How to use Sync method of state Package

Best Syzkaller code snippet using state.Sync

statesync.go

Source:statesync.go

...41// timedOut returns if this request timed out.42func (req *stateReq) timedOut() bool {43	return req.response == nil44}45// stateSyncStats is a collection of progress stats to report during a state trie46// sync to RPC requests as well as to display in user logs.47type stateSyncStats struct {48	processed  uint64 // Number of state entries processed49	duplicate  uint64 // Number of state entries downloaded twice50	unexpected uint64 // Number of non-requested state entries received51	pending    uint64 // Number of still pending state entries52}53// syncState starts downloading state with the given root hash.54func (d *Downloader) syncState(root common.Hash) *stateSync {55	// Create the state sync56	s := newStateSync(d, root)57	select {58	case d.stateSyncStart <- s:59	case <-d.quitCh:60		s.err = errCancelStateFetch61		close(s.done)62	}63	return s64}65// stateFetcher manages the active state sync and accepts requests66// on its behalf.67func (d *Downloader) stateFetcher() {68	for {69		select {70		case s := <-d.stateSyncStart:71			for next := s; next != nil; {72				next = d.runStateSync(next)73			}74		case <-d.stateCh:75			// Ignore state responses while no sync is running.76		case <-d.quitCh:77			return78		}79	}80}81// runStateSync runs a state synchronisation until it completes or another root82// hash is requested to be switched over to.83func (d *Downloader) runStateSync(s *stateSync) *stateSync {84	var (85		active   = make(map[string]*stateReq) // Currently in-flight requests86		finished []*stateReq                  // Completed or failed requests87		timeout  = make(chan *stateReq)       // Timed out active requests88	)89	defer func() {90		// Cancel active request timers on exit. Also set peers to idle so they're91		// available for the next sync.92		for _, req := range active {93			req.timer.Stop()94			req.peer.SetNodeDataIdle(len(req.items))95		}96	}()97	// Run the state sync.98	go s.run()99	defer s.Cancel()100	// Listen for peer departure events to cancel assigned tasks101	peerDrop := make(chan *peerConnection, 1024)102	peerSub := s.d.peers.SubscribePeerDrops(peerDrop)103	defer peerSub.Unsubscribe()104	for {105		// Enable sending of the first buffered element if there is one.106		var (107			deliverReq   *stateReq108			deliverReqCh chan *stateReq109		)110		if len(finished) > 0 {111			deliverReq = finished[0]112			deliverReqCh = s.deliver113		}114		select {115		// The stateSync lifecycle:116		case next := <-d.stateSyncStart:117			return next118		case <-s.done:119			return nil120		// Send the next finished request to the current sync:121		case deliverReqCh <- deliverReq:122			// Shift out the first request, but also set the emptied slot to nil for GC123			copy(finished, finished[1:])124			finished[len(finished)-1] = nil125			finished = finished[:len(finished)-1]126		// Handle incoming state packs:127		case pack := <-d.stateCh:128			// Discard any data not requested (or previously timed out)129			req := active[pack.PeerId()]130			if req == nil {131				log.Debug("Unrequested node data", "peer", pack.PeerId(), "len", pack.Items())132				continue133			}134			// Finalize the request and queue up for processing135			req.timer.Stop()136			req.response = pack.(*statePack).states137			finished = append(finished, req)138			delete(active, pack.PeerId())139		// Handle dropped peer connections:140		case p := <-peerDrop:141			// Skip if no request is currently pending142			req := active[p.id]143			if req == nil {144				continue145			}146			// Finalize the request and queue up for processing147			req.timer.Stop()148			req.dropped = true149			finished = append(finished, req)150			delete(active, p.id)151		// Handle timed-out requests:152		case req := <-timeout:153			// If the peer is already requesting something else, ignore the stale timeout.154			// This can happen when the timeout and the delivery happens simultaneously,155			// causing both pathways to trigger.156			if active[req.peer.id] != req {157				continue158			}159			// Move the timed out data back into the download queue160			finished = append(finished, req)161			delete(active, req.peer.id)162		// Track outgoing state requests:163		case req := <-d.trackStateReq:164			// If an active request already exists for this peer, we have a problem. In165			// theory the trie node schedule must never assign two requests to the same166			// peer. In practice however, a peer might receive a request, disconnect and167			// immediately reconnect before the previous times out. In this case the first168			// request is never honored, alas we must not silently overwrite it, as that169			// causes valid requests to go missing and sync to get stuck.170			if old := active[req.peer.id]; old != nil {171				log.Warn("Busy peer assigned new state fetch", "peer", old.peer.id)172				// Make sure the previous one doesn't get siletly lost173				old.timer.Stop()174				old.dropped = true175				finished = append(finished, old)176			}177			// Start a timer to notify the sync loop if the peer stalled.178			req.timer = time.AfterFunc(req.timeout, func() {179				select {180				case timeout <- req:181				case <-s.done:182					// Prevent leaking of timer goroutines in the unlikely case where a183					// timer is fired