op-challenger: Return the TraceAccessor directly from the resourceCreator

Allows different game types to use a different TraceAccessor implementation.
Prestate validation moved to a game type specific function returned by the resourceCreator.

op-challenger/game/fault/player.go

@@ -8,7 +8,6 @@ import (
 	"github.com/ethereum-optimism/optimism/op-challenger/config"
 	"github.com/ethereum-optimism/optimism/op-challenger/game/fault/contracts"
 	"github.com/ethereum-optimism/optimism/op-challenger/game/fault/responder"
-	"github.com/ethereum-optimism/optimism/op-challenger/game/fault/trace"
 	"github.com/ethereum-optimism/optimism/op-challenger/game/fault/types"
 	gameTypes "github.com/ethereum-optimism/optimism/op-challenger/game/types"
 	"github.com/ethereum-optimism/optimism/op-challenger/metrics"
@@ -26,6 +25,10 @@ type GameInfo interface {
 	GetClaimCount(context.Context) (uint64, error)
 }
 
+// gameValidator checks that the specific game instance is compatible with the configuration.
+// Typically, this is done by verifying the absolute prestate of the game matches the local absolute prestate.
+type gameValidator func(ctx context.Context, gameContract *contracts.FaultDisputeGameContract) error
+
 type GamePlayer struct {
 	act                     actor
 	agreeWithProposedOutput bool
@@ -34,7 +37,7 @@ type GamePlayer struct {
 	status                  gameTypes.GameStatus
 }
 
-type resourceCreator func(addr common.Address, gameDepth uint64, dir string) (types.TraceProvider, types.OracleUpdater, error)
+type resourceCreator func(addr common.Address, gameDepth uint64, dir string) (types.TraceAccessor, types.OracleUpdater, gameValidator, error)
 
 func NewGamePlayer(
 	ctx context.Context,
@@ -77,12 +80,12 @@ func NewGamePlayer(
 		return nil, fmt.Errorf("failed to fetch the game depth: %w", err)
 	}
 
-	provider, updater, err := creator(addr, gameDepth, dir)
+	accessor, updater, validator, err := creator(addr, gameDepth, dir)
 	if err != nil {
-		return nil, fmt.Errorf("failed to create trace provider: %w", err)
+		return nil, fmt.Errorf("failed to create trace accessor: %w", err)
 	}
 
-	if err := ValidateAbsolutePrestate(ctx, provider, loader); err != nil {
+	if err := validator(ctx, loader); err != nil {
 		return nil, fmt.Errorf("failed to validate absolute prestate: %w", err)
 	}
 
@@ -91,7 +94,6 @@ func NewGamePlayer(
 		return nil, fmt.Errorf("failed to create the responder: %w", err)
 	}
 
-	accessor := trace.NewSimpleTraceAccessor(provider)
 	agent := NewAgent(m, loader, int(gameDepth), accessor, responder, updater, cfg.AgreeWithProposedOutput, logger)
 	return &GamePlayer{
 		act:                     agent.Act,

op-challenger/game/fault/register.go

@@ -5,6 +5,8 @@ import (
 	"fmt"
 
 	"github.com/ethereum-optimism/optimism/op-challenger/config"
+	"github.com/ethereum-optimism/optimism/op-challenger/game/fault/contracts"
+	"github.com/ethereum-optimism/optimism/op-challenger/game/fault/trace"
 	"github.com/ethereum-optimism/optimism/op-challenger/game/fault/trace/alphabet"
 	"github.com/ethereum-optimism/optimism/op-challenger/game/fault/trace/cannon"
 	faultTypes "github.com/ethereum-optimism/optimism/op-challenger/game/fault/types"
@@ -36,16 +38,19 @@ func RegisterGameTypes(
 	client *ethclient.Client,
 ) {
 	if cfg.TraceTypeEnabled(config.TraceTypeCannon) {
-		resourceCreator := func(addr common.Address, gameDepth uint64, dir string) (faultTypes.TraceProvider, faultTypes.OracleUpdater, error) {
+		resourceCreator := func(addr common.Address, gameDepth uint64, dir string) (faultTypes.TraceAccessor, faultTypes.OracleUpdater, gameValidator, error) {
 			provider, err := cannon.NewTraceProvider(ctx, logger, m, cfg, client, dir, addr, gameDepth)
 			if err != nil {
-				return nil, nil, fmt.Errorf("create cannon trace provider: %w", err)
+				return nil, nil, nil, fmt.Errorf("create cannon trace provider: %w", err)
 			}
 			updater, err := cannon.NewOracleUpdater(ctx, logger, txMgr, addr, client)
 			if err != nil {
-				return nil, nil, fmt.Errorf("failed to create the cannon updater: %w", err)
+				return nil, nil, nil, fmt.Errorf("failed to create the cannon updater: %w", err)
 			}
-			return provider, updater, nil
+			validator := func(ctx context.Context, contract *contracts.FaultDisputeGameContract) error {
+				return ValidateAbsolutePrestate(ctx, provider, contract)
+			}
+			return trace.NewSimpleTraceAccessor(provider), updater, validator, nil
 		}
 		playerCreator := func(game types.GameMetadata, dir string) (scheduler.GamePlayer, error) {
 			return NewGamePlayer(ctx, logger, m, cfg, dir, game.Proxy, txMgr, client, resourceCreator)
@@ -53,10 +58,13 @@ func RegisterGameTypes(
 		registry.RegisterGameType(cannonGameType, playerCreator)
 	}
 	if cfg.TraceTypeEnabled(config.TraceTypeAlphabet) {
-		resourceCreator := func(addr common.Address, gameDepth uint64, dir string) (faultTypes.TraceProvider, faultTypes.OracleUpdater, error) {
+		resourceCreator := func(addr common.Address, gameDepth uint64, dir string) (faultTypes.TraceAccessor, faultTypes.OracleUpdater, gameValidator, error) {
 			provider := alphabet.NewTraceProvider(cfg.AlphabetTrace, gameDepth)
 			updater := alphabet.NewOracleUpdater(logger)
-			return provider, updater, nil
+			validator := func(ctx context.Context, contract *contracts.FaultDisputeGameContract) error {
+				return ValidateAbsolutePrestate(ctx, provider, contract)
+			}
+			return trace.NewSimpleTraceAccessor(provider), updater, validator, nil
 		}
 		playerCreator := func(game types.GameMetadata, dir string) (scheduler.GamePlayer, error) {
 			return NewGamePlayer(ctx, logger, m, cfg, dir, game.Proxy, txMgr, client, resourceCreator)