Cosmos SDK Interview Questions - Hard

 1package app
 2
 3import (
 4    "github.com/cosmos/cosmos-sdk/baseapp"
 5    "github.com/cosmos/cosmos-sdk/types"
 6)
 7
 8type CustomApp struct {
 9    *baseapp.BaseApp
10    customState *CustomState
11}
12
13// CustomState manages application state
14type CustomState struct {
15    snapshots   *SnapshotManager
16    checkpoints *CheckpointManager
17    cache       *StateCache
18}
19
20// BeginBlock with custom logic
21func (app *CustomApp) BeginBlock(req abci.RequestBeginBlock) abci.ResponseBeginBlock {
22    // Custom pre-processing
23    app.customState.cache.BeginBlock()
24    
25    // Standard BeginBlock
26    res := app.BaseApp.BeginBlock(req)
27    
28    // Custom post-processing
29    app.customState.checkpoints.CreateCheckpoint(req.Height)
30    
31    return res
32}
33
34// DeliverTx with custom validation
35func (app *CustomApp) DeliverTx(req abci.RequestDeliverTx) abci.ResponseDeliverTx {
36    ctx := app.NewContext(false, req.Header)
37    
38    // Custom validation
39    if err := app.customState.ValidateTx(ctx, req.Tx); err != nil {
40        return abci.ResponseDeliverTx{
41            Code: uint32(sdkerrors.ErrInvalidRequest.ABCICode()),
42            Log:  err.Error(),
43        }
44    }
45    
46    // Standard DeliverTx
47    res := app.BaseApp.DeliverTx(req)
48    
49    // Custom post-processing
50    app.customState.cache.CacheTx(req.Tx, res)
51    
52    return res
53}
54
55// Commit with snapshot creation
56func (app *CustomApp) Commit() abci.ResponseCommit {
57    // Standard commit
58    res := app.BaseApp.Commit()
59    
60    // Create snapshot periodically
61    if app.customState.snapshots.ShouldCreateSnapshot(app.LastBlockHeight()) {
62        app.customState.snapshots.CreateSnapshot(app.LastBlockHeight())
63    }
64    
65    return res
66}

 1package state
 2
 3// SnapshotManager manages state snapshots
 4type SnapshotManager struct {
 5    store    sdk.KVStore
 6    interval uint64
 7}
 8
 9func (sm *SnapshotManager) CreateSnapshot(height int64) error {
10    // Create snapshot of all stores
11    snapshot := &Snapshot{
12        Height: height,
13        Stores: make(map[string][]byte),
14    }
15    
16    // Snapshot each module store
17    for _, storeKey := range sm.storeKeys {
18        store := sm.getStore(storeKey)
19        snapshot.Stores[storeKey.Name()] = sm.snapshotStore(store)
20    }
21    
22    // Persist snapshot
23    return sm.persistSnapshot(snapshot)
24}
25
26func (sm *SnapshotManager) RestoreSnapshot(height int64) error {
27    snapshot, err := sm.loadSnapshot(height)
28    if err != nil {
29        return err
30    }
31    
32    // Restore each store
33    for storeKey, data := range snapshot.Stores {
34        store := sm.getStore(storeKey)
35        sm.restoreStore(store, data)
36    }
37    
38    return nil
39}

 1package mempool
 2
 3// EncryptedMempool encrypts transactions to prevent front-running
 4type EncryptedMempool struct {
 5    transactions map[string]*EncryptedTx
 6    decryptionKey []byte
 7}
 8
 9type EncryptedTx struct {
10    EncryptedData []byte
11    Commitment    []byte
12    Timestamp     time.Time
13}
14
15// Insert encrypts transaction before adding
16func (mp *EncryptedMempool) Insert(ctx sdk.Context, tx sdk.Tx) error {
17    // Encrypt transaction
18    encrypted, err := mp.encryptTx(tx)
19    if err != nil {
20        return err
21    }
22    
23    // Create commitment
24    commitment := mp.createCommitment(tx)
25    
26    // Store encrypted
27    mp.transactions[string(tx.Hash())] = &EncryptedTx{
28        EncryptedData: encrypted,
29        Commitment:    commitment,
30        Timestamp:     ctx.BlockTime(),
31    }
32    
33    return nil
34}
35
36// Reveal decrypts transactions at block proposal time
37func (mp *EncryptedMempool) Reveal(ctx sdk.Context, txHashes [][]byte) ([]sdk.Tx, error) {
38    var txs []sdk.Tx
39    
40    for _, hash := range txHashes {
41        encryptedTx, exists := mp.transactions[string(hash)]
42        if !exists {
43            continue
44        }
45        
46        // Verify commitment
47        if !mp.verifyCommitment(encryptedTx.Commitment, encryptedTx.EncryptedData) {
48            return nil, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "invalid commitment")
49        }
50        
51        // Decrypt
52        tx, err := mp.decryptTx(encryptedTx.EncryptedData)
53        if err != nil {
54            return nil, err
55        }
56        
57        txs = append(txs, tx)
58    }
59    
60    return txs, nil
61}

