From 7cd1330acd9802ee5709b324ba584f3882d8d2af Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ra=C3=BAl=20Kripalani?= <raul@protocol.ai>
Date: Wed, 7 Oct 2020 15:52:03 +0100
Subject: [PATCH] make vm.EnableGasTracing public.

---
 chain/vm/runtime.go      |  9 +++++----
 chain/vm/runtime_test.go | 20 ++++++++++++++++++++
 chain/vm/vm.go           |  2 +-
 3 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/chain/vm/runtime.go b/chain/vm/runtime.go
index 72dd413ed..c612e374f 100644
--- a/chain/vm/runtime.go
+++ b/chain/vm/runtime.go
@@ -28,6 +28,9 @@ import (
 	"github.com/filecoin-project/lotus/chain/types"
 )
 
+// EnableGasTracing, if true, outputs gas tracing in execution traces.
+var EnableGasTracing = false
+
 type Runtime struct {
 	types.Message
 	rt0.Syscalls
@@ -459,7 +462,7 @@ func (rt *Runtime) stateCommit(oldh, newh cid.Cid) aerrors.ActorError {
 }
 
 func (rt *Runtime) finilizeGasTracing() {
-	if enableTracing {
+	if EnableGasTracing {
 		if rt.lastGasCharge != nil {
 			rt.lastGasCharge.TimeTaken = time.Since(rt.lastGasChargeTime)
 		}
@@ -491,11 +494,9 @@ func (rt *Runtime) chargeGasFunc(skip int) func(GasCharge) {
 
 }
 
-var enableTracing = false
-
 func (rt *Runtime) chargeGasInternal(gas GasCharge, skip int) aerrors.ActorError {
 	toUse := gas.Total()
-	if enableTracing {
+	if EnableGasTracing {
 		var callers [10]uintptr
 
 		cout := 0 //gruntime.Callers(2+skip, callers[:])
diff --git a/chain/vm/runtime_test.go b/chain/vm/runtime_test.go
index c22a8b615..9fc87f7c5 100644
--- a/chain/vm/runtime_test.go
+++ b/chain/vm/runtime_test.go
@@ -45,3 +45,23 @@ func TestRuntimePutErrors(t *testing.T) {
 	rt.StorePut(&NotAVeryGoodMarshaler{})
 	t.Error("expected panic")
 }
+
+func BenchmarkRuntime_CreateRuntimeChargeGas_TracingDisabled(b *testing.B) {
+	var (
+		cst = cbor.NewCborStore(nil)
+		gch = newGasCharge("foo", 1000, 1000)
+	)
+
+	b.ResetTimer()
+
+	EnableGasTracing = false
+	noop := func() bool { return EnableGasTracing }
+	for n := 0; n < b.N; n++ {
+		// flip the value and access it to make sure
+		// the compiler doesn't optimize away
+		EnableGasTracing = true
+		_ = noop()
+		EnableGasTracing = false
+		_ = (&Runtime{cst: cst}).chargeGasInternal(gch, 0)
+	}
+}
diff --git a/chain/vm/vm.go b/chain/vm/vm.go
index 44979454f..e2ccd33c7 100644
--- a/chain/vm/vm.go
+++ b/chain/vm/vm.go
@@ -227,7 +227,7 @@ func (vm *VM) send(ctx context.Context, msg *types.Message, parent *Runtime,
 	}
 
 	rt := vm.makeRuntime(ctx, msg, origin, on, gasUsed, nac)
-	if enableTracing {
+	if EnableGasTracing {
 		rt.lastGasChargeTime = start
 		if parent != nil {
 			rt.lastGasChargeTime = parent.lastGasChargeTime