just before exiting runStateSync.184				}185			})186			active[req.peer.id] = req187		}188	}189}190// stateSync schedules requests for downloading a particular state trie defined191// by a given state root.192type stateSync struct {193	d *Downloader // Downloader instance to access and manage current peerset194	sched  *trie.Sync                 // State trie sync scheduler defining the tasks195	keccak hash.Hash                  // Keccak256 hasher to verify deliveries with196	tasks  map[common.Hash]*stateTask // Set of tasks currently queued for retrieval197	numUncommitted   int198	bytesUncommitted int199	deliver    chan *stateReq // Delivery channel multiplexing peer responses200	cancel     chan struct{}  // Channel to signal a termination request201	cancelOnce sync.Once      // Ensures cancel only ever gets called once202	done       chan struct{}  // Channel to signal termination completion203	err        error          // Any error hit during sync (set before completion)204}205// stateTask represents a single trie node download task, containing a set of206// peers already attempted retrieval from to detect stalled syncs and abort.207type stateTask struct {208	attempts map[string]struct{}209}210// newStateSync creates a new state trie download scheduler. This method does not211// yet start the sync. The user needs to call run to initiate.212func newStateSync(d *Downloader, root common.Hash) *stateSync {213	return &stateSync{214		d:       d,215		sched:   state.NewStateSync(root, d.stateDB, d.stateBloom),216		keccak:  sha3.NewLegacyKeccak256(),217		tasks:   make(map[common.Hash]*stateTask),218		deliver: make(chan *stateReq),219		cancel:  make(chan struct{}),220		done:    make(chan struct{}),221	}222}223// run starts the task assignment and response processing loop, blocking until224// it finishes, and finally notifying any goroutines waiting for the loop to225// finish.226func (s *stateSync) run() {227	s.err = s.loop()228	close(s.done)229}230// Wait blocks until the sync is done or canceled.231func (s *stateSync) Wait() error {232	<-s.done233	return s.err234}235// Cancel cancels the sync and waits until it has shut down.236func (s *stateSync) Cancel() error {237	s.cancelOnce.Do(func() { close(s.cancel) })238	return s.Wait()239}240// loop is the main event loop of a state trie sync. It it responsible for the241// assignment of new tasks to peers (including sending it to them) as well as242// for the processing of inbound data. Note, that the loop does not directly243// receive data from peers, rather those are buffered up in the downloader and244// pushed here async. The reason is to decouple processing from data receipt245// and timeouts.246func (s *stateSync) loop() (err error) {247	// Listen for new peer events to assign tasks to them248	newPeer := make(chan *peerConnection, 1024)249	peerSub := s.d.peers.SubscribeNewPeers(newPeer)250	defer peerSub.Unsubscribe()251	defer func() {252		cerr := s.commit(true)253		if err == nil {254			err = cerr255		}256	}()257	// Keep assigning new tasks until the sync completes or aborts258	for s.sched.Pending() > 0 {259		if err = s.commit(false); err != nil {260			return err261		}262		s.assignTasks()263		// Tasks assigned, wait for something to happen264		select {265		case <-newPeer:266			// New peer arrived, try to assign it download tasks267		case <-s.cancel:268			return errCancelStateFetch269		case <-s.d.cancelCh:270			return errCanceled271		case req := <-s.deliver:272			// Response, disconnect or timeout triggered, drop the peer if stalling273			log.Trace("Received node data response", "peer", req.peer.id, "count", len(req.response), "dropped", req.dropped, "timeout", !req.dropped && req.timedOut())274			if len(req.items) <= 2 && !req.dropped && req.timedOut() {275				// 2 items are the minimum requested, if even that times out, we've no use of276				// this peer at the moment.277				log.Warn("Stalling state sync, dropping peer", "peer", req.peer.id)278				if s.d.dropPeer == nil {279					// The dropPeer method is nil when `--copydb` is used for a local copy.280					// Timeouts can occur if e.g. compaction hits at the wrong time, and can be ignored281					req.peer.log.Warn("Downloader wants to drop peer, but peerdrop-function is not set", "peer", req.peer.id)282				} else {283					s.d.dropPeer(req.peer.id)284					// If this peer was the master peer, abort sync immediately285					s.d.cancelLock.RLock()286					master := req.peer.id == s.d.cancelPeer287					s.d.cancelLock.RUnlock()288					if master {289						s.d.cancel()290						return errTimeout291					}292				}293			}294			// Process all the received blobs and check for stale delivery295			delivered, err := s.process(req)296			if err != nil {297				log.Warn("Node data write error", "err", err)298				return err299			}300			req.peer.SetNodeDataIdle(delivered)301		}302	}303	return nil304}305func (s *stateSync) commit(force bool) error {306	if !force && s.bytesUncommitted < ethdb.IdealBatchSize {307		return nil308	}309	start := time.Now()310	b := s.d.stateDB.NewBatch()311	if err := s.sched.Commit(b); err != nil {312		return err313	}314	if err := b.Write(); err != nil {315		return fmt.Errorf("DB write error: %v", err)316	}317	s.updateStats(s.numUncommitted, 0, 0, time.Since(start))318	s.numUncommitted = 0319	s.bytesUncommitted = 0320	return nil321}322// assignTasks attempts