accounts, eth, les: blockhash based filtering on all code paths

eth/filters/filter.go

@@ -18,6 +18,7 @@ package filters
 
 import (
 	"context"
+	"errors"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -33,6 +34,7 @@ type Backend interface {
 	ChainDb() ethdb.Database
 	EventMux() *event.TypeMux
 	HeaderByNumber(ctx context.Context, blockNr rpc.BlockNumber) (*types.Header, error)
+	HeaderByHash(ctx context.Context, blockHash common.Hash) (*types.Header, error)
 	GetReceipts(ctx context.Context, blockHash common.Hash) (types.Receipts, error)
 	GetLogs(ctx context.Context, blockHash common.Hash) ([][]*types.Log, error)
 
@@ -49,17 +51,19 @@ type Backend interface {
 type Filter struct {
 	backend Backend
 
-	db         ethdb.Database
-	begin, end int64
-	addresses  []common.Address
-	topics     [][]common.Hash
+	db        ethdb.Database
+	addresses []common.Address
+	topics    [][]common.Hash
+
+	block      common.Hash // Block hash if filtering a single block
+	begin, end int64       // Range interval if filtering multiple blocks
 
 	matcher *bloombits.Matcher
 }
 
-// New creates a new filter which uses a bloom filter on blocks to figure out whether
-// a particular block is interesting or not.
-func New(backend Backend, begin, end int64, addresses []common.Address, topics [][]common.Hash) *Filter {
+// NewRangeFilter creates a new filter which uses a bloom filter on blocks to
+// figure out whether a particular block is interesting or not.
+func NewRangeFilter(backend Backend, begin, end int64, addresses []common.Address, topics [][]common.Hash) *Filter {
 	// Flatten the address and topic filter clauses into a single bloombits filter
 	// system. Since the bloombits are not positional, nil topics are permitted,
 	// which get flattened into a nil byte slice.
@@ -78,23 +82,52 @@ func New(backend Backend, begin, end int64, addresses []common.Address, topics [
 		}
 		filters = append(filters, filter)
 	}
-	// Assemble and return the filter
 	size, _ := backend.BloomStatus()
 
+	// Create a generic filter and convert it into a range filter
+	filter := newFilter(backend, addresses, topics)
+
+	filter.matcher = bloombits.NewMatcher(size, filters)
+	filter.begin = begin
+	filter.end = end
+
+	return filter
+}
+
+// NewBlockFilter creates a new filter which directly inspects the contents of
+// a block to figure out whether it is interesting or not.
+func NewBlockFilter(backend Backend, block common.Hash, addresses []common.Address, topics [][]common.Hash) *Filter {
+	// Create a generic filter and convert it into a block filter
+	filter := newFilter(backend, addresses, topics)
+	filter.block = block
+	return filter
+}
+
+// newFilter creates a generic filter that can either filter based on a block hash,
+// or based on range queries. The search criteria needs to be explicitly set.
+func newFilter(backend Backend, addresses []common.Address, topics [][]common.Hash) *Filter {
 	return &Filter{
 		backend:   backend,
-		begin:     begin,
-		end:       end,
 		addresses: addresses,
 		topics:    topics,
 		db:        backend.ChainDb(),
-		matcher:   bloombits.NewMatcher(size, filters),
 	}
 }
 
 // Logs searches the blockchain for matching log entries, returning all from the
 // first block that contains matches, updating the start of the filter accordingly.
 func (f *Filter) Logs(ctx context.Context) ([]*types.Log, error) {
+	// If we're doing singleton block filtering, execute and return
+	if f.block != (common.Hash{}) {
+		header, err := f.backend.HeaderByHash(ctx, f.block)
+		if err != nil {
+			return nil, err
+		}
+		if header == nil {
+			return nil, errors.New("unknown block")
+		}
+		return f.blockLogs(ctx, header)
+	}
 	// Figure out the limits of the filter range
 	header, _ := f.backend.HeaderByNumber(ctx, rpc.LatestBlockNumber)
 	if header == nil {
@@ -187,13 +220,23 @@ func (f *Filter) unindexedLogs(ctx context.Context, end uint64) ([]*types.Log, e
 		if header == nil || err != nil {
 			return logs, err
 		}
-		if bloomFilter(header.Bloom, f.addresses, f.topics) {
-			found, err := f.checkMatches(ctx, header)
-			if err != nil {
-				return logs, err
-			}
-			logs = append(logs, found...)
+		found, err := f.blockLogs(ctx, header)
+		if err != nil {
+			return logs, err
 		}
+		logs = append(logs, found...)
+	}
+	return logs, nil
+}
+
+// blockLogs returns the logs matching the filter criteria within a single block.
+func (f *Filter) blockLogs(ctx context.Context, header *types.Header) (logs []*types.Log, err error) {
+	if bloomFilter(header.Bloom, f.addresses, f.topics) {
+		found, err := f.checkMatches(ctx, header)
+		if err != nil {
+			return logs, err
+		}
+		logs = append(logs, found...)
 	}
 	return logs, nil
 }