eth/filters, eth/tracers: add request cancellation checks (#26320)

This ensures that RPC method handlers will react to a timeout or
cancelled request soon after the event occurs.
Co-authored-by: Sina Mahmoodi <itz.s1na@gmail.com>

eth/api.go

@@ -405,13 +405,13 @@ type storageEntry struct {
 }
 
 // StorageRangeAt returns the storage at the given block height and transaction index.
-func (api *DebugAPI) StorageRangeAt(blockHash common.Hash, txIndex int, contractAddress common.Address, keyStart hexutil.Bytes, maxResult int) (StorageRangeResult, error) {
+func (api *DebugAPI) StorageRangeAt(ctx context.Context, blockHash common.Hash, txIndex int, contractAddress common.Address, keyStart hexutil.Bytes, maxResult int) (StorageRangeResult, error) {
 	// Retrieve the block
 	block := api.eth.blockchain.GetBlockByHash(blockHash)
 	if block == nil {
 		return StorageRangeResult{}, fmt.Errorf("block %#x not found", blockHash)
 	}
-	_, _, statedb, release, err := api.eth.stateAtTransaction(block, txIndex, 0)
+	_, _, statedb, release, err := api.eth.stateAtTransaction(ctx, block, txIndex, 0)
 	if err != nil {
 		return StorageRangeResult{}, err
 	}

eth/api_backend.go

@@ -365,9 +365,9 @@ func (b *EthAPIBackend) StartMining(threads int) error {
 }
 
 func (b *EthAPIBackend) StateAtBlock(ctx context.Context, block *types.Block, reexec uint64, base *state.StateDB, readOnly bool, preferDisk bool) (*state.StateDB, tracers.StateReleaseFunc, error) {
-	return b.eth.StateAtBlock(block, reexec, base, readOnly, preferDisk)
+	return b.eth.StateAtBlock(ctx, block, reexec, base, readOnly, preferDisk)
 }
 
 func (b *EthAPIBackend) StateAtTransaction(ctx context.Context, block *types.Block, txIndex int, reexec uint64) (core.Message, vm.BlockContext, *state.StateDB, tracers.StateReleaseFunc, error) {
-	return b.eth.stateAtTransaction(block, txIndex, reexec)
+	return b.eth.stateAtTransaction(ctx, block, txIndex, reexec)
 }

eth/filters/filter.go

@@ -234,6 +234,9 @@ func (f *Filter) unindexedLogs(ctx context.Context, end uint64) ([]*types.Log, e
 	var logs []*types.Log
 
 	for ; f.begin <= int64(end); f.begin++ {
+		if f.begin%10 == 0 && ctx.Err() != nil {
+			return logs, ctx.Err()
+		}
 		header, err := f.sys.backend.HeaderByNumber(ctx, rpc.BlockNumber(f.begin))
 		if header == nil || err != nil {
 			return logs, err

eth/state_accessor.go

@@ -17,6 +17,7 @@
 package eth
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"time"
@@ -56,7 +57,7 @@ var noopReleaser = tracers.StateReleaseFunc(func() {})
 //   - preferDisk: this arg can be used by the caller to signal that even though the 'base' is
 //     provided, it would be preferable to start from a fresh state, if we have it
 //     on disk.
-func (eth *Ethereum) StateAtBlock(block *types.Block, reexec uint64, base *state.StateDB, readOnly bool, preferDisk bool) (statedb *state.StateDB, release tracers.StateReleaseFunc, err error) {
+func (eth *Ethereum) StateAtBlock(ctx context.Context, block *types.Block, reexec uint64, base *state.StateDB, readOnly bool, preferDisk bool) (statedb *state.StateDB, release tracers.StateReleaseFunc, err error) {
 	var (
 		current  *types.Block
 		database state.Database
@@ -111,6 +112,9 @@ func (eth *Ethereum) StateAtBlock(block *types.Block, reexec uint64, base *state
 		}
 		// Database does not have the state for the given block, try to regenerate
 		for i := uint64(0); i < reexec; i++ {
+			if err := ctx.Err(); err != nil {
+				return nil, nil, err
+			}
 			if current.NumberU64() == 0 {
 				return nil, nil, errors.New("genesis state is missing")
 			}
@@ -142,6 +146,9 @@ func (eth *Ethereum) StateAtBlock(block *types.Block, reexec uint64, base *state
 		parent common.Hash
 	)
 	for current.NumberU64() < origin {
+		if err := ctx.Err(); err != nil {
+			return nil, nil, err
+		}
 		// Print progress logs if long enough time elapsed
 		if time.Since(logged) > 8*time.Second && report {
 			log.Info("Regenerating historical state", "block", current.NumberU64()+1, "target", origin, "remaining", origin-current.NumberU64()-1, "elapsed", time.Since(start))
@@ -182,7 +189,7 @@ func (eth *Ethereum) StateAtBlock(block *types.Block, reexec uint64, base *state
 }
 