to assign new tasks to all idle peers, either from the323// batch currently being retried, or fetching new data from the trie sync itself.324func (s *stateSync) assignTasks() {325	// Iterate over all idle peers and try to assign them state fetches326	peers, _ := s.d.peers.NodeDataIdlePeers()327	for _, p := range peers {328		// Assign a batch of fetches proportional to the estimated latency/bandwidth329		cap := p.NodeDataCapacity(s.d.requestRTT())330		req := &stateReq{peer: p, timeout: s.d.requestTTL()}331		s.fillTasks(cap, req)332		// If the peer was assigned tasks to fetch, send the network request333		if len(req.items) > 0 {334			req.peer.log.Trace("Requesting new batch of data", "type", "state", "count", len(req.items))335			select {336			case s.d.trackStateReq <- req:337				req.peer.FetchNodeData(req.items)338			case <-s.cancel:339			case <-s.d.cancelCh:340			}341		}342	}343}344// fillTasks fills the given request object with a maximum of n state download345// tasks to send to the remote peer.346func (s *stateSync) fillTasks(n int, req *stateReq) {347	// Refill available tasks from the scheduler.348	if len(s.tasks) < n {349		new := s.sched.Missing(n - len(s.tasks))350		for _, hash := range new {351			s.tasks[hash] = &stateTask{make(map[string]struct{})}352		}353	}354	// Find tasks that haven't been tried with the request's peer.355	req.items = make([]common.Hash, 0, n)356	req.tasks = make(map[common.Hash]*stateTask, n)357	for hash, t := range s.tasks {358		// Stop when we've gathered enough requests359		if len(req.items) == n {360			break361		}362		// Skip any requests we've already tried from this peer363		if _, ok := t.attempts[req.peer.id]; ok {364			continue365		}366		// Assign the request to this peer367		t.attempts[req.peer.id] = struct{}{}368		req.items = append(req.items, hash)369		req.tasks[hash] = t370		delete(s.tasks, hash)371	}372}373// process iterates over a batch of delivered state data, injecting each item374// into a running state sync, re-queuing any items that were requested but not375// delivered. Returns whether the peer actually managed to deliver anything of376// value, and any error that occurred.377func (s *stateSync) process(req *stateReq) (int, error) {378	// Collect processing stats and update progress if valid data was received379	duplicate, unexpected, successful := 0, 0, 0380	defer func(start time.Time) {381		if duplicate > 0 || unexpected > 0 {382			s.updateStats(0, duplicate, unexpected, time.Since(start))383		}384	}(time.Now())385	// Iterate over all the delivered data and inject one-by-one into the trie386	for _, blob := range req.response {387		_, hash, err := s.processNodeData(blob)388		switch err {389		case nil:390			s.numUncommitted++391			s.bytesUncommitted += len(blob)392			successful++393		case trie.ErrNotRequested:394			unexpected++395		case trie.ErrAlreadyProcessed:396			duplicate++397		default:398			return successful, fmt.Errorf("invalid state node %s: %v", hash.TerminalString(), err)399		}400		delete(req.tasks, hash)401	}402	// Put unfulfilled tasks back into the retry queue403	npeers := s.d.peers.Len()404	for hash, task := range req.tasks {405		// If the node did deliver something, missing items may be due to a protocol406		// limit or a previous timeout + delayed delivery. Both cases should permit407		// the node to retry the missing items (to avoid single-peer stalls).408		if len(req.response) > 0 || req.timedOut() {409			delete(task.attempts, req.peer.id)410		}411		// If we've requested the node too many times already, it may be a malicious412		// sync where nobody has the right data. Abort.413		if len(task.attempts) >= npeers {414			return successful, fmt.Errorf("state node %s failed with all peers (%d tries, %d peers)", hash.TerminalString(), len(task.attempts), npeers)415		}416		// Missing item, place into the retry queue.417		s.tasks[hash] = task418	}419	return successful, nil420}421// processNodeData tries to inject a trie node data blob delivered from a remote422// peer into the state trie, returning whether anything useful was written or any423// error occurred.424func (s *stateSync) processNodeData(blob []byte) (bool, common.Hash, error) {425	res := trie.SyncResult{Data: blob}426	s.keccak.Reset()427	s.keccak.Write(blob)428	s.keccak.Sum(res.Hash[:0])429	committed, _, err := s.sched.Process([]trie.SyncResult{res})430	return committed, res.Hash, err431}432// updateStats bumps the various state sync progress counters and displays a log433// message for the user to see.434func (s *stateSync) updateStats(written, duplicate, unexpected int, duration time.Duration) {435	s.d.syncStatsLock.Lock()436	defer s.d.syncStatsLock.Unlock()437	s.d.syncStatsState.pending = uint64(s.sched.Pending())438	s.d.syncStatsState.processed += uint64(written)439	s.d.syncStatsState.duplicate += uint64(duplicate)440	s.d.syncStatsState.unexpected += uint64(unexpected)441	if written > 0 || duplicate > 0 || unexpected > 0 {442		log.Info("Imported new state entries", "count", written, "elapsed", common.PrettyDuration(duration), "processed", s.d.syncStatsState.processed, "pending", s.d.syncStatsState.pending, "retry", len(s.tasks), "duplicate", s.d.syncStatsState.duplicate, "unexpected", s.d.syncStatsState.unexpected)443	}444	if written > 0 {445		rawdb.WriteFastTrieProgress(s.d.stateDB, s.d.syncStatsState.processed)446	}447}...

