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// Copyright (c) 2010 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 CHROME_BROWSER_POLICY_FILE_BASED_POLICY_LOADER_H_
#define CHROME_BROWSER_POLICY_FILE_BASED_POLICY_LOADER_H_
#pragma once
#include "chrome/browser/file_path_watcher/file_path_watcher.h"
#include "chrome/browser/policy/asynchronous_policy_loader.h"
#include "chrome/browser/policy/file_based_policy_provider.h"
namespace policy {
// A customized asynchronous policy loader that handles loading policy from a
// file using a FilePathWatcher. The loader creates a fallback task to load
// policy periodically in case the watcher fails and retries policy loads when
// the watched file is in flux.
class FileBasedPolicyLoader : public AsynchronousPolicyLoader {
public:
FileBasedPolicyLoader(
FileBasedPolicyProvider::ProviderDelegate* provider_delegate);
// AsynchronousPolicyLoader implementation:
virtual void Init();
virtual void Stop();
virtual void Reload();
void OnFilePathChanged(const FilePath& path);
void OnError();
protected:
// FileBasedPolicyLoader objects should only be deleted by
// RefCountedThreadSafe.
friend class base::RefCountedThreadSafe<AsynchronousPolicyLoader>;
virtual ~FileBasedPolicyLoader() {}
const FilePath& config_file_path() { return config_file_path_; }
private:
// Finishes initialization after the threading system has been fully
// intiialized.
void InitAfterFileThreadAvailable();
// Creates the file path watcher and configures it watch |config_file_path_|.
// Must be called on the file thread.
void InitWatcher();
// Cancels file path watch notification and destroys the watcher.
// Must be called on file thread.
void StopOnFileThread();
// Schedules a reload task to run when |delay| expires. Must be called on the
// file thread.
void ScheduleReloadTask(const base::TimeDelta& delay);
// Schedules a reload task to run after the number of minutes specified
// in |reload_interval_minutes_|. Must be called on the file thread.
void ScheduleFallbackReloadTask();
// Invoked from the reload task on the file thread.
void ReloadFromTask();
// Checks whether policy information is safe to read. If not, returns false
// and then delays until it is considered safe to reload in |delay|.
// Must be called on the file thread.
bool IsSafeToReloadPolicy(const base::Time& now, base::TimeDelta* delay);
// The path at which we look for configuration files.
const FilePath config_file_path_;
// Managed with a scoped_ptr rather than being declared as an inline member to
// decouple the watcher's life cycle from the loader's. This decoupling makes
// it possible to destroy the watcher before the loader's destructor is called
// (e.g. during Stop), since |watcher_| internally holds a reference to the
// loader and keeps it alive.
scoped_ptr<FilePathWatcher> watcher_;
// The reload task. Access only on the file thread. Holds a reference to the
// currently posted task, so we can cancel and repost it if necessary.
CancelableTask* reload_task_;
// The interval that a policy reload will be triggered as a fallback even if
// the delegate doesn't indicate that one is needed.
const base::TimeDelta reload_interval_;
// Settle interval.
const base::TimeDelta settle_interval_;
// Records last known modification timestamp of |config_file_path_|.
base::Time last_modification_file_;
// The wall clock time at which the last modification timestamp was
// recorded. It's better to not assume the file notification time and the
// wall clock times come from the same source, just in case there is some
// non-local filesystem involved.
base::Time last_modification_clock_;
DISALLOW_COPY_AND_ASSIGN(FileBasedPolicyLoader);
};
} // namespace policy
#endif // CHROME_BROWSER_POLICY_FILE_BASED_POLICY_LOADER_H_
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