Refactor shard handling to use configurable shard number from config

config/config.go

@@ -21,6 +21,12 @@ type NetworkConfig struct {
 	MaxDelayMs   int  `json:"max_delay_ms"` // Maximum delay in milliseconds
 }
 
+var Configuration Config
+
+func GetConfig() Config {
+	return Configuration
+}
+
 // Load reads and parses the config.json file
 func Load(configPath string) (*Config, error) {
 	data, err := os.ReadFile(configPath)
@@ -33,6 +39,7 @@ func Load(configPath string) (*Config, error) {
 		return nil, fmt.Errorf("failed to parse config file: %w", err)
 	}
 
+	Configuration = *cfg
 	return cfg, nil
 }
 

internal/orchestrator/simulator.go

@@ -11,6 +11,7 @@ import (
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/holiman/uint256"
+	"github.com/sharding-experiment/sharding/config"
 	"github.com/sharding-experiment/sharding/internal/protocol"
 )
 
@@ -26,8 +27,8 @@ type Simulator struct {
 	fetcher     *StateFetcher
 	queue       chan *simulationJob
 	results     map[string]*SimulationResult
-	onSuccess   func(tx protocol.CrossShardTx)    // Callback when simulation succeeds
-	onError     func(tx protocol.CrossShardTx)    // Callback when simulation fails (V2)
+	onSuccess   func(tx protocol.CrossShardTx) // Callback when simulation succeeds
+	onError     func(tx protocol.CrossShardTx) // Callback when simulation fails (V2)
 	chainConfig *params.ChainConfig
 	vmConfig    vm.Config
 	numShards   int // V2.2: Total number of shards for address mapping
@@ -55,7 +56,7 @@ func NewSimulator(fetcher *StateFetcher, onSuccess func(tx protocol.CrossShardTx
 		queue:       make(chan *simulationJob, 100),
 		results:     make(map[string]*SimulationResult),
 		onSuccess:   onSuccess,
-		numShards:   NumShards, // V2.2: Use constant from statedb.go
+		numShards:   config.GetConfig().ShardNum, // V2.2: Use constant from statedb.go
 		stopCleanup: make(chan struct{}),
 		chainConfig: &params.ChainConfig{
 			ChainID:             big.NewInt(1337),

internal/orchestrator/statedb.go

@@ -15,10 +15,6 @@ import (
 	"github.com/sharding-experiment/sharding/internal/protocol"
 )
 
-// NumShards is the total number of shards in the system
-// Used for address-to-shard mapping
-const NumShards = 8
-
 // SimulationStateDB implements vm.StateDB for cross-shard transaction simulation.
 // It fetches state on-demand from State Shards and tracks all reads/writes for RwSet construction.
 //
@@ -29,32 +25,32 @@ const NumShards = 8
 // This design allows the EVM to continue executing (collecting partial RwSet data for debugging)
 // while ensuring the simulation ultimately fails if any required state couldn't be fetched.
 type SimulationStateDB struct {
-	mu           sync.RWMutex
-	txID         string
-	fetcher      *StateFetcher
+	mu      sync.RWMutex
+	txID    string
+	fetcher *StateFetcher
 
 	// Cached account state (fetched on first access)
-	accounts     map[common.Address]*accountState
+	accounts map[common.Address]*accountState
 
 	// Track reads and writes for RwSet construction
-	reads        map[common.Address]map[common.Hash]common.Hash // addr -> slot -> value read
-	writes       map[common.Address]map[common.Hash]common.Hash // addr -> slot -> new value written
-	writeOlds    map[common.Address]map[common.Hash]common.Hash // addr -> slot -> old value before write
+	reads     map[common.Address]map[common.Hash]common.Hash // addr -> slot -> value read
+	writes    map[common.Address]map[common.Hash]common.Hash // addr -> slot -> new value written
+	writeOlds map[common.Address]map[common.Hash]common.Hash // addr -> slot -> old value before write
 
 	// Access list for EIP-2929
-	accessList   *accessList
+	accessList *accessList
 
 	// Transaction logs
-	logs         []*types.Log
+	logs []*types.Log
 
 	// Refund counter
-	refund       uint64
+	refund uint64
 
 	// Snapshots for revert
-	snapshots    []snapshot
+	snapshots []snapshot
 
 	// Transient storage (EIP-1153)
-	transient    map[common.Address]map[common.Hash]common.Hash
+	transient map[common.Address]map[common.Hash]common.Hash
 
