watcher.go

package ethereum_watcher

import (
	"container/list"
	"context"
	"errors"
	"fmt"
	"github.com/HydroProtocol/ethereum-watcher/blockchain"
	"github.com/HydroProtocol/ethereum-watcher/plugin"
	"github.com/HydroProtocol/ethereum-watcher/rpc"
	"github.com/HydroProtocol/ethereum-watcher/structs"
	"github.com/sirupsen/logrus"
	"sync"
	"time"
)

type AbstractWatcher struct {
	rpc rpc.IBlockChainRPC

	Ctx  context.Context
	lock sync.RWMutex

	NewBlockChan        chan *structs.RemovableBlock
	NewTxAndReceiptChan chan *structs.RemovableTxAndReceipt
	NewReceiptLogChan   chan *structs.RemovableReceiptLog

	SyncedBlocks         *list.List
	SyncedTxAndReceipts  *list.List
	MaxSyncedBlockToKeep int

	BlockPlugins      []plugin.IBlockPlugin
	TxPlugins         []plugin.ITxPlugin
	TxReceiptPlugins  []plugin.ITxReceiptPlugin
	ReceiptLogPlugins []plugin.IReceiptLogPlugin

	ReceiptCatchUpFromBlock uint64

	sleepSecondsForNewBlock int
	wg                      sync.WaitGroup
}

func NewHttpBasedEthWatcher(ctx context.Context, api string) *AbstractWatcher {
	rpc := rpc.NewEthRPCWithRetry(api, 5)

	return &AbstractWatcher{
		Ctx:                     ctx,
		rpc:                     rpc,
		NewBlockChan:            make(chan *structs.RemovableBlock, 32),
		NewTxAndReceiptChan:     make(chan *structs.RemovableTxAndReceipt, 518),
		NewReceiptLogChan:       make(chan *structs.RemovableReceiptLog, 518),
		SyncedBlocks:            list.New(),
		SyncedTxAndReceipts:     list.New(),
		MaxSyncedBlockToKeep:    64,
		sleepSecondsForNewBlock: 5,
		wg:                      sync.WaitGroup{},
	}
}

func (watcher *AbstractWatcher) RegisterBlockPlugin(plugin plugin.IBlockPlugin) {
	watcher.BlockPlugins = append(watcher.BlockPlugins, plugin)
}

func (watcher *AbstractWatcher) RegisterTxPlugin(plugin plugin.ITxPlugin) {
	watcher.TxPlugins = append(watcher.TxPlugins, plugin)
}

func (watcher *AbstractWatcher) RegisterTxReceiptPlugin(plugin plugin.ITxReceiptPlugin) {
	watcher.TxReceiptPlugins = append(watcher.TxReceiptPlugins, plugin)
}

func (watcher *AbstractWatcher) RegisterReceiptLogPlugin(plugin plugin.IReceiptLogPlugin) {
	watcher.ReceiptLogPlugins = append(watcher.ReceiptLogPlugins, plugin)
}

// start sync from latest block
func (watcher *AbstractWatcher) RunTillExit() error {
	return watcher.RunTillExitFromBlock(0)
}

// start sync from given block
// 0 means start from latest block
func (watcher *AbstractWatcher) RunTillExitFromBlock(startBlockNum uint64) error {

	watcher.wg.Add(1)
	go func() {
		for block := range watcher.NewBlockChan {
			// run thru block plugins
			for i := 0; i < len(watcher.BlockPlugins); i++ {
				blockPlugin := watcher.BlockPlugins[i]

				blockPlugin.AcceptBlock(block)
			}

			// run thru tx plugins
			txPlugins := watcher.TxPlugins
			for i := 0; i < len(txPlugins); i++ {
				txPlugin := txPlugins[i]

				for j := 0; j < len(block.GetTransactions()); j++ {
					tx := structs.NewRemovableTx(block.GetTransactions()[j], false)
					txPlugin.AcceptTx(tx)
				}
			}
		}

		watcher.wg.Done()
	}()

	watcher.wg.Add(1)
	go func() {
		for removableTxAndReceipt := range watcher.NewTxAndReceiptChan {

			txReceiptPlugins := watcher.TxReceiptPlugins
			for i := 0; i < len(txReceiptPlugins); i++ {
				txReceiptPlugin := txReceiptPlugins[i]