 1// FairOrderingMempool implements fair transaction ordering
 2type FairOrderingMempool struct {
 3    transactions []*PrioritizedTx
 4    maxPriority  int64
 5}
 6
 7type PrioritizedTx struct {
 8    Tx       sdk.Tx
 9    Priority int64
10    Nonce    uint64
11    Sender   sdk.AccAddress
12}
13
14// Insert with fair priority calculation
15func (mp *FairOrderingMempool) Insert(ctx sdk.Context, tx sdk.Tx) error {
16    // Calculate priority based on fee and time
17    priority := mp.calculatePriority(ctx, tx)
18    
19    // Get sender nonce
20    sender := tx.GetSigners()[0]
21    nonce := mp.getNonce(ctx, sender)
22    
23    prioritized := &PrioritizedTx{
24        Tx:       tx,
25        Priority: priority,
26        Nonce:    nonce,
27        Sender:   sender,
28    }
29    
30    // Insert maintaining order
31    mp.insertSorted(prioritized)
32    
33    return nil
34}
35
36// calculatePriority calculates fair priority
37func (mp *FairOrderingMempool) calculatePriority(ctx sdk.Context, tx sdk.Tx) int64 {
38    feeTx := tx.(sdk.FeeTx)
39    fee := feeTx.GetFee()
40    
41    // Base priority from fee
42    priority := fee.AmountOf("stake").Int64()
43    
44    // Reduce priority for recent transactions (prevent front-running)
45    age := ctx.BlockTime().Unix() - mp.getTxTimestamp(tx).Unix()
46    if age < 60 { // Less than 1 minute
47        priority = priority / 2
48    }
49    
50    return priority
51}

 1package keeper
 2
 3import (
 4    "github.com/cosmos/ibc-go/v3/modules/core/keeper"
 5    channeltypes "github.com/cosmos/ibc-go/v3/modules/core/04-channel/types"
 6)
 7
 8type Keeper struct {
 9    storeKey    sdk.StoreKey
10    ibcKeeper   *ibckeeper.Keeper
11    channelKeeper channelkeeper.Keeper
12}
13
14// SendPacket sends packet via IBC
15func (k Keeper) SendPacket(
16    ctx sdk.Context,
17    sourcePort,
18    sourceChannel string,
19    packetData []byte,
20    timeoutHeight clienttypes.Height,
21    timeoutTimestamp uint64,
22) error {
23    // Create packet
24    packet := channeltypes.NewPacket(
25        packetData,
26        k.getNextSequenceSend(ctx, sourcePort, sourceChannel),
27        sourcePort,
28        sourceChannel,
29        k.getCounterpartyPort(sourcePort),
30        k.getCounterpartyChannel(sourceChannel),
31        timeoutHeight,
32        timeoutTimestamp,
33    )
34    
35    // Send via IBC
36    return k.channelKeeper.SendPacket(ctx, packet)
37}
38
39// OnRecvPacket handles received IBC packet
40func (k Keeper) OnRecvPacket(
41    ctx sdk.Context,
42    packet channeltypes.Packet,
43    relayer sdk.AccAddress,
44) (*sdk.Result, error) {
45    // Unmarshal packet data
46    var data MyPacketData
47    if err := k.cdc.Unmarshal(packet.GetData(), &data); err != nil {
48        return nil, err
49    }
50    
51    // Process packet
52    switch data.Type {
53    case PacketTypeOrder:
54        return k.handleOrderPacket(ctx, data, relayer)
55    case PacketTypePayment:
56        return k.handlePaymentPacket(ctx, data, relayer)
57    default:
58        return nil, sdkerrors.Wrap(sdkerrors.ErrUnknownRequest, "unknown packet type")
59    }
60}
61
62// AcknowledgePacket handles packet acknowledgment
63func (k Keeper) OnAcknowledgementPacket(
64    ctx sdk.Context,
65    packet channeltypes.Packet,
66    acknowledgement []byte,
67    relayer sdk.AccAddress,
68) (*sdk.Result, error) {
69    // Parse acknowledgement
70    var ack channeltypes.Acknowledgement
71    if err := k.cdc.Unmarshal(acknowledgement, &ack); err != nil {
72        return nil, err
73    }
74    
75    if ack.Success() {
76        // Handle successful acknowledgement
77        return k.handleSuccessAck(ctx, packet, relayer)
78    } else {
79        // Handle failure
80        return k.handleFailureAck(ctx, packet, ack.Error(), relayer)
81    }
82}