sync_test.go

Source:sync_test.go

...109	}110	return it.Error111}112// Tests that an empty state is not scheduled for syncing.113func TestEmptyStateSync(t *testing.T) {114	empty := common.HexToHash("56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421")115	if req := NewStateSync(empty, rawdb.NewMemoryDatabase(), trie.NewSyncBloom(1, memorydb.New())).Missing(1); len(req) != 0 {116		t.Errorf("content requested for empty state: %v", req)117	}118}119// Tests that given a root hash, a state can sync iteratively on a single thread,120// requesting retrieval tasks and returning all of them in one go.121func TestIterativeStateSyncIndividual(t *testing.T) { testIterativeStateSync(t, 1) }122func TestIterativeStateSyncBatched(t *testing.T)    { testIterativeStateSync(t, 100) }123func testIterativeStateSync(t *testing.T, count int) {124	// Create a random state to copy125	srcDb, srcRoot, srcAccounts := makeTestState()126	// Create a destination state and sync with the scheduler127	dstDb := rawdb.NewMemoryDatabase()128	sched := NewStateSync(srcRoot, dstDb, trie.NewSyncBloom(1, dstDb))129	queue := append([]common.Hash{}, sched.Missing(count)...)130	for len(queue) > 0 {131		results := make([]trie.SyncResult, len(queue))132		for i, hash := range queue {133			data, err := srcDb.TrieDB().Node(hash)134			if err != nil {135				t.Fatalf("failed to retrieve node data for %x", hash)136			}137			results[i] = trie.SyncResult{Hash: hash, Data: data}138		}139		if _, index, err := sched.Process(results); err != nil {140			t.Fatalf("failed to process result #%d: %v", index, err)141		}142		batch := dstDb.NewBatch()143		if err := sched.Commit(batch); err != nil {144			t.Fatalf("failed to commit data: %v", err)145		}146		batch.Write()147		queue = append(queue[:0], sched.Missing(count)...)148	}149	// Cross check that the two states are in sync150	checkStateAccounts(t, dstDb, srcRoot, srcAccounts)151}152// Tests that the trie scheduler can correctly reconstruct the state even if only153// partial results are returned, and the others sent only later.154func TestIterativeDelayedStateSync(t *testing.T) {155	// Create a random state to copy156	srcDb, srcRoot, srcAccounts := makeTestState()157	// Create a destination state and sync with the scheduler158	dstDb := rawdb.NewMemoryDatabase()159	sched := NewStateSync(srcRoot, dstDb, trie.NewSyncBloom(1, dstDb))160	queue := append([]common.Hash{}, sched.Missing(0)...)161	for len(queue) > 0 {162		// Sync only half of the scheduled nodes163		results := make([]trie.SyncResult, len(queue)/2+1)164		for i, hash := range queue[:len(results)] {165			data, err := srcDb.TrieDB().Node(hash)166			if err != nil {167				t.Fatalf("failed to retrieve node data for %x", hash)168			}169			results[i] = trie.SyncResult{Hash: hash, Data: data}170		}171		if _, index, err := sched.Process(results); err != nil {172			t.Fatalf("failed to process result #%d: %v", index, err)173		}174		batch := dstDb.NewBatch()175		if err := sched.Commit(batch); err != nil {176			t.Fatalf("failed to commit data: %v", err)177		}178		batch.Write()179		queue = append(queue[len(results):], sched.Missing(0)...)180	}181	// Cross check that the two states are in sync182	checkStateAccounts(t, dstDb, srcRoot, srcAccounts)183}184// Tests that given a root hash, a trie can sync iteratively on a single thread,185// requesting retrieval tasks and returning all of them in one go, however in a186// random order.187func TestIterativeRandomStateSyncIndividual(t *testing.T) { testIterativeRandomStateSync(t, 1) }188func TestIterativeRandomStateSyncBatched(t *testing.T)    { testIterativeRandomStateSync(t, 100) }189func testIterativeRandomStateSync(t *testing.T, count int) {190	// Create a random state to copy191	srcDb, srcRoot, srcAccounts := makeTestState()192	// Create a destination state and sync with the scheduler193	dstDb := rawdb.NewMemoryDatabase()194	sched := NewStateSync(srcRoot, dstDb, trie.NewSyncBloom(1, dstDb))195	queue := make(map[common.Hash]struct{})196	for _, hash := range