				if p, ok := txReceiptPlugin.(*plugin.TxReceiptPluginWithFilter); ok {
					// for filter plugin, only feed receipt it wants
					if p.NeedReceipt(removableTxAndReceipt.Tx) {
						txReceiptPlugin.Accept(removableTxAndReceipt)
					}
				} else {
					txReceiptPlugin.Accept(removableTxAndReceipt)
				}
			}
		}

		watcher.wg.Done()
	}()

	watcher.wg.Add(1)
	go func() {
		for removableReceiptLog := range watcher.NewReceiptLogChan {
			logrus.Debugf("get receipt log from chan: %+v, txHash: %s", removableReceiptLog, removableReceiptLog.IReceiptLog.GetTransactionHash())

			receiptLogsPlugins := watcher.ReceiptLogPlugins
			for i := 0; i < len(receiptLogsPlugins); i++ {
				p := receiptLogsPlugins[i]

				if p.NeedReceiptLog(removableReceiptLog) {
					logrus.Debugln("receipt log accepted")
					p.Accept(removableReceiptLog)
				} else {
					logrus.Debugln("receipt log not accepted")
				}
			}
		}

		watcher.wg.Done()
	}()

	for {
		latestBlockNum, err := watcher.rpc.GetCurrentBlockNum()
		if err != nil {
			return err
		}

		if startBlockNum <= 0 {
			startBlockNum = latestBlockNum
		}

		noNewBlockForSync := watcher.LatestSyncedBlockNum() >= latestBlockNum
		logrus.Debugln("watcher.LatestSyncedBlockNum()", watcher.LatestSyncedBlockNum())

		if noNewBlockForSync {
			logrus.Debugf("no new block to sync, sleep for %d secs", watcher.sleepSecondsForNewBlock)

			// sleep for 3 secs
			select {
			case <-watcher.Ctx.Done():
				closeWatcher(watcher)
				return nil
			case <-time.After(time.Duration(watcher.sleepSecondsForNewBlock) * time.Second):
				continue
			}
		}

		for watcher.LatestSyncedBlockNum() < latestBlockNum {
			select {
			case <-watcher.Ctx.Done():
				logrus.Info("watcher context down, closing channels to exit...")
				closeWatcher(watcher)
				logrus.Info("watcher done!")

				return nil
			default:
				var newBlockNumToSync uint64
				if watcher.LatestSyncedBlockNum() <= 0 {
					newBlockNumToSync = startBlockNum
				} else {
					newBlockNumToSync = watcher.LatestSyncedBlockNum() + 1
				}

				logrus.Debugln("newBlockNumToSync:", newBlockNumToSync)

				newBlock, err := watcher.rpc.GetBlockByNum(newBlockNumToSync)
				if err != nil {
					return err
				}

				if newBlock == nil {
					msg := fmt.Sprintf("GetBlockByNum(%d) returns nil block", newBlockNumToSync)
					return errors.New(msg)
				}

				if watcher.FoundFork(newBlock) {
					logrus.Infoln("found fork, popping")
					err = watcher.popBlocksUntilReachMainChain()
				} else {
					logrus.Debugln("adding new block:", newBlock.Number())
					err = watcher.addNewBlock(structs.NewRemovableBlock(newBlock, false), latestBlockNum)
				}

				if err != nil {
					return err
				}
			}
		}
	}
}

func closeWatcher(w *AbstractWatcher) {
	close(w.NewBlockChan)
	close(w.NewTxAndReceiptChan)
	close(w.NewReceiptLogChan)

	w.wg.Wait()
}

func (watcher *AbstractWatcher) SetSleepSecondsForNewBlock(sec int) {
	watcher.sleepSecondsForNewBlock = sec
}

func (watcher *AbstractWatcher) LatestSyncedBlockNum() uint64 {
	watcher.lock.RLock()
	defer watcher.lock.RUnlock()

	if watcher.SyncedBlocks.Len() <= 0 {
		return 0
	}

	b := watcher.SyncedBlocks.Back().Value.(blockchain.Block)

	return b.Number()
}

// go thru plugins to check if this watcher need fetch receipt for tx
// network load for fetching receipts per tx is heavy,
// we use this method to make sure we only do the work we need
func (watcher *AbstractWatcher) needReceipt(tx blockchain.Transaction) bool {
	plugins := watcher.TxReceiptPlugins

	for _, p := range plugins {
		if filterPlugin, ok := p.(plugin.TxReceiptPluginWithFilter); ok {
			if filterPlugin.NeedReceipt(tx) {
				return true
			}
		} else {
			// exist global tx-receipt listener
			return true
		}
	}