 1// CrossChainStateSync synchronizes state across chains
 2type CrossChainStateSync struct {
 3    keeper      Keeper
 4    ibcKeeper   *ibckeeper.Keeper
 5}
 6
 7// SyncState syncs state to target chain
 8func (ccs *CrossChainStateSync) SyncState(
 9    ctx sdk.Context,
10    targetChain string,
11    stateKey string,
12) error {
13    // Get state
14    state := ccs.keeper.GetState(ctx, stateKey)
15    
16    // Create sync packet
17    packetData := SyncPacketData{
18        Type:   PacketTypeStateSync,
19        Key:    stateKey,
20        State:  state,
21        Height: ctx.BlockHeight(),
22    }
23    
24    // Send via IBC
25    return ccs.keeper.SendPacket(
26        ctx,
27        "transfer",
28        ccs.getChannel(targetChain),
29        packetData,
30        clienttypes.Height{},
31        0,
32    )
33}

 1package cache
 2
 3// MultiLevelCache implements L1/L2 caching
 4type MultiLevelCache struct {
 5    l1Cache *sync.Map // In-memory
 6    l2Cache *LRUCache // Persistent
 7    store   sdk.KVStore
 8}
 9
10func (mlc *MultiLevelCache) Get(ctx sdk.Context, key []byte) ([]byte, error) {
11    // Check L1 cache
12    if value, ok := mlc.l1Cache.Load(string(key)); ok {
13        return value.([]byte), nil
14    }
15    
16    // Check L2 cache
17    if value, ok := mlc.l2Cache.Get(string(key)); ok {
18        // Promote to L1
19        mlc.l1Cache.Store(string(key), value)
20        return value.([]byte), nil
21    }
22    
23    // Load from store
24    value := mlc.store.Get(key)
25    if value == nil {
26        return nil, sdkerrors.Wrap(sdkerrors.ErrKeyNotFound, "key not found")
27    }
28    
29    // Cache in L2
30    mlc.l2Cache.Set(string(key), value)
31    
32    // Cache in L1
33    mlc.l1Cache.Store(string(key), value)
34    
35    return value, nil
36}
37
38// Write-through cache
39func (mlc *MultiLevelCache) Set(ctx sdk.Context, key, value []byte) {
40    // Write to store first
41    mlc.store.Set(key, value)
42    
43    // Update L2 cache
44    mlc.l2Cache.Set(string(key), value)
45    
46    // Update L1 cache
47    mlc.l1Cache.Store(string(key), value)
48}

 1// CompressedStore compresses values before storing
 2type CompressedStore struct {
 3    store     sdk.KVStore
 4    compressor *Compressor
 5}
 6
 7func (cs *CompressedStore) Set(key, value []byte) {
 8    // Compress value
 9    compressed := cs.compressor.Compress(value)
10    
11    // Store compressed
12    cs.store.Set(key, compressed)
13}
14
15func (cs *CompressedStore) Get(key []byte) []byte {
16    // Get compressed
17    compressed := cs.store.Get(key)
18    if compressed == nil {
19        return nil
20    }
21    
22    // Decompress
23    return cs.compressor.Decompress(compressed)
24}

