eth/tracers: support for golang tracers + add golang callTracer (#23708)

* eth/tracers: add basic native loader

* eth/tracers: add GetResult to tracer interface

* eth/tracers: add native call tracer

* eth/tracers: fix call tracer json result

* eth/tracers: minor fix

* eth/tracers: fix

* eth/tracers: fix benchTracer

* eth/tracers: test native call tracer

* eth/tracers: fix

* eth/tracers: rm extra make

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

* eth/tracers: rm extra make

* eth/tracers: make callFrame private

* eth/tracers: clean-up and comments

* eth/tracers: add license

* eth/tracers: rework the model a bit

* eth/tracers: move tracecall tests to subpackage

* cmd/geth: load native tracers

* eth/tracers: minor fix

* eth/tracers: impl stop

* eth/tracers: add native noop tracer

* renamings

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

* eth/tracers: more renamings

* eth/tracers: make jstracer non-exported, avoid cast

* eth/tracers, core/vm: rename vm.Tracer to vm.EVMLogger for clarity

* eth/tracers: minor comment fix

* eth/tracers/testing: lint nitpicks

* core,eth: cancel evm on nativecalltracer stop

* Revert "core,eth: cancel evm on nativecalltracer stop"

This reverts commit 01bb908790a369c1bb9d3937df9325c6857bf855.

* eth/tracers: linter nits

* eth/tracers: fix output on err

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

cmd/evm/internal/t8ntool/execution.go

@@ -96,7 +96,7 @@ type rejectedTx struct {
 // Apply applies a set of transactions to a pre-state
 func (pre *Prestate) Apply(vmConfig vm.Config, chainConfig *params.ChainConfig,
 	txs types.Transactions, miningReward int64,
-	getTracerFn func(txIndex int, txHash common.Hash) (tracer vm.Tracer, err error)) (*state.StateDB, *ExecutionResult, error) {
+	getTracerFn func(txIndex int, txHash common.Hash) (tracer vm.EVMLogger, err error)) (*state.StateDB, *ExecutionResult, error) {
 
 	// Capture errors for BLOCKHASH operation, if we haven't been supplied the
 	// required blockhashes

cmd/evm/internal/t8ntool/transition.go

@@ -89,10 +89,10 @@ func Transition(ctx *cli.Context) error {
 
 	var (
 		err     error
-		tracer  vm.Tracer
+		tracer  vm.EVMLogger
 		baseDir = ""
 	)
-	var getTracer func(txIndex int, txHash common.Hash) (vm.Tracer, error)
+	var getTracer func(txIndex int, txHash common.Hash) (vm.EVMLogger, error)
 
 	// If user specified a basedir, make sure it exists
 	if ctx.IsSet(OutputBasedir.Name) {
@@ -119,7 +119,7 @@ func Transition(ctx *cli.Context) error {
 				prevFile.Close()
 			}
 		}()
-		getTracer = func(txIndex int, txHash common.Hash) (vm.Tracer, error) {
+		getTracer = func(txIndex int, txHash common.Hash) (vm.EVMLogger, error) {
 			if prevFile != nil {
 				prevFile.Close()
 			}
@@ -131,7 +131,7 @@ func Transition(ctx *cli.Context) error {
 			return vm.NewJSONLogger(logConfig, traceFile), nil
 		}
 	} else {
-		getTracer = func(txIndex int, txHash common.Hash) (tracer vm.Tracer, err error) {
+		getTracer = func(txIndex int, txHash common.Hash) (tracer vm.EVMLogger, err error) {
 			return nil, nil
 		}
 	}

cmd/evm/runner.go

@@ -116,7 +116,7 @@ func runCmd(ctx *cli.Context) error {
 	}
 
 	var (
-		tracer        vm.Tracer
+		tracer        vm.EVMLogger
 		debugLogger   *vm.StructLogger
 		statedb       *state.StateDB
 		chainConfig   *params.ChainConfig

cmd/evm/staterunner.go

@@ -65,7 +65,7 @@ func stateTestCmd(ctx *cli.Context) error {
 		EnableReturnData: !ctx.GlobalBool(DisableReturnDataFlag.Name),
 	}
 	var (
-		tracer   vm.Tracer
+		tracer   vm.EVMLogger
 		debugger *vm.StructLogger
 	)
 	switch {

cmd/geth/main.go

@@ -39,6 +39,10 @@ import (
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/ethereum/go-ethereum/node"
+
+	// Force-load the native, to trigger registration
+	_ "github.com/ethereum/go-ethereum/eth/tracers/native"
+
 	"gopkg.in/urfave/cli.v1"
 )
 

core/vm/interpreter.go

@@ -27,11 +27,11 @@ import (
 
 // Config are the configuration options for the Interpreter
 type Config struct {
-	Debug                   bool   // Enables debugging
+	Debug                   bool      // Enables debugging
-	Tracer                  Tracer // Opcode logger
+	Tracer                  EVMLogger // Opcode logger
-	NoRecursion             bool   // Disables call, callcode, delegate call and create
+	NoRecursion             bool      // Disables call, callcode, delegate call and create
-	NoBaseFee               bool   // Forces the EIP-1559 baseFee to 0 (needed for 0 price calls)
+	NoBaseFee               bool      // Forces the EIP-1559 baseFee to 0 (needed for 0 price calls)
-	EnablePreimageRecording bool   // Enables recording of SHA3/keccak preimages
+	EnablePreimageRecording bool      // Enables recording of SHA3/keccak preimages
 
