Update API of requester.BlocksProvider type to avoid concurrency issues

Author: m-Peter

api/debug.go

@@ -178,10 +178,9 @@ func (d *DebugAPI) TraceCall(
 	blocksProvider := requester.NewBlocksProvider(
 		d.blocks,
 		d.config.FlowNetworkID,
-	)
-	blocksProvider.SetTracer(tracer)
+	).WithTracer(tracer)
 	if config.BlockOverrides != nil {
-		blocksProvider.SetBlockOverrides(&ethTypes.BlockOverrides{
+		blocksProvider = blocksProvider.WithBlockOverrides(&ethTypes.BlockOverrides{
 			Number:   config.BlockOverrides.Number,
 			Time:     config.BlockOverrides.Time,
 			Coinbase: config.BlockOverrides.Coinbase,

bootstrap/bootstrap.go

@@ -208,11 +208,6 @@ func (b *Bootstrap) StartAPIServer(ctx context.Context) error {
 		b.config,
 	)
 
-	blocksProvider := requester.NewBlocksProvider(
-		b.storages.Blocks,
-		b.config.FlowNetworkID,
-	)
-
 	accountKeys := make([]*requester.AccountKey, 0)
 	if !b.config.IndexOnly {
 		account, err := b.client.GetAccount(ctx, b.config.COAAddress)
@@ -245,7 +240,6 @@ func (b *Bootstrap) StartAPIServer(ctx context.Context) error {
 
 	evm, err := requester.NewEVM(
 		b.storages.Registers,
-		blocksProvider,
 		b.client,
 		b.config,
 		b.logger,

services/replayer/blocks_provider.go

@@ -41,6 +41,13 @@ func (bs *blockSnapshot) BlockContext() (evmTypes.BlockContext, error) {
 	)
 }
 
+// This BlocksProvider implementation is used in the EVM events ingestion pipeline.
+// The ingestion module notifies the BlocksProvider of incoming EVM blocks, by
+// calling the `OnBlockReceived` method. This method guarantees that blocks are
+// processed sequentially, and keeps track of the latest block, which is used
+// for generating the proper `BlockContext`. This is necessary for replaying
+// EVM blocks/transactions locally, and verifying that there are no state
+// mismatches.
 type BlocksProvider struct {
 	blocks      storage.BlockIndexer
 	chainID     flowGo.ChainID

services/requester/blocks_provider.go

@@ -65,6 +65,10 @@ func (bs *blockSnapshot) BlockContext() (evmTypes.BlockContext, error) {
 	return blockContext, nil
 }
 
+// This BlocksProvider implementation is only used for the `eth_call` &
+// `debug_traceCall` JSON-RPC endpoints. It accepts optional `Tracer` &
+// `BlockOverrides` objects, which are used when constructing the
+// `BlockContext` object.
 type BlocksProvider struct {
 	blocks         storage.BlockIndexer
 	chainID        flowGo.ChainID
@@ -84,12 +88,24 @@ func NewBlocksProvider(
 	}
 }
 
-func (bp *BlocksProvider) SetTracer(tracer *tracers.Tracer) {
-	bp.tracer = tracer
+func (bp *BlocksProvider) WithTracer(tracer *tracers.Tracer) *BlocksProvider {
+	return &BlocksProvider{
+		blocks:         bp.blocks,
+		chainID:        bp.chainID,
+		tracer:         tracer,
+		blockOverrides: bp.blockOverrides,
+	}
 }
 
-func (bp *BlocksProvider) SetBlockOverrides(blockOverrides *ethTypes.BlockOverrides) {
-	bp.blockOverrides = blockOverrides
+func (bp *BlocksProvider) WithBlockOverrides(
+	blockOverrides *ethTypes.BlockOverrides,
+) *BlocksProvider {
+	return &BlocksProvider{
+		blocks:         bp.blocks,
+		chainID:        bp.chainID,
+		tracer:         bp.tracer,
+		blockOverrides: blockOverrides,
+	}
 }
 
 func (bp *BlocksProvider) GetSnapshotAt(height uint64) (

services/requester/requester.go

@@ -95,15 +95,14 @@ type Requester interface {
 var _ Requester = &EVM{}
 
 type EVM struct {
-	registerStore  *pebble.RegisterStorage
-	blocksProvider *BlocksProvider
-	client         *CrossSporkClient
-	config         config.Config
-	txPool         *TxPool
-	logger         zerolog.Logger
-	blocks         storage.BlockIndexer
-	mux            sync.Mutex
-	keystore       *KeyStore
+	registerStore *pebble.RegisterStorage
+	client        *CrossSporkClient
+	config        config.Config
+	txPool        *TxPool
+	logger        zerolog.Logger
+	blocks        storage.BlockIndexer
+	mux           sync.Mutex
+	keystore      *KeyStore
 
 	head              *types.Header
 	evmSigner         types.Signer
@@ -113,7 +112,6 @@ type EVM struct {
 
 func NewEVM(
 	registerStore *pebble.RegisterStorage,
-	blocksProvider *BlocksProvider,
 	client *CrossSporkClient,
 	config config.Config,
 	logger zerolog.Logger,
@@ -168,7 +166,6 @@ func NewEVM(
 
 	evm := &EVM{
 		registerStore:     registerStore,
-		blocksProvider:    blocksProvider,
 		client:            client,
 		config:            config,
 		logger:            logger,
@@ -443,15 +440,17 @@ func (e *EVM) getBlockView(
 	height uint64,
 	blockOverrides *ethTypes.BlockOverrides,
 ) (*query.View, error) {
+	blocksProvider := NewBlocksProvider(e.blocks, e.config.FlowNetworkID)
+
 	if blockOverrides != nil {
-		e.blocksProvider.SetBlockOverrides(blockOverrides)
+		blocksProvider = blocksProvider.WithBlockOverrides(blockOverrides)
 	}
 
 	viewProvider := query.NewViewProvider(
 		e.config.FlowNetworkID,
 		evm.StorageAccountAddress(e.config.FlowNetworkID),
 		e.registerStore,
-		e.blocksProvider,
+		blocksProvider,
 		blockGasLimit,
 	)