runtime/pprof: symbolize proto profiles

When generating pprof profiles in proto format, symbolize the profiles.

Change-Id: I2471ed7f919483e5828868306418a63e41aff5c5
Reviewed-on: https://go-review.googlesource.com/34192
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

2 files changed, 169 insertions, 0 deletions

diff --git a/src/runtime/pprof/internal/protopprof/protopprof.go b/src/runtime/pprof/internal/protopprof/protopprof.go
index 5d269c4f65..8a10716f0a 100644
--- a/src/runtime/pprof/internal/protopprof/protopprof.go
+++ b/src/runtime/pprof/internal/protopprof/protopprof.go
@@ -11,6 +11,7 @@ import (
 	"fmt"
 	"os"
 	"runtime"
+	"strings"
 	"time"
 	"unsafe"
 
@@ -91,6 +92,7 @@ func TranslateCPUProfile(b []byte, startTime time.Time) (*profile.Profile, error
 			return nil, err
 		}
 	}
+	symbolize(p)
 	return p, nil
 }
 
@@ -103,3 +105,73 @@ func addMappings(p *profile.Profile) error {
 	defer f.Close()
 	return p.ParseMemoryMap(f)
 }
+
+type function interface {
+	Name() string
+	FileLine(pc uintptr) (string, int)
+}
+
+// funcForPC is a wrapper for runtime.FuncForPC. Defined as var for testing.
+var funcForPC = func(pc uintptr) function {
+	if f := runtime.FuncForPC(pc); f != nil {
+		return f
+	}
+	return nil
+}
+
+func symbolize(p *profile.Profile) {
+	fns := profileFunctionMap{}
+	for _, l := range p.Location {
+		pc := uintptr(l.Address)
+		f := funcForPC(pc)
+		if f == nil {
+			continue
+		}
+		file, lineno := f.FileLine(pc)
+		l.Line = []profile.Line{
+			{
+				Function: fns.findOrAddFunction(f.Name(), file, p),
+				Line:     int64(lineno),
+			},
+		}
+	}
+	// Trim runtime functions. Always hide runtime.goexit. Other runtime
+	// functions are only hidden for heapz when they appear at the beginning.
+	isHeapz := p.PeriodType != nil && p.PeriodType.Type == "space"
+	for _, s := range p.Sample {
+		show := !isHeapz
+		var i int
+		for _, l := range s.Location {
+			if len(l.Line) > 0 && l.Line[0].Function != nil {
+				name := l.Line[0].Function.Name
+				if name == "runtime.goexit" || !show && strings.HasPrefix(name, "runtime.") {
+					continue
+				}
+			}
+			show = true
+			s.Location[i] = l
+			i++
+		}
+		s.Location = s.Location[:i]
+	}
+}
+
+type profileFunctionMap map[profile.Function]*profile.Function
+
+func (fns profileFunctionMap) findOrAddFunction(name, filename string, p *profile.Profile) *profile.Function {
+	f := profile.Function{
+		Name:       name,
+		SystemName: name,
+		Filename:   filename,
+	}
+	if fp := fns[f]; fp != nil {
+		return fp
+	}
+	fp := new(profile.Function)
+	fns[f] = fp
+
+	*fp = f
+	fp.ID = uint64(len(p.Function) + 1)
+	p.Function = append(p.Function, fp)
+	return fp
+}
diff --git a/src/runtime/pprof/internal/protopprof/protopprof_test.go b/src/runtime/pprof/internal/protopprof/protopprof_test.go
index f1937b5bd0..33d19d8566 100644
--- a/src/runtime/pprof/internal/protopprof/protopprof_test.go
+++ b/src/runtime/pprof/internal/protopprof/protopprof_test.go
@@ -169,3 +169,100 @@ func TestTranslateCPUProfileWithSamples(t *testing.T) {
 			getSampleAsString(p.Sample))
 	}
 }
+
+type fakeFunc struct {
+	name   string
+	file   string
+	lineno int
+}
+
+func (f *fakeFunc) Name() string {
+	return f.name
+}
+func (f *fakeFunc) FileLine(_ uintptr) (string, int) {
+	return f.file, f.lineno
+}
+
+// TestRuntimeFunctionTrimming tests if symbolize trims runtime functions as intended.
