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x/telemetry/counter: fix stack computation
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The line number computation in stack counters was wrong
(thank you Russ), and has been changed. There is no longer
a special case for 386s.

Part of the issue for 386s is
golang/go#60673
but it is not relevant for this.

Change-Id: Iccc9a43ac05d94df2aa7915bfc3d4d74e4d2ff6a
Reviewed-on: https://go-review.googlesource.com/c/telemetry/+/501596
Run-TryBot: Peter Weinberger <[email protected]>
Reviewed-by: Jamal Carvalho <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
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@pjweinbgo
pjweinbgo committed Jun 12, 2023
1 parent 33f6895 commit d63a359
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Showing 3 changed files with 48 additions and 108 deletions.
118 changes: 24 additions & 94 deletions counter/counter_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6,13 +6,12 @@

package counter

// Missing any tests of concurrent uses of a counter.
// This is a TODO.
// Builders at
// https://build.golang.org/?repo=golang.org%2fx%2ftelemetry

import (
"encoding/hex"
"fmt"
"log"
"os"
"path/filepath"
"reflect"
Expand All @@ -26,9 +25,10 @@ import (
)

func TestBasic(t *testing.T) {
if runtime.GOOS == "openbsd" {
t.Skip("broken for openbsd")
if runtime.GOOS == "openbsd" || runtime.GOOS == "js" || runtime.GOOS == "wasip1" {
t.Skip("broken for openbsd etc")
}
t.Logf("GOOS %s GARCH %s", runtime.GOOS, runtime.GOARCH)
setup(t)
defer restore()
var f file
Expand Down Expand Up @@ -66,14 +66,19 @@ func TestBasic(t *testing.T) {
// this is needed in Windows so that the generated testing.go file
// can clean up the temporary test directory
func close(f *file) {
if f == nil {
// telemetry might have been off
return
}
f.current.Load().f.Close()
mmap.Munmap(f.current.Load().mapping)
}

func TestLarge(t *testing.T) {
if runtime.GOOS == "openbsd" {
t.Skip("broken for openbsd")
if runtime.GOOS == "openbsd" || runtime.GOOS == "js" || runtime.GOOS == "wasip1" {
t.Skip("broken for openbsd etc")
}
t.Logf("GOOS %s GARCH %s", runtime.GOOS, runtime.GOARCH)
setup(t)
defer restore()
var f file
Expand Down Expand Up @@ -118,6 +123,7 @@ func TestLarge(t *testing.T) {
}

func TestRepeatedNew(t *testing.T) {
t.Logf("GOOS %s GARCH %s", runtime.GOOS, runtime.GOARCH)
setup(t)
defer restore()
var f file
Expand Down Expand Up @@ -155,6 +161,7 @@ func hexDump(data []byte) string {
}

func TestNewFile(t *testing.T) {
t.Logf("GOOS %s GARCH %s", runtime.GOOS, runtime.GOARCH)
setup(t)
defer restore()
year, month, day := time.Now().Date()
Expand Down Expand Up @@ -209,7 +216,8 @@ func TestNewFile(t *testing.T) {
}
days := (then.Sub(now)) / (24 * time.Hour)
if days <= 7 || days > 14 {
t.Errorf("days = %d, want 7 < days <= 14", days)
// this fails on Solaris, but only once, so print i.
t.Errorf("%d: days = %d, want 7 < days <= 14", i, days)
}
close(&f)
// remove the file for the next iteration of the loop
Expand All @@ -218,6 +226,7 @@ func TestNewFile(t *testing.T) {
}

func TestRotate(t *testing.T) {
t.Logf("GOOS %s GARCH %s", runtime.GOOS, runtime.GOARCH)
year, month, day := time.Now().Date()
now := time.Date(year, month, day, 0, 0, 0, 0, time.UTC)
setup(t)
Expand Down Expand Up @@ -272,9 +281,6 @@ func TestRotate(t *testing.T) {
}

func TestStack(t *testing.T) {
if runtime.GOARCH == "386" && runtime.GOOS == "linux" {
t.Skip("some bad line numbers for linux-386")
}
t.Logf("GOOS %s GARCH %s", runtime.GOOS, runtime.GOARCH)
setup(t)
defer restore()
Expand All @@ -287,20 +293,19 @@ func TestStack(t *testing.T) {
if len(names) != 2 {
t.Fatalf("got %d names, want 2", len(names))
}
// each name should be 6 lines, and the two names should
// differ only in the second line. The last few lines should
// be blank.
// each name should be 4 lines, and the two names should
// differ only in the second line.
n0 := strings.Split(names[0], "\n")
n1 := strings.Split(names[1], "\n")
if len(n0) != 6 || len(n1) != 6 {
t.Fatalf("got %d and %d lines, want 6 (%q,%q)", len(n0), len(n1), n0, n1)
if len(n0) != 4 || len(n1) != 4 {
t.Errorf("got %d and %d lines, want 4 (%q,%q)", len(n0), len(n1), n0, n1)
}
for i := 0; i < 6; i++ { // loop generated by copilot (from comment?)
for i := 0; i < 4 && i < len(n0) && i < len(n1); i++ {
if i == 1 {
continue
}
if n0[i] != n1[i] {
t.Fatalf("line %d differs:\n%s\n%s", i, n0[i], n1[i])
t.Errorf("line %d differs:\n%s\n%s", i, n0[i], n1[i])
}
}
oldnames := make(map[string]bool)
Expand All @@ -318,7 +323,7 @@ func TestStack(t *testing.T) {
}
// expect 5 new names, one for each level of recursion
if len(newnames) != 5 {
t.Fatalf("got %d new names, want 5", len(newnames))
t.Errorf("got %d new names, want 5", len(newnames))
}
// look inside. old names should have a count of 1, new ones 2
for _, ct := range c.Counters() {
Expand Down Expand Up @@ -362,78 +367,3 @@ func restore() {
func (f *file) New(name string) *Counter {
return &Counter{name: name, file: f}
}

