feat(evmreader): fast sync application inputs

This is an optimization to decrease the number of blocks the node has to
scan for an new application. By retrieving zero from GetNumberOfInputs
call, we can skip scanning the blocks previous to this, thus reducing
the total block range.

Author: mpolitzer

internal/evmreader/application_adapter.go

@@ -95,3 +95,7 @@ func (a *ApplicationContractAdapterImpl) RetrieveOutputExecutionEvents(
 	}
 	return events, nil
 }
+
+func (a *ApplicationContractAdapterImpl) GetDeploymentBlockNumber(opts *bind.CallOpts) (*big.Int, error) {
+	return a.application.GetDeploymentBlockNumber(opts)
+}

internal/evmreader/evmreader.go

@@ -57,6 +57,7 @@ type ApplicationContractAdapter interface {
 	RetrieveOutputExecutionEvents(
 		opts *bind.FilterOpts,
 	) ([]*iapplication.IApplicationOutputExecuted, error)
+	GetDeploymentBlockNumber(opts *bind.CallOpts) (*big.Int, error)
 }
 
 // Interface for Input reading
@@ -65,6 +66,7 @@ type InputSourceAdapter interface {
 	// by go-ethereum and cannot be used for testing
 	RetrieveInputs(opts *bind.FilterOpts, appAddresses []common.Address, index []*big.Int,
 	) ([]iinputbox.IInputBoxInputAdded, error)
+	GetNumberOfInputs(opts *bind.CallOpts, appContract common.Address) (*big.Int, error)
 }
 
 type SubscriptionError struct {

internal/evmreader/evmreader_test.go

@@ -377,6 +377,11 @@ func (m *MockInputBox) RetrieveInputs(
 	return args.Get(0).([]iinputbox.IInputBoxInputAdded), args.Error(1)
 }
 
+func (m *MockInputBox) GetNumberOfInputs(opts *bind.CallOpts, appContract common.Address) (*big.Int, error) {
+	args := m.Called(opts, appContract)
+	return args.Get(0).(*big.Int), args.Error(1)
+}
+
 // Mock InputReaderRepository
 type MockRepository struct {
 	mock.Mock
@@ -567,6 +572,11 @@ func (m *MockApplicationContract) RetrieveOutputExecutionEvents(
 	return args.Get(0).([]*iapplication.IApplicationOutputExecuted), args.Error(1)
 }
 
+func (m *MockApplicationContract) GetDeploymentBlockNumber(opts *bind.CallOpts) (*big.Int, error) {
+	args := m.Called(opts)
+	return args.Get(0).(*big.Int), args.Error(1)
+}
+
 type MockAdapterFactory struct {
 	mock.Mock
 }

internal/evmreader/input.go

@@ -7,6 +7,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"math/big"
 
 	. "github.com/cartesi/rollups-node/internal/model"
 	"github.com/ethereum/go-ethereum/accounts/abi/bind"
@@ -25,6 +26,50 @@ func (r *Service) checkForNewInputs(
 
 	r.Logger.Debug("Checking for new inputs")
 
+	mostRecentBlockNumberCallOpts := &bind.CallOpts{
+		BlockNumber: new(big.Int).SetUint64(mostRecentBlockNumber),
+	}
+
+	findFirstInputBlock := func(app *appContracts) uint64 {
+		var noiBig *big.Int
+		var err error
+
+		// application has never received an input
+		noiBig, err = app.inputSource.GetNumberOfInputs(
+			mostRecentBlockNumberCallOpts,
+			app.application.IApplicationAddress,
+		)
+		if err != nil {
+			return app.application.LastInputCheckBlock
+		}
+		if noiBig.Uint64() == 0 {
+			return mostRecentBlockNumber
+		}
+
+		// application has not received an input since its deployment
+		// but find its deployment block number first
+		deploymentBlockNumberBig, err := app.applicationContract.GetDeploymentBlockNumber(mostRecentBlockNumberCallOpts)
+		if err != nil {
+			return app.application.LastInputCheckBlock
+		}
+
+		noiBig, err = app.inputSource.GetNumberOfInputs(&bind.CallOpts{
+			BlockNumber: deploymentBlockNumberBig,
+		},
+			app.application.IApplicationAddress,
+		)
+		if err != nil {
+			return app.application.LastInputCheckBlock
+		}
+		if noiBig.Uint64() == 0 {
+			return deploymentBlockNumberBig.Uint64()
+		}
+
+		// TODO(mpolitzer): use GetNumberOfInputs to binary search the
+		//                  block of the first input
+		return app.application.IInputBoxBlock
+	}
+
 	appsByInputBox := map[common.Address][]appContracts{}
 	for _, app := range applications {
 		if !app.application.HasDataAvailabilitySelector(DataAvailability_InputBox) {
@@ -39,18 +84,24 @@ func (r *Service) checkForNewInputs(
 			"inputbox_address", inputBoxAddress,
 			"most recent block", mostRecentBlockNumber,
 		)
-		appsByLastInputCheckBlock := indexApps(byLastInputCheckBlock, inputBoxApps)
+
+		appsByLastInputCheckBlock := make(map[uint64][]appContracts)
+		for _, app := range inputBoxApps {
+			i := app.application.LastInputCheckBlock
+			if i == 0 { // fast sync applications with no inputs
+				i = findFirstInputBlock(&app)-1
+				r.Logger.Info("Fast sync application inputs",
+					"application", app.application.Name,
+					"start_block", i,
+				)
+				app.application.LastInputCheckBlock = i
+			}
+			appsByLastInputCheckBlock[i] = append(appsByLastInputCheckBlock[i], app)
+		}
 
