ForceTLS: persist to disk

chrome/browser/force_tls_persister.h

+// Copyright (c) 2006-2008 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.
+
+// ForceTLSState maintains an in memory database containing the list of hosts
+// that currently have ForceTLS enabled. This singleton object deals with
+// writing that data out to disk as needed and loading it at startup.
+
+// At startup we need to load the ForceTLS state from the disk. For the moment,
+// we don't want to delay startup for this load, so we let the ForceTLSState
+// run for a while without being loaded. This means that it's possible for
+// pages opened very quickly not to get the correct ForceTLS information.
+//
+// To load the state, we schedule a Task on the file thread which loads,
+// deserialises and configures the ForceTLSState.
+//
+// The ForceTLSState object supports running a callback function when it
+// changes. This object registers the callback, pointing at itself.
+//
+// ForceTLSState calls...
+// ForceTLSPersister::StateIsDirty
+//   since the callback isn't allowed to block or reenter, we schedule a Task
+//   on |file_thread_| after some small amount of time
+//
+// ...
+//
+// ForceTLSPersister::SerialiseState
+//   copies the current state of the ForceTLSState, serialises and writes to
+//   disk.
+
+#include "base/lock.h"
+#include "base/ref_counted.h"
+#include "net/base/force_tls_state.h"
+
+namespace base {
+class Thread;
+}
+
+class ForceTLSPersister : public base::RefCountedThreadSafe<ForceTLSPersister> {
+ public:
+  ForceTLSPersister(net::ForceTLSState* state, base::Thread* file_thread);
+
+  // Called by the ForceTLSState when it changes its state.
+  void StateIsDirty();
+
+ private:
+  // a Task callback for when the state needs to be written out.
+  void SerialiseState();
+
+  // a Task callback for when the state needs to be loaded from disk at startup.
+  void LoadState();
+
+  Lock lock_;  // protects all the members
+
+  // true when the state object has signaled that we're dirty and we haven't
+  // serialised the state yet.
+  bool state_is_dirty_;
+
+  scoped_refptr<net::ForceTLSState> force_tls_state_;
+
+  // This is a thread which can perform file access.
+  base::Thread* const file_thread_;
+};