Initial QSfera import

Server/vendor/github.com/open-policy-agent/opa/v1/util/wait.go

@@ -0,0 +1,34 @@
+// Copyright 2020 The OPA Authors.  All rights reserved.
+// Use of this source code is governed by an Apache2
+// license that can be found in the LICENSE file.
+
+package util
+
+import (
+	"errors"
+	"time"
+)
+
+// WaitFunc will call passed function at an interval and return nil
+// as soon this function returns true.
+// If timeout is reached before the passed in function returns true
+// an error is returned.
+func WaitFunc(fun func() bool, interval, timeout time.Duration) error {
+	if fun() {
+		return nil
+	}
+	ticker := time.NewTicker(interval)
+	timer := time.NewTimer(timeout)
+	defer ticker.Stop()
+	defer timer.Stop()
+	for {
+		select {
+		case <-timer.C:
+			return errors.New("timeout")
+		case <-ticker.C:
+			if fun() {
+				return nil
+			}
+		}
+	}
+}