core/bloombits: handle non 8-bit boundary section matches

2 files changed, 40 insertions, 23 deletions

diff --git a/core/bloombits/matcher.go b/core/bloombits/matcher.go
index d38d4ba83..ce3031702 100644
--- a/core/bloombits/matcher.go
+++ b/core/bloombits/matcher.go
@@ -192,10 +192,12 @@ func (m *Matcher) Start(ctx context.Context, begin, end uint64, results chan uin
 				}
 				// Iterate over all the blocks in the section and return the matching ones
 				for i := first; i <= last; i++ {
-					// Skip the entire byte if no matches are found inside
+					// Skip the entire byte if no matches are found inside (and we're processing an entire byte!)
 					next := res.bitset[(i-sectionStart)/8]
 					if next == 0 {
-						i += 7
+						if i%8 == 0 {
+							i += 7
+						}
 						continue
 					}
 					// Some bit it set, do the actual submatching
diff --git a/core/bloombits/matcher_test.go b/core/bloombits/matcher_test.go
index 4a31854c5..7a5f78ef3 100644
--- a/core/bloombits/matcher_test.go
+++ b/core/bloombits/matcher_test.go
@@ -56,33 +56,48 @@ func TestMatcherWildcards(t *testing.T) {
 
 // Tests the matcher pipeline on a single continuous workflow without interrupts.
 func TestMatcherContinuous(t *testing.T) {
-	testMatcherDiffBatches(t, [][]bloomIndexes{{{10, 20, 30}}}, 100000, false, 75)
-	testMatcherDiffBatches(t, [][]bloomIndexes{{{32, 3125, 100}}, {{40, 50, 10}}}, 100000, false, 81)
-	testMatcherDiffBatches(t, [][]bloomIndexes{{{4, 8, 11}, {7, 8, 17}}, {{9, 9, 12}, {15, 20, 13}}, {{18, 15, 15}, {12, 10, 4}}}, 10000, false, 36)
+	testMatcherDiffBatches(t, [][]bloomIndexes{{{10, 20, 30}}}, 0, 100000, false, 75)
+	testMatcherDiffBatches(t, [][]bloomIndexes{{{32, 3125, 100}}, {{40, 50, 10}}}, 0, 100000, false, 81)
+	testMatcherDiffBatches(t, [][]bloomIndexes{{{4, 8, 11}, {7, 8, 17}}, {{9, 9, 12}, {15, 20, 13}}, {{18, 15, 15}, {12, 10, 4}}}, 0, 10000, false, 36)
 }
 
 // Tests the matcher pipeline on a constantly interrupted and resumed work pattern
 // with the aim of ensuring data items are requested only once.
 func TestMatcherIntermittent(t *testing.T) {
-	testMatcherDiffBatches(t, [][]bloomIndexes{{{10, 20, 30}}}, 100000, true, 75)
-	testMatcherDiffBatches(t, [][]bloomIndexes{{{32, 3125, 100}}, {{40, 50, 10}}}, 100000, true, 81)
-	testMatcherDiffBatches(t, [][]bloomIndexes{{{4, 8, 11}, {7, 8, 17}}, {{9, 9, 12}, {15, 20, 13}}, {{18, 15, 15}, {12, 10, 4}}}, 10000, true, 36)
+	testMatcherDiffBatches(t, [][]bloomIndexes{{{10, 20, 30}}}, 0, 100000, true, 75)
+	testMatcherDiffBatches(t, [][]bloomIndexes{{{32, 3125, 100}}, {{40, 50, 10}}}, 0, 100000, true, 81)
+	testMatcherDiffBatches(t, [][]bloomIndexes{{{4, 8, 11}, {7, 8, 17}}, {{9, 9, 12}, {15, 20, 13}}, {{18, 15, 15}, {12, 10, 4}}}, 0, 10000, true, 36)
 }
 
 // Tests the matcher pipeline on random input to hopefully catch anomalies.
 func TestMatcherRandom(t *testing.T) {
 	for i := 0; i < 10; i++ {
-		testMatcherBothModes(t, makeRandomIndexes([]int{1}, 50), 10000, 0)
-		testMatcherBothModes(t, makeRandomIndexes([]int{3}, 50), 10000, 0)
-		testMatcherBothModes(t, makeRandomIndexes([]int{2, 2, 2}, 20), 10000, 0)
-		testMatcherBothModes(t, makeRandomIndexes([]int{5, 5, 5}, 50), 10000, 0)
-		testMatcherBothModes(t, makeRandomIndexes([]int{4, 4, 4}, 20), 10000, 0)
+		testMatcherBothModes(t, makeRandomIndexes([]int{1}, 50), 0, 10000, 0)
+		testMatcherBothModes(t, makeRandomIndexes([]int{3}, 50), 0, 10000, 0)
+		testMatcherBothModes(t, makeRandomIndexes([]int{2, 2, 2}, 20), 0, 10000, 0)
+		testMatcherBothModes(t, makeRandomIndexes([]int{5, 5, 5}, 50), 0, 10000, 0)
+		testMatcherBothModes(t, makeRandomIndexes([]int{4, 4, 4}, 20), 0, 10000, 0)
 	}
 }
 
