eth/tracers: refactor traceTx to separate out struct logging (#24326)

* eth/tracers: refactor traceTx to separate out struct logging

review fix

Update eth/tracers/api.go

Co-authored-by: Martin Holst Swende <martin@swende.se>

Mv ExecutionResult type to logger package

review fix

impl GetResult for StructLogger

make formatLogs private

confused exit and end..

account for intrinsicGas in structlogger, fix TraceCall test

Add Stop method to logger

Simplify traceTx

Fix test

rm logger from blockchain test

account for refund in structLogger

* use tx hooks in struct logger

* minor

* avoid executionResult in struct logger

* revert blockchain test changes

eth/tracers/api.go

@@ -862,71 +862,46 @@ func (api *API) TraceCall(ctx context.Context, args ethapi.TransactionArgs, bloc
 // executes the given message in the provided environment. The return value will
 // be tracer dependent.
 func (api *API) traceTx(ctx context.Context, message core.Message, txctx *Context, vmctx vm.BlockContext, statedb *state.StateDB, config *TraceConfig) (interface{}, error) {
-	// Assemble the structured logger or the JavaScript tracer
 	var (
-		tracer    vm.EVMLogger
+		tracer    Tracer
 		err       error
+		timeout   = defaultTraceTimeout
 		txContext = core.NewEVMTxContext(message)
 	)
-	switch {
-	case config == nil:
-		tracer = logger.NewStructLogger(nil)
-	case config.Tracer != nil:
+	if config == nil {
+		config = &TraceConfig{}
+	}
+	// Default tracer is the struct logger
+	tracer = logger.NewStructLogger(config.Config)
+	if config.Tracer != nil {
+		tracer, err = New(*config.Tracer, txctx)
+		if err != nil {
+			return nil, err
+		}
+	}
 	// Define a meaningful timeout of a single transaction trace
-		timeout := defaultTraceTimeout
 	if config.Timeout != nil {
 		if timeout, err = time.ParseDuration(*config.Timeout); err != nil {
 			return nil, err
 		}
 	}
-		if t, err := New(*config.Tracer, txctx); err != nil {
-			return nil, err
-		} else {
 	deadlineCtx, cancel := context.WithTimeout(ctx, timeout)
 	go func() {
 		<-deadlineCtx.Done()
 		if errors.Is(deadlineCtx.Err(), context.DeadlineExceeded) {
-					t.Stop(errors.New("execution timeout"))
+			tracer.Stop(errors.New("execution timeout"))
 		}
 	}()
 	defer cancel()
-			tracer = t
-		}
-	default:
-		tracer = logger.NewStructLogger(config.Config)
-	}
+
 	// Run the transaction with tracing enabled.
 	vmenv := vm.NewEVM(vmctx, txContext, statedb, api.backend.ChainConfig(), vm.Config{Debug: true, Tracer: tracer, NoBaseFee: true})
-
 	// Call Prepare to clear out the statedb access list
 	statedb.Prepare(txctx.TxHash, txctx.TxIndex)
-
-	result, err := core.ApplyMessage(vmenv, message, new(core.GasPool).AddGas(message.Gas()))
-	if err != nil {
+	if _, err = core.ApplyMessage(vmenv, message, new(core.GasPool).AddGas(message.Gas())); err != nil {
 		return nil, fmt.Errorf("tracing failed: %w", err)
 	}
-
-	// Depending on the tracer type, format and return the output.
-	switch tracer := tracer.(type) {
-	case *logger.StructLogger:
-		// If the result contains a revert reason, return it.
-		returnVal := fmt.Sprintf("%x", result.Return())
-		if len(result.Revert()) > 0 {
-			returnVal = fmt.Sprintf("%x", result.Revert())
-		}
-		return &ethapi.ExecutionResult{
-			Gas:         result.UsedGas,
-			Failed:      result.Failed(),
-			ReturnValue: returnVal,
-			StructLogs:  ethapi.FormatLogs(tracer.StructLogs()),
-		}, nil
-
-	case Tracer:
 	return tracer.GetResult()
-
-	default:
-		panic(fmt.Sprintf("bad tracer type %T", tracer))
-	}
 }
 
 // APIs return the collection of RPC services the tracer package offers.

