chore: Default Process Proposal (backport #543)

abci/abci.go

@@ -7,6 +7,7 @@
 	abci "github.com/cometbft/cometbft/abci/types"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 
+	"github.com/cosmos/cosmos-sdk/baseapp"
 	"github.com/skip-mev/block-sdk/v2/block"
 	"github.com/skip-mev/block-sdk/v2/block/proposals"
 	"github.com/skip-mev/block-sdk/v2/block/utils"
@@ -16,28 +17,49 @@
 	// ProposalHandler is a wrapper around the ABCI++ PrepareProposal and ProcessProposal
 	// handlers.
 	ProposalHandler struct {
-		logger              log.Logger
-		txDecoder           sdk.TxDecoder
-		txEncoder           sdk.TxEncoder
-		prepareLanesHandler block.PrepareLanesHandler
-		mempool             block.Mempool
+		logger                   log.Logger
+		txDecoder                sdk.TxDecoder
+		txEncoder                sdk.TxEncoder
+		mempool                  block.Mempool
+		useCustomProcessProposal bool
 	}
 )
 
-// NewProposalHandler returns a new ABCI++ proposal handler. This proposal handler will
-// iteratively call each of the lanes in the chain to prepare and process the proposal.
-func NewProposalHandler(
+// NewDefaultProposalHandler returns a new ABCI++ proposal handler. This proposal handler will
+// iteratively call each of the lanes in the chain to prepare and process the proposal. This
+// will not use custom process proposal logic.
+func NewDefaultProposalHandler(
 	logger log.Logger,
 	txDecoder sdk.TxDecoder,
 	txEncoder sdk.TxEncoder,
 	mempool block.Mempool,
 ) *ProposalHandler {
 	return &ProposalHandler{
-		logger:              logger,
-		txDecoder:           txDecoder,
-		txEncoder:           txEncoder,
-		prepareLanesHandler: ChainPrepareLanes(mempool.Registry()),
-		mempool:             mempool,
+		logger:                   logger,
+		txDecoder:                txDecoder,
+		txEncoder:                txEncoder,
+		mempool:                  mempool,
+		useCustomProcessProposal: false,
+	}
+}
+
+// New returns a new ABCI++ proposal handler with the ability to use custom process proposal logic.
+//
+// NOTE: It is highly recommended to use the default proposal handler unless you have a specific
+// use case that requires custom process proposal logic.
+func New(
+	logger log.Logger,
+	txDecoder sdk.TxDecoder,
+	txEncoder sdk.TxEncoder,
+	mempool block.Mempool,
+	useCustomProcessProposal bool,
+) *ProposalHandler {
+	return &ProposalHandler{
+		logger:                   logger,
+		txDecoder:                txDecoder,
+		txEncoder:                txEncoder,
+		mempool:                  mempool,
+		useCustomProcessProposal: useCustomProcessProposal,
 	}
 }
 
@@ -75,7 +97,8 @@
 		proposal := proposals.NewProposal(h.logger, req.MaxTxBytes, maxGasLimit)
 
 		// Fill the proposal with transactions from each lane.
-		finalProposal, err := h.prepareLanesHandler(ctx, proposal)
+		prepareLanesHandler := ChainPrepareLanes(h.mempool.Registry())
+		finalProposal, err := prepareLanesHandler(ctx, proposal)
 		if err != nil {
 			h.logger.Error("failed to prepare proposal", "err", err)
 			return &abci.ResponsePrepareProposal{Txs: make([][]byte, 0)}, err
@@ -110,6 +133,10 @@
 // verify all transactions in the proposal that belong to the lane and pass any remaining transactions
 // to the next lane in the chain.
 func (h *ProposalHandler) ProcessProposalHandler() sdk.ProcessProposalHandler {
+	if !h.useCustomProcessProposal {
+		return baseapp.NoOpProcessProposal()
+	}
+
 	return func(ctx sdk.Context, req *abci.RequestProcessProposal) (resp *abci.ResponseProcessProposal, err error) {
 		if req.Height <= 1 {
 			return &abci.ResponseProcessProposal{Status: abci.ResponseProcessProposal_ACCEPT}, nil

abci/abci_test.go

@@ -498,11 +498,12 @@ func (s *ProposalsTestSuite) TestPrepareProposalEdgeCases() {
 		)
 		s.Require().NoError(err)
 