sched.Missing(count) {197		queue[hash] = struct{}{}198	}199	for len(queue) > 0 {200		// Fetch all the queued nodes in a random order201		results := make([]trie.SyncResult, 0, len(queue))202		for hash := range queue {203			data, err := srcDb.TrieDB().Node(hash)204			if err != nil {205				t.Fatalf("failed to retrieve node data for %x", hash)206			}207			results = append(results, trie.SyncResult{Hash: hash, Data: data})208		}209		// Feed the retrieved results back and queue new tasks210		if _, index, err := sched.Process(results); err != nil {211			t.Fatalf("failed to process result #%d: %v", index, err)212		}213		batch := dstDb.NewBatch()214		if err := sched.Commit(batch); err != nil {215			t.Fatalf("failed to commit data: %v", err)216		}217		batch.Write()218		queue = make(map[common.Hash]struct{})219		for _, hash := range sched.Missing(count) {220			queue[hash] = struct{}{}221		}222	}223	// Cross check that the two states are in sync224	checkStateAccounts(t, dstDb, srcRoot, srcAccounts)225}226// Tests that the trie scheduler can correctly reconstruct the state even if only227// partial results are returned (Even those randomly), others sent only later.228func TestIterativeRandomDelayedStateSync(t *testing.T) {229	// Create a random state to copy230	srcDb, srcRoot, srcAccounts := makeTestState()231	// Create a destination state and sync with the scheduler232	dstDb := rawdb.NewMemoryDatabase()233	sched := NewStateSync(srcRoot, dstDb, trie.NewSyncBloom(1, dstDb))234	queue := make(map[common.Hash]struct{})235	for _, hash := range sched.Missing(0) {236		queue[hash] = struct{}{}237	}238	for len(queue) > 0 {239		// Sync only half of the scheduled nodes, even those in random order240		results := make([]trie.SyncResult, 0, len(queue)/2+1)241		for hash := range queue {242			delete(queue, hash)243			data, err := srcDb.TrieDB().Node(hash)244			if err != nil {245				t.Fatalf("failed to retrieve node data for %x", hash)246			}247			results = append(results, trie.SyncResult{Hash: hash, Data: data})248			if len(results) >= cap(results) {249				break250			}251		}252		// Feed the retrieved results back and queue new tasks253		if _, index, err := sched.Process(results); err != nil {254			t.Fatalf("failed to process result #%d: %v", index, err)255		}256		batch := dstDb.NewBatch()257		if err := sched.Commit(batch); err != nil {258			t.Fatalf("failed to commit data: %v", err)259		}260		batch.Write()261		for _, hash := range sched.Missing(0) {262			queue[hash] = struct{}{}263		}264	}265	// Cross check that the two states are in sync266	checkStateAccounts(t, dstDb, srcRoot, srcAccounts)267}268// Tests that at any point in time during a sync, only complete sub-tries are in269// the database.270func TestIncompleteStateSync(t *testing.T) {271	// Create a random state to copy272	srcDb, srcRoot, srcAccounts := makeTestState()273	checkTrieConsistency(srcDb.TrieDB().DiskDB().(ethdb.Database), srcRoot)274	// Create a destination state and sync with the scheduler275	dstDb := rawdb.NewMemoryDatabase()276	sched := NewStateSync(srcRoot, dstDb, trie.NewSyncBloom(1, dstDb))277	added := []common.Hash{}278	queue := append([]common.Hash{}, sched.Missing(1)...)279	for len(queue) > 0 {280		// Fetch a batch of state nodes281		results := make([]trie.SyncResult, len(queue))282		for i, hash := range queue {283			data, err := srcDb.TrieDB().Node(hash)284			if err != nil {285				t.Fatalf("failed to retrieve node data for %x", hash)286			}287			results[i] = trie.SyncResult{Hash: hash, Data: data}288		}289		// Process each of the state nodes290		if _, index, err := sched.Process(results); err != nil {291			t.Fatalf("failed to process result #%d: %v", index, err)292		}293		batch := dstDb.NewBatch()294		if err := sched.Commit(batch); err != nil {295			t.Fatalf("failed to commit data: %v", err)296		}297		batch.Write()298		for _, result := range results {299			added = append(added, result.Hash)300		}301		// Check that all known sub-tries added so far are complete or missing entirely....

