soroban-rpc: simulateTransaction: automatically detect ledger entries which require restoring

cmd/soroban-rpc/internal/methods/simulate_transaction.go

@@ -28,13 +28,19 @@ type SimulateHostFunctionResult struct {
 	XDR  string   `json:"xdr"`
 }
 
+type RestorePreamble struct {
+	TransactionData string `json:"transactionData"` // SorobanTransactionData XDR in base64
+	MinResourceFee  int64  `json:"minResourceFee,string"`
+}
+
 type SimulateTransactionResponse struct {
 	Error           string                       `json:"error,omitempty"`
 	TransactionData string                       `json:"transactionData"` // SorobanTransactionData XDR in base64
-	Events          []string                     `json:"events"`          // DiagnosticEvent XDR in base64
 	MinResourceFee  int64                        `json:"minResourceFee,string"`
-	Results         []SimulateHostFunctionResult `json:"results,omitempty"` // an array of the individual host function call results
-	Cost            SimulateTransactionCost      `json:"cost"`              // the effective cpu and memory cost of the invoked transaction execution.
+	Events          []string                     `json:"events,omitempty"`          // DiagnosticEvent XDR in base64
+	Results         []SimulateHostFunctionResult `json:"results,omitempty"`         // an array of the individual host function call results
+	Cost            SimulateTransactionCost      `json:"cost"`                      // the effective cpu and memory cost of the invoked transaction execution.
+	RestorePreamble RestorePreamble              `json:"restorePreamble,omitempty"` // If present, it indicates that a prior RestoreFootprint is required
 	LatestLedger    int64                        `json:"latestLedger,string"`
 }
 
@@ -114,21 +120,32 @@ func NewSimulateTransactionHandler(logger *log.Entry, ledgerEntryReader db.Ledge
 			}
 		}
 
+		var results []SimulateHostFunctionResult
+		if result.Result != "" {
+			results = append(results, SimulateHostFunctionResult{
+				XDR:  result.Result,
+				Auth: result.Auth,
+			})
+		}
+		restorePreable := RestorePreamble{}
+		if result.PreRestoreTransactionData != "" {
+			restorePreable = RestorePreamble{
+				TransactionData: result.PreRestoreTransactionData,
+				MinResourceFee:  result.PreRestoreMinFee,
+			}
+		}
+
 		return SimulateTransactionResponse{
-			Results: []SimulateHostFunctionResult{
-				{
-					XDR:  result.Result,
-					Auth: result.Auth,
-				},
-			},
+			Results:         results,
 			Events:          result.Events,
 			TransactionData: result.TransactionData,
 			MinResourceFee:  result.MinFee,
 			Cost: SimulateTransactionCost{
 				CPUInstructions: result.CPUInstructions,
 				MemoryBytes:     result.MemoryBytes,
 			},
-			LatestLedger: int64(latestLedger),
+			LatestLedger:    int64(latestLedger),
+			RestorePreamble: restorePreable,
 		}
 	})
 }

cmd/soroban-rpc/internal/preflight/preflight.go

@@ -61,28 +61,6 @@ func SnapshotSourceGet(handle C.uintptr_t, cLedgerKey *C.char, includeExpired C.
 	return C.CString(out)
 }
 
-// SnapshotSourceHas takes LedgerKey XDR in base64 and returns whether it exists
-// It's used by the Rust preflight code to obtain ledger entries.
-//
-//export SnapshotSourceHas
-func SnapshotSourceHas(handle C.uintptr_t, cLedgerKey *C.char) C.int {
-	h := cgo.Handle(handle).Value().(snapshotSourceHandle)
-	ledgerKeyB64 := C.GoString(cLedgerKey)
-	var ledgerKey xdr.LedgerKey
-	if err := xdr.SafeUnmarshalBase64(ledgerKeyB64, &ledgerKey); err != nil {
-		panic(err)
-	}
-	present, _, err := h.readTx.GetLedgerEntry(ledgerKey, false)
-	if err != nil {
-		h.logger.WithError(err).Error("SnapshotSourceHas(): GetLedgerEntry() failed")
-		return 0
-	}
-	if present {
-		return 1
-	}
-	return 0
-}
-
 //export FreeGoCString
 func FreeGoCString(str *C.char) {
 	C.free(unsafe.Pointer(str))
@@ -99,13 +77,15 @@ type PreflightParameters struct {
 }
 
 type Preflight struct {
-	Events          []string // DiagnosticEvents XDR in base64
-	TransactionData string   // SorobanTransactionData XDR in base64
-	MinFee          int64
-	Result          string   // XDR SCVal in base64
-	Auth            []string // SorobanAuthorizationEntrys XDR in base64
-	CPUInstructions uint64
-	MemoryBytes     uint64
+	Events                    []string // DiagnosticEvents XDR in base64
+	TransactionData           string   // SorobanTransactionData XDR in base64
+	MinFee                    int64
+	Result                    string   // XDR SCVal in base64
+	Auth                      []string // SorobanAuthorizationEntrys XDR in base64
+	CPUInstructions           uint64
+	MemoryBytes               uint64
+	PreRestoreTransactionData string // SorobanTransactionData XDR in base64
+	PreRestoreMinFee          int64
 }
 
 // GoNullTerminatedStringSlice transforms a C NULL-terminated char** array to a Go string slice
@@ -240,13 +220,15 @@ func GoPreflight(result *C.CPreflightResult) (Preflight, error) {
 	}
 
 	preflight := Preflight{
-		Events:          GoNullTerminatedStringSlice(result.events),
-		TransactionData: C.GoString(result.transaction_data),
-		MinFee:          int64(result.min_fee),
-		Result:          C.GoString(result.result),
-		Auth:            GoNullTerminatedStringSlice(result.auth),
-		CPUInstructions: uint64(result.cpu_instructions),
-		MemoryBytes:     uint64(result.memory_bytes),
+		Events:                    GoNullTerminatedStringSlice(result.events),
+		TransactionData:           C.GoString(result.transaction_data),
+		MinFee:                    int64(result.min_fee),
+		Result:                    C.GoString(result.result),
+		Auth:                      GoNullTerminatedStringSlice(result.auth),
+		CPUInstructions:           uint64(result.cpu_instructions),
+		MemoryBytes:               uint64(result.memory_bytes),
+		PreRestoreTransactionData: C.GoString(result.pre_restore_transaction_data),
+		PreRestoreMinFee:          int64(result.pre_restore_min_fee),
 	}
 	return preflight, nil
 }

cmd/soroban-rpc/internal/preflight/preflight_test.go

@@ -305,6 +305,7 @@ func getPreflightParameters(t testing.TB, inMemory bool) PreflightParameters {
 }
 
 func TestGetPreflight(t *testing.T) {
+
 	params := getPreflightParameters(t, false)
 	_, err := GetPreflight(context.Background(), params)
 	require.NoError(t, err)

cmd/soroban-rpc/internal/test/captive-core-integration-tests.cfg

@@ -7,7 +7,7 @@ FAILURE_SAFETY=0
 ENABLE_SOROBAN_DIAGNOSTIC_EVENTS=true
 # Lower the expiration of persistent ledger entries
 # so that ledger expiration/restoring becomes testeable
-TESTING_MINIMUM_PERSISTENT_ENTRY_LIFETIME=20
+TESTING_MINIMUM_PERSISTENT_ENTRY_LIFETIME=10
 
 [[VALIDATORS]]
 NAME="local_core"