How to use Nil method of td Package

Best Go-testdeep code snippet using td.Nil

fetcher.go

Source:fetcher.go

1// Copyright 2016 The go-ethereum Authors2// This file is part of the go-ethereum library.3//4// The go-ethereum library is free software: you can redistribute it and/or modify5// it under the terms of the GNU Lesser General Public License as published by6// the Free Software Foundation, either version 3 of the License, or7// (at your option) any later version.8//9// The go-ethereum library is distributed in the hope that it will be useful,10// but WITHOUT ANY WARRANTY; without even the implied warranty of11// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the12// GNU Lesser General Public License for more details.13//14// You should have received a copy of the GNU Lesser General Public License15// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.16// Package les implements the Light Ethereum Subprotocol.17package les18import (19	"math/big"20	"sync"21	"time"22	"github.com/ethereum/go-ethereum/common"23	"github.com/ethereum/go-ethereum/common/mclock"24	"github.com/ethereum/go-ethereum/consensus"25	"github.com/ethereum/go-ethereum/core/rawdb"26	"github.com/ethereum/go-ethereum/core/types"27	"github.com/ethereum/go-ethereum/light"28	"github.com/ethereum/go-ethereum/log"29)30const (31	blockDelayTimeout    = time.Second * 10 // timeout for a peer to announce a head that has already been confirmed by others32	maxNodeCount         = 20               // maximum number of fetcherTreeNode entries remembered for each peer33	serverStateAvailable = 100              // number of recent blocks where state availability is assumed34)35// lightFetcher implements retrieval of newly announced headers. It also provides a peerHasBlock function for the36// ODR system to ensure that we only request data related to a certain block from peers who have already processed37// and announced that block.38type lightFetcher struct {39	pm    *ProtocolManager40	odr   *LesOdr41	chain *light.LightChain42	lock            sync.Mutex // lock protects access to the fetcher's internal state variables except sent requests43	maxConfirmedTd  *big.Int44	peers           map[*peer]*fetcherPeerInfo45	lastUpdateStats *updateStatsEntry46	syncing         bool47	syncDone        chan *peer48	reqMu      sync.RWMutex // reqMu protects access to sent header fetch requests49	requested  map[uint64]fetchRequest50	deliverChn chan fetchResponse51	timeoutChn chan uint6452	requestChn chan bool // true if initiated from outside53}54// fetcherPeerInfo holds fetcher-specific information about each active peer55type fetcherPeerInfo struct {56	root, lastAnnounced *fetcherTreeNode57	nodeCnt             int58	confirmedTd         *big.Int59	bestConfirmed       *fetcherTreeNode60	nodeByHash          map[common.Hash]*fetcherTreeNode61	firstUpdateStats    *updateStatsEntry62}63// fetcherTreeNode is a node of a tree that holds information about blocks recently64// announced and confirmed by a certain peer. Each new announce message from a peer65// adds nodes to the tree, based on the previous announced head and the reorg depth.66// There are three possible states for a tree node:67// - announced: not downloaded (known) yet, but we know its head, number and td68// - intermediate: not known, hash and td are empty, they are filled out when it becomes known69// - known: both announced by this peer and downloaded (from any peer).70// This structure makes it possible to always know which peer has a certain block,71// which is necessary for selecting a suitable peer for ODR requests and also for72// canonizing new heads. It also helps to always download the minimum necessary73// amount of headers with a single request.74type fetcherTreeNode struct {75	hash             common.Hash76	number           uint6477	td               *big.Int78	known, requested bool79	parent           *fetcherTreeNode80	children         []*fetcherTreeNode81}82// fetchRequest represents a header download request83type fetchRequest struct {84	hash    common.Hash85	amount  uint6486	peer    *peer87	sent    mclock.AbsTime88	timeout bool89}90// fetchResponse represents a header download response91type fetchResponse struct {92	reqID   uint6493	headers []*types.Header94	peer    *peer95}96// newLightFetcher creates a new light fetcher97func newLightFetcher(pm *ProtocolManager) *lightFetcher {98	f := &lightFetcher{99		pm:             pm,100		chain:          pm.blockchain.