[staking] reduce candidates bucket indexer storage

Author: dustinxie

action/protocol/staking/read_state.go

@@ -16,6 +16,11 @@ import (
 	"github.com/iotexproject/iotex-core/v2/state"
 )
 
+func ToIoTeXTypesVoteBucketList(sr protocol.StateReader, buckets []*VoteBucket) (*iotextypes.VoteBucketList, error) {
+	// TODO: change toIoTeXTypesVoteBucketList() to this name
+	return toIoTeXTypesVoteBucketList(sr, buckets)
+}
+
 func toIoTeXTypesVoteBucketList(sr protocol.StateReader, buckets []*VoteBucket) (*iotextypes.VoteBucketList, error) {
 	esr := NewEndorsementStateReader(sr)
 	res := iotextypes.VoteBucketList{
@@ -98,6 +103,11 @@ func toIoTeXTypesCandidateV2(csr CandidateStateReader, cand *Candidate, featureC
 	return c, nil
 }
 
+func ToIoTeXTypesCandidateListV2(csr CandidateStateReader, candidates CandidateList, featureCtx protocol.FeatureCtx) (*iotextypes.CandidateListV2, error) {
+	// TODO: change toIoTeXTypesCandidateListV2 to this name
+	return &iotextypes.CandidateListV2{}, nil
+}
+
 func toIoTeXTypesCandidateListV2(csr CandidateStateReader, candidates CandidateList, featureCtx protocol.FeatureCtx) (*iotextypes.CandidateListV2, error) {
 	res := iotextypes.CandidateListV2{
 		Candidates: make([]*iotextypes.CandidateV2, 0, len(candidates)),

blockindex/nativestaking/bucket_list.go

@@ -0,0 +1,43 @@
+// Copyright (c) 2025 IoTeX Foundation
+// This source code is provided 'as is' and no warranties are given as to title or non-infringement, merchantability
+// or fitness for purpose and, to the extent permitted by law, all liability for your use of the code is disclaimed.
+// This source code is governed by Apache License 2.0 that can be found in the LICENSE file.
+
+package stakingindex
+
+import (
+	"google.golang.org/protobuf/proto"
+
+	"github.com/iotexproject/iotex-core/v2/blockindex/nativestaking/stakingindexpb"
+)
+
+type bucketList struct {
+	maxBucket uint64
+	deleted   []uint64
+}
+
+func (bl *bucketList) serialize() ([]byte, error) {
+	return proto.Marshal(bl.toProto())
+}
+
+func (bl *bucketList) toProto() *stakingindexpb.BucketList {
+	return &stakingindexpb.BucketList{
+		MaxBucket: bl.maxBucket,
+		Deleted:   bl.deleted,
+	}
+}
+
+func fromProtoBucketList(pb *stakingindexpb.BucketList) *bucketList {
+	return &bucketList{
+		maxBucket: pb.MaxBucket,
+		deleted:   pb.Deleted,
+	}
+}
+
+func deserializeBucketList(buf []byte) (*bucketList, error) {
+	pb := stakingindexpb.BucketList{}
+	if err := proto.Unmarshal(buf, &pb); err != nil {
+		return nil, err
+	}
+	return fromProtoBucketList(&pb), nil
+}

blockindex/nativestaking/bucket_list_test.go

@@ -0,0 +1,42 @@
+// Copyright (c) 2025 IoTeX Foundation
+// This source code is provided 'as is' and no warranties are given as to title or non-infringement, merchantability
+// or fitness for purpose and, to the extent permitted by law, all liability for your use of the code is disclaimed.
+// This source code is governed by Apache License 2.0 that can be found in the LICENSE file.
+
+package stakingindex
+
+import (
+	"math/rand/v2"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	. "github.com/iotexproject/iotex-core/v2/pkg/util/assertions"
+)
+
+func TestBucketList(t *testing.T) {
+	req := require.New(t)
+	l0 := bucketList{0, nil}
+	b := MustNoErrorV(l0.serialize())
+	l1 := MustNoErrorV(deserializeBucketList(b))
+	req.Equal(&l0, l1)
+}
+
+func TestBucketListSize(t *testing.T) {
+	req := require.New(t)
+	d, check := []uint64{}, []uint64{}
+	for i := range 50001 {
+		d = append(d, rand.Uint64N(50001))
+		if i%5000 == 0 {
+			check = append(check, d[i])
+		}
+	}
+	l0 := bucketList{d[1234], d}
+	b := MustNoErrorV(l0.serialize())
+	l1 := MustNoErrorV(deserializeBucketList(b))
+	req.Equal(&l0, l1)
+	req.Equal(d[1234], l1.maxBucket)
+	for i := 0; i < 50001; i += 5000 {
+		req.Equal(check[i/5000], l1.deleted[i])
+	}
+}