Stop counting handlers before terminating.

The requirement to do so is obsolete and has already been removed from
other pluggable transports.

https://bugs.torproject.org/32046

client/lib/snowflake.go

@@ -13,17 +13,9 @@ const (
 	SnowflakeTimeout = 30
 )
 
-// HandlerChan - When a connection handler starts, +1 is written to this channel; when it
-// ends, -1 is written.
-var HandlerChan = make(chan int)
-
 // Given an accepted SOCKS connection, establish a WebRTC connection to the
 // remote peer and exchange traffic.
 func Handler(socks SocksConnector, snowflakes SnowflakeCollector) error {
-	HandlerChan <- 1
-	defer func() {
-		HandlerChan <- -1
-	}()
 	// Obtain an available WebRTC remote. May block.
 	snowflake := snowflakes.Pop()
 	if nil == snowflake {

client/snowflake.go

@@ -184,8 +184,6 @@ func main() {
 	}
 	pt.CmethodsDone()
 
-	var numHandlers int
-	var sig os.Signal
 	sigChan := make(chan os.Signal, 1)
 	signal.Notify(sigChan, syscall.SIGTERM)
 
@@ -202,22 +200,12 @@ func main() {
 	}
 
 	// keep track of handlers and wait for a signal
-	sig = nil
-	for sig == nil {
-		select {
-		case n := <-sf.HandlerChan:
-			numHandlers += n
-		case sig = <-sigChan:
-		}
-	}
+	<-sigChan
 
 	// signal received, shut down
 	for _, ln := range listeners {
 		ln.Close()
 	}
 	snowflakes.End()
-	for numHandlers > 0 {
-		numHandlers += <-sf.HandlerChan
-	}
 	log.Println("snowflake is done.")
 }