Add connection pool implementation (part 2)

Signed-off-by: Pavel Korotkov <pavel@nspcc.ru>

global/context.go

@@ -8,16 +8,13 @@ import (
 )
 
 var (
-	globalContext        context.Context
-	globalContextOnce    sync.Once
-	globalContextBarrier = make(chan struct{})
+	globalContext     context.Context
+	globalContextOnce sync.Once
 )
 
 func Context() context.Context {
 	globalContextOnce.Do(func() {
 		globalContext, _ = signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP)
-		close(globalContextBarrier)
 	})
-	<-globalContextBarrier
 	return globalContext
 }