eth/tracers/api_test.go

@@ -39,6 +39,7 @@ import (
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/eth/tracers/logger"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/internal/ethapi"
 	"github.com/ethereum/go-ethereum/params"
@@ -213,11 +214,11 @@ func TestTraceCall(t *testing.T) {
 			},
 			config:    nil,
 			expectErr: nil,
-			expect: &ethapi.ExecutionResult{
+			expect: &logger.ExecutionResult{
 				Gas:         params.TxGas,
 				Failed:      false,
 				ReturnValue: "",
-				StructLogs:  []ethapi.StructLogRes{},
+				StructLogs:  []logger.StructLogRes{},
 			},
 		},
 		// Standard JSON trace upon the head, plain transfer.
@@ -230,11 +231,11 @@ func TestTraceCall(t *testing.T) {
 			},
 			config:    nil,
 			expectErr: nil,
-			expect: &ethapi.ExecutionResult{
+			expect: &logger.ExecutionResult{
 				Gas:         params.TxGas,
 				Failed:      false,
 				ReturnValue: "",
-				StructLogs:  []ethapi.StructLogRes{},
+				StructLogs:  []logger.StructLogRes{},
 			},
 		},
 		// Standard JSON trace upon the non-existent block, error expects
@@ -259,11 +260,11 @@ func TestTraceCall(t *testing.T) {
 			},
 			config:    nil,
 			expectErr: nil,
-			expect: &ethapi.ExecutionResult{
+			expect: &logger.ExecutionResult{
 				Gas:         params.TxGas,
 				Failed:      false,
 				ReturnValue: "",
-				StructLogs:  []ethapi.StructLogRes{},
+				StructLogs:  []logger.StructLogRes{},
 			},
 		},
 		// Standard JSON trace upon the pending block
@@ -276,11 +277,11 @@ func TestTraceCall(t *testing.T) {
 			},
 			config:    nil,
 			expectErr: nil,
-			expect: &ethapi.ExecutionResult{
+			expect: &logger.ExecutionResult{
 				Gas:         params.TxGas,
 				Failed:      false,
 				ReturnValue: "",
-				StructLogs:  []ethapi.StructLogRes{},
+				StructLogs:  []logger.StructLogRes{},
 			},
 		},
 	}
@@ -299,8 +300,12 @@ func TestTraceCall(t *testing.T) {
 				t.Errorf("Expect no error, get %v", err)
 				continue
 			}
-			if !reflect.DeepEqual(result, testspec.expect) {
-				t.Errorf("Result mismatch, want %v, get %v", testspec.expect, result)
+			var have *logger.ExecutionResult
+			if err := json.Unmarshal(result.(json.RawMessage), &have); err != nil {
+				t.Errorf("failed to unmarshal result %v", err)
+			}
+			if !reflect.DeepEqual(have, testspec.expect) {
+				t.Errorf("Result mismatch, want %v, get %v", testspec.expect, have)
 			}
 		}
 	}
@@ -329,11 +334,15 @@ func TestTraceTransaction(t *testing.T) {
 	if err != nil {
 		t.Errorf("Failed to trace transaction %v", err)
 	}
-	if !reflect.DeepEqual(result, &ethapi.ExecutionResult{
+	var have *logger.ExecutionResult
+	if err := json.Unmarshal(result.(json.RawMessage), &have); err != nil {
+		t.Errorf("failed to unmarshal result %v", err)
+	}
+	if !reflect.DeepEqual(have, &logger.ExecutionResult{
 		Gas:         params.TxGas,
 		Failed:      false,
 		ReturnValue: "",
-		StructLogs:  []ethapi.StructLogRes{},
+		StructLogs:  []logger.StructLogRes{},
 	}) {
 		t.Error("Transaction tracing result is different")
 	}

eth/tracers/logger/logger.go

@@ -18,10 +18,12 @@ package logger
 
 import (
 	"encoding/hex"
+	"encoding/json"
 	"fmt"
 	"io"
 	"math/big"
 	"strings"
+	"sync/atomic"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -112,6 +114,11 @@ type StructLogger struct {
 	logs     []StructLog
 	output   []byte
 	err      error
+	gasLimit uint64
+	usedGas  uint64
+
+	interrupt uint32 // Atomic flag to signal execution interruption
+	reason    error  // Textual reason for the interruption
 }
 
