eth/filters: avoid block body retrieval when no matching logs (ethereum#25199)

Logs stored on disk have minimal information. Contextual information such as block
number, index of log in block, index of transaction in block are filled in upon request.
We can fill in all these fields only having the block header and list of receipts.
But determining the transaction hash of a log requires the block body.

The goal of this PR is postponing this retrieval until we are sure we the transaction hash.
It happens often that the header bloom filter signals there might be matches in a block,
but after actually checking them reveals the logs do not match. We want to avoid fetching
the body in this case.

Note that this changes the semantics of Backend.GetLogs. Downstream callers of
GetLogs now assume log context fields have not been derived, and need to call
DeriveFields on the logs if necessary.

Author: s1na

accounts/abi/bind/backends/simulated.go

@@ -872,6 +872,13 @@ func (fb *filterBackend) HeaderByHash(ctx context.Context, hash common.Hash) (*t
 	return fb.bc.GetHeaderByHash(hash), nil
 }
 
+func (fb *filterBackend) GetBody(ctx context.Context, hash common.Hash, number rpc.BlockNumber) (*types.Body, error) {
+	if body := fb.bc.GetBody(hash); body != nil {
+		return body, nil
+	}
+	return nil, errors.New("block body not found")
+}
+
 func (fb *filterBackend) PendingBlockAndReceipts() (*types.Block, types.Receipts) {
 	return fb.backend.pendingBlock, fb.backend.pendingReceipts
 }

core/rawdb/accessors_chain.go

@@ -714,9 +714,9 @@ func deriveLogFields(receipts []*receiptLogs, hash common.Hash, number uint64, t
 	return nil
 }
 
-// ReadLogs retrieves the logs for all transactions in a block. The log fields
-// are populated with metadata. In case the receipts or the block body
-// are not found, a nil is returned.
+// ReadLogs retrieves the logs for all transactions in a block. In case
+// receipts is not found, a nil is returned.
+// Note: ReadLogs does not derive unstored log fields.
 func ReadLogs(db ethdb.Reader, hash common.Hash, number uint64, config *params.ChainConfig) [][]*types.Log {
 	// Retrieve the flattened receipt slice
 	data := ReadReceiptsRLP(db, hash, number)
@@ -729,15 +729,6 @@ func ReadLogs(db ethdb.Reader, hash common.Hash, number uint64, config *params.C
 		return nil
 	}
 
-	body := ReadBody(db, hash, number)
-	if body == nil {
-		log.Error("Missing body but have receipt", "hash", hash, "number", number)
-		return nil
-	}
-	if err := deriveLogFields(receipts, hash, number, body.Transactions); err != nil {
-		log.Error("Failed to derive block receipts fields", "hash", hash, "number", number, "err", err)
-		return nil
-	}
 	logs := make([][]*types.Log, len(receipts))
 	for i, receipt := range receipts {
 		logs[i] = receipt.Logs

core/rawdb/accessors_chain_test.go

@@ -750,10 +750,6 @@ func TestReadLogs(t *testing.T) {
 		t.Fatalf("unexpected number of logs[1] returned, have %d want %d", have, want)
 	}
 
-	// Fill in log fields so we can compare their rlp encoding
-	if err := types.Receipts(receipts).DeriveFields(params.TestChainConfig, hash, 0, body.Transactions); err != nil {
-		t.Fatal(err)
-	}
 	for i, pr := range receipts {
 		for j, pl := range pr.Logs {
 			rlpHave, err := rlp.EncodeToBytes(newFullLogRLP(logs[i][j]))

eth/api_backend.go

@@ -135,6 +135,17 @@ func (b *EthAPIBackend) BlockByHash(ctx context.Context, hash common.Hash) (*typ
 	return b.eth.blockchain.GetBlockByHash(hash), nil
 }
 