Sync

Using AI Code Generation

1import (2func main() {3	wg.Add(2)4	go func() {5		fmt.Println("Hello")6		wg.Done()7	}()8	go func() {9		fmt.Println("World")10		wg.Done()11	}()12	wg.Wait()13}14import (15func main() {16	wg.Add(2)17	go func() {18		fmt.Println("Hello")19		wg.Done()20	}()21	go func() {22		fmt.Println("World")23		wg.Done()24	}()25	wg.Wait()26}27import (28func main() {29	wg.Add(2)30	go func() {31		fmt.Println("Hello")32		wg.Done()33	}()34	go func() {35		fmt.Println("World")36		wg.Done()37	}()38	wg.Wait()39}40import (41func main() {42	wg.Add(2)43	go func() {44		fmt.Println("Hello")45		wg.Done()46	}()47	go func() {48		fmt.Println("World")49		wg.Done()50	}()51	wg.Wait()52}53import (54func main() {55	wg.Add(2)56	go func() {57		fmt.Println("Hello")58		wg.Done()59	}()60	go func() {61		fmt.Println("World")62		wg.Done()63	}()64	wg.Wait()65}66import (67func main() {68	wg.Add(2)69	go func() {70		fmt.Println("Hello")71		wg.Done()72	}()73	go func() {74		fmt.Println("World")75		wg.Done()76	}()77	wg.Wait()78}79import (80func main() {