(*light.LightChain),101		odr:            pm.odr,102		peers:          make(map[*peer]*fetcherPeerInfo),103		deliverChn:     make(chan fetchResponse, 100),104		requested:      make(map[uint64]fetchRequest),105		timeoutChn:     make(chan uint64),106		requestChn:     make(chan bool, 100),107		syncDone:       make(chan *peer),108		maxConfirmedTd: big.NewInt(0),109	}110	pm.peers.notify(f)111	f.pm.wg.Add(1)112	go f.syncLoop()113	return f114}115// syncLoop is the main event loop of the light fetcher116func (f *lightFetcher) syncLoop() {117	requesting := false118	defer f.pm.wg.Done()119	for {120		select {121		case <-f.pm.quitSync:122			return123		// when a new announce is received, request loop keeps running until124		// no further requests are necessary or possible125		case newAnnounce := <-f.requestChn:126			f.lock.Lock()127			s := requesting128			requesting = false129			var (130				rq      *distReq131				reqID   uint64132				syncing bool133			)134			if !f.syncing && !(newAnnounce && s) {135				rq, reqID, syncing = f.nextRequest()136			}137			f.lock.Unlock()138			if rq != nil {139				requesting = true140				if _, ok := <-f.pm.reqDist.queue(rq); ok {141					if syncing {142						f.lock.Lock()143						f.syncing = true144						f.lock.Unlock()145					} else {146						go func() {147							time.Sleep(softRequestTimeout)148							f.reqMu.Lock()149							req, ok := f.requested[reqID]150							if ok {151								req.timeout = true152								f.requested[reqID] = req153							}154							f.reqMu.Unlock()155							// keep starting new requests while possible156							f.requestChn <- false157						}()158					}159				} else {160					f.requestChn <- false161				}162			}163		case reqID := <-f.timeoutChn:164			f.reqMu.Lock()165			req, ok := f.requested[reqID]166			if ok {167				delete(f.requested, reqID)168			}169			f.reqMu.Unlock()170			if ok {171				f.pm.serverPool.adjustResponseTime(req.peer.poolEntry, time.Duration(mclock.Now()-req.sent), true)172				req.peer.Log().Debug("Fetching data timed out hard")173				go f.pm.removePeer(req.peer.id)174			}175		case resp := <-f.deliverChn:176			f.reqMu.Lock()177			req, ok := f.requested[resp.reqID]178			if ok && req.peer != resp.peer {179				ok = false180			}181			if ok {182				delete(f.requested, resp.reqID)183			}184			f.reqMu.Unlock()185			if ok {186				f.pm.serverPool.adjustResponseTime(req.peer.poolEntry, time.Duration(mclock.Now()-req.sent), req.timeout)187			}188			f.lock.Lock()189			if !ok || !(f.syncing || f.processResponse(req, resp)) {190				resp.peer.Log().Debug("Failed processing response")191				go f.pm.removePeer(resp.peer.id)192			}193			f.lock.Unlock()194		case p := <-f.syncDone:195			f.lock.Lock()196			p.Log().Debug("Done synchronising with peer")197			f.checkSyncedHeaders(p)198			f.syncing = false199			f.lock.Unlock()200			f.requestChn <- false201		}202	}203}204// registerPeer adds a new peer to the fetcher's peer set205func (f *lightFetcher) registerPeer(p *peer) {206	p.lock.Lock()207	p.hasBlock = func(hash common.Hash, number uint64, hasState bool) bool {208		return f.peerHasBlock(p, hash, number, hasState)209	}210	p.lock.Unlock()211	f.lock.Lock()212	defer f.lock.Unlock()213	f.peers[p] = &fetcherPeerInfo{nodeByHash: make(map[common.Hash]*fetcherTreeNode)}214}215// unregisterPeer removes a new peer from the fetcher's peer set216func (f *lightFetcher) unregisterPeer(p *peer) {217	p.lock.Lock()218	p.hasBlock = nil219	p.lock.Unlock()220	f.lock.Lock()221	defer f.lock.Unlock()222	// check for potential timed out block delay statistics223	f.checkUpdateStats(p, nil)224	delete(f.peers, p)225}226// announce processes a new announcement message received from a peer, adding new227// nodes to the peer's block tree and removing old nodes if necessary228func (f *lightFetcher) announce(p *peer, head *announceData) {229	f.lock.Lock()230	defer f.lock.Unlock()231	p.Log().Debug("Received new announcement", "number", head.Number, "hash", head.Hash, "reorg", head.ReorgDepth)232	fp := f.peers[p]233	if fp == nil {234		p.Log().Debug("Announcement from unknown peer")235		return236	}237	if fp.lastAnnounced != nil && head.Td.Cmp(fp.lastAnnounced.td) <= 0 {238		// announced tds should be strictly monotonic239		