 		for lastProcessedBlock, apps := range appsByLastInputCheckBlock {
 			appAddresses := appsToAddresses(apps)
 
-			// Only check blocks starting from the block where the InputBox
-			// contract was deployed as Inputs can be added to that same block
-			inputBoxDeploymentBlock := apps[0].application.IInputBoxBlock
-			if lastProcessedBlock < inputBoxDeploymentBlock {
-				lastProcessedBlock = inputBoxDeploymentBlock - 1
-			}
-
 			if mostRecentBlockNumber > lastProcessedBlock {
 
 				r.Logger.Debug("Checking inputs for applications",

internal/evmreader/input_test.go

@@ -4,6 +4,7 @@
 package evmreader
 
 import (
+	"math/big"
 	"time"
 
 	. "github.com/cartesi/rollups-node/internal/model"
@@ -129,6 +130,24 @@ func (s *EvmReaderSuite) TestItReadsInputsFromNewBlocksFilteredByDA() {
 		mock.Anything,
 	).Return(events_1, nil)
 
+	inputBox.Unset("GetNumberOfInputs")
+	inputBox.On(
+		"GetNumberOfInputs",
+		mock.Anything,
+		mock.Anything,
+	).Return(new(big.Int).SetUint64(2), nil)
+
+	applicationContract.On(
+		"GetDeploymentBlockNumber",
+		mock.Anything,
+	).Return(new(big.Int).SetUint64(10), nil)
+
+	inputBox.On(
+		"GetNumberOfInputs",
+		mock.Anything,
+		mock.Anything,
+	).Return(new(big.Int).SetUint64(0), nil)
+
 	// Start service
 	ready := make(chan struct{}, 1)
 	errChannel := make(chan error, 1)
@@ -267,6 +286,24 @@ func (s *EvmReaderSuite) TestItUpdatesLastInputCheckBlockWhenThereIsNoInputs() {
 		mock.Anything,
 	).Return(events_0, nil)
 
+	inputBox.Unset("GetNumberOfInputs")
+	inputBox.On(
+		"GetNumberOfInputs",
+		mock.Anything,
+		mock.Anything,
+	).Return(new(big.Int).SetUint64(1), nil)
+
+	applicationContract.On(
+		"GetDeploymentBlockNumber",
+		mock.Anything,
+	).Return(new(big.Int).SetUint64(10), nil)
+
+	inputBox.On(
+		"GetNumberOfInputs",
+		mock.Anything,
+		mock.Anything,
+	).Return(new(big.Int).SetUint64(0), nil)
+
 	events_1 := []iinputbox.IInputBoxInputAdded{}
 	mostRecentBlockNumber_1 := uint64(0x12)
 	retrieveInputsOpts_1 := bind.FilterOpts{

internal/evmreader/inputsource_adapter.go

@@ -110,3 +110,7 @@ func (i *InputSourceAdapterImpl) RetrieveInputs(
 	}
 	return events, nil
 }
+
+func (i *InputSourceAdapterImpl) GetNumberOfInputs(opts *bind.CallOpts, addr common.Address) (*big.Int, error) {
+	return i.inputbox.GetNumberOfInputs(opts, addr)
+}

internal/evmreader/output_test.go

@@ -39,6 +39,7 @@ func (s *EvmReaderSuite) TestOutputExecution() {
 		DataAvailability:     DataAvailability_InputBox[:],
 		IInputBoxBlock:       0x10,
 		EpochLength:          10,
+		LastInputCheckBlock:  0x01, // don't fast sync inputs
 		LastOutputCheckBlock: 0x10,
 	}}, uint64(1), nil).Once()
 	s.repository.On(