	return false
}

// return query map: contractAddress -> interested 1stTopics
func (watcher *AbstractWatcher) getReceiptLogQueryMap() (queryMap map[string][]string) {
	queryMap = make(map[string][]string, 16)

	for _, p := range watcher.ReceiptLogPlugins {
		key := p.FromContract()

		if v, exist := queryMap[key]; exist {
			queryMap[key] = append(v, p.InterestedTopics()...)
		} else {
			queryMap[key] = p.InterestedTopics()
		}
	}

	return
}

func (watcher *AbstractWatcher) addNewBlock(block *structs.RemovableBlock, curHighestBlockNum uint64) error {
	watcher.lock.Lock()
	defer watcher.lock.Unlock()

	// get tx receipts in block, which is time consuming
	signals := make([]*SyncSignal, 0, len(block.GetTransactions()))
	for i := 0; i < len(block.GetTransactions()); i++ {
		tx := block.GetTransactions()[i]

		if !watcher.needReceipt(tx) {
			//logrus.Debugf("no need to get receipt of tx(%s), skipped", tx.GetHash())
			continue
		} else {
			logrus.Debugf("needReceipt of tx: %s in block: %d", tx.GetHash(), block.Number())
		}

		syncSigName := fmt.Sprintf("B:%d T:%s", block.Number(), tx.GetHash())

		sig := newSyncSignal(syncSigName)
		signals = append(signals, sig)

		go func() {
			txReceipt, err := watcher.rpc.GetTransactionReceipt(tx.GetHash())

			if err != nil {
				fmt.Printf("GetTransactionReceipt fail, err: %s", err)
				sig.err = err

				// one fails all
				return
			}

			sig.WaitPermission()

			sig.rst = structs.NewRemovableTxAndReceipt(tx, txReceipt, false, block.Timestamp())

			sig.Done()
		}()
	}

	for i := 0; i < len(signals); i++ {
		sig := signals[i]
		sig.Permit()
		sig.WaitDone()

		if sig.err != nil {
			return sig.err
		}
	}

	for i := 0; i < len(signals); i++ {
		watcher.SyncedTxAndReceipts.PushBack(signals[i].rst.TxAndReceipt)
		watcher.NewTxAndReceiptChan <- signals[i].rst
	}

	queryMap := watcher.getReceiptLogQueryMap()
	logrus.Debugln("getReceiptLogQueryMap:", queryMap)

	bigStep := uint64(50)
	if curHighestBlockNum-block.Number() > bigStep {
		// only do request with bigStep
		if watcher.ReceiptCatchUpFromBlock == 0 {
			// init
			logrus.Debugf("bigStep, init to %d", block.Number())
			watcher.ReceiptCatchUpFromBlock = block.Number()
		} else {
			// check if we need do requests
			if (block.Number() - watcher.ReceiptCatchUpFromBlock + 1) == bigStep {
				fromBlock := watcher.ReceiptCatchUpFromBlock
				toBlock := block.Number()

				logrus.Debugf("bigStep, doing request, range: %d -> %d (minus: %d)", fromBlock, toBlock, block.Number()-watcher.ReceiptCatchUpFromBlock)

				for k, v := range queryMap {
					err := watcher.fetchReceiptLogs(false, block, fromBlock, toBlock, k, v)
					if err != nil {
						return err
					}
				}

				// update catch up block
				watcher.ReceiptCatchUpFromBlock = block.Number() + 1
			} else {
				logrus.Debugf("bigStep, holding %d blocks: %d -> %d", block.Number()-watcher.ReceiptCatchUpFromBlock+1, watcher.ReceiptCatchUpFromBlock, block.Number())
			}
		}
	} else {
		// reset
		if watcher.ReceiptCatchUpFromBlock != 0 {
			logrus.Debugf("exit bigStep mode, ReceiptCatchUpFromBlock: %d, curBlock: %d, gap: %d", watcher.ReceiptCatchUpFromBlock, block.Number(), curHighestBlockNum-block.Number())
			watcher.ReceiptCatchUpFromBlock = 0
		}

		for k, v := range queryMap {
			err := watcher.fetchReceiptLogs(block.IsRemoved, block, block.Number(), block.Number(), k, v)
			if err != nil {
				return err
			}
		}
	}

	// clean synced data
	for watcher.SyncedBlocks.Len() >= watcher.MaxSyncedBlockToKeep {
		// clean block
		b := watcher.SyncedBlocks.Remove(watcher.SyncedBlocks.Front()).(blockchain.Block)

