feat(evm-reader): fast sync the last input check block when the application has no inputs

Author: mpolitzer

internal/evmreader/evmreader.go

@@ -187,6 +187,10 @@ func (r *Service) watchForNewBlocks(ctx context.Context, ready chan<- struct{})
 				r.Logger.Debug(fmt.Sprintf("Using block %d and not %d because of commitment policy: %s",
 					mostRecentHeader.Number.Uint64(), header.Number.Uint64(), r.defaultBlock))
 			}
+			errs := r.syncApplicationsWithNoInput(ctx, apps, r.client, blockNumber)
+			if len(errs) != 0 {
+				r.Logger.Info("failed to fast sync applications, using checkForNewInputs method")
+			}
 
 			r.checkForNewInputs(ctx, apps, blockNumber)
 

internal/evmreader/input.go

@@ -7,12 +7,80 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"math/big"
 
 	. "github.com/cartesi/rollups-node/internal/model"
+	"github.com/cartesi/rollups-node/pkg/contracts/iinputbox"
 	"github.com/ethereum/go-ethereum/accounts/abi/bind"
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/ethclient"
 )
 
+// checkApplicationsWithNoInputAndSync is an optimization that updates the lastProcessedBlock of applications with
+// no inputs to the mostRecentBlockNumber, no need to check block ranges.
+// NOTE(mpolitzer): Ideally this only gets called when new applications are created or registered.
+func (r *Service) syncApplicationsWithNoInput(
+	ctx context.Context,
+	applications []appContracts,
+	iclient EthClientInterface,
+	mostRecentBlockNumber uint64,
+) []error {
+	errs := []error{}
+
+	// we need the concrete client type to interact with the contracts so we type assert
+	// that works via a type switch
+	var client *ethclient.Client
+	switch unwrapped := iclient.(type) {
+	case *ethclient.Client:
+		client = unwrapped
+	default:
+		return []error{fmt.Errorf("error: unexpected type for ethclient")}
+	}
+
+	callOpts := bind.CallOpts{Context: ctx}
+	zero := big.NewInt(0)
+	for _, app := range applications {
+		r.Logger.Debug("Check application for fast sync",
+			"application", app.application.Name,
+			"last_input_check_block", app.application.LastInputCheckBlock,
+			"input_box_block", app.application.IInputBoxBlock,
+		)
+
+		// Only for input box
+		if !app.application.HasDataAvailabilitySelector(DataAvailability_InputBox) {
+			continue
+		}
+
+		// and for applications that have not been synced yet
+		if app.application.LastInputCheckBlock > app.application.IInputBoxBlock {
+			continue
+		}
+
+		iib, err := iinputbox.NewIInputBox(app.application.IInputBoxAddress, client)
+		if err != nil {
+			errs = append(errs, fmt.Errorf("error: syncApplicationsWithNoInput failed to instantiate iinput box for application: %v", app.application.IApplicationAddress))
+			continue
+		}
+
+		nInputs, err := iib.GetNumberOfInputs(&callOpts, app.application.IApplicationAddress)
+		if err != nil {
+			errs = append(errs, fmt.Errorf("error: syncApplicationsWithNoInput failed retrieve the number of inputs for application: %v", app.application.IApplicationAddress))
+			continue
+		}
+
+		if nInputs.Cmp(zero) == 0 {
+			r.Logger.Info("Fast sync last input block",
+				"application", app.application.Name,
+				"from", app.application.LastInputCheckBlock,
+				"to", mostRecentBlockNumber)
+
+			// leave DB interaction to checkForNewInputs
+			app.application.LastInputCheckBlock = mostRecentBlockNumber-1
+		}
+	}
+	return nil
+}
+
 // checkForNewInputs checks if is there new Inputs for all running Applications
 func (r *Service) checkForNewInputs(
 	ctx context.Context,