
+		return err
+	}
+
+	vm.chainID = g.Config.ChainID
+
+	config := eth.DefaultConfig
+	config.ManualCanonical = true
+	config.Genesis = g
+	config.Miner.ManualMining = true
+	config.Miner.DisableUncle = true
+	if err := config.SetGCMode("archive"); err != nil {
+		panic(err)
+	}
+	nodecfg := node.Config{NoUSB: true}
+	chain := coreth.NewETHChain(&config, &nodecfg, nil, vm.chaindb)
+	vm.chain = chain
+	vm.networkID = config.NetworkId
+	chain.SetOnHeaderNew(func(header *types.Header) {
+		hid := make([]byte, 32)
+		_, err := rand.Read(hid)
+		if err != nil {
+			panic("cannot generate hid")
+		}
+		header.Extra = append(header.Extra, hid...)
+	})
+	chain.SetOnSeal(func(block *types.Block) error {
+		if len(block.Transactions()) == 0 {
+			// this could happen due to the async logic of geth tx pool
+			vm.newBlockChan <- nil
+			return errEmptyBlock
+		}
+		return nil
+	})
+	chain.SetOnSealFinish(func(block *types.Block) error {
+		vm.ctx.Log.Verbo("EVM sealed a block")
+
+		blk := &Block{
+			id:       ids.NewID(block.Hash()),
+			ethBlock: block,
+			vm:       vm,
+		}
+		vm.newBlockChan <- blk
+		vm.updateStatus(ids.NewID(block.Hash()), choices.Processing)
+		vm.txPoolStabilizedLock.Lock()
+		vm.txPoolStabilizedHead = block.Hash()
+		vm.txPoolStabilizedLock.Unlock()
+		return nil
+	})
+	chain.SetOnQueryAcceptedBlock(func() *types.Block {
+		return vm.getLastAccepted().ethBlock
+	})
+	vm.blockCache = cache.LRU{Size: 2048}
+	vm.blockStatusCache = cache.LRU{Size: 1024}
+	vm.newBlockChan = make(chan *Block)
+	vm.networkChan = toEngine
+	vm.blockDelayTimer = timer.NewTimer(func() {
+		vm.bdlock.Lock()
+		switch vm.bdTimerState {
+		case bdTimerStateMin:
+			vm.bdTimerState = bdTimerStateMax
+			vm.blockDelayTimer.SetTimeoutIn(maxDuration(maxBlockTime-minBlockTime, 0))
+		case bdTimerStateMax:
+			vm.bdTimerState = bdTimerStateLong
+		}
+		tryAgain := vm.bdGenWaitFlag
+		vm.bdlock.Unlock()
+		if tryAgain {
+			vm.tryBlockGen()
+		}
+	})
+	go ctx.Log.RecoverAndPanic(vm.blockDelayTimer.Dispatch)
+
+	vm.bdTimerState = bdTimerStateLong
+	vm.bdGenWaitFlag = true
+	vm.newTxPoolHeadChan = make(chan core.NewTxPoolHeadEvent, 1)
+	vm.txPoolStabilizedOk = make(chan struct{}, 1)
+	chain.GetTxPool().SubscribeNewHeadEvent(vm.newTxPoolHeadChan)
+	// TODO: shutdown this go routine
+	go ctx.Log.RecoverAndPanic(func() {
+		for {
+			select {
+			case h := <-vm.newTxPoolHeadChan:
+				vm.txPoolStabilizedLock.Lock()
+				if vm.txPoolStabilizedHead == h.Block.Hash() {
+					vm.txPoolStabilizedOk <- struct{}{}
+					vm.txPoolStabilizedHead = common.Hash{}
+				}
+				vm.txPoolStabilizedLock.Unlock()
+			}
+		}
+	})
+	chain.Start()
+
+	var lastAccepted *types.Block
+	if b, err := vm.chaindb.Get([]byte(lastAcceptedKey)); err == nil {
+		var hash common.Hash
+		if err = rlp.DecodeBytes(b, &hash); err == nil {
+			if block := chain.GetBlockByHash(hash); block == nil {
+				vm.ctx.Log.Debug("lastAccepted block not found in chaindb")
+			} else {
+				lastAccepted = block
+			}
+		}
+	}
+	if lastAccepted == nil {
+		vm.ctx.Log.Debug("lastAccepted is unavailable, setting to the genesis block")
+		lastAccepted = chain.GetGenesisBlock()
+	}
+	vm.lastAccepted = &Block{
+		id:       ids.NewID(lastAccepted.Hash()),
+		ethBlock: lastAccepted,
+		vm:       vm,
+	}
+	vm.ctx.Log.Info(fmt.Sprintf("lastAccepted = %s", vm.lastAccepted.ethBlock.Hash().Hex()))
+
+	// TODO: shutdown this go routine
+	go vm.ctx.Log.RecoverAndPanic(func() {
+		vm.txSubmitChan = vm.chain.GetTxSubmitCh()
+		for {
