libgo: update to Go1.10beta2 release

    
    Reviewed-on: https://go-review.googlesource.com/87897

From-SVN: r256794

1 files changed, 11 insertions, 1 deletions

diff --git a/libgo/go/net/lookup.go b/libgo/go/net/lookup.go
index c9f327050af..85e472932fc 100644
--- a/libgo/go/net/lookup.go
+++ b/libgo/go/net/lookup.go
@@ -8,6 +8,7 @@ import (
 	"context"
 	"internal/nettrace"
 	"internal/singleflight"
+	"sync"
 )
 
 // protocols contains minimal mappings between internet protocol
@@ -53,6 +54,10 @@ var services = map[string]map[string]int{
 	},
 }
 
+// dnsWaitGroup can be used by tests to wait for all DNS goroutines to
+// complete. This avoids races on the test hooks.
+var dnsWaitGroup sync.WaitGroup
+
 const maxProtoLength = len("RSVP-E2E-IGNORE") + 10 // with room to grow
 
 func lookupProtocolMap(name string) (int, error) {
@@ -189,9 +194,14 @@ func (r *Resolver) LookupIPAddr(ctx context.Context, host string) ([]IPAddr, err
 		resolverFunc = alt
 	}
 
-	ch := lookupGroup.DoChan(host, func() (interface{}, error) {
+	dnsWaitGroup.Add(1)
+	ch, called := lookupGroup.DoChan(host, func() (interface{}, error) {
+		defer dnsWaitGroup.Done()
 		return testHookLookupIP(ctx, resolverFunc, host)
 	})
+	if !called {
+		dnsWaitGroup.Done()
+	}
 
 	select {
 	case <-ctx.Done():