p.Log().Debug("Received non-monotonic td", "current", head.Td, "previous", fp.lastAnnounced.td)240		go f.pm.removePeer(p.id)241		return242	}243	n := fp.lastAnnounced244	for i := uint64(0); i < head.ReorgDepth; i++ {245		if n == nil {246			break247		}248		n = n.parent249	}250	// n is now the reorg common ancestor, add a new branch of nodes251	if n != nil && (head.Number >= n.number+maxNodeCount || head.Number <= n.number) {252		// if announced head block height is lower or same as n or too far from it to add253		// intermediate nodes then discard previous announcement info and trigger a resync254		n = nil255		fp.nodeCnt = 0256		fp.nodeByHash = make(map[common.Hash]*fetcherTreeNode)257	}258	if n != nil {259		// check if the node count is too high to add new nodes, discard oldest ones if necessary260		locked := false261		for uint64(fp.nodeCnt)+head.Number-n.number > maxNodeCount && fp.root != nil {262			if !locked {263				f.chain.LockChain()264				defer f.chain.UnlockChain()265				locked = true266			}267			// if one of root's children is canonical, keep it, delete other branches and root itself268			var newRoot *fetcherTreeNode269			for i, nn := range fp.root.children {270				if rawdb.ReadCanonicalHash(f.pm.chainDb, nn.number) == nn.hash {271					fp.root.children = append(fp.root.children[:i], fp.root.children[i+1:]...)272					nn.parent = nil273					newRoot = nn274					break275				}276			}277			fp.deleteNode(fp.root)278			if n == fp.root {279				n = newRoot280			}281			fp.root = newRoot282			if newRoot == nil || !f.checkKnownNode(p, newRoot) {283				fp.bestConfirmed = nil284				fp.confirmedTd = nil285			}286			if n == nil {287				break288			}289		}290		if n != nil {291			for n.number < head.Number {292				nn := &fetcherTreeNode{number: n.number + 1, parent: n}293				n.children = append(n.children, nn)294				n = nn295				fp.nodeCnt++296			}297			n.hash = head.Hash298			n.td = head.Td299			fp.nodeByHash[n.hash] = n300		}301	}302	if n == nil {303		// could not find reorg common ancestor or had to delete entire tree, a new root and a resync is needed304		if fp.root != nil {305			fp.deleteNode(fp.root)306		}307		n = &fetcherTreeNode{hash: head.Hash, number: head.Number, td: head.Td}308		fp.root = n309		fp.nodeCnt++310		fp.nodeByHash[n.hash] = n311		fp.bestConfirmed = nil312		fp.confirmedTd = nil313	}314	f.checkKnownNode(p, n)315	p.lock.Lock()316	p.headInfo = head317	fp.lastAnnounced = n318	p.lock.Unlock()319	f.checkUpdateStats(p, nil)320	f.requestChn <- true321}322// peerHasBlock returns true if we can assume the peer knows the given block323// based on its announcements324func (f *lightFetcher) peerHasBlock(p *peer, hash common.Hash, number uint64, hasState bool) bool {325	f.lock.Lock()326	defer f.lock.Unlock()327	fp := f.peers[p]328	if fp == nil || fp.root == nil {329		return false330	}331	if hasState {332		if fp.lastAnnounced == nil || fp.lastAnnounced.number > number+serverStateAvailable {333			return false334		}335	}336	if f.syncing {337		// always return true when syncing338		// false positives are acceptable, a more sophisticated condition can be implemented later339		return true340	}341	if number >= fp.root.number {342		// it is recent enough that if it is known, is should be in the peer's block tree343		return fp.nodeByHash[hash] != nil344	}345	f.chain.LockChain()346	defer f.chain.UnlockChain()347	// if it's older than the peer's block tree root but it's in the same canonical chain348	// as the root, we can still be sure the peer knows it349	//350	// when syncing, just check if it is part of the known chain, there is nothing better we351	// can do since we do not know the most recent block hash yet352	return rawdb.ReadCanonicalHash(f.pm.chainDb, fp.root.number) == fp.root.hash && rawdb.ReadCanonicalHash(f.pm.chainDb, number) == hash353}354// requestAmount calculates the amount of headers to be downloaded starting355// from a certain head backwards356func (f *lightFetcher) requestAmount(p *peer, n *fetcherTreeNode) uint64 {357	amount := uint64(0)358	nn := n359	for nn != nil && !f.checkKnownNode(p, nn) {360		nn = nn.parent361		amount++362	}363	if nn == nil {364		amount = n.number365	}366	return amount367}368// requestedID tells if a certain reqID has been requested by the fetcher369func (f *lightFetcher) requestedID(reqID uint64) bool {370	