go/worker/compute/merge: Drop support for multiple committees

Since there is currently no transaction scheduler implementation which would
support multiple committees, there is no sense in the merge node to try to
support such cases as it could be a source of bugs. Additionally it results
in extra round trips to storage nodes due to the Merge operation which in
case of a single committee does not do anything.

The merge node is also the only client for the Merge* storage operations, so
they can just be removed in order to reduce the exposed API surface.

.changelog/3179.breaking.md

@@ -0,0 +1,10 @@
+go/worker/compute/merge: Drop support for multiple committees
+
+Since there is currently no transaction scheduler implementation which would
+support multiple committees, there is no sense in the merge node to try to
+support such cases as it could be a source of bugs. Additionally it results
+in extra round trips to storage nodes due to the Merge operation which in
+case of a single committee does not do anything.
+
+The merge node is also the only client for the Merge* storage operations, so
+they can just be removed in order to reduce the exposed API surface.

go/genesis/genesis_test.go

@@ -219,7 +219,7 @@ func TestGenesisSanityCheck(t *testing.T) {
 			MinWriteReplication:     1,
 			MaxApplyWriteLogEntries: 100_000,
 			MaxApplyOps:             2,
-			MaxMergeRoots:           8,
+			MaxMergeRoots:           1,
 			MaxMergeOps:             2,
 		},
 		AdmissionPolicy: registry.RuntimeAdmissionPolicy{

go/oasis-net-runner/fixtures/default.go

@@ -106,7 +106,7 @@ func newDefaultFixture() (*oasis.NetworkFixture, error) {
 					MinWriteReplication:     1,
 					MaxApplyWriteLogEntries: 100_000,
 					MaxApplyOps:             2,
-					MaxMergeRoots:           8,
+					MaxMergeRoots:           1,
 					MaxMergeOps:             2,
 				},
 				AdmissionPolicy: registry.RuntimeAdmissionPolicy{

go/oasis-node/cmd/debug/byzantine/merge.go

@@ -6,21 +6,18 @@ import (
 
 	"github.com/oasisprotocol/oasis-core/go/common"
 	"github.com/oasisprotocol/oasis-core/go/common/crypto/hash"
-	"github.com/oasisprotocol/oasis-core/go/common/crypto/signature"
 	"github.com/oasisprotocol/oasis-core/go/common/identity"
 	consensus "github.com/oasisprotocol/oasis-core/go/consensus/api"
 	"github.com/oasisprotocol/oasis-core/go/roothash/api/block"
 	"github.com/oasisprotocol/oasis-core/go/roothash/api/commitment"
-	storage "github.com/oasisprotocol/oasis-core/go/storage/api"
 )
 
 type mergeBatchContext struct {
 	currentBlock *block.Block
 	commitments  []*commitment.OpenExecutorCommitment
 
-	storageReceipts []*storage.Receipt
-	newBlock        *block.Block
-	commit          *commitment.MergeCommitment
+	newBlock *block.Block
+	commit   *commitment.MergeCommitment
 }
 
 func newMergeBatchContext() *mergeBatchContext {
@@ -86,36 +83,14 @@ func (mbc *mergeBatchContext) process(ctx context.Context, hnss []*honestNodeSto
 		}
 	}
 
-	var emptyRoot hash.Hash
-	emptyRoot.Empty()
-
-	var err error
-	mbc.storageReceipts, err = storageBroadcastMergeBatch(ctx, hnss, mbc.currentBlock.Header.Namespace, mbc.currentBlock.Header.Round, []storage.MergeOp{
-		{
-			Base:   emptyRoot,
-			Others: ioRoots,
-		},
-		{
-			Base:   mbc.currentBlock.Header.StateRoot,
-			Others: stateRoots,
-		},
-	})
-	if err != nil {
-		return fmt.Errorf("storage broadcast merge batch: %w", err)
-	}
-
-	var firstReceiptBody storage.ReceiptBody
-	if err := mbc.storageReceipts[0].Open(&firstReceiptBody); err != nil {
-		return fmt.Errorf("storage receipt Open: %w", err)
-	}
-	var signatures []signature.Signature
-	for _, receipt := range mbc.storageReceipts {
-		signatures = append(signatures, receipt.Signature)
+	if len(collectedCommittees) != 1 {
+		return fmt.Errorf("multiple committees not supported: %d", len(collectedCommittees))
 	}
+	signatures := mbc.commitments[0].Body.StorageSignatures
 
 	mbc.newBlock = block.NewEmptyBlock(mbc.currentBlock, 0, block.Normal)
-	mbc.newBlock.Header.IORoot = firstReceiptBody.Roots[0]
-	mbc.newBlock.Header.StateRoot = firstReceiptBody.Roots[1]
+	mbc.newBlock.Header.IORoot = ioRoots[0]
+	mbc.newBlock.Header.StateRoot = stateRoots[0]
 	mbc.newBlock.Header.Messages = messages
 	mbc.newBlock.Header.StorageSignatures = signatures
 

go/oasis-node/cmd/debug/byzantine/storage.go

@@ -106,14 +106,6 @@ func (hns *honestNodeStorage) ApplyBatch(ctx context.Context, request *storage.A
 	return hns.client.ApplyBatch(ctx, request)
 }
 