 	JumpTable [256]*operation // EVM instruction table, automatically populated if unset
 
@@ -152,9 +152,9 @@ func (in *EVMInterpreter) Run(contract *Contract, input []byte, readOnly bool) (
 		pc   = uint64(0) // program counter
 		cost uint64
 		// copies used by tracer
-		pcCopy  uint64 // needed for the deferred Tracer
+		pcCopy  uint64 // needed for the deferred EVMLogger
-		gasCopy uint64 // for Tracer to log gas remaining before execution
+		gasCopy uint64 // for EVMLogger to log gas remaining before execution
-		logged  bool   // deferred Tracer should ignore already logged steps
+		logged  bool   // deferred EVMLogger should ignore already logged steps
 		res     []byte // result of the opcode execution function
 	)
 	// Don't move this deferrred function, it's placed before the capturestate-deferred method,

core/vm/logger.go

@@ -98,12 +98,12 @@ func (s *StructLog) ErrorString() string {
 	return ""
 }
 
-// Tracer is used to collect execution traces from an EVM transaction
+// EVMLogger is used to collect execution traces from an EVM transaction
 // execution. CaptureState is called for each step of the VM with the
 // current VM state.
 // Note that reference types are actual VM data structures; make copies
 // if you need to retain them beyond the current call.
-type Tracer interface {
+type EVMLogger interface {
 	CaptureStart(env *EVM, from common.Address, to common.Address, create bool, input []byte, gas uint64, value *big.Int)
 	CaptureState(env *EVM, pc uint64, op OpCode, gas, cost uint64, scope *ScopeContext, rData []byte, depth int, err error)
 	CaptureEnter(typ OpCode, from common.Address, to common.Address, input []byte, gas uint64, value *big.Int)
@@ -112,7 +112,7 @@ type Tracer interface {
 	CaptureEnd(output []byte, gasUsed uint64, t time.Duration, err error)
 }
 
-// StructLogger is an EVM state logger and implements Tracer.
+// StructLogger is an EVM state logger and implements EVMLogger.
 //
 // StructLogger can capture state based on the given Log configuration and also keeps
 // a track record of modified storage which is used in reporting snapshots of the
@@ -145,7 +145,7 @@ func (l *StructLogger) Reset() {
 	l.err = nil
 }
 
-// CaptureStart implements the Tracer interface to initialize the tracing operation.
+// CaptureStart implements the EVMLogger interface to initialize the tracing operation.
 func (l *StructLogger) CaptureStart(env *EVM, from common.Address, to common.Address, create bool, input []byte, gas uint64, value *big.Int) {
 }
 
@@ -210,7 +210,7 @@ func (l *StructLogger) CaptureState(env *EVM, pc uint64, op OpCode, gas, cost ui
 	l.logs = append(l.logs, log)
 }
 
-// CaptureFault implements the Tracer interface to trace an execution fault
+// CaptureFault implements the EVMLogger interface to trace an execution fault
 // while running an opcode.
 func (l *StructLogger) CaptureFault(env *EVM, pc uint64, op OpCode, gas, cost uint64, scope *ScopeContext, depth int, err error) {
 }

eth/tracers/api.go

@@ -862,12 +862,14 @@ func (api *API) TraceCall(ctx context.Context, args ethapi.TransactionArgs, bloc
 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.Tracer
+		tracer    vm.EVMLogger
 		err       error
 		txContext = core.NewEVMTxContext(message)
 	)
 	switch {
-	case config != nil && config.Tracer != nil:
+	case config == nil:
+		tracer = vm.NewStructLogger(nil)
+	case config.Tracer != nil:
 		// Define a meaningful timeout of a single transaction trace
 		timeout := defaultTraceTimeout
 		if config.Timeout != nil {
@@ -875,23 +877,19 @@ func (api *API) traceTx(ctx context.Context, message core.Message, txctx *Contex
 				return nil, err
 			}
 		}
-		// Constuct the JavaScript tracer to execute with
+		if t, err := New(*config.Tracer, txctx); err != nil {
-		if tracer, 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"))
+				}
+			}()
+			defer cancel()
+			tracer = t
 		}
-		// 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)
-
 	default:
 		tracer = vm.NewStructLogger(config.LogConfig)
 	}
@@ -921,7 +919,7 @@ func (api *API) traceTx(ctx context.Context, message core.Message, txctx *Contex
 			StructLogs:  ethapi.FormatLogs(tracer.StructLogs()),
 		}, nil
 