+// GetBody returns body of a block. It does not resolve special block numbers.
+func (b *EthAPIBackend) GetBody(ctx context.Context, hash common.Hash, number rpc.BlockNumber) (*types.Body, error) {
+	if number < 0 || hash == (common.Hash{}) {
+		return nil, errors.New("invalid arguments; expect hash and no special block numbers")
+	}
+	if body := b.eth.blockchain.GetBody(hash); body != nil {
+		return body, nil
+	}
+	return nil, errors.New("block body not found")
+}
+
 func (b *EthAPIBackend) BlockByNumberOrHash(ctx context.Context, blockNrOrHash rpc.BlockNumberOrHash) (*types.Block, error) {
 	if blockNr, ok := blockNrOrHash.Number(); ok {
 		return b.BlockByNumber(ctx, blockNr)

eth/filters/filter.go

@@ -104,7 +104,7 @@ func (f *Filter) Logs(ctx context.Context) ([]*types.Log, error) {
 		if header == nil {
 			return nil, errors.New("unknown block")
 		}
-		return f.blockLogs(ctx, header, false)
+		return f.blockLogs(ctx, header)
 	}
 	// Short-cut if all we care about is pending logs
 	if f.begin == rpc.PendingBlockNumber.Int64() {
@@ -216,7 +216,7 @@ func (f *Filter) indexedLogs(ctx context.Context, end uint64) ([]*types.Log, err
 			if header == nil || err != nil {
 				return logs, err
 			}
-			found, err := f.blockLogs(ctx, header, true)
+			found, err := f.checkMatches(ctx, header)
 			if err != nil {
 				return logs, err
 			}
@@ -241,7 +241,7 @@ func (f *Filter) unindexedLogs(ctx context.Context, end uint64) ([]*types.Log, e
 		if header == nil || err != nil {
 			return logs, err
 		}
-		found, err := f.blockLogs(ctx, header, false)
+		found, err := f.blockLogs(ctx, header)
 		if err != nil {
 			return logs, err
 		}
@@ -251,46 +251,46 @@ func (f *Filter) unindexedLogs(ctx context.Context, end uint64) ([]*types.Log, e
 }
 
 // blockLogs returns the logs matching the filter criteria within a single block.
-func (f *Filter) blockLogs(ctx context.Context, header *types.Header, skipBloom bool) ([]*types.Log, error) {
-	// Fast track: no filtering criteria
-	if len(f.addresses) == 0 && len(f.topics) == 0 {
-		list, err := f.sys.cachedGetLogs(ctx, header.Hash(), header.Number.Uint64())
-		if err != nil {
-			return nil, err
-		}
-		return flatten(list), nil
-	} else if skipBloom || bloomFilter(header.Bloom, f.addresses, f.topics) {
+func (f *Filter) blockLogs(ctx context.Context, header *types.Header) ([]*types.Log, error) {
+	if bloomFilter(header.Bloom, f.addresses, f.topics) {
 		return f.checkMatches(ctx, header)
 	}
 	return nil, nil
 }
 
 // checkMatches checks if the receipts belonging to the given header contain any log events that
 // match the filter criteria. This function is called when the bloom filter signals a potential match.
+// skipFilter signals all logs of the given block are requested.
 func (f *Filter) checkMatches(ctx context.Context, header *types.Header) ([]*types.Log, error) {
-	logsList, err := f.sys.cachedGetLogs(ctx, header.Hash(), header.Number.Uint64())
+	hash := header.Hash()
+	// Logs in cache are partially filled with context data
+	// such as tx index, block hash, etc.
+	// Notably tx hash is NOT filled in because it needs
+	// access to block body data.
+	cached, err := f.sys.cachedLogElem(ctx, hash, header.Number.Uint64())
 	if err != nil {
 		return nil, err
 	}
-
-	unfiltered := flatten(logsList)
-	logs := filterLogs(unfiltered, nil, nil, f.addresses, f.topics)
-	if len(logs) > 0 {
-		// We have matching logs, check if we need to resolve full logs via the light client
-		if logs[0].TxHash == (common.Hash{}) {
-			receipts, err := f.sys.backend.GetReceipts(ctx, header.Hash())
-			if err != nil {
-				return nil, err
-			}
-			unfiltered = unfiltered[:0]
-			for _, receipt := range receipts {
-				unfiltered = append(unfiltered, receipt.Logs...)
-			}
-			logs = filterLogs(unfiltered, nil, nil, f.addresses, f.topics)
-		}
+	logs := filterLogs(cached.logs, nil, nil, f.addresses, f.topics)
+	if len(logs) == 0 {
+		return nil, nil
+	}
+	// Most backends will deliver un-derived logs, but check nevertheless.
+	if len(logs) > 0 && logs[0].TxHash != (common.Hash{}) {
 		return logs, nil
 	}
-	return nil, nil
+
+	body, err := f.sys.cachedGetBody(ctx, cached, hash, header.Number.Uint64())
+	if err != nil {
+		return nil, err
+	}
+	for i, log := range logs {
+		// Copy log not to modify cache elements
+		logcopy := *log
+		logcopy.TxHash = body.Transactions[logcopy.TxIndex].Hash()
+		logs[i] = &logcopy
+	}
+	return logs, nil
 }
 