f.reqMu.RLock()371	_, ok := f.requested[reqID]372	f.reqMu.RUnlock()373	return ok374}375// nextRequest selects the peer and announced head to be requested next, amount376// to be downloaded starting from the head backwards is also returned377func (f *lightFetcher) nextRequest() (*distReq, uint64, bool) {378	var (379		bestHash   common.Hash380		bestAmount uint64381	)382	bestTd := f.maxConfirmedTd383	bestSyncing := false384	for p, fp := range f.peers {385		for hash, n := range fp.nodeByHash {386			if !f.checkKnownNode(p, n) && !n.requested && (bestTd == nil || n.td.Cmp(bestTd) >= 0) {387				amount := f.requestAmount(p, n)388				if bestTd == nil || n.td.Cmp(bestTd) > 0 || amount < bestAmount {389					bestHash = hash390					bestAmount = amount391					bestTd = n.td392					bestSyncing = fp.bestConfirmed == nil || fp.root == nil || !f.checkKnownNode(p, fp.root)393				}394			}395		}396	}397	if bestTd == f.maxConfirmedTd {398		return nil, 0, false399	}400	var rq *distReq401	reqID := genReqID()402	if bestSyncing {403		rq = &distReq{404			getCost: func(dp distPeer) uint64 {405				return 0406			},407			canSend: func(dp distPeer) bool {408				p := dp.(*peer)409				f.lock.Lock()410				defer f.lock.Unlock()411				fp := f.peers[p]412				return fp != nil && fp.nodeByHash[bestHash] != nil413			},414			request: func(dp distPeer) func() {415				go func() {416					p := dp.(*peer)417					p.Log().Debug("Synchronisation started")418					f.pm.synchronise(p)419					f.syncDone <- p420				}()421				return nil422			},423		}424	} else {425		rq = &distReq{426			getCost: func(dp distPeer) uint64 {427				p := dp.(*peer)428				return p.GetRequestCost(GetBlockHeadersMsg, int(bestAmount))429			},430			canSend: func(dp distPeer) bool {431				p := dp.(*peer)432				f.lock.Lock()433				defer f.lock.Unlock()434				fp := f.peers[p]435				if fp == nil {436					return false437				}438				n := fp.nodeByHash[bestHash]439				return n != nil && !n.requested440			},441			request: func(dp distPeer) func() {442				p := dp.(*peer)443				f.lock.Lock()444				fp := f.peers[p]445				if fp != nil {446					n := fp.nodeByHash[bestHash]447					if n != nil {448						n.requested = true449					}450				}451				f.lock.Unlock()452				cost := p.GetRequestCost(GetBlockHeadersMsg, int(bestAmount))453				p.fcServer.QueueRequest(reqID, cost)454				f.reqMu.Lock()455				f.requested[reqID] = fetchRequest{hash: bestHash, amount: bestAmount, peer: p, sent: mclock.Now()}456				f.reqMu.Unlock()457				go func() {458					time.Sleep(hardRequestTimeout)459					f.timeoutChn <- reqID460				}()461				return func() { p.RequestHeadersByHash(reqID, cost, bestHash, int(bestAmount), 0, true) }462			},463		}464	}465	return rq, reqID, bestSyncing466}467// deliverHeaders delivers header download request responses for processing468func (f *lightFetcher) deliverHeaders(peer *peer, reqID uint64, headers []*types.Header) {469	f.deliverChn <- fetchResponse{reqID: reqID, headers: headers, peer: peer}470}471// processResponse processes header download request responses, returns true if successful472func (f *lightFetcher) processResponse(req fetchRequest, resp fetchResponse) bool {473	if uint64(len(resp.headers)) != req.amount || resp.headers[0].Hash() != req.hash {474		req.peer.Log().Debug("Response content mismatch", "requested", len(resp.headers), "reqfrom", resp.headers[0], "delivered", req.amount, "delfrom", req.hash)475		return false476	}477	headers := make([]*types.Header, req.amount)478	for i, header := range resp.headers {479		headers[int(req.amount)-1-i] = header480	}481	if _, err := f.chain.InsertHeaderChain(headers, 1); err != nil {482		if err == consensus.ErrFutureBlock {483			return true484		}485		log.Debug("Failed to insert header chain", "err", err)486		return false487	}488	tds := make([]*big.Int, len(headers))489	for i, header := range headers {490		td := f.chain.GetTd(header.Hash(), header.Number.Uint64())491		if td == nil {492			log.Debug("Total difficulty not found for header", "index", i+1, "number", header.Number, "hash", header.Hash())493			return false494		}495		tds[i] = td496	}497	f.newHeaders(headers, tds)498	return true499}500// newHeaders updates the block trees of all active peers according to a newly501// downloaded and validated batch or headers502func (f *lightFetcher) newHeaders(headers []*types.Header, tds []*big.Int) {503	