-	case *Tracer:
+	case Tracer:
 		return tracer.GetResult()
 
 	default:

eth/tracers/native/call.go

@@ -0,0 +1,170 @@
+// Copyright 2021 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package native
+
+import (
+	"encoding/json"
+	"errors"
+	"math/big"
+	"strconv"
+	"strings"
+	"sync/atomic"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/eth/tracers"
+)
+
+func init() {
+	tracers.RegisterNativeTracer("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
+	interrupt uint32 // Atomic flag to signal execution interruption
+	reason    error  // Textual reason for the interruption
+}
+
+// NewCallTracer returns a native go tracer which tracks
+// call frames of a tx, and implements vm.EVMLogger.
+func NewCallTracer() tracers.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].GasUsed = uintToHex(gasUsed)
+	if err != nil {
+		t.callstack[0].Error = err.Error()
+		if err.Error() == "execution reverted" && len(output) > 0 {
+			t.callstack[0].Output = bytesToHex(output)
+		}
+	} else {
+		t.callstack[0].Output = bytesToHex(output)
+	}
+}
+
+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) {
+	// Skip if tracing was interrupted
+	if atomic.LoadUint32(&t.interrupt) > 0 {
+		// TODO: env.Cancel()
+		return
+	}
+
+	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), t.reason
+}
+
+func (t *callTracer) Stop(err error) {
+	t.reason = err
+	atomic.StoreUint32(&t.interrupt, 1)
+}
+
+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/noop.go

@@ -0,0 +1,46 @@
+package native
+
+import (
+	"encoding/json"
+	"math/big"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/eth/tracers"
+)
+
+func init() {
+	tracers.RegisterNativeTracer("noopTracerNative", NewNoopTracer)
+}
+
+type noopTracer struct{}
+
+func NewNoopTracer() tracers.Tracer {
+	return &noopTracer{}
+}
+
+func (t *noopTracer) CaptureStart(env *vm.EVM, from common.Address, to common.Address, create bool, input []byte, gas uint64, value *big.Int) {
+}
+
+func (t *noopTracer) CaptureEnd(output []byte, gasUsed uint64, _ time.Duration, err error) {
+}
+
+func (t *noopTracer) CaptureState(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, rData []byte, depth int, err error) {
+}
+
+func (t *noopTracer) CaptureFault(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost uint64, _ *vm.ScopeContext, depth int, err error) {
+}
+
+func (t *noopTracer) CaptureEnter(typ vm.OpCode, from common.Address, to common.Address, input []byte, gas uint64, value *big.Int) {
+}
+
+func (t *noopTracer) CaptureExit(output []byte, gasUsed uint64, err error) {
+}
+
+func (t *noopTracer) GetResult() (json.RawMessage, error) {
+	return json.RawMessage(`{}`), nil
+}
+
+func (t *noopTracer) Stop(err error) {
+}