-func (hns *honestNodeStorage) Merge(ctx context.Context, request *storage.MergeRequest) ([]*storage.Receipt, error) {
-	return hns.client.Merge(ctx, request)
-}
-
-func (hns *honestNodeStorage) MergeBatch(ctx context.Context, request *storage.MergeBatchRequest) ([]*storage.Receipt, error) {
-	return hns.client.MergeBatch(ctx, request)
-}
-
 func (hns *honestNodeStorage) GetDiff(ctx context.Context, request *storage.GetDiffRequest) (storage.WriteLogIterator, error) {
 	return hns.client.GetDiff(ctx, request)
 }
@@ -176,23 +168,3 @@ func storageBroadcastApplyBatch(
 
 	return receipts, nil
 }
-
-func storageBroadcastMergeBatch(
-	ctx context.Context,
-	hnss []*honestNodeStorage,
-	ns common.Namespace,
-	round uint64,
-	ops []storage.MergeOp,
-) ([]*storage.Receipt, error) {
-	var receipts []*storage.Receipt
-	for _, hns := range hnss {
-		r, err := hns.MergeBatch(ctx, &storage.MergeBatchRequest{Namespace: ns, Round: round, Ops: ops})
-		if err != nil {
-			return receipts, fmt.Errorf("honest node storage MergeBatch %s: %w", hns.nodeID, err)
-		}
-
-		receipts = append(receipts, r...)
-	}
-
-	return receipts, nil
-}

go/oasis-node/cmd/debug/txsource/workload/registration.go

@@ -68,7 +68,7 @@ func getRuntime(entityID signature.PublicKey, id common.Namespace) *registry.Run
 			MinWriteReplication:     1,
 			MaxApplyWriteLogEntries: 100_000,
 			MaxApplyOps:             2,
-			MaxMergeRoots:           8,
+			MaxMergeRoots:           1,
 			MaxMergeOps:             2,
 		},
 		AdmissionPolicy: registry.RuntimeAdmissionPolicy{

go/oasis-node/cmd/registry/runtime/runtime.go

@@ -571,7 +571,7 @@ func init() {
 	runtimeFlags.Uint64(CfgStorageMinWriteReplication, 1, "Minimum required storage write replication")
 	runtimeFlags.Uint64(CfgStorageMaxApplyWriteLogEntries, 100_000, "Maximum number of write log entries")
 	runtimeFlags.Uint64(CfgStorageMaxApplyOps, 2, "Maximum number of apply operations in a batch")
-	runtimeFlags.Uint64(CfgStorageMaxMergeRoots, 8, "Maximum number of merge roots")
+	runtimeFlags.Uint64(CfgStorageMaxMergeRoots, 1, "Maximum number of merge roots")
 	runtimeFlags.Uint64(CfgStorageMaxMergeOps, 2, "Maximum number of merge operations in a batch")
 	runtimeFlags.Uint64(CfgStorageCheckpointInterval, 0, "Storage checkpoint interval (in rounds)")
 	runtimeFlags.Uint64(CfgStorageCheckpointNumKept, 0, "Number of storage checkpoints to keep")

go/oasis-node/node_test.go

@@ -106,7 +106,7 @@ var (
 			MinWriteReplication:     1,
 			MaxApplyWriteLogEntries: 100_000,
 			MaxApplyOps:             2,
-			MaxMergeRoots:           8,
+			MaxMergeRoots:           1,
 			MaxMergeOps:             2,
 		},
 		AdmissionPolicy: registry.RuntimeAdmissionPolicy{

go/oasis-test-runner/scenario/e2e/runtime/multiple_runtimes.go

@@ -107,7 +107,7 @@ func (sc *multipleRuntimesImpl) Fixture() (*oasis.NetworkFixture, error) {
 				MinWriteReplication:     1,
 				MaxApplyWriteLogEntries: 100_000,
 				MaxApplyOps:             2,
-				MaxMergeRoots:           8,
+				MaxMergeRoots:           1,
 				MaxMergeOps:             2,
 			},
 			AdmissionPolicy: registry.RuntimeAdmissionPolicy{

go/oasis-test-runner/scenario/e2e/runtime/runtime.go

@@ -180,7 +180,7 @@ func (sc *runtimeImpl) Fixture() (*oasis.NetworkFixture, error) {
 					MinWriteReplication:     2,
 					MaxApplyWriteLogEntries: 100_000,
 					MaxApplyOps:             2,
-					MaxMergeRoots:           8,
+					MaxMergeRoots:           1,
 					MaxMergeOps:             2,
 				},
 				AdmissionPolicy: registry.RuntimeAdmissionPolicy{

go/registry/tests/tester.go

@@ -1629,7 +1629,7 @@ func NewTestRuntime(seed []byte, ent *TestEntity, isKeyManager bool) (*TestRunti
 			MinWriteReplication:     3,
 			MaxApplyWriteLogEntries: 100_000,
 			MaxApplyOps:             2,
-			MaxMergeRoots:           8,
+			MaxMergeRoots:           1,
 			MaxMergeOps:             2,
 		},
 		AdmissionPolicy: api.RuntimeAdmissionPolicy{