-		proposalHandler := abci.NewProposalHandler(
+		proposalHandler := abci.New(
 			log.NewNopLogger(),
 			s.encodingConfig.TxConfig.TxDecoder(),
 			s.encodingConfig.TxConfig.TxEncoder(),
 			mempool,
+			true,
 		).PrepareProposalHandler()
 
 		maxTxBytes := s.ctx.ConsensusParams().Block.MaxBytes
@@ -545,11 +546,12 @@ func (s *ProposalsTestSuite) TestPrepareProposalEdgeCases() {
 		)
 		s.Require().NoError(err)
 
-		proposalHandler := abci.NewProposalHandler(
+		proposalHandler := abci.New(
 			log.NewNopLogger(),
 			s.encodingConfig.TxConfig.TxDecoder(),
 			s.encodingConfig.TxConfig.TxEncoder(),
 			mempool,
+			true,
 		).PrepareProposalHandler()
 
 		maxTxBytes := s.ctx.ConsensusParams().Block.MaxBytes
@@ -594,11 +596,12 @@ func (s *ProposalsTestSuite) TestPrepareProposalEdgeCases() {
 		)
 		s.Require().NoError(err)
 
-		proposalHandler := abci.NewProposalHandler(
+		proposalHandler := abci.New(
 			log.NewNopLogger(),
 			s.encodingConfig.TxConfig.TxDecoder(),
 			s.encodingConfig.TxConfig.TxEncoder(),
 			mempool,
+			true,
 		).PrepareProposalHandler()
 
 		maxTxBytes := s.ctx.ConsensusParams().Block.MaxBytes
@@ -643,11 +646,12 @@ func (s *ProposalsTestSuite) TestPrepareProposalEdgeCases() {
 		)
 		s.Require().NoError(err)
 
-		proposalHandler := abci.NewProposalHandler(
+		proposalHandler := abci.New(
 			log.NewNopLogger(),
 			s.encodingConfig.TxConfig.TxDecoder(),
 			s.encodingConfig.TxConfig.TxEncoder(),
 			mempool,
+			true,
 		).PrepareProposalHandler()
 
 		maxTxBytes := s.ctx.ConsensusParams().Block.MaxBytes

abci/utils_test.go

@@ -148,11 +148,12 @@ func (s *ProposalsTestSuite) setUpProposalHandlers(lanes []block.Lane) *abci.Pro
 	mempool, err := block.NewLanedMempool(log.NewNopLogger(), lanes)
 	s.Require().NoError(err)
 
-	return abci.NewProposalHandler(
+	return abci.New(
 		log.NewNopLogger(),
 		s.encodingConfig.TxConfig.TxDecoder(),
 		s.encodingConfig.TxConfig.TxEncoder(),
 		mempool,
+		true,
 	)
 }
 

tests/app/README.md

@@ -19,6 +19,8 @@ There are fix critical steps to building a test app that uses the Block SDK:
 5. Setting the antehandlers - used for transaction validation - for each lane.
 6. Setting the proposal handlers - used for block creation and verification - for the application to utilize the Block SDK's Prepare and Process Proposal handlers.
 
+**IMPORTANT NOTE:** It is recommended that applications use the **`NewDefaultProposalHandler`** when constructing their Prepare and Process Proposal handlers. This is because the priority nonce mempool - the underlying storage device of transactions - has non-deterministic ordering of transactions on chains with multiple fees. The use of the `NewDefaultProposalHandler` ensures that the ordering of transactions on proposal construction follows the ordering logic of the lanes, which is deterministic, and that process proposal optimistically assumes that the ordering of transactions is correct.
+
 ### 1. Signer Extractor
 
 The signer extractor is responsible for extracting signers and relevant information about who is signing the transaction. We recommend using the default implementation provided by the Block SDK. 

tests/app/app.go

@@ -304,11 +304,20 @@ func New(
 
 	// Step 6: Create the proposal handler and set it on the app. Now the application
 	// will build and verify proposals using the Block SDK!
-	proposalHandler := abci.NewProposalHandler(
+	//
+	// NOTE: It is recommended to use the default proposal handler by constructing
+	// using the NewDefaultProposalHandler function. This will use the correct prepare logic
+	// for the lanes, but the process logic will be a no-op. To read more about the default
+	// proposal handler, see the documentation in readme.md in this directory.
+	//
+	// If you want to customize the prepare and process logic, you can construct the proposal
+	// handler using the New function and setting the useProcess flag to true.
+	proposalHandler := abci.New( // use NewDefaultProposalHandler instead for default behavior (RECOMMENDED)
 		app.Logger(),
 		app.TxConfig().TxDecoder(),
 		app.TxConfig().TxEncoder(),
 		mempool,
+		true,
 	)
 	app.App.SetPrepareProposal(proposalHandler.PrepareProposalHandler())
 	app.App.SetProcessProposal(proposalHandler.ProcessProposalHandler())