eth/tracers/testing/calltrace_test.go

@@ -0,0 +1,246 @@
+package testing
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"math/big"
+	"path/filepath"
+	"reflect"
+	"strings"
+	"testing"
+	"unicode"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum/go-ethereum/common/math"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/rawdb"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/eth/tracers"
+	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/tests"
+
+	// Force-load the native, to trigger registration
+	_ "github.com/ethereum/go-ethereum/eth/tracers/native"
+)
+
+type callContext struct {
+	Number     math.HexOrDecimal64   `json:"number"`
+	Difficulty *math.HexOrDecimal256 `json:"difficulty"`
+	Time       math.HexOrDecimal64   `json:"timestamp"`
+	GasLimit   math.HexOrDecimal64   `json:"gasLimit"`
+	Miner      common.Address        `json:"miner"`
+}
+
+// callTrace is the result of a callTracer run.
+type callTrace struct {
+	Type    string          `json:"type"`
+	From    common.Address  `json:"from"`
+	To      common.Address  `json:"to"`
+	Input   hexutil.Bytes   `json:"input"`
+	Output  hexutil.Bytes   `json:"output"`
+	Gas     *hexutil.Uint64 `json:"gas,omitempty"`
+	GasUsed *hexutil.Uint64 `json:"gasUsed,omitempty"`
+	Value   *hexutil.Big    `json:"value,omitempty"`
+	Error   string          `json:"error,omitempty"`
+	Calls   []callTrace     `json:"calls,omitempty"`
+}
+
+// callTracerTest defines a single test to check the call tracer against.
+type callTracerTest struct {
+	Genesis *core.Genesis `json:"genesis"`
+	Context *callContext  `json:"context"`
+	Input   string        `json:"input"`
+	Result  *callTrace    `json:"result"`
+}
+
+// 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)
+}
+
+func TestCallTracer(t *testing.T) {
+	testCallTracer("callTracer", "call_tracer", t)
+}
+
+func TestCallTracerNative(t *testing.T) {
+	testCallTracer("callTracerNative", "call_tracer", t)
+}
+
+func testCallTracer(tracerName string, 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)
+	}
+	for _, file := range files {
+		if !strings.HasSuffix(file.Name(), ".json") {
+			continue
+		}
+		file := file // capture range variable
+		t.Run(camel(strings.TrimSuffix(file.Name(), ".json")), func(t *testing.T) {
+			t.Parallel()
+
+			var (
+				test = new(callTracerTest)
+				tx   = new(types.Transaction)
+			)
+			// Call tracer test found, read if from disk
+			if blob, err := ioutil.ReadFile(filepath.Join("..", "testdata", dirPath, file.Name())); err != nil {
+				t.Fatalf("failed to read testcase: %v", err)
+			} else if err := json.Unmarshal(blob, test); err != nil {
+				t.Fatalf("failed to parse testcase: %v", err)
+			}
+			if err := rlp.DecodeBytes(common.FromHex(test.Input), tx); err != nil {
+				t.Fatalf("failed to parse testcase input: %v", err)
+			}
+			// Configure a blockchain with the given prestate
+			var (
+				signer    = types.MakeSigner(test.Genesis.Config, new(big.Int).SetUint64(uint64(test.Context.Number)))
+				origin, _ = signer.Sender(tx)
+				txContext = vm.TxContext{
+					Origin:   origin,
+					GasPrice: tx.GasPrice(),
+				}
+				context = vm.BlockContext{
+					CanTransfer: core.CanTransfer,
+					Transfer:    core.Transfer,
+					Coinbase:    test.Context.Miner,
+					BlockNumber: new(big.Int).SetUint64(uint64(test.Context.Number)),
+					Time:        new(big.Int).SetUint64(uint64(test.Context.Time)),
+					Difficulty:  (*big.Int)(test.Context.Difficulty),
+					GasLimit:    uint64(test.Context.GasLimit),
+				}
+				_, statedb = tests.MakePreState(rawdb.NewMemoryDatabase(), test.Genesis.Alloc, false)
+			)
+			tracer, err := tracers.New(tracerName, new(tracers.Context))
+			if err != nil {
+				t.Fatalf("failed to create call tracer: %v", err)
+			}
+			evm := vm.NewEVM(context, txContext, statedb, test.Genesis.Config, vm.Config{Debug: true, Tracer: tracer})
+			msg, err := tx.AsMessage(signer, nil)
+			if err != nil {
+				t.Fatalf("failed to prepare transaction for tracing: %v", err)
+			}
+			st := core.NewStateTransition(evm, msg, new(core.GasPool).AddGas(tx.Gas()))
+			if _, err = st.TransitionDb(); err != nil {
+				t.Fatalf("failed to execute transaction: %v", err)
+			}
+			// Retrieve the trace result and compare against the etalon
+			res, err := tracer.GetResult()
+			if err != nil {
+				t.Fatalf("failed to retrieve trace result: %v", err)
+			}
+			ret := new(callTrace)
+			if err := json.Unmarshal(res, ret); err != nil {
+				t.Fatalf("failed to unmarshal trace result: %v", err)
+			}
+
+			if !jsonEqual(ret, test.Result) {
+				// uncomment this for easier debugging
+				//have, _ := json.MarshalIndent(ret, "", " ")
+				//want, _ := json.MarshalIndent(test.Result, "", " ")
+				//t.Fatalf("trace mismatch: \nhave %+v\nwant %+v", string(have), string(want))
+				t.Fatalf("trace mismatch: \nhave %+v\nwant %+v", ret, test.Result)
+			}
+		})
+	}
+}
+
+// jsonEqual is similar to reflect.DeepEqual, but does a 'bounce' via json prior to
+// comparison
+func jsonEqual(x, y interface{}) bool {
+	xTrace := new(callTrace)
+	yTrace := new(callTrace)
+	if xj, err := json.Marshal(x); err == nil {
+		json.Unmarshal(xj, xTrace)
+	} else {
+		return false
+	}
+	if yj, err := json.Marshal(y); err == nil {
+		json.Unmarshal(yj, yTrace)
+	} else {
+		return false
+	}
+	return reflect.DeepEqual(xTrace, yTrace)
+}
+
+// camel converts a snake cased input string into a camel cased output.
+func camel(str string) string {
+	pieces := strings.Split(str, "_")
+	for i := 1; i < len(pieces); i++ {
+		pieces[i] = string(unicode.ToUpper(rune(pieces[i][0]))) + pieces[i][1:]
+	}
+	return strings.Join(pieces, "")
+}
+func BenchmarkTracers(b *testing.B) {
+	files, err := ioutil.ReadDir(filepath.Join("..", "testdata", "call_tracer"))
+	if err != nil {
+		b.Fatalf("failed to retrieve tracer test suite: %v", err)
+	}
+	for _, file := range files {
+		if !strings.HasSuffix(file.Name(), ".json") {
+			continue
+		}
+		file := file // capture range variable
+		b.Run(camel(strings.TrimSuffix(file.Name(), ".json")), func(b *testing.B) {
+			blob, err := ioutil.ReadFile(filepath.Join("..", "testdata", "call_tracer", file.Name()))
+			if err != nil {
+				b.Fatalf("failed to read testcase: %v", err)
+			}
+			test := new(callTracerTest)
+			if err := json.Unmarshal(blob, test); err != nil {
+				b.Fatalf("failed to parse testcase: %v", err)
+			}
+			benchTracer("callTracerNative", test, b)
+		})
+	}
+}
+
+func benchTracer(tracerName string, 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 {
+		b.Fatalf("failed to parse testcase input: %v", err)
+	}
+	signer := types.MakeSigner(test.Genesis.Config, new(big.Int).SetUint64(uint64(test.Context.Number)))
+	msg, err := tx.AsMessage(signer, nil)
+	if err != nil {
+		b.Fatalf("failed to prepare transaction for tracing: %v", err)
+	}
+	origin, _ := signer.Sender(tx)
+	txContext := vm.TxContext{
+		Origin:   origin,
+		GasPrice: tx.GasPrice(),
+	}
+	context := vm.BlockContext{
+		CanTransfer: core.CanTransfer,
+		Transfer:    core.Transfer,
+		Coinbase:    test.Context.Miner,
+		BlockNumber: new(big.Int).SetUint64(uint64(test.Context.Number)),
+		Time:        new(big.Int).SetUint64(uint64(test.Context.Time)),
+		Difficulty:  (*big.Int)(test.Context.Difficulty),
+		GasLimit:    uint64(test.Context.GasLimit),
+	}
+	_, statedb := tests.MakePreState(rawdb.NewMemoryDatabase(), test.Genesis.Alloc, false)
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		tracer, err := tracers.New(tracerName, new(tracers.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})
+		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)
+		}
+		if _, err = tracer.GetResult(); err != nil {
+			b.Fatal(err)
+		}
+		statedb.RevertToSnapshot(snap)
+	}
+}