 1package keeper
 2
 3// ValidatorSetManager manages custom validator set
 4type ValidatorSetManager struct {
 5    keeper Keeper
 6}
 7
 8// UpdateValidatorSet updates validators based on custom rules
 9func (vsm *ValidatorSetManager) UpdateValidatorSet(ctx sdk.Context) error {
10    // Get current validators
11    validators := vsm.keeper.GetAllValidators(ctx)
12    
13    // Calculate new set based on:
14    // - Staking power
15    // - Performance metrics
16    // - Reputation
17    newSet := vsm.calculateNewSet(ctx, validators)
18    
19    // Apply changes
20    return vsm.applyValidatorSet(ctx, newSet)
21}
22
23// calculateNewSet calculates optimal validator set
24func (vsm *ValidatorSetManager) calculateNewSet(
25    ctx sdk.Context,
26    validators []Validator,
27) []Validator {
28    // Score validators
29    scored := make([]ScoredValidator, len(validators))
30    for i, val := range validators {
31        scored[i] = ScoredValidator{
32            Validator: val,
33            Score:     vsm.calculateScore(ctx, val),
34        }
35    }
36    
37    // Sort by score
38    sort.Slice(scored, func(i, j int) bool {
39        return scored[i].Score > scored[j].Score
40    })
41    
42    // Select top N
43    maxValidators := vsm.keeper.GetMaxValidators(ctx)
44    selected := make([]Validator, 0, maxValidators)
45    for i := 0; i < len(scored) && i < maxValidators; i++ {
46        selected = append(selected, scored[i].Validator)
47    }
48    
49    return selected
50}
51
52// calculateScore calculates validator score
53func (vsm *ValidatorSetManager) calculateScore(
54    ctx sdk.Context,
55    val Validator,
56) sdk.Dec {
57    // Base score from staking power
58    baseScore := sdk.NewDecFromInt(val.Tokens)
59    
60    // Performance multiplier
61    uptime := vsm.keeper.GetUptime(ctx, val.OperatorAddress)
62    performanceMultiplier := sdk.NewDec(1).Add(uptime.Mul(sdk.NewDecWithPrec(1, 1)))
63    
64    // Reputation multiplier
65    reputation := vsm.keeper.GetReputation(ctx, val.OperatorAddress)
66    reputationMultiplier := sdk.NewDec(1).Add(reputation.Mul(sdk.NewDecWithPrec(5, 2)))
67    
68    // Final score
69    return baseScore.Mul(performanceMultiplier).Mul(reputationMultiplier)
70}

 1// SlashingManager implements advanced slashing
 2type SlashingManager struct {
 3    keeper Keeper
 4}
 5
 6// SlashValidator slashes validator with custom logic
 7func (sm *SlashingManager) SlashValidator(
 8    ctx sdk.Context,
 9    validator sdk.ValAddress,
10    infractionType InfractionType,
11    evidence Evidence,
12) error {
13    // Get validator
14    val, found := sm.keeper.GetValidator(ctx, validator)
15    if !found {
16        return sdkerrors.Wrap(sdkerrors.ErrNotFound, "validator not found")
17    }
18    
19    // Calculate slash amount based on:
20    // - Infraction type
21    // - Validator history
22    // - Evidence strength
23    slashAmount := sm.calculateSlashAmount(ctx, val, infractionType, evidence)
24    
25    // Apply slash
26    val.Tokens = val.Tokens.Sub(slashAmount)
27    sm.keeper.SetValidator(ctx, val)
28    
29    // Distribute slashed tokens
30    sm.distributeSlashedTokens(ctx, slashAmount, evidence)
31    
32    // Update reputation
33    sm.keeper.DecreaseReputation(ctx, validator, infractionType)
34    
35    // Emit event
36    ctx.EventManager().EmitEvent(
37        sdk.NewEvent(
38            types.EventTypeSlash,
39            sdk.NewAttribute(types.AttributeKeyValidator, validator.String()),
40            sdk.NewAttribute(types.AttributeKeySlashAmount, slashAmount.String()),
41            sdk.NewAttribute(types.AttributeKeyInfractionType, string(infractionType)),
42        ),
43    )
44    
45    return nil
46}

 1package execution
 2
 3// ParallelExecutor executes transactions in parallel
 4type ParallelExecutor struct {
 5    maxWorkers int
 6    semaphore  chan struct{}
 7}
 8
 9func NewParallelExecutor(maxWorkers int) *ParallelExecutor {
10    return &ParallelExecutor{
11        maxWorkers: maxWorkers,
12        semaphore:  make(chan struct{}, maxWorkers),
13    }
14}
15
16// ExecuteBatch executes transactions in parallel
17func (pe *ParallelExecutor) ExecuteBatch(
18    ctx sdk.Context,
19    txs []sdk.Tx,
20) ([]sdk.Result, []error) {
21    results := make([]sdk.Result, len(txs))
22    errors := make([]error, len(txs))
23    
24    var wg sync.WaitGroup
25    
26    for i, tx := range txs {
27        wg.Add(1)
28        
29        go func(idx int, transaction sdk.Tx) {
30            defer wg.Done()
31            
32            // Acquire semaphore
33            pe.semaphore <- struct{}{}
34            defer func() { <-pe.semaphore }()
35            
36            // Execute transaction
37            result, err := pe.executeTx(ctx, transaction)
38            results[idx] = result
39            errors[idx] = err
40        }(i, tx)
41    }
42    
43    wg.Wait()
44    
45    return results, errors
46}
47
48// executeTx executes single transaction
49func (pe *ParallelExecutor) executeTx(ctx sdk.Context, tx sdk.Tx) (sdk.Result, error) {
50    // Create isolated context for parallel execution
51    isolatedCtx := ctx.WithIsolated(true)
52    
53    // Execute
54    return pe.handler.DeliverTx(isolatedCtx, tx)
55}