var maxTd *big.Int504	for p, fp := range f.peers {505		if !f.checkAnnouncedHeaders(fp, headers, tds) {506			p.Log().Debug("Inconsistent announcement")507			go f.pm.removePeer(p.id)508		}509		if fp.confirmedTd != nil && (maxTd == nil || maxTd.Cmp(fp.confirmedTd) > 0) {510			maxTd = fp.confirmedTd511		}512	}513	if maxTd != nil {514		f.updateMaxConfirmedTd(maxTd)515	}516}517// checkAnnouncedHeaders updates peer's block tree if necessary after validating518// a batch of headers. It searches for the latest header in the batch that has a519// matching tree node (if any), and if it has not been marked as known already,520// sets it and its parents to known (even those which are older than the currently521// validated ones). Return value shows if all hashes, numbers and Tds matched522// correctly to the announced values (otherwise the peer should be dropped).523func (f *lightFetcher) checkAnnouncedHeaders(fp *fetcherPeerInfo, headers []*types.Header, tds []*big.Int) bool {524	var (525		n      *fetcherTreeNode526		header *types.Header527		td     *big.Int528	)529	for i := len(headers) - 1; ; i-- {530		if i < 0 {531			if n == nil {532				// no more headers and nothing to match533				return true534			}535			// we ran out of recently delivered headers but have not reached a node known by this peer yet, continue matching536			hash, number := header.ParentHash, header.Number.Uint64()-1537			td = f.chain.GetTd(hash, number)538			header = f.chain.GetHeader(hash, number)539			if header == nil || td == nil {540				log.Error("Missing parent of validated header", "hash", hash, "number", number)541				return false542			}543		} else {544			header = headers[i]545			td = tds[i]546		}547		hash := header.Hash()548		number := header.Number.Uint64()549		if n == nil {550			n = fp.nodeByHash[hash]551		}552		if n != nil {553			if n.td == nil {554				// node was unannounced555				if nn := fp.nodeByHash[hash]; nn != nil {556					// if there was already a node with the same hash, continue there and drop this one557					nn.children = append(nn.children, n.children...)558					n.children = nil559					fp.deleteNode(n)560					n = nn561				} else {562					n.hash = hash563					n.td = td564					fp.nodeByHash[hash] = n565				}566			}567			// check if it matches the header568			if n.hash != hash || n.number != number || n.td.Cmp(td) != 0 {569				// peer has previously made an invalid announcement570				return false571			}572			if n.known {573				// we reached a known node that matched our expectations, return with success574				return true575			}576			n.known = true577			if fp.confirmedTd == nil || td.Cmp(fp.confirmedTd) > 0 {578				fp.confirmedTd = td579				fp.bestConfirmed = n580			}581			n = n.parent582			if n == nil {583				return true584			}585		}586	}587}588// checkSyncedHeaders updates peer's block tree after synchronisation by marking589// downloaded headers as known. If none of the announced headers are found after590// syncing, the peer is dropped.591func (f *lightFetcher) checkSyncedHeaders(p *peer) {592	fp := f.peers[p]593	if fp == nil {594		p.Log().Debug("Unknown peer to check sync headers")595		return596	}597	n := fp.lastAnnounced598	var td *big.Int599	for n != nil {600		if td = f.chain.GetTd(n.hash, n.number); td != nil {601			break602		}603		n = n.parent604	}605	// now n is the latest downloaded header after syncing606	if n == nil {607		p.Log().Debug("Synchronisation failed")608		go f.pm.removePeer(p.id)609	} else {610		header := f.chain.GetHeader(n.hash, n.number)611		f.newHeaders([]*types.Header{header}, []*big.Int{td})612	}613}614// checkKnownNode checks if a block tree node is known (downloaded and validated)615// If it was not known previously but found in the database, sets its known flag616func (f *lightFetcher) checkKnownNode(p *peer, n *fetcherTreeNode) bool {617	if n.known {618		return true619	}620	td := f.chain.GetTd(n.hash, n.number)621	if td == nil {622		return false623	}624	header := f.chain.GetHeader(n.hash, n.number)625	// check the availability of both header and td because reads are not protected by chain db mutex626	// Note: returning false is always safe here627	if header == nil {628		return false629	}630	fp := f.peers[p]631	if fp == nil {632		p.Log().Debug("Unknown peer to check known nodes")633		return false634	}635	if !f.checkAnnouncedHeaders(fp, []*types.Header{header}, []*big.Int{td}) {636		p.Log().Debug("Inconsistent announcement")637		go f.pm.removePeer(p.id)638	}639	if fp.confirmedTd != nil {640		f.updateMaxConfirmedTd(fp.confirmedTd)641	}642	return n.known643}644// deleteNode deletes a node and its child subtrees from a peer's block tree645func (fp *fetcherPeerInfo) deleteNode(n *fetcherTreeNode) {646	if n.parent != nil {647		for i, nn := range n.parent.children {648			if nn == n {649				n.parent.children = append(n.parent.children[:i], n.parent.children[i+1:]...)650				break651			}652		}653	}654	for {655		if n.td != nil {656			delete(fp.nodeByHash, n.hash)657		}658		fp.nodeCnt--659		if len(n.children) == 0 {660			return661		}662		for i, nn := range n.children {663			if i == 0 {664				n = nn665			} else {666				fp.deleteNode(nn)667			}668		}669	}670}671// updateStatsEntry items form a linked list that is expanded with a new item every time a new head with a higher Td672// than the previous one has been downloaded and validated. The list contains a series of maximum confirmed Td values673// and the time these values have been confirmed, both increasing monotonically. A maximum confirmed Td is calculated674// both globally for all peers and also for each individual peer (meaning that the given peer has announced the head675// and it has also been downloaded from any peer, either before or after the given announcement).676// The linked list has a global tail where new confirmed Td entries are added and a separate head for each peer,677// pointing to the next Td entry that is higher than the peer's max confirmed Td (nil if it has already confirmed678// the current global head).679type updateStatsEntry struct {680	time mclock.AbsTime681	td   *big.Int682	next *updateStatsEntry683}684// updateMaxConfirmedTd updates the block delay statistics of active peers. Whenever a new highest Td is confirmed,685// adds it to the end of a linked list together with the time it has been confirmed. Then checks which peers have686// already confirmed a head with the same or higher Td (which counts as zero block delay) and updates their statistics.687// Those who have not confirmed such a head by now will be updated by a subsequent checkUpdateStats call with a688// positive block delay value.689func (f *lightFetcher) updateMaxConfirmedTd(td *big.Int) {690	if f.maxConfirmedTd == nil || td.Cmp(f.maxConfirmedTd) > 0 {691		f.maxConfirmedTd = td692		newEntry := &updateStatsEntry{693			time: mclock.Now(),694			td:   td,695		}696		if f.lastUpdateStats != nil {697			f.lastUpdateStats.next = newEntry698		}699		f.lastUpdateStats = newEntry700		for p := range f.peers {701			f.checkUpdateStats(p, newEntry)702		}703	}704}705// checkUpdateStats checks those peers who have not confirmed a certain highest Td (or a larger one) by the time it706// has been confirmed by another peer. If they have confirmed such a head by now, their stats are updated with the707// block delay which is (this peer's confirmation time)-(first confirmation time). After blockDelayTimeout has passed,708// the stats are updated with blockDelayTimeout value. In either case, the confirmed or timed out updateStatsEntry709// items are removed from the head of the linked list.710// If a new entry has been added to the global tail, it is passed as a parameter here even though this function711// assumes that it has already been added, so that if the peer's list is empty (all heads confirmed, head is nil),712// it can set the new head to newEntry.713func (f *lightFetcher) checkUpdateStats(p *peer, newEntry *updateStatsEntry) {714	now := mclock.Now()715	fp := f.peers[p]716	if fp == nil {717		p.Log().Debug("Unknown peer to check update stats")718		return719	}720	if newEntry != nil && fp.firstUpdateStats == nil {721		fp.firstUpdateStats = newEntry722	}723	for fp.firstUpdateStats != nil && fp.firstUpdateStats.time <= now-mclock.AbsTime(blockDelayTimeout) {724		f.pm.serverPool.adjustBlockDelay(p.poolEntry, blockDelayTimeout)725		fp.firstUpdateStats = fp.firstUpdateStats.next726	}727	if fp.confirmedTd != nil {728		for fp.firstUpdateStats != nil && fp.firstUpdateStats.td.Cmp(fp.confirmedTd) <= 0 {729			f.pm.serverPool.adjustBlockDelay(p.poolEntry, time.Duration(now-fp.firstUpdateStats.time))730			fp.firstUpdateStats = fp.firstUpdateStats.next731		}732	}733}...