eth/tracers/tracer.go

@@ -363,9 +363,9 @@ func (r *frameResult) pushObject(vm *duktape.Context) {
 	vm.PutPropString(obj, "getError")
 }
 
-// Tracer provides an implementation of Tracer that evaluates a Javascript
+// jsTracer provides an implementation of Tracer that evaluates a Javascript
 // function for each VM execution step.
-type Tracer struct {
+type jsTracer struct {
 	vm *duktape.Context // Javascript VM instance
 
 	tracerObject int // Stack index of the tracer JavaScript object
@@ -409,12 +409,8 @@ type Context struct {
 // New instantiates a new tracer instance. code specifies a Javascript snippet,
 // which must evaluate to an expression returning an object with 'step', 'fault'
 // and 'result' functions.
-func New(code string, ctx *Context) (*Tracer, error) {
+func newJsTracer(code string, ctx *Context) (*jsTracer, error) {
-	// Resolve any tracers by name and assemble the tracer object
+	tracer := &jsTracer{
-	if tracer, ok := tracer(code); ok {
-		code = tracer
-	}
-	tracer := &Tracer{
 		vm:              duktape.New(),
 		ctx:             make(map[string]interface{}),
 		opWrapper:       new(opWrapper),
@@ -620,14 +616,14 @@ func New(code string, ctx *Context) (*Tracer, error) {
 }
 
 // Stop terminates execution of the tracer at the first opportune moment.
-func (jst *Tracer) Stop(err error) {
+func (jst *jsTracer) Stop(err error) {
 	jst.reason = err
 	atomic.StoreUint32(&jst.interrupt, 1)
 }
 
 // call executes a method on a JS object, catching any errors, formatting and
 // returning them as error objects.
-func (jst *Tracer) call(noret bool, method string, args ...string) (json.RawMessage, error) {
+func (jst *jsTracer) call(noret bool, method string, args ...string) (json.RawMessage, error) {
 	// Execute the JavaScript call and return any error
 	jst.vm.PushString(method)
 	for _, arg := range args {
@@ -663,7 +659,7 @@ func wrapError(context string, err error) error {
 }
 
 // CaptureStart implements the Tracer interface to initialize the tracing operation.
-func (jst *Tracer) CaptureStart(env *vm.EVM, from common.Address, to common.Address, create bool, input []byte, gas uint64, value *big.Int) {
+func (jst *jsTracer) CaptureStart(env *vm.EVM, from common.Address, to common.Address, create bool, input []byte, gas uint64, value *big.Int) {
 	jst.ctx["type"] = "CALL"
 	if create {
 		jst.ctx["type"] = "CREATE"
@@ -693,7 +689,7 @@ func (jst *Tracer) CaptureStart(env *vm.EVM, from common.Address, to common.Addr
 }
 
