eth/tracers: support for golang tracers + add golang callTracer

eth/tracers/api.go

@@ -36,6 +36,7 @@ import (
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/eth/tracers/native"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/internal/ethapi"
 	"github.com/ethereum/go-ethereum/log"
@@ -858,19 +859,23 @@ func (api *API) traceTx(ctx context.Context, message core.Message, txctx *Contex
 				return nil, err
 			}
 		}
-		// Constuct the JavaScript tracer to execute with
-		if tracer, err = New(*config.Tracer, txctx); err != nil {
-			return nil, err
-		}
-		// Handle timeouts and RPC cancellations
-		deadlineCtx, cancel := context.WithTimeout(ctx, timeout)
-		go func() {
-			<-deadlineCtx.Done()
-			if deadlineCtx.Err() == context.DeadlineExceeded {
-				tracer.(*Tracer).Stop(errors.New("execution timeout"))
+		// Native tracers take precedence
+		var ok bool
+		if tracer, ok = native.New(*config.Tracer); !ok {
+			if tracer, err = New(*config.Tracer, txctx); err != nil {
+				return nil, err
 			}
-		}()
-		defer cancel()
+			// TODO(s1na): do we need timeout for native tracers?
+			// Handle timeouts and RPC cancellations
+			deadlineCtx, cancel := context.WithTimeout(ctx, timeout)
+			go func() {
+				<-deadlineCtx.Done()
+				if deadlineCtx.Err() == context.DeadlineExceeded {
+					tracer.(*Tracer).Stop(errors.New("execution timeout"))
+				}
+			}()
+			defer cancel()
+		}
 
 	case config == nil:
 		tracer = vm.NewStructLogger(nil)
@@ -904,7 +909,7 @@ func (api *API) traceTx(ctx context.Context, message core.Message, txctx *Contex
 			StructLogs:  ethapi.FormatLogs(tracer.StructLogs()),
 		}, nil
 
-	case *Tracer:
+	case native.Tracer:
 		return tracer.GetResult()
 
 	default:

eth/tracers/native/call.go

@@ -0,0 +1,135 @@
+package native
+
+import (
+	"encoding/json"
+	"errors"
+	"math/big"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/vm"
+)
+
+func init() {
+	register("callTracerNative", NewCallTracer)
+}
+
+type callFrame struct {
+	Type    string      `json:"type"`
+	From    string      `json:"from"`
+	To      string      `json:"to,omitempty"`
+	Value   string      `json:"value,omitempty"`
+	Gas     string      `json:"gas"`
+	GasUsed string      `json:"gasUsed"`
+	Input   string      `json:"input"`
+	Output  string      `json:"output,omitempty"`
+	Error   string      `json:"error,omitempty"`
+	Calls   []callFrame `json:"calls,omitempty"`
+}
+
+type CallTracer struct {
+	callstack []callFrame
+}
+
+// NewCallTracer returns a native go tracer which tracks
+// call frames of a tx, and implements vm.Tracer.
+func NewCallTracer() Tracer {
+	// First callframe contains tx context info
+	// and is populated on start and end.
+	t := &CallTracer{callstack: make([]callFrame, 1)}
+	return t
+}
+
+func (t *CallTracer) CaptureStart(env *vm.EVM, from common.Address, to common.Address, create bool, input []byte, gas uint64, value *big.Int) {
+	t.callstack[0] = callFrame{
+		Type:  "CALL",
+		From:  addrToHex(from),
+		To:    addrToHex(to),
+		Input: bytesToHex(input),
+		Gas:   uintToHex(gas),
+		Value: bigToHex(value),
+	}
+	if create {
+		t.callstack[0].Type = "CREATE"
+	}
+}
+
+func (t *CallTracer) CaptureEnd(output []byte, gasUsed uint64, _ time.Duration, err error) {
+	t.callstack[0].Output = bytesToHex(output)
+	t.callstack[0].GasUsed = uintToHex(gasUsed)
+	if err != nil {
+		t.callstack[0].Error = err.Error()
+	}
+}
+
+func (t *CallTracer) CaptureState(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, rData []byte, depth int, err error) {
+}
+
+func (t *CallTracer) CaptureFault(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost uint64, _ *vm.ScopeContext, depth int, err error) {
+}
+
+func (t *CallTracer) CaptureEnter(typ vm.OpCode, from common.Address, to common.Address, input []byte, gas uint64, value *big.Int) {
+	call := callFrame{
+		Type:  typ.String(),
+		From:  addrToHex(from),
+		To:    addrToHex(to),
+		Input: bytesToHex(input),
+		Gas:   uintToHex(gas),
+		Value: bigToHex(value),
+	}
+	t.callstack = append(t.callstack, call)
+}
+
+func (t *CallTracer) CaptureExit(output []byte, gasUsed uint64, err error) {
+	size := len(t.callstack)
+	if size <= 1 {
+		return
+	}
+	// pop call
+	call := t.callstack[size-1]
+	t.callstack = t.callstack[:size-1]
+	size -= 1
+
+	call.GasUsed = uintToHex(gasUsed)
+	if err == nil {
+		call.Output = bytesToHex(output)
+	} else {
+		call.Error = err.Error()
+		if call.Type == "CREATE" || call.Type == "CREATE2" {
+			call.To = ""
+		}
+	}
+	t.callstack[size-1].Calls = append(t.callstack[size-1].Calls, call)
+}
+
+func (t *CallTracer) GetResult() (json.RawMessage, error) {
+	if len(t.callstack) != 1 {
+		return nil, errors.New("incorrect number of top-level calls")
+	}
+	res, err := json.Marshal(t.callstack[0])
+	if err != nil {
+		return nil, err
+	}
+	return json.RawMessage(res), nil
+}
+
+func bytesToHex(s []byte) string {
+	return "0x" + common.Bytes2Hex(s)
+}
+
+func bigToHex(n *big.Int) string {
+	if n == nil {
+		return ""
+	}
+	return "0x" + n.Text(16)
+}
+
+func uintToHex(n uint64) string {
+	return "0x" + strconv.FormatUint(n, 16)
+}
+
+func addrToHex(a common.Address) string {
+	return strings.ToLower(a.Hex())
+}

eth/tracers/native/native.go

@@ -0,0 +1,35 @@
+package native
+
+import (
+	"encoding/json"
+
+	"github.com/ethereum/go-ethereum/core/vm"
+)
+
+// Tracer interface extends vm.Tracer and additionally
+// allows collecting the tracing result.
+type Tracer interface {
+	vm.Tracer
+	GetResult() (json.RawMessage, error)
+}
+
+// constructor creates a new instance of a Tracer.
+type constructor func() Tracer
+
+var tracers map[string]constructor = make(map[string]constructor)
+
+// register makes native tracers in this directory which adhere
+// to the `Tracer` interface available to the rest of the codebase.
+// It is typically invoked in the `init()` function.
+func register(name string, fn constructor) {
+	tracers[name] = fn
+}
+
+// New returns a new instance of a tracer, if one was
+// registered under the given name.
+func New(name string) (Tracer, bool) {
+	if fn, ok := tracers[name]; ok {
+		return fn(), true
+	}
+	return nil, false
+}

eth/tracers/tracers_test.go

@@ -35,6 +35,7 @@ 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/native"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/tests"
@@ -204,10 +205,42 @@ func TestPrestateTracerCreate2(t *testing.T) {
 // Iterates over all the input-output datasets in the tracer test harness and
 // runs the JavaScript tracers against them.
 func TestCallTracerLegacy(t *testing.T) {
-	testCallTracer("callTracerLegacy", "call_tracer_legacy", t)
+	newTracer := func() native.Tracer {
+		tracer, err := New("callTracerLegacy", new(Context))
+		if err != nil {
+			t.Fatalf("failed to create call tracer: %v", err)
+		}
+		return tracer
+	}
+
+	testCallTracer(newTracer, "call_tracer_legacy", t)
+}
+
+func TestCallTracer(t *testing.T) {
+	newTracer := func() native.Tracer {
+		tracer, err := New("callTracer", new(Context))
+		if err != nil {
+			t.Fatalf("failed to create call tracer: %v", err)
+		}
+		return tracer
+	}
+
+	testCallTracer(newTracer, "call_tracer", t)
+}
+
+func TestCallTracerNative(t *testing.T) {
+	newTracer := func() native.Tracer {
+		tracer, ok := native.New("callTracerNative")
+		if !ok {
+			t.Fatal("failed to create native call tracer")
+		}
+		return tracer
+	}
+
+	testCallTracer(newTracer, "call_tracer", t)
 }
 