check.go

Source:check.go

1// +build linux2package overlay2 // import "github.com/docker/docker/daemon/graphdriver/overlay2"3import (4	"fmt"5	"io/ioutil"6	"os"7	"path"8	"path/filepath"9	"syscall"10	"github.com/docker/docker/pkg/system"11	"github.com/pkg/errors"12	"golang.org/x/sys/unix"13)14// doesSupportNativeDiff checks whether the filesystem has a bug15// which copies up the opaque flag when copying up an opaque16// directory or the kernel enable CONFIG_OVERLAY_FS_REDIRECT_DIR.17// When these exist naive diff should be used.18func doesSupportNativeDiff(d string) error {19	td, err := ioutil.TempDir(d, "opaque-bug-check")20	if err != nil {21		return err22	}23	defer func() {24		if err := os.RemoveAll(td); err != nil {25			logger.Warnf("Failed to remove check directory %v: %v", td, err)26		}27	}()28	// Make directories l1/d, l1/d1, l2/d, l3, work, merged29	if err := os.MkdirAll(filepath.Join(td, "l1", "d"), 0755); err != nil {30		return err31	}32	if err := os.MkdirAll(filepath.Join(td, "l1", "d1"), 0755); err != nil {33		return err34	}35	if err := os.MkdirAll(filepath.Join(td, "l2", "d"), 0755); err != nil {36		return err37	}38	if err := os.Mkdir(filepath.Join(td, "l3"), 0755); err != nil {39		return err40	}41	if err := os.Mkdir(filepath.Join(td, workDirName), 0755); err != nil {42		return err43	}44	if err := os.Mkdir(filepath.Join(td, mergedDirName), 0755); err != nil {45		return err46	}47	// Mark l2/d as opaque48	if err := system.Lsetxattr(filepath.Join(td, "l2", "d"), "trusted.overlay.opaque", []byte("y"), 0); err != nil {49		return errors.Wrap(err, "failed to set opaque flag on middle layer")50	}51	opts := fmt.Sprintf("lowerdir=%s:%s,upperdir=%s,workdir=%s", path.Join(td, "l2"), path.Join(td, "l1"), path.Join(td, "l3"), path.Join(td, workDirName))52	if err := unix.Mount("overlay", filepath.Join(td, mergedDirName), "overlay", 0, opts); err != nil {53		return errors.Wrap(err, "failed to mount overlay")54	}55	defer func() {56		if err := unix.Unmount(filepath.Join(td, mergedDirName), 0); err != nil {57			logger.Warnf("Failed to unmount check directory %v: %v", filepath.Join(td, mergedDirName), err)58		}59	}()60	// Touch file in d to force copy up of opaque directory "d" from "l2" to "l3"61	if err := ioutil.WriteFile(filepath.Join(td, mergedDirName, "d", "f"), []byte{}, 0644); err != nil {62		return errors.Wrap(err, "failed to write to merged directory")63	}64	// Check l3/d does not have opaque flag65	xattrOpaque, err := system.Lgetxattr(filepath.Join(td, "l3", "d"), "trusted.overlay.opaque")66	if err != nil {67		return errors.Wrap(err, "failed to read opaque flag on upper layer")68	}69	if string(xattrOpaque) == "y" {70		return errors.New("opaque flag erroneously copied up, consider update to kernel 4.8 or later to fix")71	}72	// rename "d1" to "d2"73	if err := os.Rename(filepath.Join(td, mergedDirName, "d1"), filepath.Join(td, mergedDirName, "d2")); err != nil {74		// if rename failed with syscall.EXDEV, the kernel doesn't have CONFIG_OVERLAY_FS_REDIRECT_DIR enabled75		if err.(*os.LinkError).Err == syscall.EXDEV {76			return nil77		}78		return errors.Wrap(err, "failed to rename dir in merged directory")79	}80	// get the xattr of "d2"81	xattrRedirect, err := system.Lgetxattr(filepath.Join(td, "l3", "d2"), "trusted.overlay.redirect")82	if err != nil {83		return errors.Wrap(err, "failed to read redirect flag on upper layer")84	}85	if string(xattrRedirect) == "d1" {86		return errors.New("kernel has CONFIG_OVERLAY_FS_REDIRECT_DIR enabled")87	}88	return nil89}...

Nil

Using AI Code Generation

1import "fmt"2func main() {3    if a == nil {4        fmt.Println("a is nil")5    } else {6        fmt.Println("a is not nil")7    }8}9import "fmt"10func main() {11    if a == nil {12        fmt.Println("a is nil")13    } else {14        fmt.Println("a is not nil")15    }16    a = new(int)17    if a == nil {18        fmt.Println("a is nil")19    } else {20        fmt.Println("a is not nil")21    }22}23import "fmt"24func main() {25    if a == nil {26        fmt.Println("a is nil")27    } else {28        fmt.Println("a is not nil")29    }30    a = new(int)31    if a == nil {32        fmt.Println("a is nil")33    } else {34        fmt.Println("a is not nil")35    }36    fmt.Println("value of a:", *a)37}38import "fmt"39func main() {40    if a == nil {41        fmt.Println("a is nil")42    } else {43        fmt.Println("a is not nil")44    }45    a = new(int)46    if a == nil {47        fmt.Println("a is nil")48    } else {49        fmt.Println("a is not nil")50    }51    fmt.Println("value of a:", *a)52    fmt.Println("value of a:", a)53}54import "fmt"55func main() {56    if a == nil {