Sync

Using AI Code Generation

1import (2func main() {3	wg.Add(2)4	go func() {5		fmt.Println("Hello")6		wg.Done()7	}()8	go func() {9		fmt.Println("World")10		wg.Done()11	}()12	wg.Wait()13}14import (15func main() {16	wg.Add(2)17	go func() {18		fmt.Println("Hello")19		wg.Done()20	}()21	go func() {22		fmt.Println("World")23		wg.Done()24	}()25	wg.Wait()26}27import (28func main() {29	wg.Add(2)30	go func() {31		fmt.Println("Hello")32		wg.Done()33	}()34	go func() {35		fmt.Println("World")36		wg.Done()37	}()38	wg.Wait()39}40import (41func main() {42	wg.Add(2)43	go func() {44		fmt.Println("Hello")45		wg.Done()46	}()47	go func() {48		fmt.Println("World")49		wg.Done()50	}()51	wg.Wait()52}53import (54func main() {55	wg.Add(2)56	go func() {57		fmt.Println("Hello")58		wg.Done()59	}()60	go func() {61		fmt.Println("World")62		wg.Done()63	}()64	wg.Wait()65}66import (67func main() {68	wg.Add(2)69	go func() {70		fmt.Println("Hello")71		wg.Done()72	}()73	go func() {74		fmt.Println("World")75		wg.Done()76	}()77	wg.Wait()78}79import (

Sync

Using AI Code Generation

1import (2func main() {3	wg.Add(2)4	go func() {5		fmt.Println("first go routine")6		wg.Done()7	}()8	go func() {9		fmt.Println("second go routine")10		wg.Done()11	}()12	wg.Wait()13	fmt.Println("main go routine")14}15import (16func main() {17	wg.Add(2)18	go func() {19		fmt.Println("first go routine")20		wg.Done()21	}()22	go func() {23		fmt.Println("second go routine")24		wg.Done()25	}()26	wg.Wait()27	fmt.Println("main go routine")28}29import (30func main() {31	wg.Add(2)32	go func() {33		fmt.Println("first go routine")34		wg.Done()35	}()36	go func() {37		fmt.Println("second go routine")38		wg.Done()39	}()40	wg.Wait()41	fmt.Println("main go routine")42}43import (44func main() {45	wg.Add(2)46	go func() {47		fmt.Println("first go routine")48		wg.Done()49	}()50	go func() {51		fmt.Println("second go routine")52		wg.Done()53	}()54	wg.Wait()55	fmt.Println("main go routine")56}57import (58func main() {59	wg.Add(2)60	go func() {61		fmt.Println("first go routine")62		wg.Done()63	}()64	go func() {65		fmt.Println("second go routine")

Sync

Using AI Code Generation

1import (2func main() {3	wg.Add(2)4	fmt.Println("Start Goroutines")5	go func() {6		defer wg.Done()7		for count := 0; count < 3; count++ {8			for char := 'a'; char < 'a'+26; char++ {9				fmt.Printf("%c ", char)10			}11		}12	}()13	go func() {14		defer wg.Done()15		for count := 0; count < 3; count++ {16			for char := 'A'; char < 'A'+26; char++ {17				fmt.Printf("%c ", char)18			}19		}20	}()21	fmt.Println("Waiting to finish")22	wg.Wait()23	fmt.Println("\nTerminating Program")24}25import (26func main() {27	wg.Add(2)28	fmt.Println("Start Goroutines")29	go func() {30		defer wg.Done()31		for count := 0; count < 3; count++ {32			for char := 'a'; char < 'a'+26; char++ {33				fmt.Printf("%c ", char)34			}35		}36	}()37	go func() {38		defer wg.Done()39		for count := 0;