 	// Track fetch errors - if any fetch fails, simulation should abort
 	fetchErrors []error
@@ -72,11 +68,11 @@ type accountState struct {
 }
 
 type snapshot struct {
-	accounts  map[common.Address]*accountState
-	reads     map[common.Address]map[common.Hash]common.Hash
-	writes    map[common.Address]map[common.Hash]common.Hash
-	refund    uint64
-	logsLen   int
+	accounts map[common.Address]*accountState
+	reads    map[common.Address]map[common.Hash]common.Hash
+	writes   map[common.Address]map[common.Hash]common.Hash
+	refund   uint64
+	logsLen  int
 }
 
 type accessList struct {
@@ -710,4 +706,3 @@ func (s *SimulationStateDB) GetFetchErrors() []error {
 	copy(result, s.fetchErrors)
 	return result
 }
-

internal/shard/evm.go

@@ -649,7 +649,7 @@ func (e *EVMState) SimulateCallForRwSet(caller, contract common.Address, input [
 
 	// Create tracking wrapper - for local simulation, all addresses are "local"
 	// We track reads/writes regardless of shard assignment
-	trackingDB := NewTrackingStateDB(e.stateDB, refBlock.ShardNum, NumShards)
+	trackingDB := NewTrackingStateDB(e.stateDB, refBlock.ShardNum, config.GetConfig().ShardNum)
 
 	// Create EVM with tracking state
 	blockCtx := vm.BlockContext{

internal/shard/server.go

@@ -585,7 +585,7 @@ func (s *Server) handleDeploy(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Use tracked deployment to capture constructor storage writes
-	contractAddr, returnData, gasUsed, _, storageWrites, err := s.evmState.DeployContractTracked(from, bytecode, value, gas, NumShards)
+	contractAddr, returnData, gasUsed, _, storageWrites, err := s.evmState.DeployContractTracked(from, bytecode, value, gas, config.GetConfig().ShardNum)
 	if err != nil {
 		log.Printf("Shard %d: Deploy failed: %v", s.shardID, err)
 		json.NewEncoder(w).Encode(map[string]interface{}{
@@ -597,7 +597,7 @@ func (s *Server) handleDeploy(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Check which shard this contract address maps to
-	targetShard := int(contractAddr[len(contractAddr)-1]) % NumShards
+	targetShard := int(contractAddr[len(contractAddr)-1]) % config.GetConfig().ShardNum
 	deployedCode := s.evmState.GetCode(contractAddr)
 
 	if targetShard != s.shardID {
@@ -669,7 +669,7 @@ func (s *Server) handleSetCode(w http.ResponseWriter, r *http.Request) {
 	code := common.FromHex(req.Code)
 
 	// Verify this address belongs to this shard
-	targetShard := int(addr[len(addr)-1]) % NumShards
+	targetShard := int(addr[len(addr)-1]) % config.GetConfig().ShardNum
 	if targetShard != s.shardID {
 		http.Error(w, fmt.Sprintf("address %s belongs to shard %d, not %d",
 			addr.Hex(), targetShard, s.shardID), http.StatusBadRequest)
@@ -1026,7 +1026,7 @@ func (s *Server) processOrchestratorBlock(block *protocol.OrchestratorShardBlock
 		if tx.FromShard == s.shardID {
 			// V2 Optimistic: Don't lock funds now - Lock tx will validate and lock atomically
 			// Store pending credit info for destination if this shard is also destination
-			toShard := int(tx.To[len(tx.To)-1]) % NumShards
+			toShard := int(tx.To[len(tx.To)-1]) % config.GetConfig().ShardNum
 			if tx.Value.ToBigInt().Sign() > 0 && toShard == s.shardID {
 				s.chain.StorePendingCredit(tx.ID, tx.To, tx.Value.ToBigInt())
 			}
@@ -1050,7 +1050,7 @@ func (s *Server) processOrchestratorBlock(block *protocol.OrchestratorShardBlock
 			// V2 Optimistic: Don't lock addresses now - Lock tx validates+locks atomically
 
 			// Store pending credit ONLY for tx.To address
-			toShard := int(tx.To[len(tx.To)-1]) % NumShards
+			toShard := int(tx.To[len(tx.To)-1]) % config.GetConfig().ShardNum
 			if tx.Value.ToBigInt().Sign() > 0 && toShard == s.shardID {
 				s.chain.StorePendingCredit(tx.ID, tx.To, tx.Value.ToBigInt())
 				log.Printf("Shard %d: Pending credit %s for %s (value=%s)",
@@ -1089,12 +1089,12 @@ type StateFetchRequest struct {
 