-func testCallTracer(tracer string, dirPath string, t *testing.T) {
+func testCallTracer(newTracer func() native.Tracer, dirPath string, t *testing.T) {
 	files, err := ioutil.ReadDir(filepath.Join("testdata", dirPath))
 	if err != nil {
 		t.Fatalf("failed to retrieve tracer test suite: %v", err)
@@ -251,11 +284,7 @@ func testCallTracer(tracer string, dirPath string, t *testing.T) {
 			}
 			_, statedb := tests.MakePreState(rawdb.NewMemoryDatabase(), test.Genesis.Alloc, false)
 
-			// Create the tracer, the EVM environment and run it
-			tracer, err := New(tracer, new(Context))
-			if err != nil {
-				t.Fatalf("failed to create call tracer: %v", err)
-			}
+			tracer := newTracer()
 			evm := vm.NewEVM(context, txContext, statedb, test.Genesis.Config, vm.Config{Debug: true, Tracer: tracer})
 
 			msg, err := tx.AsMessage(signer, nil)
@@ -287,10 +316,6 @@ func testCallTracer(tracer string, dirPath string, t *testing.T) {
 	}
 }
 
-func TestCallTracer(t *testing.T) {
-	testCallTracer("callTracer", "call_tracer", t)
-}
-
 // jsonEqual is similar to reflect.DeepEqual, but does a 'bounce' via json prior to
 // comparison
 func jsonEqual(x, y interface{}) bool {
@@ -406,12 +431,19 @@ func BenchmarkTracers(b *testing.B) {
 			if err := json.Unmarshal(blob, test); err != nil {
 				b.Fatalf("failed to parse testcase: %v", err)
 			}
-			benchTracer("callTracer", test, b)
+			newTracer := func() native.Tracer {
+				tracer, err := New("callTracer", new(Context))
+				if err != nil {
+					b.Fatalf("failed to create call tracer: %v", err)
+				}
+				return tracer
+			}
+			benchTracer(newTracer, test, b)
 		})
 	}
 }
 
-func benchTracer(tracerName string, test *callTracerTest, b *testing.B) {
+func benchTracer(newTracer func() native.Tracer, test *callTracerTest, b *testing.B) {
 	// Configure a blockchain with the given prestate
 	tx := new(types.Transaction)
 	if err := rlp.DecodeBytes(common.FromHex(test.Input), tx); err != nil {
@@ -438,21 +470,21 @@ func benchTracer(tracerName string, test *callTracerTest, b *testing.B) {
 	}
 	_, statedb := tests.MakePreState(rawdb.NewMemoryDatabase(), test.Genesis.Alloc, false)
 
-	// Create the tracer, the EVM environment and run it
-	tracer, err := New(tracerName, new(Context))
-	if err != nil {
-		b.Fatalf("failed to create call tracer: %v", err)
-	}
-	evm := vm.NewEVM(context, txContext, statedb, test.Genesis.Config, vm.Config{Debug: true, Tracer: tracer})
-
 	b.ReportAllocs()
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
+		tracer := newTracer()
+		evm := vm.NewEVM(context, txContext, statedb, test.Genesis.Config, vm.Config{Debug: true, Tracer: tracer})
 		snap := statedb.Snapshot()
 		st := core.NewStateTransition(evm, msg, new(core.GasPool).AddGas(tx.Gas()))
 		if _, err = st.TransitionDb(); err != nil {
 			b.Fatalf("failed to execute transaction: %v", err)
 		}
+		_, err := tracer.GetResult()
+		if err != nil {
+			b.Fatal(err)
+		}
+
 		statedb.RevertToSnapshot(snap)
 	}
 }