fix(blockstate): if blocktree fails to search a hash in memory, load it from disk (#3059)

If blocktree fails to get highest finalised hash (which is stored in memory), load it from disk.

Author: kishansagathiya

dot/state/block.go

@@ -268,14 +268,68 @@ func (bs *BlockState) GetHashesByNumber(blockNumber uint) ([]common.Hash, error)
 	return blockHashes, nil
 }
 
+// GetAllDescendants gets all the descendants for a given block hash (including itself), by first checking in memory
+// and, if not found, reading from the block state database.
+func (bs *BlockState) GetAllDescendants(hash common.Hash) ([]common.Hash, error) {
+	allDescendants, err := bs.bt.GetAllDescendants(hash)
+	if err != nil && !errors.Is(err, blocktree.ErrNodeNotFound) {
+		return nil, err
+	}
+
+	if err == nil {
+		return allDescendants, nil
+	}
+
+	allDescendants = []common.Hash{hash}
+
+	header, err := bs.GetHeader(hash)
+	if err != nil {
+		return nil, fmt.Errorf("getting header: %w", err)
+	}
+
+	nextBlockHashes, err := bs.GetHashesByNumber(header.Number + 1)
+	if err != nil {
+		return nil, fmt.Errorf("getting hashes by number: %w", err)
+	}
+
+	for _, nextBlockHash := range nextBlockHashes {
+		nextHeader, err := bs.GetHeader(nextBlockHash)
+		if err != nil {
+			return nil, fmt.Errorf("getting header from block hash %s: %w", nextBlockHash, err)
+		}
+		// next block is not a descendant of the block for the given hash
+		if nextHeader.ParentHash != hash {
+			return []common.Hash{hash}, nil
+		}
+
+		nextDescendants, err := bs.bt.GetAllDescendants(nextBlockHash)
+		if err != nil && !errors.Is(err, blocktree.ErrNodeNotFound) {
+			return nil, fmt.Errorf("getting all descendants: %w", err)
+		}
+		if err == nil {
+			allDescendants = append(allDescendants, nextDescendants...)
+			return allDescendants, nil
+		}
+
+		nextDescendants, err = bs.GetAllDescendants(nextBlockHash)
+		if err != nil {
+			return nil, err
+		}
+
+		allDescendants = append(allDescendants, nextDescendants...)
+	}
+
+	return allDescendants, nil
+}
+
 // GetBlockHashesBySlot gets all block hashes that were produced in the given slot.
 func (bs *BlockState) GetBlockHashesBySlot(slotNum uint64) ([]common.Hash, error) {
 	highestFinalisedHash, err := bs.GetHighestFinalisedHash()
 	if err != nil {
 		return nil, fmt.Errorf("failed to get highest finalised hash: %w", err)
 	}
 
-	descendants, err := bs.bt.GetAllDescendants(highestFinalisedHash)
+	descendants, err := bs.GetAllDescendants(highestFinalisedHash)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get descendants: %w", err)
 	}

dot/state/block_test.go

@@ -254,6 +254,69 @@ func TestGetHashesByNumber(t *testing.T) {
 	require.ElementsMatch(t, blocks, []common.Hash{block.Header.Hash(), block2.Header.Hash()})
 }
 
+func TestGetAllDescendants(t *testing.T) {
+	t.Parallel()
+
+	bs := newTestBlockState(t, newTriesEmpty())
+	slot := uint64(77)
+
+	babeHeader := types.NewBabeDigest()
+	err := babeHeader.Set(*types.NewBabePrimaryPreDigest(0, slot, [32]byte{}, [64]byte{}))
+	require.NoError(t, err)
+	data, err := scale.Marshal(babeHeader)
+	require.NoError(t, err)
+	preDigest := types.NewBABEPreRuntimeDigest(data)
+
+	digest := types.NewDigest()
+	err = digest.Add(*preDigest)
+	require.NoError(t, err)
+	block := &types.Block{
+		Header: types.Header{
+			ParentHash: testGenesisHeader.Hash(),
+			Number:     1,
+			Digest:     digest,
+		},
+		Body: sampleBlockBody,
+	}
+
+	err = bs.AddBlockWithArrivalTime(block, time.Now())
+	require.NoError(t, err)
+
+	babeHeader2 := types.NewBabeDigest()
+	err = babeHeader2.Set(*types.NewBabePrimaryPreDigest(1, slot+1, [32]byte{}, [64]byte{}))
+	require.NoError(t, err)
+	data2, err := scale.Marshal(babeHeader2)
+	require.NoError(t, err)
+	preDigest2 := types.NewBABEPreRuntimeDigest(data2)
+
+	digest2 := types.NewDigest()
+	err = digest2.Add(*preDigest2)
+	require.NoError(t, err)
+	block2 := &types.Block{
+		Header: types.Header{
+			ParentHash: block.Header.Hash(),
+			Number:     2,
+			Digest:     digest2,
+		},
+		Body: sampleBlockBody,
+	}
+	err = bs.AddBlockWithArrivalTime(block2, time.Now())
+	require.NoError(t, err)
+
+	err = bs.SetFinalisedHash(block2.Header.Hash(), 1, 1)
+	require.NoError(t, err)
+
+	// can't fetch given block's descendants since the given block get removed from memory after
+	// being finalised, using blocktree.GetAllDescendants
+	_, err = bs.bt.GetAllDescendants(block.Header.Hash())
+	require.ErrorIs(t, err, blocktree.ErrNodeNotFound)
+
+	// can fetch given finalised block's descendants using disk, using using blockstate.GetAllDescendants
+	blockHashes, err := bs.GetAllDescendants(block.Header.Hash())
+	require.NoError(t, err)
+	require.ElementsMatch(t, blockHashes, []common.Hash{block.Header.Hash(), block2.Header.Hash()})
+}
+
 func TestGetBlockHashesBySlot(t *testing.T) {
 	t.Parallel()
 

lib/blocktree/blocktree.go

@@ -422,7 +422,7 @@ func (bt *BlockTree) GetAllBlocks() []Hash {
 	return bt.root.getAllDescendants(nil)
 }
 