 // stateAtTransaction returns the execution environment of a certain transaction.
-func (eth *Ethereum) stateAtTransaction(block *types.Block, txIndex int, reexec uint64) (core.Message, vm.BlockContext, *state.StateDB, tracers.StateReleaseFunc, error) {
+func (eth *Ethereum) stateAtTransaction(ctx context.Context, block *types.Block, txIndex int, reexec uint64) (core.Message, vm.BlockContext, *state.StateDB, tracers.StateReleaseFunc, error) {
 	// Short circuit if it's genesis block.
 	if block.NumberU64() == 0 {
 		return nil, vm.BlockContext{}, nil, nil, errors.New("no transaction in genesis")
@@ -194,7 +201,7 @@ func (eth *Ethereum) stateAtTransaction(block *types.Block, txIndex int, reexec
 	}
 	// Lookup the statedb of parent block from the live database,
 	// otherwise regenerate it on the flight.
-	statedb, release, err := eth.StateAtBlock(parent, reexec, nil, true, false)
+	statedb, release, err := eth.StateAtBlock(ctx, parent, reexec, nil, true, false)
 	if err != nil {
 		return nil, vm.BlockContext{}, nil, nil, err
 	}

eth/tracers/api.go

@@ -549,6 +549,9 @@ func (api *API) IntermediateRoots(ctx context.Context, hash common.Hash, config
 		deleteEmptyObjects = chainConfig.IsEIP158(block.Number())
 	)
 	for i, tx := range block.Transactions() {
+		if err := ctx.Err(); err != nil {
+			return nil, err
+		}
 		var (
 			msg, _    = tx.AsMessage(signer, block.BaseFee())
 			txContext = core.NewEVMTxContext(msg)
@@ -609,14 +612,13 @@ func (api *API) traceBlock(ctx context.Context, block *types.Block, config *Trac
 		signer  = types.MakeSigner(api.backend.ChainConfig(), block.Number())
 		txs     = block.Transactions()
 		results = make([]*txTraceResult, len(txs))
-
-		pend = new(sync.WaitGroup)
-		jobs = make(chan *txTraceTask, len(txs))
+		pend    sync.WaitGroup
 	)
 	threads := runtime.NumCPU()
 	if threads > len(txs) {
 		threads = len(txs)
 	}
+	jobs := make(chan *txTraceTask, threads)
 	blockHash := block.Hash()
 	for th := 0; th < threads; th++ {
 		pend.Add(1)
@@ -640,12 +642,20 @@ func (api *API) traceBlock(ctx context.Context, block *types.Block, config *Trac
 			}
 		}()
 	}
+
 	// Feed the transactions into the tracers and return
 	var failed error
 	blockCtx := core.NewEVMBlockContext(block.Header(), api.chainContext(ctx), nil)
+txloop:
 	for i, tx := range txs {
 		// Send the trace task over for execution
-		jobs <- &txTraceTask{statedb: statedb.Copy(), index: i}
+		task := &txTraceTask{statedb: statedb.Copy(), index: i}
+		select {
+		case <-ctx.Done():
+			failed = ctx.Err()
+			break txloop
+		case jobs <- task:
+		}
 
 		// Generate the next state snapshot fast without tracing
 		msg, _ := tx.AsMessage(signer, block.BaseFee())
@@ -653,12 +663,13 @@ func (api *API) traceBlock(ctx context.Context, block *types.Block, config *Trac
 		vmenv := vm.NewEVM(blockCtx, core.NewEVMTxContext(msg), statedb, api.backend.ChainConfig(), vm.Config{})
 		if _, err := core.ApplyMessage(vmenv, msg, new(core.GasPool).AddGas(msg.Gas())); err != nil {
 			failed = err
-			break
+			break txloop
 		}
 		// Finalize the state so any modifications are written to the trie
 		// Only delete empty objects if EIP158/161 (a.k.a Spurious Dragon) is in effect
 		statedb.Finalise(vmenv.ChainConfig().IsEIP158(block.Number()))
 	}
+
 	close(jobs)
 	pend.Wait()