Certificate Transparency: Start tracking logs' state

net/cert/sth_observer.h

+// Copyright 2016 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 NET_CERT_STH_OBSERVER_H_
+#define NET_CERT_STH_OBSERVER_H_
+
+#include <set>
+
+#include "net/base/net_export.h"
+
+namespace net {
+
+namespace ct {
+
+struct SignedTreeHead;
+
+class NET_EXPORT STHObserver {
+ public:
+  virtual ~STHObserver() {}
+
+  virtual void NewSTHObserved(const SignedTreeHead& sth) = 0;
+};
+
+class NET_EXPORT STHReporter {
+ public:
+  virtual ~STHReporter() {}
+
+  virtual void RegisterObserver(STHObserver* observer) = 0;
+  virtual void UnregisterObserver(STHObserver* observer) = 0;
+};
+
+class NET_EXPORT STHReporterRegistrar {
+ public:
+  STHReporterRegistrar();
+  ~STHReporterRegistrar();
+
+  // Stores the |observer| for later registration when a reporter
+  // is provided, or registers it immediately if one was already
+  // provided via AssignReporter.
+  void SignUpForRegistration(STHObserver* observer);
+  // Can only be called once; Calls STHReporter::RegisterObserver
+  // for each of the observers registered with SignUpForRegistration
+  void AssignReporter(STHReporter* reporter);
+  // Calls STHReporter::UnregisterObserver for all observers
+  // registered with SignUpForRegistration
+  void UnregisterAll();
+  // Unregisters an individual reporter.
+  void UnregisterObserver(STHObserver* observer);
+
+ private:
+  STHReporter* reporter_;
+  std::set<STHObserver*> pending_observers_;
+};
+
+}  // namespace ct
+
+}  // namespace net
+
+#endif  // NET_CERT_STH_OBSERVER_H_