+func TestRuntimeRunctionTrimming(t *testing.T) {
+	fakeFuncMap := map[uintptr]*fakeFunc{
+		0x10: &fakeFunc{"runtime.goexit", "runtime.go", 10},
+		0x20: &fakeFunc{"runtime.other", "runtime.go", 20},
+		0x30: &fakeFunc{"foo", "foo.go", 30},
+		0x40: &fakeFunc{"bar", "bar.go", 40},
+	}
+	backupFuncForPC := funcForPC
+	funcForPC = func(pc uintptr) function {
+		return fakeFuncMap[pc]
+	}
+	defer func() {
+		funcForPC = backupFuncForPC
+	}()
+	testLoc := []*profile.Location{
+		{ID: 1, Address: 0x10},
+		{ID: 2, Address: 0x20},
+		{ID: 3, Address: 0x30},
+		{ID: 4, Address: 0x40},
+	}
+	testProfile := &profile.Profile{
+		Sample: []*profile.Sample{
+			{Location: []*profile.Location{testLoc[0], testLoc[1], testLoc[3], testLoc[2]}},
+			{Location: []*profile.Location{testLoc[1], testLoc[3], testLoc[2]}},
+			{Location: []*profile.Location{testLoc[3], testLoc[2], testLoc[1]}},
+			{Location: []*profile.Location{testLoc[3], testLoc[2], testLoc[0]}},
+			{Location: []*profile.Location{testLoc[0], testLoc[1], testLoc[3], testLoc[0]}},
+		},
+		Location: testLoc,
+	}
+	testProfiles := make([]*profile.Profile, 2)
+	testProfiles[0] = testProfile.Copy()
+	testProfiles[1] = testProfile.Copy()
+	// Test case for profilez.
+	testProfiles[0].PeriodType = &profile.ValueType{Type: "cpu", Unit: "nanoseconds"}
+	// Test case for heapz.
+	testProfiles[1].PeriodType = &profile.ValueType{Type: "space", Unit: "bytes"}
+	wantFunc := []*profile.Function{
+		{ID: 1, Name: "runtime.goexit", SystemName: "runtime.goexit", Filename: "runtime.go"},
+		{ID: 2, Name: "runtime.other", SystemName: "runtime.other", Filename: "runtime.go"},
+		{ID: 3, Name: "foo", SystemName: "foo", Filename: "foo.go"},
+		{ID: 4, Name: "bar", SystemName: "bar", Filename: "bar.go"},
+	}
+	wantLoc := []*profile.Location{
+		{ID: 1, Address: 0x10, Line: []profile.Line{{Function: wantFunc[0], Line: 10}}},
+		{ID: 2, Address: 0x20, Line: []profile.Line{{Function: wantFunc[1], Line: 20}}},
+		{ID: 3, Address: 0x30, Line: []profile.Line{{Function: wantFunc[2], Line: 30}}},
+		{ID: 4, Address: 0x40, Line: []profile.Line{{Function: wantFunc[3], Line: 40}}},
+	}
+	wantProfiles := []*profile.Profile{
+		{
+			PeriodType: &profile.ValueType{Type: "cpu", Unit: "nanoseconds"},
+			Sample: []*profile.Sample{
+				{Location: []*profile.Location{wantLoc[1], wantLoc[3], wantLoc[2]}},
+				{Location: []*profile.Location{wantLoc[1], wantLoc[3], wantLoc[2]}},
+				{Location: []*profile.Location{wantLoc[3], wantLoc[2], wantLoc[1]}},
+				{Location: []*profile.Location{wantLoc[3], wantLoc[2]}},
+				{Location: []*profile.Location{wantLoc[1], wantLoc[3]}},
+			},
+			Location: wantLoc,
+			Function: wantFunc,
+		},
+		{
+			PeriodType: &profile.ValueType{Type: "space", Unit: "bytes"},
+			Sample: []*profile.Sample{
+				{Location: []*profile.Location{wantLoc[3], wantLoc[2]}},
+				{Location: []*profile.Location{wantLoc[3], wantLoc[2]}},
+				{Location: []*profile.Location{wantLoc[3], wantLoc[2], wantLoc[1]}},
+				{Location: []*profile.Location{wantLoc[3], wantLoc[2]}},
+				{Location: []*profile.Location{wantLoc[3]}},
+			},
+			Location: wantLoc,
+			Function: wantFunc,
+		},
+	}
+	for i := 0; i < 2; i++ {
+		symbolize(testProfiles[i])
+		if !reflect.DeepEqual(testProfiles[i], wantProfiles[i]) {
+			t.Errorf("incorrect trimming (testcase = %d): got {%v}, want {%v}", i, testProfiles[i], wantProfiles[i])
+		}
+	}
+}