 // NewStructLogger returns a new logger
@@ -142,13 +149,19 @@ func (l *StructLogger) CaptureStart(env *vm.EVM, from common.Address, to common.
 //
 // CaptureState also tracks SLOAD/SSTORE ops to track storage change.
 func (l *StructLogger) CaptureState(pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, rData []byte, depth int, err error) {
-	memory := scope.Memory
-	stack := scope.Stack
-	contract := scope.Contract
+	// If tracing was interrupted, set the error and stop
+	if atomic.LoadUint32(&l.interrupt) > 0 {
+		l.env.Cancel()
+		return
+	}
 	// check if already accumulated the specified number of logs
 	if l.cfg.Limit != 0 && l.cfg.Limit <= len(l.logs) {
 		return
 	}
+
+	memory := scope.Memory
+	stack := scope.Stack
+	contract := scope.Contract
 	// Copy a snapshot of the current memory state to a new buffer
 	var mem []byte
 	if l.cfg.EnableMemory {
@@ -221,11 +234,42 @@ func (l *StructLogger) CaptureEnd(output []byte, gasUsed uint64, t time.Duration
 func (l *StructLogger) CaptureEnter(typ vm.OpCode, from common.Address, to common.Address, input []byte, gas uint64, value *big.Int) {
 }
 
-func (l *StructLogger) CaptureExit(output []byte, gasUsed uint64, err error) {}
+func (l *StructLogger) CaptureExit(output []byte, gasUsed uint64, err error) {
+}
 
-func (*StructLogger) CaptureTxStart(gasLimit uint64) {}
+func (l *StructLogger) GetResult() (json.RawMessage, error) {
+	// Tracing aborted
+	if l.reason != nil {
+		return nil, l.reason
+	}
+	failed := l.err != nil
+	returnData := common.CopyBytes(l.output)
+	// Return data when successful and revert reason when reverted, otherwise empty.
+	returnVal := fmt.Sprintf("%x", returnData)
+	if failed && l.err != vm.ErrExecutionReverted {
+		returnVal = ""
+	}
+	return json.Marshal(&ExecutionResult{
+		Gas:         l.usedGas,
+		Failed:      failed,
+		ReturnValue: returnVal,
+		StructLogs:  formatLogs(l.StructLogs()),
+	})
+}
 
-func (*StructLogger) CaptureTxEnd(restGas uint64) {}
+// Stop terminates execution of the tracer at the first opportune moment.
+func (l *StructLogger) Stop(err error) {
+	l.reason = err
+	atomic.StoreUint32(&l.interrupt, 1)
+}
+
+func (l *StructLogger) CaptureTxStart(gasLimit uint64) {
+	l.gasLimit = gasLimit
+}
+
+func (l *StructLogger) CaptureTxEnd(restGas uint64) {
+	l.usedGas = l.gasLimit - restGas
+}
 
 // StructLogs returns the captured log entries.
 func (l *StructLogger) StructLogs() []StructLog { return l.logs }
@@ -355,3 +399,66 @@ func (t *mdLogger) CaptureExit(output []byte, gasUsed uint64, err error) {}
 func (*mdLogger) CaptureTxStart(gasLimit uint64) {}
 