		// clean txAndReceipt
		for watcher.SyncedTxAndReceipts.Front() != nil {
			head := watcher.SyncedTxAndReceipts.Front()

			if head.Value.(*structs.TxAndReceipt).Tx.GetBlockNumber() <= b.Number() {
				watcher.SyncedTxAndReceipts.Remove(head)
			} else {
				break
			}
		}
	}

	// block
	watcher.SyncedBlocks.PushBack(block.Block)
	watcher.NewBlockChan <- block

	return nil
}

func (watcher *AbstractWatcher) fetchReceiptLogs(isRemoved bool, block blockchain.Block, from, to uint64, address string, topics []string) error {

	receiptLogs, err := watcher.rpc.GetLogs(from, to, address, topics)
	if err != nil {
		return err
	}

	for i := 0; i < len(receiptLogs); i++ {
		log := receiptLogs[i]
		logrus.Debugln("insert into chan: ", log.GetTransactionHash())

		watcher.NewReceiptLogChan <- &structs.RemovableReceiptLog{
			IReceiptLog: log,
			IsRemoved:   isRemoved,
		}
	}

	return nil
}

type SyncSignal struct {
	name       string
	permission chan bool
	jobDone    chan bool
	rst        *structs.RemovableTxAndReceipt
	err        error
}

func newSyncSignal(name string) *SyncSignal {
	return &SyncSignal{
		name:       name,
		permission: make(chan bool, 1),
		jobDone:    make(chan bool, 1),
	}
}

func (s *SyncSignal) Permit() {
	s.permission <- true
}

func (s *SyncSignal) WaitPermission() {
	<-s.permission
}

func (s *SyncSignal) Done() {
	s.jobDone <- true
}

func (s *SyncSignal) WaitDone() {
	<-s.jobDone
}

func (watcher *AbstractWatcher) popBlocksUntilReachMainChain() error {
	watcher.lock.Lock()
	defer watcher.lock.Unlock()

	for {
		if watcher.SyncedBlocks.Back() == nil {
			return nil
		}

		// NOTE: instead of watcher.LatestSyncedBlockNum() cuz it has lock
		lastSyncedBlock := watcher.SyncedBlocks.Back().Value.(blockchain.Block)
		block, err := watcher.rpc.GetBlockByNum(lastSyncedBlock.Number())
		if err != nil {
			return err
		}

		if block.Hash() != lastSyncedBlock.Hash() {
			fmt.Println("removing tail block:", watcher.SyncedBlocks.Back())
			removedBlock := watcher.SyncedBlocks.Remove(watcher.SyncedBlocks.Back()).(blockchain.Block)

			for watcher.SyncedTxAndReceipts.Back() != nil {

				tail := watcher.SyncedTxAndReceipts.Back()

				if tail.Value.(*structs.TxAndReceipt).Tx.GetBlockNumber() >= removedBlock.Number() {
					fmt.Printf("removing tail txAndReceipt: %+v", tail.Value)
					tuple := watcher.SyncedTxAndReceipts.Remove(tail).(*structs.TxAndReceipt)

					watcher.NewTxAndReceiptChan <- structs.NewRemovableTxAndReceipt(tuple.Tx, tuple.Receipt, true, block.Timestamp())
				} else {
					fmt.Printf("all txAndReceipts removed for block: %+v", removedBlock)
					break
				}
			}

			watcher.NewBlockChan <- structs.NewRemovableBlock(removedBlock, true)
		} else {
			return nil
		}
	}
}

func (watcher *AbstractWatcher) FoundFork(newBlock blockchain.Block) bool {
	for e := watcher.SyncedBlocks.Back(); e != nil; e = e.Prev() {
		syncedBlock := e.Value.(blockchain.Block)

		//if syncedBlock == nil {
		//	logrus.Warnln("error, syncedBlock is nil")
		//}
		//logrus.Debugf("syncedBlock: %+v", syncedBlock)

		//if newBlock == nil {
		//	logrus.Warnln("error, newBlock is nil")
		//}
		//logrus.Debugf("newBlock: %+v", newBlock)

		if syncedBlock.Number()+1 == newBlock.Number() {
			notMatch := (syncedBlock).Hash() != newBlock.ParentHash()

			if notMatch {
				fmt.Printf("found fork, new block(%d): %s, new block's parent: %s, parent we synced: %s",
					newBlock.Number(), newBlock.Hash(), newBlock.ParentHash(), syncedBlock.Hash())

				return true
			}
		}
	}

	return false
}