// This checks the computation of of line numbers for creating
// stack counters. It is named after the strangest system,
// but will provide a timely warning if the runtime changes how it
// computes line numbers.
func TestLinux386(t *testing.T) {
t.Logf("GOOS %s GARCH %s", runtime.GOOS, runtime.GOARCH)
x := infoFromHere(0)
if msg, wanted := check(0, x); msg != "" {
t.Errorf("got %q, wanted %s", msg, wanted)
}
x = deeper()
if msg, wanted := check(1, x); msg != "" {
t.Errorf("got %q, wanted %s", msg, wanted)
}
}

var ans = []string{
"GOOS freebsd GARCH amd64: 3 7",
"GOOS linux GARCH amd64: 3 7",
"GOOS linux GARCH arm64: 3 7",
"GOOS linux GARCH 386: 2 6",
"GOOS openbsd GARCH amd64: 3 7",
"GOOS windows GARCH amd64: 3 7",
"GOOS darwin GARCH amd64: 3 7",
"GOOS darwin GARCH arm64: 3 7",
}

func check(n int, got string) (string, string) {
const prefix = "golang.org/x/telemetry/counter.TestLinux386:"
start := fmt.Sprintf("GOOS %s GARCH %s", runtime.GOOS, runtime.GOARCH)
if !strings.HasPrefix(got, prefix) {
return got, "doesn't start with " + prefix
}
for _, a := range ans {
before, after, ok := strings.Cut(a, ":")
if !ok {
return got, "bad ans, no colon"
}
if before == start {
flds := strings.Fields(after)
if prefix+flds[n] == got {
return "", ""
}
return got, flds[n]
}
}
return got, fmt.Sprintf("%s not found", start)
}

func deeper() string {
log.SetFlags(log.Lshortfile)
x := infoFromHere(1)
return x
}

// the code from file.go that creates stack counter names
func infoFromHere(w int) string {
pcs := make([]uintptr, 4)
n := runtime.Callers(2, pcs)
pcs = pcs[:n]
locs := make([]string, n)
frs := runtime.CallersFrames(pcs)
for i := 0; i < n; i++ {
fr, more := frs.Next()
_, pcline := fr.Func.FileLine(pcs[i])
entryptr := fr.Func.Entry()
_, entryline := fr.Func.FileLine(entryptr)
locs[i] = fmt.Sprintf("%s:%d", fr.Function, pcline-entryline)
if !more {
break
}
}
return locs[w]
}
2 changes: 1 addition & 1 deletion counter/doc.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@
// are implemented as a set of regular counters whose names
// are the concatenation of the name and the stack trace. There is an upper
// limit on the size of this name, about 256 bytes. If the name is too long
// the counter will be silently ignored.)
// the stack will be truncated and "truncated" appended.)
//
// Counter files are turned into reports by the upload package.
// This happens weekly, except for the first time a counter file is
Expand Down
36 changes: 23 additions & 13 deletions counter/stackcounter.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,6 @@ package counter

import (
"fmt"
"log"
"runtime"
"strings"
"sync"
Expand Down Expand Up @@ -53,32 +52,43 @@ func (c *StackCounter) Inc() {
defer c.mu.Unlock()
for _, s := range c.stacks {
if eq(s.pcs, pcs) {
s.counter.Inc()
if s.counter != nil {
s.counter.Inc()
}
return
}
}
// have to create the new counter's name, and the new counter itself
locs := make([]string, c.depth)
locs := make([]string, 0, c.depth)
frs := runtime.CallersFrames(pcs)
for i := 0; i < n; i++ {
for i := 0; ; i++ {
fr, more := frs.Next()
_, pcline := fr.Func.FileLine(pcs[i])
entryptr := fr.Func.Entry()
_, entryline := fr.Func.FileLine(entryptr)
locs[i] = fmt.Sprintf("%s:%d", fr.Function, pcline-entryline)
if pcline-entryline < 0 {
// should never happen, remove before production TODO(pjw)
log.Printf("i=%d, f=%s, pcline=%d entryLine=%d", i, fr.Function, pcline, entryline)
log.Printf("pcs[i]=%x, entryptr=%x", pcs[i], entryptr)
pcline := fr.Line
entryptr := fr.Entry
var locline string
if fr.Func != nil {
_, entryline := fr.Func.FileLine(entryptr)
if pcline >= entryline {
// anything else is unexpected
locline = fmt.Sprintf("%s:%d", fr.Function, pcline-entryline)
} else {
locline = fmt.Sprintf("%s:??%d", fr.Function, pcline)
}
} else {
// might happen if the function is non-Go code or is fully inlined.
locline = fmt.Sprintf("%s:?%d", fr.Function, pcline)
}
locs = append(locs, locline)
if !more {
break
}
}

name := c.name + "\n" + strings.Join(locs, "\n")
if len(name) > maxNameLen {
return // fails silently, every time
const bad = "\ntruncated\n"
name = name[:maxNameLen-len(bad)] + bad

}
ctr := New(name)
c.stacks = append(c.stacks, stack{pcs: pcs, counter: ctr})
Expand Down

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