commit e3351cb08abe6b806fa018bc8915f0f5ae045a40
Author: Cecylia Bocovich <coh...@torproject.org>
Date: Mon Jun 21 15:39:41 2021 -0400
Fix data race for Peers.collection
We used a WaitGroup to prevent a call to Peers.End from melting
snowflakes while a new one is being collected. However, calls to
WaitGroup.Add are in a race with WaitGroup.Wait. To fix this, we use a
Mutex instead.
---
client/lib/peers.go | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/client/lib/peers.go b/client/lib/peers.go
index 66373f1..7fba572 100644
--- a/client/lib/peers.go
+++ b/client/lib/peers.go
@@ -28,7 +28,7 @@ type Peers struct {
melt chan struct{}
- collection sync.WaitGroup
+ collectLock sync.Mutex
}
// Construct a fresh container of remote peers.
@@ -48,8 +48,8 @@ func NewPeers(tongue Tongue) (*Peers, error) {
// As part of |SnowflakeCollector| interface.
func (p *Peers) Collect() (*WebRTCPeer, error) {
// Engage the Snowflake Catching interface, which must be available.
- p.collection.Add(1)
- defer p.collection.Done()
+ p.collectLock.Lock()
+ defer p.collectLock.Unlock()
select {
case <-p.melt:
return nil, fmt.Errorf("Snowflakes have melted")
@@ -121,7 +121,8 @@ func (p *Peers) purgeClosedPeers() {
// Close all Peers contained here.
func (p *Peers) End() {
close(p.melt)
- p.collection.Wait()
+ p.collectLock.Lock()
+ defer p.collectLock.Unlock()
close(p.snowflakeChan)
cnt := p.Count()
for e := p.activePeers.Front(); e != nil; {
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