Nil

Using AI Code Generation

1import (2type td struct {3}4func (v td) abs() float64 {5	return math.Sqrt(v.x*v.x + v.y*v.y)6}7func main() {8	v := td{3, 4}9	fmt.Println(v.abs())10}11import (12type td struct {13}14func (v td) abs() float64 {15	return math.Sqrt(v.x*v.x + v.y*v.y)16}17func main() {18	v := td{3, 4}19	fmt.Println(p.abs())20}21import (22type td struct {23}24func (v td) abs() float64 {25	return math.Sqrt(v.x*v.x + v.y*v.y)26}27func main() {28	v := td{3, 4}29	fmt.Println(v.abs())30}31import (32type td struct {33}34func (v td) abs() float64 {35	return math.Sqrt(v.x*v.x + v.y*v.y)36}37func main() {38	v := td{3, 4}39	fmt.Println(p.abs())40}41import (42type td struct {43}44func (v td) abs() float64 {45	return math.Sqrt(v.x*v.x + v.y*v.y)46}47func main() {48	v := td{3, 4}49	fmt.Println(p.abs())50}51import (52type td struct {53}54func (v td) abs() float64 {55	return math.Sqrt(v.x

Nil

Using AI Code Generation

1import "fmt"2type td struct {3}4func (t td) Nil() bool {5}6func main() {7    t := td{}8    fmt.Println(t.Nil())9    fmt.Println(t.Nil())10}11import "fmt"12type td struct {13}14func (t *td) Nil() bool {15}16func main() {17    t := &td{}18    fmt.Println(t.Nil())19    fmt.Println(t.Nil())20}

Nil

Using AI Code Generation

1import (2type td struct {3}4func (t td) Nil() bool {5    if t.x == 0 && t.y == 0 {6    }7}8func main() {9    t := td{1, 2}10    fmt.Println(t.Nil())11    fmt.Println(t.Nil())12}13import (14type td struct {15}16func (t td) IsZero() bool {17    if t.x == 0 && t.y == 0 {18    }19}20func main() {21    t := td{1, 2}22    fmt.Println(t.IsZero())23    fmt.Println(t.IsZero())24}25import (26type td struct {27}28func (t td) String() string {29    return fmt.Sprintf("x:%d,y:%d", t.x, t.y)30}31func main() {32    t := td{1, 2}33    fmt.Println(t.String())34}

Nil

Using AI Code Generation

1import "fmt"2type td struct {3}4func (t *td) Nil() {5}6func main() {7  t := new(td)8  fmt.Println(t)9  t.Nil()10  fmt.Println(t)11}12import "fmt"13type td struct {14}15func (t td) Nil() {16}17func main() {18  t := new(td)19  fmt.Println(t)20  t.Nil()21  fmt.Println(t)22}23import "fmt"24type td struct {25}26func (t td) Nil() {27}28func main() {29  t := td{}30  fmt.Println(t)31  t.Nil()32  fmt.Println(t)33}34import "fmt"35type td struct {36}37func (t *td) Nil() {38}39func main() {40  t := td{}41  fmt.Println(t)42  t.Nil()43  fmt.Println(t)44}45import "fmt"46type td struct {

Nil

Using AI Code Generation

1import (2func main() {3	t = td.Nil()4	fmt.Println(t)5}6import (7func main() {8	t = td.Nil()9	fmt.Println(t)10}11import (12func main() {13	t = td.Nil()14	fmt.Println(t)15}16import (17func main() {18	t = td.Nil()19	fmt.Println(t)20}21import (22func main() {23	t = td.Nil()24	fmt.Println(t)25}26import (27func main() {28	t = td.Nil()29	fmt.Println(t)30}31import (32func main() {33	t = td.Nil()34	fmt.Println(t)35}36import (37func main() {38	t = td.Nil()39	fmt.Println(t)40}41import (42func main() {43	t = td.Nil()44	fmt.Println(t)45}46import (47func main() {48	t = td.Nil()49	fmt.Println(t)50}

Nil

Using AI Code Generation

1import "fmt"2func main() {3	fmt.Println(t.Nil())4}5Golang Program to use String() method of td class6import "fmt"7func main() {8	fmt.Println(t.String())9}10Golang Program to use String() method of td class11import "fmt"12func main() {13	fmt.Println(t.String())14}15Golang Program to use String() method of td class16import "fmt"17func main() {18	fmt.Println(t.String())19}20Golang Program to use String() method of td class21import "fmt"22func main() {23	fmt.Println(t.String())24}25Golang Program to use String() method of td class26import "fmt"27func main() {28	fmt.Println(t.String())29}30Golang Program to use String() method of td class31import "fmt"32func main() {33	fmt.Println(t.String())34}35Golang Program to use String() method of td class36import "fmt"37func main() {38	fmt.Println(t.String())39}40Golang Program to use String() method of td class41import "fmt"42func main() {43	fmt.Println(t.String())44}

Automation Testing Tutorials

Learn to execute automation testing from scratch with LambdaTest Learning Hub. Right from setting up the prerequisites to run your first automation test, to following best practices and diving deeper into advanced test scenarios. LambdaTest Learning Hubs compile a list of step-by-step guides to help you be proficient with different test automation frameworks i.e. Selenium, Cypress, TestNG etc.