 // StateFetchResponse is the response format for /state/fetch
 type StateFetchResponse struct {
-	Success  bool            `json:"success"`
-	Error    string          `json:"error,omitempty"`
-	Balance  *big.Int        `json:"balance"`
-	Nonce    uint64          `json:"nonce"`
-	Code     []byte          `json:"code,omitempty"`
-	CodeHash common.Hash     `json:"code_hash"`
+	Success  bool        `json:"success"`
+	Error    string      `json:"error,omitempty"`
+	Balance  *big.Int    `json:"balance"`
+	Nonce    uint64      `json:"nonce"`
+	Code     []byte      `json:"code,omitempty"`
+	CodeHash common.Hash `json:"code_hash"`
 }
 
 // handleStateFetch returns account state WITHOUT acquiring locks.
@@ -1135,7 +1135,7 @@ func (s *Server) handleRwSet(w http.ResponseWriter, r *http.Request) {
 		s.shardID, req.TxID, req.Address.Hex())
 
 	// Verify the target address belongs to this shard
-	targetShard := int(req.Address[len(req.Address)-1]) % NumShards
+	targetShard := int(req.Address[len(req.Address)-1]) % config.GetConfig().ShardNum
 	if targetShard != s.shardID {
 		log.Printf("Shard %d: RwSetRequest for address %s belongs to shard %d",
 			s.shardID, req.Address.Hex(), targetShard)
@@ -1201,11 +1201,10 @@ type TxSubmitRequest struct {
 }
 
 const (
-	NumShards          = 8           // TODO: make configurable (see issue #28)
-	MinGasLimit        = 21_000      // Minimum gas for a basic transfer (Ethereum standard)
-	DefaultGasLimit    = 1_000_000   // Default gas limit for transactions
-	MaxGasLimit        = 30_000_000  // Maximum gas limit per transaction
-	SimulationGasLimit = 3_000_000   // Higher gas limit for simulation
+	MinGasLimit        = 21_000     // Minimum gas for a basic transfer (Ethereum standard)
+	DefaultGasLimit    = 1_000_000  // Default gas limit for transactions
+	MaxGasLimit        = 30_000_000 // Maximum gas limit per transaction
+	SimulationGasLimit = 3_000_000  // Higher gas limit for simulation
 )
 
 // handleTxSubmit is the unified transaction endpoint
@@ -1251,15 +1250,15 @@ func (s *Server) handleTxSubmit(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Check which shard the sender is on
-	fromShard := int(from[len(from)-1]) % NumShards
+	fromShard := int(from[len(from)-1]) % config.GetConfig().ShardNum
 	if fromShard != s.shardID {
 		// Sender is on a different shard - reject
 		http.Error(w, fmt.Sprintf("sender %s belongs to shard %d, not shard %d", from.Hex(), fromShard, s.shardID), http.StatusBadRequest)
 		return
 	}
 
 	// Quick check: is 'to' address on another shard?
-	toShard := int(to[len(to)-1]) % NumShards
+	toShard := int(to[len(to)-1]) % config.GetConfig().ShardNum
 
 	// Check if 'to' is a contract (has code)
 	toCode := s.evmState.GetCode(to)
@@ -1286,7 +1285,7 @@ func (s *Server) handleTxSubmit(w http.ResponseWriter, r *http.Request) {
 			simGas = SimulationGasLimit
 		}
 
-		_, accessedAddrs, hasCrossShard, simErr := s.evmState.SimulateCall(from, to, data, value, simGas, s.shardID, NumShards)
+		_, accessedAddrs, hasCrossShard, simErr := s.evmState.SimulateCall(from, to, data, value, simGas, s.shardID, config.GetConfig().ShardNum)
 
 		if simErr != nil {
 			// Classify the error to determine if it's cross-shard or a real error
@@ -1307,7 +1306,7 @@ func (s *Server) handleTxSubmit(w http.ResponseWriter, r *http.Request) {
 			// Build map of cross-shard addresses
 			crossShardAddrs = make(map[common.Address]int)
 			for _, addr := range accessedAddrs {
-				addrShard := int(addr[len(addr)-1]) % NumShards
+				addrShard := int(addr[len(addr)-1]) % config.GetConfig().ShardNum
 				if addrShard != s.shardID {
 					crossShardAddrs[addr] = addrShard
 				}

internal/shard/shard_test.go

@@ -326,7 +326,7 @@ func TestShardAssignment(t *testing.T) {
 
 	for _, tc := range tests {
 		addr := common.HexToAddress(tc.address)
-		shard := int(addr[len(addr)-1]) % NumShards
+		shard := int(addr[len(addr)-1]) % config.GetConfig().ShardNum
 		if shard != tc.expected {
 			t.Errorf("Address %s: expected shard %d, got %d", tc.address, tc.expected, shard)
 		}