testing: read coverage counters atomically
For -mode=atomic, we need to read the counters
using an atomic load to avoid a race. Not worth worrying
about when -mode=atomic is set during generation
of the profile, so we use atomic loads always.
Fixes #8630.
LGTM=rsc
R=dvyukov, rsc
CC=golang-codereviews
https://golang.org/cl/141800043
diff --git a/src/testing/cover.go b/src/testing/cover.go
index eb7249d..a4ce37f 100644
--- a/src/testing/cover.go
+++ b/src/testing/cover.go
@@ -9,6 +9,7 @@
import (
"fmt"
"os"
+ "sync/atomic"
)
// CoverBlock records the coverage data for a single basic block.
@@ -44,8 +45,8 @@
func Coverage() float64 {
var n, d int64
for _, counters := range cover.Counters {
- for _, c := range counters {
- if c > 0 {
+ for i := range counters {
+ if atomic.LoadUint32(&counters[i]) > 0 {
n++
}
d++
@@ -84,11 +85,13 @@
}
var active, total int64
+ var count uint32
for name, counts := range cover.Counters {
blocks := cover.Blocks[name]
- for i, count := range counts {
+ for i := range counts {
stmts := int64(blocks[i].Stmts)
total += stmts
+ count = atomic.LoadUint32(&counts[i]) // For -mode=atomic.
if count > 0 {
active += stmts
}