+			select {
+			case <-vm.txSubmitChan:
+				vm.ctx.Log.Verbo("New tx detected, trying to generate a block")
+				vm.tryBlockGen()
+			case <-time.After(5 * time.Second):
+				vm.tryBlockGen()
+			}
+		}
+	})
+
+	return nil
+}
+
+// Shutdown implements the snowman.ChainVM interface
+func (vm *VM) Shutdown() {
+	if vm.ctx == nil {
+		return
+	}
+
+	vm.writeBackMetadata()
+	vm.chain.Stop()
+}
+
+// BuildBlock implements the snowman.ChainVM interface
+func (vm *VM) BuildBlock() (snowman.Block, error) {
+	vm.chain.GenBlock()
+	block := <-vm.newBlockChan
+	if block == nil {
+		return nil, errCreateBlock
+	}
+	// reset the min block time timer
+	vm.bdlock.Lock()
+	vm.bdTimerState = bdTimerStateMin
+	vm.bdGenWaitFlag = false
+	vm.bdGenFlag = false
+	vm.blockDelayTimer.SetTimeoutIn(minBlockTime)
+	vm.bdlock.Unlock()
+
+	vm.ctx.Log.Debug("built block 0x%x", block.ID().Bytes())
+	// make sure Tx Pool is updated
+	<-vm.txPoolStabilizedOk
+	return block, nil
+}
+
+// ParseBlock implements the snowman.ChainVM interface
+func (vm *VM) ParseBlock(b []byte) (snowman.Block, error) {
+	vm.metalock.Lock()
+	defer vm.metalock.Unlock()
+
+	ethBlock := new(types.Block)
+	if err := rlp.DecodeBytes(b, ethBlock); err != nil {
+		return nil, err
+	}
+	block := &Block{
+		id:       ids.NewID(ethBlock.Hash()),
+		ethBlock: ethBlock,
+		vm:       vm,
+	}
+	vm.blockCache.Put(block.ID(), block)
+	return block, nil
+}
+
+// GetBlock implements the snowman.ChainVM interface
+func (vm *VM) GetBlock(id ids.ID) (snowman.Block, error) {
+	vm.metalock.Lock()
+	defer vm.metalock.Unlock()
+
+	block := vm.getBlock(id)
+	if block == nil {
+		return nil, errUnknownBlock
+	}
+	return block, nil
+}
+
+// SetPreference sets what the current tail of the chain is
+func (vm *VM) SetPreference(blkID ids.ID) {
+	err := vm.chain.SetTail(blkID.Key())
+	vm.ctx.Log.AssertNoError(err)
+}
+
+// LastAccepted returns the ID of the block that was last accepted
+func (vm *VM) LastAccepted() ids.ID {
+	vm.metalock.Lock()
+	defer vm.metalock.Unlock()
+
+	return vm.lastAccepted.ID()
+}
+
+// CreateHandlers makes new http handlers that can handle API calls
+func (vm *VM) CreateHandlers() map[string]*commonEng.HTTPHandler {
+	handler := vm.chain.NewRPCHandler()
+	vm.chain.AttachEthService(handler, []string{"eth", "personal", "txpool"})
+	handler.RegisterName("net", &NetAPI{vm})
+	handler.RegisterName("snowman", &SnowmanAPI{vm})
+	handler.RegisterName("web3", &Web3API{})
+	handler.RegisterName("debug", &DebugAPI{vm})
+
+	return map[string]*commonEng.HTTPHandler{
+		"/rpc": &commonEng.HTTPHandler{LockOptions: commonEng.NoLock, Handler: handler},
+		"/ws":  &commonEng.HTTPHandler{LockOptions: commonEng.NoLock, Handler: handler.WebsocketHandler([]string{"*"})},
+	}
+}
+
+// CreateStaticHandlers makes new http handlers that can handle API calls
+func (vm *VM) CreateStaticHandlers() map[string]*commonEng.HTTPHandler {
+	handler := rpc.NewServer()
+	handler.RegisterName("static", &StaticService{})
+	return map[string]*commonEng.HTTPHandler{
+		"/rpc": &commonEng.HTTPHandler{LockOptions: commonEng.NoLock, Handler: handler},
+		"/ws":  &commonEng.HTTPHandler{LockOptions: commonEng.NoLock, Handler: handler.WebsocketHandler([]string{"*"})},
+	}
+}
+
+/*
+ ******************************************************************************
+ *********************************** Helpers **********************************
+ ******************************************************************************
+ */
+