 // pendingLogs returns the logs matching the filter criteria within the pending block.
@@ -380,11 +380,3 @@ func bloomFilter(bloom types.Bloom, addresses []common.Address, topics [][]commo
 	}
 	return true
 }
-
-func flatten(list [][]*types.Log) []*types.Log {
-	var flat []*types.Log
-	for _, logs := range list {
-		flat = append(flat, logs...)
-	}
-	return flat
-}

eth/filters/filter_system.go

@@ -22,6 +22,7 @@ import (
 	"context"
 	"fmt"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/ethereum/go-ethereum"
@@ -58,6 +59,7 @@ type Backend interface {
 	ChainDb() ethdb.Database
 	HeaderByNumber(ctx context.Context, blockNr rpc.BlockNumber) (*types.Header, error)
 	HeaderByHash(ctx context.Context, blockHash common.Hash) (*types.Header, error)
+	GetBody(ctx context.Context, hash common.Hash, number rpc.BlockNumber) (*types.Body, error)
 	GetReceipts(ctx context.Context, blockHash common.Hash) (types.Receipts, error)
 	GetLogs(ctx context.Context, blockHash common.Hash, number uint64) ([][]*types.Log, error)
 	PendingBlockAndReceipts() (*types.Block, types.Receipts)
@@ -77,7 +79,7 @@ type Backend interface {
 // FilterSystem holds resources shared by all filters.
 type FilterSystem struct {
 	backend   Backend
-	logsCache *lru.Cache[common.Hash, [][]*types.Log]
+	logsCache *lru.Cache[common.Hash, *logCacheElem]
 	cfg       *Config
 }
 
@@ -86,13 +88,18 @@ func NewFilterSystem(backend Backend, config Config) *FilterSystem {
 	config = config.withDefaults()
 	return &FilterSystem{
 		backend:   backend,
-		logsCache: lru.NewCache[common.Hash, [][]*types.Log](config.LogCacheSize),
+		logsCache: lru.NewCache[common.Hash, *logCacheElem](config.LogCacheSize),
 		cfg:       &config,
 	}
 }
 
-// cachedGetLogs loads block logs from the backend and caches the result.
-func (sys *FilterSystem) cachedGetLogs(ctx context.Context, blockHash common.Hash, number uint64) ([][]*types.Log, error) {
+type logCacheElem struct {
+	logs []*types.Log
+	body atomic.Pointer[types.Body]
+}
+
+// cachedLogElem loads block logs from the backend and caches the result.
+func (sys *FilterSystem) cachedLogElem(ctx context.Context, blockHash common.Hash, number uint64) (*logCacheElem, error) {
 	cached, ok := sys.logsCache.Get(blockHash)
 	if ok {
 		return cached, nil
@@ -105,8 +112,35 @@ func (sys *FilterSystem) cachedGetLogs(ctx context.Context, blockHash common.Has
 	if logs == nil {
 		return nil, fmt.Errorf("failed to get logs for block #%d (0x%s)", number, blockHash.TerminalString())
 	}
-	sys.logsCache.Add(blockHash, logs)
-	return logs, nil
+	// Database logs are un-derived.
+	// Fill in whatever we can (txHash is inaccessible at this point).
+	flattened := make([]*types.Log, 0)
+	var logIdx uint
+	for i, txLogs := range logs {
+		for _, log := range txLogs {
+			log.BlockHash = blockHash
+			log.BlockNumber = number
+			log.TxIndex = uint(i)
+			log.Index = logIdx
+			logIdx++
+			flattened = append(flattened, log)
+		}
+	}
+	elem := &logCacheElem{logs: flattened}
+	sys.logsCache.Add(blockHash, elem)
+	return elem, nil
+}
+
+func (sys *FilterSystem) cachedGetBody(ctx context.Context, elem *logCacheElem, hash common.Hash, number uint64) (*types.Body, error) {
+	if body := elem.body.Load(); body != nil {
+		return body, nil
+	}
+	body, err := sys.backend.GetBody(ctx, hash, rpc.BlockNumber(number))
+	if err != nil {
+		return nil, err
+	}
+	elem.body.Store(body)
+	return body, nil
 }
 