Sync

Using AI Code Generation

1import (2func main() {3	wg.Add(2)4	go func() {5		fmt.Println("Hello")6		wg.Done()7	}()8	go func() {9		fmt.Println("World")10		wg.Done()11	}()12	wg.Wait()13}14import (15func main() {16	wg.Add(2)17	go func() {18		defer wg.Done()19		fmt.Println("Hello")20	}()21	go func() {22		defer wg.Done()23		fmt.Println("World")24	}()25	wg.Wait()26}27import (28func main() {29	wg.Add(2)30	go func() {31		defer wg.Done()32		fmt.Println("Hello")33	}()34	go func() {35		defer wg.Done()36		fmt.Println("World")37	}()38	wg.Wait()39}40import (41func main() {42	wg.Add(2)43	go func() {44		defer wg.Done()45		fmt.Println("Hello")46	}()47	go func() {48		defer wg.Done()49		fmt.Println("World")50	}()51	wg.Wait()52}53import (54func main() {55	wg.Add(2)56	go func() {57		defer wg.Done()58		fmt.Println("Hello")59	}()60	go func() {61		defer wg.Done()62		fmt.Println("World")63	}()64	wg.Wait()65}66import (67func main() {68	wg.Add(2)69	go func() {70		defer wg.Done()71		fmt.Println("Hello")72	}()73	go func() {74		defer wg.Done()75		fmt.Println("World")76	}()77	wg.Wait()78}79import (

Sync

Using AI Code Generation

1import (2type state struct {3}4func (s *state) inc(key string) {5	s.Lock()6	defer s.Unlock()7}8func (s *state) value(key string) int {9	s.Lock()10	defer s.Unlock()11}12func main() {13	s := state{m: make(map[string]int)}14	s.inc("foo")15	fmt.Println(s.value("foo"))16}17import (18func main() {19	m.Store("foo", 42)20	v, _ := m.Load("foo")21	fmt.Println(v)22}23import (24func main() {25	m.Store("foo", 42)26	v, _ := m.Load("foo")27	fmt.Println(v)28}29import (30func main() {31	m.Store("foo", 42)32	v, _ := m.Load("foo")33	fmt.Println(v)34}35import (36func main() {37	m.Store("foo", 42)38	v, _ := m.Load("foo")39	fmt.Println(v)40}

Sync

Using AI Code Generation

1import "fmt"2type State struct {3}4func (s *State) Sync() {5}6func main() {7	s := &State{sync: make(chan bool)}8	go func() {9		fmt.Println("Hello")10	}()11	s.Sync()12	fmt.Println("World")13}

Sync

Using AI Code Generation

1func main() {2    state := state.NewState()3    state := state.NewState(state.WithStateDir("/path/to/state"))4    state := state.NewState(state.WithStateFileName("terraform.tfstate"))5    state := state.NewState(state.WithStateFilePath("/path/to/custom/terraform.tfstate"))6    state := state.NewState(state.WithStateFilePath("/path/to/custom"), state.WithStateFileName("terraform.tfstate"))7    state := state.NewState(state.WithStateFilePath("/path/to/custom/terraform.tfstate"))8    state := state.NewState(state.WithStateFilePath("/path/to/custom/terraform.tfstate"))9    state := state.NewState(state.WithStateFilePath("/path/to/custom/terraform.tfstate"))10    state := state.NewState(state.WithStateFilePath("/path/to/custom/terraform.tfstate"))11    state := state.NewState(state.WithStateFilePath("/path/to/custom/terraform.tfstate"))12    state := state.NewState(state.WithStateFilePath("/path/to/custom/terraform.tfstate"))13    state := state.NewState(state.WithStateFilePath("/path/to/custom/terraform.tfstate"))14    state := state.NewState(state.WithStateFilePath("/path/to/custom/terraform.tfstate"))15    state := state.NewState(state.WithStateFilePath("/path/to/custom/terraform.tfstate"))16    state := state.NewState(state.WithStateFilePath("/path/to/custom/terraform.tfstate"))

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.