-// GetAllDescendants returns all block hashes that are descendants of the given block hash.
+// GetAllDescendants returns all block hashes that are descendants of the given block hash (including itself).
 func (bt *BlockTree) GetAllDescendants(hash common.Hash) ([]Hash, error) {
 	bt.RLock()
 	defer bt.RUnlock()

lib/blocktree/blocktree_test.go

@@ -6,145 +6,22 @@ package blocktree
 import (
 	"bytes"
 	"fmt"
-	"math/rand"
 	"testing"
 	"time"
 
 	"github.com/ChainSafe/gossamer/dot/types"
 	"github.com/ChainSafe/gossamer/lib/common"
-	"github.com/ChainSafe/gossamer/pkg/scale"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
-var zeroHash, _ = common.HexToHash("0x00")
-var testHeader = &types.Header{
-	ParentHash: zeroHash,
-	Number:     0,
-	Digest:     types.NewDigest(),
-}
-
-type testBranch struct {
-	hash        Hash
-	number      uint
-	arrivalTime int64
-}
-
 func newBlockTreeFromNode(root *node) *BlockTree {
 	return &BlockTree{
 		root:   root,
 		leaves: newLeafMap(root),
 	}
 }
 
-func createPrimaryBABEDigest(t testing.TB) scale.VaryingDataTypeSlice {
-	babeDigest := types.NewBabeDigest()
-	err := babeDigest.Set(types.BabePrimaryPreDigest{AuthorityIndex: 0})
-	require.NoError(t, err)
-
-	bdEnc, err := scale.Marshal(babeDigest)
-	require.NoError(t, err)
-
-	digest := types.NewDigest()
-	err = digest.Add(types.PreRuntimeDigest{
-		ConsensusEngineID: types.BabeEngineID,
-		Data:              bdEnc,
-	})
-	require.NoError(t, err)
-	return digest
-}
-
-func createTestBlockTree(t *testing.T, header *types.Header, number uint) (*BlockTree, []testBranch) {
-	bt := NewBlockTreeFromRoot(header)
-	previousHash := header.Hash()
-
-	// branch tree randomly
-	var branches []testBranch
-	r := rand.New(rand.NewSource(time.Now().UnixNano())) //skipcq: GSC-G404
-
-	at := int64(0)
-
-	// create base tree
-	for i := uint(1); i <= number; i++ {
-		header := &types.Header{
-			ParentHash: previousHash,
-			Number:     i,
-			Digest:     createPrimaryBABEDigest(t),
-		}
-
-		hash := header.Hash()
-		err := bt.AddBlock(header, time.Unix(0, at))
-		require.NoError(t, err)
-
-		previousHash = hash
-
-		isBranch := r.Intn(2)
-		if isBranch == 1 {
-			branches = append(branches, testBranch{
-				hash:        hash,
-				number:      bt.getNode(hash).number,
-				arrivalTime: at,
-			})
-		}
-
-		at += int64(r.Intn(8))
-	}
-
-	// create tree branches
-	for _, branch := range branches {
-		at := branch.arrivalTime
-		previousHash = branch.hash
-
-		for i := branch.number; i <= number; i++ {
-			header := &types.Header{
-				ParentHash: previousHash,
-				Number:     i + 1,
-				StateRoot:  common.Hash{0x1},
-				Digest:     createPrimaryBABEDigest(t),
-			}
-
-			hash := header.Hash()
-			err := bt.AddBlock(header, time.Unix(0, at))
-			require.NoError(t, err)
-
-			previousHash = hash
-			at += int64(r.Intn(8))
-
-		}
-	}
-
-	return bt, branches
-}
-
-func createFlatTree(t testing.TB, number uint) (*BlockTree, []common.Hash) {
-	rootHeader := &types.Header{
-		ParentHash: zeroHash,
-		Digest:     createPrimaryBABEDigest(t),
-	}
-
-	bt := NewBlockTreeFromRoot(rootHeader)
-	require.NotNil(t, bt)
-	previousHash := bt.root.hash
-
-	hashes := []common.Hash{bt.root.hash}
-	for i := uint(1); i <= number; i++ {
-		header := &types.Header{
-			ParentHash: previousHash,
-			Number:     i,
-			Digest:     createPrimaryBABEDigest(t),
-		}
-
-		hash := header.Hash()
-		hashes = append(hashes, hash)
-
-		err := bt.AddBlock(header, time.Unix(0, 0))
-		require.NoError(t, err)
-		previousHash = hash
-	}
-
-	return bt, hashes
-}
-
 func Test_NewBlockTreeFromNode(t *testing.T) {
 	var bt *BlockTree
 	var branches []testBranch