+// Tests that the matcher can properly find matches if the starting block is
+// shifter from a multiple of 8. This is needed to cover an optimisation with
+// bitset matching https://github.com/ethereum/go-ethereum/issues/15309.
+func TestMatcherShifted(t *testing.T) {
+	// Block 0 always matches in the tests, skip ahead of first 8 blocks with the
+	// start to get a potential zero byte in the matcher bitset.
+
+	// To keep the second bitset byte zero, the filter must only match for the first
+	// time in block 16, so doing an all-16 bit filter should suffice.
+
+	// To keep the starting block non divisible by 8, block number 9 is the first
+	// that would introduce a shift and not match block 0.
+	testMatcherBothModes(t, [][]bloomIndexes{{{16, 16, 16}}}, 9, 64, 0)
+}
+
 // Tests that matching on everything doesn't crash (special case internally).
 func TestWildcardMatcher(t *testing.T) {
-	testMatcherBothModes(t, nil, 10000, 0)
+	testMatcherBothModes(t, nil, 0, 10000, 0)
 }
 
 // makeRandomIndexes generates a random filter system, composed on multiple filter
@@ -104,9 +119,9 @@ func makeRandomIndexes(lengths []int, max int) [][]bloomIndexes {
 // testMatcherDiffBatches runs the given matches test in single-delivery and also
 // in batches delivery mode, verifying that all kinds of deliveries are handled
 // correctly withn.
-func testMatcherDiffBatches(t *testing.T, filter [][]bloomIndexes, blocks uint64, intermittent bool, retrievals uint32) {
-	singleton := testMatcher(t, filter, blocks, intermittent, retrievals, 1)
-	batched := testMatcher(t, filter, blocks, intermittent, retrievals, 16)
+func testMatcherDiffBatches(t *testing.T, filter [][]bloomIndexes, start, blocks uint64, intermittent bool, retrievals uint32) {
+	singleton := testMatcher(t, filter, start, blocks, intermittent, retrievals, 1)
+	batched := testMatcher(t, filter, start, blocks, intermittent, retrievals, 16)
 
 	if singleton != batched {
 		t.Errorf("filter = %v blocks = %v intermittent = %v: request count mismatch, %v in signleton vs. %v in batched mode", filter, blocks, intermittent, singleton, batched)
@@ -115,9 +130,9 @@ func testMatcherDiffBatches(t *testing.T, filter [][]bloomIndexes, blocks uint64
 
 // testMatcherBothModes runs the given matcher test in both continuous as well as
 // in intermittent mode, verifying that the request counts match each other.
-func testMatcherBothModes(t *testing.T, filter [][]bloomIndexes, blocks uint64, retrievals uint32) {
-	continuous := testMatcher(t, filter, blocks, false, retrievals, 16)
-	intermittent := testMatcher(t, filter, blocks, true, retrievals, 16)
+func testMatcherBothModes(t *testing.T, filter [][]bloomIndexes, start, blocks uint64, retrievals uint32) {
+	continuous := testMatcher(t, filter, start, blocks, false, retrievals, 16)
+	intermittent := testMatcher(t, filter, start, blocks, true, retrievals, 16)
 
 	if continuous != intermittent {
 		t.Errorf("filter = %v blocks = %v: request count mismatch, %v in continuous vs. %v in intermittent mode", filter, blocks, continuous, intermittent)
@@ -126,7 +141,7 @@ func testMatcherBothModes(t *testing.T, filter [][]bloomIndexes, blocks uint64,
 
 // testMatcher is a generic tester to run the given matcher test and return the
 // number of requests made for cross validation between different modes.
-func testMatcher(t *testing.T, filter [][]bloomIndexes, blocks uint64, intermittent bool, retrievals uint32, maxReqCount int) uint32 {
+func testMatcher(t *testing.T, filter [][]bloomIndexes, start, blocks uint64, intermittent bool, retrievals uint32, maxReqCount int) uint32 {
 	// Create a new matcher an simulate our explicit random bitsets
 	matcher := NewMatcher(testSectionSize, nil)
 	matcher.filters = filter
@@ -145,14 +160,14 @@ func testMatcher(t *testing.T, filter [][]bloomIndexes, blocks uint64, intermitt
 	quit := make(chan struct{})
 	matches := make(chan uint64, 16)
 
-	session, err := matcher.Start(context.Background(), 0, blocks-1, matches)
+	session, err := matcher.Start(context.Background(), start, blocks-1, matches)
 	if err != nil {
 		t.Fatalf("failed to stat matcher session: %v", err)
 	}
 	startRetrievers(session, quit, &requested, maxReqCount)
 
 	// Iterate over all the blocks and verify that the pipeline produces the correct matches
-	for i := uint64(0); i < blocks; i++ {
+	for i := start; i < blocks; i++ {
 		if expMatch3(filter, i) {
 			match, ok := <-matches
 			if !ok {