 1// DependencyAnalyzer analyzes transaction dependencies
 2type DependencyAnalyzer struct{}
 3
 4// AnalyzeDependencies finds transaction dependencies
 5func (da *DependencyAnalyzer) AnalyzeDependencies(txs []sdk.Tx) [][]int {
 6    graph := make(map[int][]int)
 7    
 8    // Build dependency graph
 9    for i, tx := range txs {
10        deps := da.findDependencies(tx, txs)
11        graph[i] = deps
12    }
13    
14    // Topological sort
15    return da.topologicalSort(graph)
16}
17
18// findDependencies finds transactions this tx depends on
19func (da *DependencyAnalyzer) findDependencies(tx sdk.Tx, allTxs []sdk.Tx) []int {
20    var deps []int
21    
22    // Check if tx reads/writes same accounts
23    txAccounts := da.getAccounts(tx)
24    
25    for i, otherTx := range allTxs {
26        if i == 0 {
27            continue
28        }
29        
30        otherAccounts := da.getAccounts(otherTx)
31        
32        // Check for overlap
33        if da.hasOverlap(txAccounts, otherAccounts) {
34            deps = append(deps, i)
35        }
36    }
37    
38    return deps
39}

 1package indexing
 2
 3// EventIndexer indexes events for efficient querying
 4type EventIndexer struct {
 5    store sdk.KVStore
 6}
 7
 8// IndexEvent indexes an event
 9func (ei *EventIndexer) IndexEvent(ctx sdk.Context, event sdk.Event) error {
10    // Index by type
11    typeKey := ei.getTypeKey(event.Type)
12    ei.addToIndex(typeKey, event)
13    
14    // Index by each attribute
15    for _, attr := range event.Attributes {
16        attrKey := ei.getAttributeKey(event.Type, attr.Key, attr.Value)
17        ei.addToIndex(attrKey, event)
18    }
19    
20    // Index by time range
21    timeKey := ei.getTimeKey(ctx.BlockTime(), event.Type)
22    ei.addToIndex(timeKey, event)
23    
24    return nil
25}
26
27// QueryEvents queries events with filters
28func (ei *EventIndexer) QueryEvents(
29    ctx sdk.Context,
30    filters []EventFilter,
31    pagination *query.PageRequest,
32) ([]sdk.Event, *query.PageResponse, error) {
33    // Build query plan
34    plan := ei.buildQueryPlan(filters)
35    
36    // Execute query
37    events, err := ei.executeQuery(ctx, plan, pagination)
38    if err != nil {
39        return nil, nil, err
40    }
41    
42    return events, pagination, nil
43}
44
45// buildQueryPlan optimizes query execution
46func (ei *EventIndexer) buildQueryPlan(filters []EventFilter) *QueryPlan {
47    plan := &QueryPlan{}
48    
49    // Find most selective filter
50    mostSelective := ei.findMostSelective(filters)
51    plan.PrimaryFilter = mostSelective
52    
53    // Add secondary filters
54    for _, filter := range filters {
55        if filter != mostSelective {
56            plan.SecondaryFilters = append(plan.SecondaryFilters, filter)
57        }
58    }
59    
60    return plan
61}