 // Type determines the kind of filter and is used to put the filter in to
@@ -431,6 +465,12 @@ func (es *EventSystem) handleChainEvent(filters filterIndex, ev core.ChainEvent)
 	if es.lightMode && len(filters[LogsSubscription]) > 0 {
 		es.lightFilterNewHead(ev.Block.Header(), func(header *types.Header, remove bool) {
 			for _, f := range filters[LogsSubscription] {
+				if f.logsCrit.FromBlock != nil && header.Number.Cmp(f.logsCrit.FromBlock) < 0 {
+					continue
+				}
+				if f.logsCrit.ToBlock != nil && header.Number.Cmp(f.logsCrit.ToBlock) > 0 {
+					continue
+				}
 				if matchedLogs := es.lightFilterLogs(header, f.logsCrit.Addresses, f.logsCrit.Topics, remove); len(matchedLogs) > 0 {
 					f.logs <- matchedLogs
 				}
@@ -474,42 +514,39 @@ func (es *EventSystem) lightFilterNewHead(newHeader *types.Header, callBack func
 
 // filter logs of a single header in light client mode
 func (es *EventSystem) lightFilterLogs(header *types.Header, addresses []common.Address, topics [][]common.Hash, remove bool) []*types.Log {
-	if bloomFilter(header.Bloom, addresses, topics) {
-		// Get the logs of the block
-		ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
-		defer cancel()
-		logsList, err := es.sys.cachedGetLogs(ctx, header.Hash(), header.Number.Uint64())
-		if err != nil {
-			return nil
-		}
-		var unfiltered []*types.Log
-		for _, logs := range logsList {
-			for _, log := range logs {
-				logcopy := *log
-				logcopy.Removed = remove
-				unfiltered = append(unfiltered, &logcopy)
-			}
-		}
-		logs := filterLogs(unfiltered, nil, nil, addresses, topics)
-		if len(logs) > 0 && logs[0].TxHash == (common.Hash{}) {
-			// We have matching but non-derived logs
-			receipts, err := es.backend.GetReceipts(ctx, header.Hash())
-			if err != nil {
-				return nil
-			}
-			unfiltered = unfiltered[:0]
-			for _, receipt := range receipts {
-				for _, log := range receipt.Logs {
-					logcopy := *log
-					logcopy.Removed = remove
-					unfiltered = append(unfiltered, &logcopy)
-				}
-			}
-			logs = filterLogs(unfiltered, nil, nil, addresses, topics)
-		}
+	if !bloomFilter(header.Bloom, addresses, topics) {
+		return nil
+	}
+	// Get the logs of the block
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+	defer cancel()
+	cached, err := es.sys.cachedLogElem(ctx, header.Hash(), header.Number.Uint64())
+	if err != nil {
+		return nil
+	}
+	unfiltered := append([]*types.Log{}, cached.logs...)
+	for i, log := range unfiltered {
+		// Don't modify in-cache elements
+		logcopy := *log
+		logcopy.Removed = remove
+		// Swap copy in-place
+		unfiltered[i] = &logcopy
+	}
+	logs := filterLogs(unfiltered, nil, nil, addresses, topics)
+	// Txhash is already resolved
+	if len(logs) > 0 && logs[0].TxHash != (common.Hash{}) {
 		return logs
 	}
-	return nil
+	// Resolve txhash
+	body, err := es.sys.cachedGetBody(ctx, cached, header.Hash(), header.Number.Uint64())
+	if err != nil {
+		return nil
+	}
+	for _, log := range logs {
+		// logs are already copied, safe to modify
+		log.TxHash = body.Transactions[log.TxIndex].Hash()
+	}
+	return logs
 }
 
 // eventLoop (un)installs filters and processes mux events.