 func (*mdLogger) CaptureTxEnd(restGas uint64) {}
+
+// ExecutionResult groups all structured logs emitted by the EVM
+// while replaying a transaction in debug mode as well as transaction
+// execution status, the amount of gas used and the return value
+type ExecutionResult struct {
+	Gas         uint64         `json:"gas"`
+	Failed      bool           `json:"failed"`
+	ReturnValue string         `json:"returnValue"`
+	StructLogs  []StructLogRes `json:"structLogs"`
+}
+
+// StructLogRes stores a structured log emitted by the EVM while replaying a
+// transaction in debug mode
+type StructLogRes struct {
+	Pc            uint64             `json:"pc"`
+	Op            string             `json:"op"`
+	Gas           uint64             `json:"gas"`
+	GasCost       uint64             `json:"gasCost"`
+	Depth         int                `json:"depth"`
+	Error         string             `json:"error,omitempty"`
+	Stack         *[]string          `json:"stack,omitempty"`
+	Memory        *[]string          `json:"memory,omitempty"`
+	Storage       *map[string]string `json:"storage,omitempty"`
+	RefundCounter uint64             `json:"refund,omitempty"`
+}
+
+// formatLogs formats EVM returned structured logs for json output
+func formatLogs(logs []StructLog) []StructLogRes {
+	formatted := make([]StructLogRes, len(logs))
+	for index, trace := range logs {
+		formatted[index] = StructLogRes{
+			Pc:            trace.Pc,
+			Op:            trace.Op.String(),
+			Gas:           trace.Gas,
+			GasCost:       trace.GasCost,
+			Depth:         trace.Depth,
+			Error:         trace.ErrorString(),
+			RefundCounter: trace.RefundCounter,
+		}
+		if trace.Stack != nil {
+			stack := make([]string, len(trace.Stack))
+			for i, stackValue := range trace.Stack {
+				stack[i] = stackValue.Hex()
+			}
+			formatted[index].Stack = &stack
+		}
+		if trace.Memory != nil {
+			memory := make([]string, 0, (len(trace.Memory)+31)/32)
+			for i := 0; i+32 <= len(trace.Memory); i += 32 {
+				memory = append(memory, fmt.Sprintf("%x", trace.Memory[i:i+32]))
+			}
+			formatted[index].Memory = &memory
+		}
+		if trace.Storage != nil {
+			storage := make(map[string]string)
+			for i, storageValue := range trace.Storage {
+				storage[fmt.Sprintf("%x", i)] = fmt.Sprintf("%x", storageValue)
+			}
+			formatted[index].Storage = &storage
+		}
+	}
+	return formatted
+}

internal/ethapi/api.go

@@ -1122,69 +1122,6 @@ func (s *PublicBlockChainAPI) EstimateGas(ctx context.Context, args TransactionA
 	return DoEstimateGas(ctx, s.b, args, bNrOrHash, s.b.RPCGasCap())
 }
 
-// ExecutionResult groups all structured logs emitted by the EVM
-// while replaying a transaction in debug mode as well as transaction
-// execution status, the amount of gas used and the return value
-type ExecutionResult struct {
-	Gas         uint64         `json:"gas"`
-	Failed      bool           `json:"failed"`
-	ReturnValue string         `json:"returnValue"`
-	StructLogs  []StructLogRes `json:"structLogs"`
-}
-
-// StructLogRes stores a structured log emitted by the EVM while replaying a
-// transaction in debug mode
-type StructLogRes struct {
-	Pc            uint64             `json:"pc"`
-	Op            string             `json:"op"`
-	Gas           uint64             `json:"gas"`
-	GasCost       uint64             `json:"gasCost"`
-	Depth         int                `json:"depth"`
-	Error         string             `json:"error,omitempty"`
-	Stack         *[]string          `json:"stack,omitempty"`
-	Memory        *[]string          `json:"memory,omitempty"`
-	Storage       *map[string]string `json:"storage,omitempty"`
-	RefundCounter uint64             `json:"refund,omitempty"`
-}
-
-// FormatLogs formats EVM returned structured logs for json output
-func FormatLogs(logs []logger.StructLog) []StructLogRes {
-	formatted := make([]StructLogRes, len(logs))
-	for index, trace := range logs {
-		formatted[index] = StructLogRes{
-			Pc:            trace.Pc,
-			Op:            trace.Op.String(),
-			Gas:           trace.Gas,
-			GasCost:       trace.GasCost,
-			Depth:         trace.Depth,
-			Error:         trace.ErrorString(),
-			RefundCounter: trace.RefundCounter,
-		}
-		if trace.Stack != nil {
-			stack := make([]string, len(trace.Stack))
-			for i, stackValue := range trace.Stack {
-				stack[i] = stackValue.Hex()
-			}
-			formatted[index].Stack = &stack
-		}
-		if trace.Memory != nil {
-			memory := make([]string, 0, (len(trace.Memory)+31)/32)
-			for i := 0; i+32 <= len(trace.Memory); i += 32 {
-				memory = append(memory, fmt.Sprintf("%x", trace.Memory[i:i+32]))
-			}
-			formatted[index].Memory = &memory
-		}
-		if trace.Storage != nil {
-			storage := make(map[string]string)
-			for i, storageValue := range trace.Storage {
-				storage[fmt.Sprintf("%x", i)] = fmt.Sprintf("%x", storageValue)
-			}
-			formatted[index].Storage = &storage
-		}
-	}
-	return formatted
-}
-
 // RPCMarshalHeader converts the given header to the RPC output .
 func RPCMarshalHeader(head *types.Header) map[string]interface{} {
 	result := map[string]interface{}{