 1package governance
 2
 3// QuadraticVoting implements quadratic voting
 4type QuadraticVoting struct {
 5    keeper Keeper
 6}
 7
 8// Vote with quadratic weighting
 9func (qv *QuadraticVoting) Vote(
10    ctx sdk.Context,
11    proposalId uint64,
12    voter sdk.AccAddress,
13    option VoteOption,
14    votingPower sdk.Int,
15) error {
16    // Calculate cost (quadratic)
17    cost := qv.calculateCost(votingPower)
18    
19    // Check if voter has enough tokens
20    balance := qv.keeper.GetBalance(ctx, voter)
21    if balance.AmountOf("stake").LT(cost) {
22        return sdkerrors.Wrap(sdkerrors.ErrInsufficientFunds, "insufficient voting power")
23    }
24    
25    // Deduct cost
26    err := qv.keeper.SendCoinsFromAccountToModule(
27        ctx,
28        voter,
29        types.GovernanceModuleName,
30        sdk.NewCoins(sdk.NewCoin("stake", cost)),
31    )
32    if err != nil {
33        return err
34    }
35    
36    // Record vote
37    vote := types.Vote{
38        ProposalId:  proposalId,
39        Voter:       voter.String(),
40        Option:      option,
41        VotingPower: votingPower,
42        Cost:        cost,
43    }
44    
45    qv.keeper.SetVote(ctx, vote)
46    
47    // Update proposal tally
48    qv.keeper.UpdateTally(ctx, proposalId, option, votingPower)
49    
50    return nil
51}
52
53// calculateCost calculates quadratic cost
54func (qv *QuadraticVoting) calculateCost(votingPower sdk.Int) sdk.Int {
55    // Cost = votingPower^2
56    return votingPower.Mul(votingPower)
57}

 1package replication
 2
 3// StateReplicator replicates state across nodes
 4type StateReplicator struct {
 5    keeper Keeper
 6    peers  []Peer
 7}
 8
 9// ReplicateState replicates state to peers
10func (sr *StateReplicator) ReplicateState(ctx sdk.Context) error {
11    // Get current state
12    state := sr.getStateSnapshot(ctx)
13    
14    // Replicate to all peers
15    var wg sync.WaitGroup
16    errors := make(chan error, len(sr.peers))
17    
18    for _, peer := range sr.peers {
19        wg.Add(1)
20        go func(p Peer) {
21            defer wg.Done()
22            if err := p.SendState(state); err != nil {
23                errors <- err
24            }
25        }(peer)
26    }
27    
28    wg.Wait()
29    close(errors)
30    
31    // Check for errors
32    for err := range errors {
33        if err != nil {
34            return err
35        }
36    }
37    
38    return nil
39}
40
41// RecoverState recovers state from peers
42func (sr *StateReplicator) RecoverState(ctx sdk.Context, targetHeight int64) error {
43    // Request state from peers
44    states := make([]StateSnapshot, 0)
45    
46    for _, peer := range sr.peers {
47        state, err := peer.RequestState(targetHeight)
48        if err != nil {
49            continue
50        }
51        states = append(states, state)
52    }
53    
54    // Verify and merge states
55    verifiedState := sr.verifyAndMerge(states)
56    
57    // Restore state
58    return sr.restoreState(ctx, verifiedState)
59}

 1// ConnectionPool manages database connections
 2type ConnectionPool struct {
 3    pool *sql.DB
 4    maxConnections int
 5}
 6
 7func NewConnectionPool(maxConn int) *ConnectionPool {
 8    db, _ := sql.Open("postgres", "...")
 9    db.SetMaxOpenConns(maxConn)
10    db.SetMaxIdleConns(maxConn / 2)
11    return &ConnectionPool{pool: db, maxConnections: maxConn}
12}

 1// BatchProcessor processes operations in batches
 2func (k Keeper) BatchUpdate(ctx sdk.Context, updates []Update) error {
 3    batch := k.store.NewBatch()
 4    defer batch.Close()
 5    
 6    for _, update := range updates {
 7        batch.Set(update.Key, update.Value)
 8    }
 9    
10    return batch.Write()
11}

 1// AsyncProcessor processes operations asynchronously
 2type AsyncProcessor struct {
 3    queue chan Operation
 4    workers int
 5}
 6
 7func (ap *AsyncProcessor) ProcessAsync(op Operation) {
 8    ap.queue <- op
 9}
10
11func (ap *AsyncProcessor) worker() {
12    for op := range ap.queue {
13        ap.process(op)
14    }
15}

 1// StatePruner prunes old state
 2func (k Keeper) PruneState(ctx sdk.Context, keepHeight int64) error {
 3    currentHeight := ctx.BlockHeight()
 4    
 5    if currentHeight-keepHeight < 100 {
 6        return nil // Don't prune recent state
 7    }
 8    
 9    // Prune old state
10    return k.pruneOldState(ctx, currentHeight-keepHeight)
11}