 // CaptureState implements the Tracer interface to trace a single step of VM execution.
-func (jst *Tracer) CaptureState(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, rData []byte, depth int, err error) {
+func (jst *jsTracer) CaptureState(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, rData []byte, depth int, err error) {
 	if !jst.traceSteps {
 		return
 	}
@@ -729,7 +725,7 @@ func (jst *Tracer) CaptureState(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost
 }
 
 // CaptureFault implements the Tracer interface to trace an execution fault
-func (jst *Tracer) CaptureFault(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, depth int, err error) {
+func (jst *jsTracer) CaptureFault(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, depth int, err error) {
 	if jst.err != nil {
 		return
 	}
@@ -743,7 +739,7 @@ func (jst *Tracer) CaptureFault(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost
 }
 
 // CaptureEnd is called after the call finishes to finalize the tracing.
-func (jst *Tracer) CaptureEnd(output []byte, gasUsed uint64, t time.Duration, err error) {
+func (jst *jsTracer) CaptureEnd(output []byte, gasUsed uint64, t time.Duration, err error) {
 	jst.ctx["output"] = output
 	jst.ctx["time"] = t.String()
 	jst.ctx["gasUsed"] = gasUsed
@@ -754,7 +750,7 @@ func (jst *Tracer) CaptureEnd(output []byte, gasUsed uint64, t time.Duration, er
 }
 
 // CaptureEnter is called when EVM enters a new scope (via call, create or selfdestruct).
-func (jst *Tracer) CaptureEnter(typ vm.OpCode, from common.Address, to common.Address, input []byte, gas uint64, value *big.Int) {
+func (jst *jsTracer) CaptureEnter(typ vm.OpCode, from common.Address, to common.Address, input []byte, gas uint64, value *big.Int) {
 	if !jst.traceCallFrames {
 		return
 	}
@@ -784,7 +780,7 @@ func (jst *Tracer) CaptureEnter(typ vm.OpCode, from common.Address, to common.Ad
 
 // CaptureExit is called when EVM exits a scope, even if the scope didn't
 // execute any code.
-func (jst *Tracer) CaptureExit(output []byte, gasUsed uint64, err error) {
+func (jst *jsTracer) CaptureExit(output []byte, gasUsed uint64, err error) {
 	if !jst.traceCallFrames {
 		return
 	}
@@ -808,7 +804,7 @@ func (jst *Tracer) CaptureExit(output []byte, gasUsed uint64, err error) {
 }
 
 // GetResult calls the Javascript 'result' function and returns its value, or any accumulated error
-func (jst *Tracer) GetResult() (json.RawMessage, error) {
+func (jst *jsTracer) GetResult() (json.RawMessage, error) {
 	// Transform the context into a JavaScript object and inject into the state
 	obj := jst.vm.PushObject()
 
@@ -830,7 +826,7 @@ func (jst *Tracer) GetResult() (json.RawMessage, error) {
 }
 
 // addToObj pushes a field to a JS object.
-func (jst *Tracer) addToObj(obj int, key string, val interface{}) {
+func (jst *jsTracer) addToObj(obj int, key string, val interface{}) {
 	pushValue(jst.vm, val)
 	jst.vm.PutPropString(obj, key)
 }

eth/tracers/tracer_test.go

@@ -58,7 +58,7 @@ func testCtx() *vmContext {
 	return &vmContext{blockCtx: vm.BlockContext{BlockNumber: big.NewInt(1)}, txCtx: vm.TxContext{GasPrice: big.NewInt(100000)}}
 }
 
-func runTrace(tracer *Tracer, vmctx *vmContext, chaincfg *params.ChainConfig) (json.RawMessage, error) {
+func runTrace(tracer Tracer, vmctx *vmContext, chaincfg *params.ChainConfig) (json.RawMessage, error) {
 	env := vm.NewEVM(vmctx.blockCtx, vmctx.txCtx, &dummyStatedb{}, chaincfg, vm.Config{Debug: true, Tracer: tracer})
 	var (
 		startGas uint64 = 10000
@@ -168,7 +168,7 @@ func TestHaltBetweenSteps(t *testing.T) {
 // TestNoStepExec tests a regular value transfer (no exec), and accessing the statedb
 // in 'result'
 func TestNoStepExec(t *testing.T) {
-	runEmptyTrace := func(tracer *Tracer, vmctx *vmContext) (json.RawMessage, error) {
+	runEmptyTrace := func(tracer Tracer, vmctx *vmContext) (json.RawMessage, error) {
 		env := vm.NewEVM(vmctx.blockCtx, vmctx.txCtx, &dummyStatedb{}, params.TestChainConfig, vm.Config{Debug: true, Tracer: tracer})
 		startGas := uint64(10000)
 		contract := vm.NewContract(account{}, account{}, big.NewInt(0), startGas)

eth/tracers/tracers.go

@@ -18,14 +18,53 @@
 package tracers
 
 import (
+	"encoding/json"
 	"strings"
 	"unicode"
 