go/roothash/api/commitment/pool.go

@@ -764,10 +764,10 @@ func (m *MultiPool) CheckEnoughCommitments() error {
 }
 
 // GetExecutorCommitments returns a list of executor commitments in the pool.
-func (m *MultiPool) GetExecutorCommitments() (result []ExecutorCommitment) {
+func (m *MultiPool) GetOpenExecutorCommitments() (result []OpenExecutorCommitment) {
 	for _, p := range m.Committees {
 		for _, c := range p.ExecuteCommitments {
-			result = append(result, c.ExecutorCommitment)
+			result = append(result, c)
 		}
 	}
 	return

go/runtime/registry/storage_router.go

@@ -59,22 +59,6 @@ func (sr *storageRouter) ApplyBatch(ctx context.Context, request *api.ApplyBatch
 	return rt.Storage().ApplyBatch(ctx, request)
 }
 
-func (sr *storageRouter) Merge(ctx context.Context, request *api.MergeRequest) ([]*api.Receipt, error) {
-	rt, err := sr.getRuntime(request.Namespace)
-	if err != nil {
-		return nil, err
-	}
-	return rt.Storage().Merge(ctx, request)
-}
-
-func (sr *storageRouter) MergeBatch(ctx context.Context, request *api.MergeBatchRequest) ([]*api.Receipt, error) {
-	rt, err := sr.getRuntime(request.Namespace)
-	if err != nil {
-		return nil, err
-	}
-	return rt.Storage().MergeBatch(ctx, request)
-}
-
 func (sr *storageRouter) GetDiff(ctx context.Context, request *api.GetDiffRequest) (api.WriteLogIterator, error) {
 	rt, err := sr.getRuntime(request.StartRoot.Namespace)
 	if err != nil {

go/storage/api/api.go

@@ -38,11 +38,8 @@ var (
 	// ErrUnsupported is the error returned when the called method is not
 	// supported by the given backend.
 	ErrUnsupported = errors.New(ModuleName, 4, "storage: method not supported by backend")
-	// ErrNoMergeRoots is the error returned when no other roots are passed
-	// to the Merge operation.
-	ErrNoMergeRoots = errors.New(ModuleName, 5, "storage: no roots to merge")
 	// ErrLimitReached means that a configured limit has been reached.
-	ErrLimitReached = errors.New(ModuleName, 6, "storage: limit reached")
+	ErrLimitReached = errors.New(ModuleName, 5, "storage: limit reached")
 
 	// The following errors are reimports from NodeDB.
 
@@ -240,14 +237,6 @@ type ApplyOp struct {
 	WriteLog WriteLog `json:"writelog"`
 }
 
-// MergeOps is a merge operation within a batch of merge operations.
-type MergeOp struct {
-	// Base is the base root for the merge.
-	Base hash.Hash `json:"base"`
-	// Others is a list of roots derived from base that should be merged.
-	Others []hash.Hash `json:"others"`
-}
-
 // ApplyRequest is an Apply request.
 type ApplyRequest struct {
 	Namespace common.Namespace `json:"namespace"`
@@ -265,21 +254,6 @@ type ApplyBatchRequest struct {
 	Ops       []ApplyOp        `json:"ops"`
 }
 
-// MergeRequest is a Merge request.
-type MergeRequest struct {
-	Namespace common.Namespace `json:"namespace"`
-	Round     uint64           `json:"round"`
-	Base      hash.Hash        `json:"base"`
-	Others    []hash.Hash      `json:"others"`
-}
-
-// MergeBatchRequest is a MergeBatch request.
-type MergeBatchRequest struct {
-	Namespace common.Namespace `json:"namespace"`
-	Round     uint64           `json:"round"`
-	Ops       []MergeOp        `json:"ops"`
-}
-
 // SyncOptions are the sync options.
 type SyncOptions struct {
 	OffsetKey []byte `json:"offset_key"`
@@ -317,21 +291,6 @@ type Backend interface {
 	// See Apply for more details.
 	ApplyBatch(ctx context.Context, request *ApplyBatchRequest) ([]*Receipt, error)
 
-	// TODO: Add proof.
-	// Merge performs a 3-way merge operation between the specified
-	// roots and returns a receipt for the merged root.
-	//
-	// Round is the round of the base root while all other roots are
-	// expected to be in the next round.
-	Merge(ctx context.Context, request *MergeRequest) ([]*Receipt, error)
-
-	// TODO: Add proof.
-	// MergeBatch performs multiple sets of merge operations and returns
-	// a single receipt covering all merged roots.
-	//
-	// See Merge for more details.
-	MergeBatch(ctx context.Context, request *MergeBatchRequest) ([]*Receipt, error)
-
 	// GetDiff returns an iterator of write log entries that must be applied
 	// to get from the first given root to the second one.
 	GetDiff(ctx context.Context, request *GetDiffRequest) (WriteLogIterator, error)