+func (vm *VM) updateStatus(blockID ids.ID, status choices.Status) {
+	vm.metalock.Lock()
+	defer vm.metalock.Unlock()
+
+	if status == choices.Accepted {
+		vm.lastAccepted = vm.getBlock(blockID)
+		// TODO: improve this naive implementation
+		if atomic.SwapUint32(&vm.writingMetadata, 1) == 0 {
+			go vm.ctx.Log.RecoverAndPanic(vm.writeBackMetadata)
+		}
+	}
+	vm.blockStatusCache.Put(blockID, status)
+}
+
+func (vm *VM) getCachedBlock(blockID ids.ID) *types.Block {
+	return vm.chain.GetBlockByHash(blockID.Key())
+}
+
+func (vm *VM) tryBlockGen() error {
+	vm.bdlock.Lock()
+	defer vm.bdlock.Unlock()
+	if vm.bdGenFlag {
+		// skip if one call already generates a block in this round
+		return nil
+	}
+	vm.bdGenWaitFlag = true
+
+	vm.genlock.Lock()
+	defer vm.genlock.Unlock()
+	// get pending size
+	size, err := vm.chain.PendingSize()
+	if err != nil {
+		return err
+	}
+	if size == 0 {
+		return nil
+	}
+
+	switch vm.bdTimerState {
+	case bdTimerStateMin:
+		return nil
+	case bdTimerStateMax:
+		if size < batchSize {
+			return nil
+		}
+	case bdTimerStateLong:
+		// timeout; go ahead and generate a new block anyway
+	}
+	select {
+	case vm.networkChan <- commonEng.PendingTxs:
+		// successfully push out the notification; this round ends
+		vm.bdGenFlag = true
+	default:
+		return errBlockFrequency
+	}
+	return nil
+}
+
+func (vm *VM) getCachedStatus(blockID ids.ID) choices.Status {
+	vm.metalock.Lock()
+	defer vm.metalock.Unlock()
+	status := choices.Processing
+
+	if statusIntf, ok := vm.blockStatusCache.Get(blockID); ok {
+		status = statusIntf.(choices.Status)
+	} else {
+		blk := vm.chain.GetBlockByHash(blockID.Key())
+		if blk == nil {
+			return choices.Unknown
+		}
+		acceptedBlk := vm.lastAccepted.ethBlock
+
+		// TODO: There must be a better way of doing this.
+		// Traverse up the chain from the lower block until the indices match
+		highBlock := blk
+		lowBlock := acceptedBlk
+		if highBlock.Number().Cmp(lowBlock.Number()) < 0 {
+			highBlock, lowBlock = lowBlock, highBlock
+		}
+		for highBlock.Number().Cmp(lowBlock.Number()) > 0 {
+			highBlock = vm.chain.GetBlockByHash(highBlock.ParentHash())
+		}
+
+		if highBlock.Hash() == lowBlock.Hash() { // on the same branch
+			if blk.Number().Cmp(acceptedBlk.Number()) <= 0 {
+				status = choices.Accepted
+			}
+		} else { // on different branches
+			status = choices.Rejected
+		}
+	}
+
+	vm.blockStatusCache.Put(blockID, status)
+	return status
+}
+
+func (vm *VM) getBlock(id ids.ID) *Block {
+	if blockIntf, ok := vm.blockCache.Get(id); ok {
+		return blockIntf.(*Block)
+	}
+	ethBlock := vm.getCachedBlock(id)
+	if ethBlock == nil {
+		return nil
+	}
+	block := &Block{
+		id:       ids.NewID(ethBlock.Hash()),
+		ethBlock: ethBlock,
+		vm:       vm,
+	}
+	vm.blockCache.Put(id, block)
+	return block
+}
+
+func (vm *VM) issueRemoteTxs(txs []*types.Transaction) error {
+	errs := vm.chain.AddRemoteTxs(txs)
+	for _, err := range errs {
+		if err != nil {
+			return err
+		}
+	}
+	return vm.tryBlockGen()
+}
+
+func (vm *VM) writeBackMetadata() {
+	vm.metalock.Lock()
+	defer vm.metalock.Unlock()
+
+	b, err := rlp.EncodeToBytes(vm.lastAccepted.ethBlock.Hash())
+	if err != nil {
+		vm.ctx.Log.Error("snowman-eth: error while writing back metadata")
+		return
+	}
+	vm.ctx.Log.Debug("writing back metadata")
+	vm.chaindb.Put([]byte(lastAcceptedKey), b)
+	atomic.StoreUint32(&vm.writingMetadata, 0)
+}
+
+func (vm *VM) getLastAccepted() *Block {
+	vm.metalock.Lock()
+	defer vm.metalock.Unlock()
+
+	return vm.lastAccepted
+}