+	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/eth/tracers/internal/tracers"
 )
 
-// all contains all the built in JavaScript tracers by name.
+// Tracer interface extends vm.EVMLogger and additionally
-var all = make(map[string]string)
+// allows collecting the tracing result.
+type Tracer interface {
+	vm.EVMLogger
+	GetResult() (json.RawMessage, error)
+	// Stop terminates execution of the tracer at the first opportune moment.
+	Stop(err error)
+}
+
+var (
+	nativeTracers map[string]func() Tracer = make(map[string]func() Tracer)
+	jsTracers                              = make(map[string]string)
+)
+
+// RegisterNativeTracer makes native tracers which adhere
+// to the `Tracer` interface available to the rest of the codebase.
+// It is typically invoked in the `init()` function, e.g. see the `native/call.go`.
+func RegisterNativeTracer(name string, ctor func() Tracer) {
+	nativeTracers[name] = ctor
+}
+
+// New returns a new instance of a tracer,
+// 1. If 'code' is the name of a registered native tracer, then that tracer
+//   is instantiated and returned
+// 2. If 'code' is the name of a registered js-tracer, then that tracer is
+//   instantiated and returned
+// 3. Otherwise, the code is interpreted as the js code of a js-tracer, and
+//   is evaluated and returned.
+func New(code string, ctx *Context) (Tracer, error) {
+	// Resolve native tracer
+	if fn, ok := nativeTracers[code]; ok {
+		return fn(), nil
+	}
+	// Resolve js-tracers by name and assemble the tracer object
+	if tracer, ok := jsTracers[code]; ok {
+		code = tracer
+	}
+	return newJsTracer(code, ctx)
+}
 
 // camel converts a snake cased input string into a camel cased output.
 func camel(str string) string {
@@ -40,14 +79,6 @@ func camel(str string) string {
 func init() {
 	for _, file := range tracers.AssetNames() {
 		name := camel(strings.TrimSuffix(file, ".js"))
-		all[name] = string(tracers.MustAsset(file))
+		jsTracers[name] = string(tracers.MustAsset(file))
 	}
 }
-
-// tracer retrieves a specific JavaScript tracer by name.
-func tracer(name string) (string, bool) {
-	if tracer, ok := all[name]; ok {
-		return tracer, true
-	}
-	return "", false
-}

eth/tracers/tracers_test.go

@@ -20,23 +20,18 @@ import (
 	"crypto/ecdsa"
 	"crypto/rand"
 	"encoding/json"
-	"io/ioutil"
 	"math/big"
-	"path/filepath"
 	"reflect"
-	"strings"
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
-	"github.com/ethereum/go-ethereum/common/math"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/rawdb"
 	"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/params"
-	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/tests"
 )
 
@@ -104,22 +99,6 @@ type callTrace struct {
 	Calls   []callTrace     `json:"calls,omitempty"`
 }
 
