fix(blooms): Reset error on LazyBloomIter.Seek (#12806)

pkg/storage/bloom/v1/bloom_querier.go

@@ -45,6 +45,11 @@ func (it *LazyBloomIter) ensureInit() {
 func (it *LazyBloomIter) Seek(offset BloomOffset) {
 	it.ensureInit()
 
+	// reset error from any previous seek/next that yield pages too large
+	if errors.Is(it.err, ErrPageTooLarge) {
+		it.err = nil
+	}
+
 	// if we need a different page or the current page hasn't been loaded,
 	// load the desired page
 	if it.curPageIndex != offset.Page || it.curPage == nil {

pkg/storage/bloom/v1/fuse_test.go

@@ -3,14 +3,17 @@ package v1
 import (
 	"bytes"
 	"context"
+	"fmt"
 	"sync"
 	"testing"
 
 	"github.com/go-kit/log"
 	"github.com/grafana/dskit/concurrency"
+	"github.com/prometheus/common/model"
 	"github.com/stretchr/testify/require"
 
 	"github.com/grafana/loki/v3/pkg/chunkenc"
+	"github.com/grafana/loki/v3/pkg/storage/bloom/v1/filter"
 )
 
 // TODO(owen-d): this is unhinged from the data it represents. I'm leaving this solely so I don't
@@ -44,6 +47,18 @@ func TestFusedQuerier(t *testing.T) {
 	numSeries := 1000
 	data, keys := MkBasicSeriesWithBlooms(numSeries, 0, 0x0000, 0xffff, 0, 10000)
 
+	// Make the first and third series blooms too big to fit into a single page so we skip them while reading
+	for i := 0; i < 10000; i++ {
+		tokenizer := NewNGramTokenizer(4, 0)
+		line := fmt.Sprintf("%04x:%04x", i, i+1)
+		it := tokenizer.Tokens(line)
+		for it.Next() {
+			key := it.At()
+			data[0].Bloom.Add(key)
+			data[2].Bloom.Add(key)
+		}
+	}
+
 	builder, err := NewBlockBuilder(
 		BlockOptions{
 			Schema: Schema{
@@ -130,6 +145,92 @@ func TestFusedQuerier(t *testing.T) {
 	}
 }
 
+func TestLazyBloomIter_Seek_ResetError(t *testing.T) {
+	// references for linking in memory reader+writer
+	indexBuf := bytes.NewBuffer(nil)
+	bloomsBuf := bytes.NewBuffer(nil)
+	writer := NewMemoryBlockWriter(indexBuf, bloomsBuf)
+	reader := NewByteReader(indexBuf, bloomsBuf)
+
+	numSeries := 4
+	data := make([]SeriesWithBloom, 0, numSeries)
+	tokenizer := NewNGramTokenizer(4, 0)
+	for i := 0; i < numSeries; i++ {
+		var series Series
+		series.Fingerprint = model.Fingerprint(i)
+		series.Chunks = []ChunkRef{
+			{
+				From:     0,
+				Through:  100,
+				Checksum: uint32(i),
+			},
+		}
+
+		var bloom Bloom
+		bloom.ScalableBloomFilter = *filter.NewScalableBloomFilter(1024, 0.01, 0.8)
+
+		nLines := 10
+		if i == 0 || i == 2 {
+			// Add enough lines to make the bloom page too large for series 1
+			nLines = 10000
+		}
+
+		for j := 0; j < nLines; j++ {
+			line := fmt.Sprintf("%04x:%04x", i, j)
+			it := tokenizer.Tokens(line)
+			for it.Next() {
+				key := it.At()
+				bloom.Add(key)
+			}
+		}
+
+		data = append(data, SeriesWithBloom{
+			Series: &series,
+			Bloom:  &bloom,
+		})
+	}
+
+	builder, err := NewBlockBuilder(
+		BlockOptions{
+			Schema: Schema{
+				version:  DefaultSchemaVersion,
+				encoding: chunkenc.EncSnappy,
+			},
+			SeriesPageSize: 100,
+			BloomPageSize:  10, // So we force one series per page
+		},
+		writer,
+	)
+	require.Nil(t, err)
+	itr := NewSliceIter[SeriesWithBloom](data)
+	_, err = builder.BuildFrom(itr)
+	require.NoError(t, err)
+	require.False(t, itr.Next())
+	block := NewBlock(reader, NewMetrics(nil))
+
+	querier := NewBlockQuerier(block, true, 1000)
+
+	for fp := model.Fingerprint(0); fp < model.Fingerprint(numSeries); fp++ {
+		err := querier.Seek(fp)
+		require.NoError(t, err)
+
+		require.True(t, querier.series.Next())
+		series := querier.series.At()
+		require.Equal(t, fp, series.Fingerprint)
+
+		querier.blooms.Seek(series.Offset)
+
+		if fp == 0 || fp == 2 {
+			require.False(t, querier.blooms.Next())
+			require.Error(t, querier.blooms.Err())
+			continue
+		}
+
+		require.True(t, querier.blooms.Next())
+		require.NoError(t, querier.blooms.Err())
+	}
+}
+
 func setupBlockForBenchmark(b *testing.B) (*BlockQuerier, [][]Request, []chan Output) {
 	indexBuf := bytes.NewBuffer(nil)
 	bloomsBuf := bytes.NewBuffer(nil)