Reporting of policy errors via host-offline-reason: part 3

remoting/host/ack_or_timeout_reporter.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef REMOTING_HOST_ACK_OR_TIMEOUT_REPORTER_H_
+#define REMOTING_HOST_ACK_OR_TIMEOUT_REPORTER_H_
+
+#include "base/callback_forward.h"
+#include "base/sequenced_task_runner.h"
+
+namespace base {
+class TimeDelta;
+}
+
+namespace remoting {
+
+enum AckOrTimeout { Ack, Timeout };
+
+// ReportAckOrTimeout will call |ack_or_timeout_callback|, when either
+// |ack_callback| is called or when |timeout| has been reached.  This
+// is helpful to add timeout functionality to a function that supports
+// acking, but doesn't support timeouts.
+//
+// As a consequence of using WeakPtr as an implementation detail,
+// ReportAckOrTimeout requires its caller to make sure that:
+// - ReportAckOfTimeout is called on |sequenced_task_runner|
+// - If called, then |ack_callback| will be called on |sequenced_task_runner|
+//
+// ReportAckOrTimeout guarantees that:
+// - |function_that_acks| will be called synchronously (i.e. caller
+//   can destroy |function_that_acks| and/or its base::Unretained
+//   arguments as soon as ReportAckOrTimeout returns).
+// - |ack_or_timeout_callback| will be called exactly once.
+// - |ack_or_timeout_callback| will be called via |sequenced_task_runner|.
+// - All references (i.e. ref-counted arguments) to |ack_or_timeout_callback|
+//   will be dropped after it is called.
+void ReportAckOrTimeout(

[Sergey Ulanov, 2014/12/15 22:39:19]

Can this be replaced with something like CreateCallbackWithTimeout() that would
just creates a callback which is expected to be called in certain period of
time? That would make both the implementation and use of this function cleaner.

[Łukasz Anforowicz, 2014/12/16 00:59:52]

I am working on removing ack_or_timeout_reporter*.* altogether (and replacing
them with timeout implementation inside heartbeat_sender*.*).

+    const base::Callback<void(const base::Closure& ack_callback)>&
+        function_that_acks,
+    const base::TimeDelta& timeout,
+    scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner,
+    const base::Callback<void(AckOrTimeout ack_or_timeout)>&
+        ack_or_timeout_callback);
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_ACK_OR_TIMEOUT_REPORTER_H_