-type callContext struct {
-	Number     math.HexOrDecimal64   `json:"number"`
-	Difficulty *math.HexOrDecimal256 `json:"difficulty"`
-	Time       math.HexOrDecimal64   `json:"timestamp"`
-	GasLimit   math.HexOrDecimal64   `json:"gasLimit"`
-	Miner      common.Address        `json:"miner"`
-}
-
-// callTracerTest defines a single test to check the call tracer against.
-type callTracerTest struct {
-	Genesis *core.Genesis `json:"genesis"`
-	Context *callContext  `json:"context"`
-	Input   string        `json:"input"`
-	Result  *callTrace    `json:"result"`
-}
-
 // TestZeroValueToNotExitCall tests the calltracer(s) on the following:
 // Tx to A, A calls B with zero value. B does not already exist.
 // Expected: that enter/exit is invoked and the inner call is shown in the result
@@ -280,96 +259,6 @@ 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)
-}
-
-func testCallTracer(tracer string, 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)
-	}
-	for _, file := range files {
-		if !strings.HasSuffix(file.Name(), ".json") {
-			continue
-		}
-		file := file // capture range variable
-		t.Run(camel(strings.TrimSuffix(file.Name(), ".json")), func(t *testing.T) {
-			t.Parallel()
-
-			// Call tracer test found, read if from disk
-			blob, err := ioutil.ReadFile(filepath.Join("testdata", dirPath, file.Name()))
-			if err != nil {
-				t.Fatalf("failed to read testcase: %v", err)
-			}
-			test := new(callTracerTest)
-			if err := json.Unmarshal(blob, test); err != nil {
-				t.Fatalf("failed to parse testcase: %v", err)
-			}
-			// Configure a blockchain with the given prestate
-			tx := new(types.Transaction)
-			if err := rlp.DecodeBytes(common.FromHex(test.Input), tx); err != nil {
-				t.Fatalf("failed to parse testcase input: %v", err)
-			}
-			signer := types.MakeSigner(test.Genesis.Config, new(big.Int).SetUint64(uint64(test.Context.Number)))
-			origin, _ := signer.Sender(tx)
-			txContext := vm.TxContext{
-				Origin:   origin,
-				GasPrice: tx.GasPrice(),
-			}
-			context := vm.BlockContext{
-				CanTransfer: core.CanTransfer,
-				Transfer:    core.Transfer,
-				Coinbase:    test.Context.Miner,
-				BlockNumber: new(big.Int).SetUint64(uint64(test.Context.Number)),
-				Time:        new(big.Int).SetUint64(uint64(test.Context.Time)),
-				Difficulty:  (*big.Int)(test.Context.Difficulty),
-				GasLimit:    uint64(test.Context.GasLimit),
-			}
-			_, 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)
-			}
-			evm := vm.NewEVM(context, txContext, statedb, test.Genesis.Config, vm.Config{Debug: true, Tracer: tracer})
-
-			msg, err := tx.AsMessage(signer, nil)
-			if err != nil {
-				t.Fatalf("failed to prepare transaction for tracing: %v", err)
-			}
-			st := core.NewStateTransition(evm, msg, new(core.GasPool).AddGas(tx.Gas()))
-			if _, err = st.TransitionDb(); err != nil {
-				t.Fatalf("failed to execute transaction: %v", err)
-			}
-			// Retrieve the trace result and compare against the etalon
-			res, err := tracer.GetResult()
-			if err != nil {
-				t.Fatalf("failed to retrieve trace result: %v", err)
-			}
-			ret := new(callTrace)
-			if err := json.Unmarshal(res, ret); err != nil {
-				t.Fatalf("failed to unmarshal trace result: %v", err)
-			}
-
-			if !jsonEqual(ret, test.Result) {
-				// uncomment this for easier debugging
-				//have, _ := json.MarshalIndent(ret, "", " ")
-				//want, _ := json.MarshalIndent(test.Result, "", " ")
-				//t.Fatalf("trace mismatch: \nhave %+v\nwant %+v", string(have), string(want))
-				t.Fatalf("trace mismatch: \nhave %+v\nwant %+v", ret, test.Result)
-			}
-		})
-	}
-}
-
-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 {
@@ -466,73 +355,3 @@ func BenchmarkTransactionTrace(b *testing.B) {
 		tracer.Reset()
 	}
 }
-
-func BenchmarkTracers(b *testing.B) {
-	files, err := ioutil.ReadDir(filepath.Join("testdata", "call_tracer"))
-	if err != nil {
-		b.Fatalf("failed to retrieve tracer test suite: %v", err)
-	}
-	for _, file := range files {
-		if !strings.HasSuffix(file.Name(), ".json") {
-			continue
-		}
-		file := file // capture range variable
-		b.Run(camel(strings.TrimSuffix(file.Name(), ".json")), func(b *testing.B) {
-			blob, err := ioutil.ReadFile(filepath.Join("testdata", "call_tracer", file.Name()))
-			if err != nil {
-				b.Fatalf("failed to read testcase: %v", err)
-			}
-			test := new(callTracerTest)
-			if err := json.Unmarshal(blob, test); err != nil {
-				b.Fatalf("failed to parse testcase: %v", err)
-			}
-			benchTracer("callTracer", test, b)
-		})
-	}
-}
-
-func benchTracer(tracerName string, 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 {
-		b.Fatalf("failed to parse testcase input: %v", err)
-	}
-	signer := types.MakeSigner(test.Genesis.Config, new(big.Int).SetUint64(uint64(test.Context.Number)))
-	msg, err := tx.AsMessage(signer, nil)
-	if err != nil {
-		b.Fatalf("failed to prepare transaction for tracing: %v", err)
-	}
-	origin, _ := signer.Sender(tx)
-	txContext := vm.TxContext{
-		Origin:   origin,
-		GasPrice: tx.GasPrice(),
-	}
-	context := vm.BlockContext{
-		CanTransfer: core.CanTransfer,
-		Transfer:    core.Transfer,
-		Coinbase:    test.Context.Miner,
-		BlockNumber: new(big.Int).SetUint64(uint64(test.Context.Number)),
-		Time:        new(big.Int).SetUint64(uint64(test.Context.Time)),
-		Difficulty:  (*big.Int)(test.Context.Difficulty),
-		GasLimit:    uint64(test.Context.GasLimit),
-	}
-	_, 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++ {
-		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)
-		}
-		statedb.RevertToSnapshot(snap)
-	}
-}