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// Copyright (c) 2012 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_CHROMEOS_DRIVE_DRIVE_PREFETCHER_H_
#define CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_PREFETCHER_H_
#include <set>
#include <deque>
#include <string>
#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "chrome/browser/chromeos/drive/drive.pb.h"
#include "chrome/browser/chromeos/drive/drive_file_system_interface.h"
#include "chrome/browser/chromeos/drive/drive_file_system_observer.h"
#include "chrome/browser/chromeos/drive/drive_sync_client_observer.h"
#include "chrome/browser/google_apis/gdata_errorcode.h"
class FilePath;
namespace drive {
class DriveFileSystemInterface;
class EventLogger;
// The parameters for DrivePrefetcher construction.
struct DrivePrefetcherOptions {
DrivePrefetcherOptions(); // Sets the default values.
int initial_prefetch_count;
int64 prefetch_file_size_limit;
};
// DrivePrefetcher is used to observe and scan the Drive file system for
// maintaining the prioritized list of files to prefetch into the cache.
//
// All the methods (including ctor and dtor) must be called from UI thread.
class DrivePrefetcher : public DriveFileSystemObserver,
public DriveSyncClientObserver {
public:
DrivePrefetcher(DriveFileSystemInterface* file_system,
EventLogger* event_logger,
const DrivePrefetcherOptions& options);
virtual ~DrivePrefetcher();
// DriveFileSystemObserver overrides.
virtual void OnInitialLoadFinished(DriveFileError error) OVERRIDE;
virtual void OnDirectoryChanged(const FilePath& directory_path) OVERRIDE;
// DriveSyncClientObserver overrides.
virtual void OnSyncTaskStarted() OVERRIDE;
virtual void OnSyncClientStopped() OVERRIDE;
virtual void OnSyncClientIdle() OVERRIDE;
private:
// Initializes the internal data to keep the prefetch priority among files.
void DoFullScan();
// Fetches the file with the highest prefetch priority. If prefetching is
// currently suspended, do nothing.
void DoPrefetch();
// Called when DoPrefetch is done.
void OnPrefetchFinished(const std::string& resource_id,
DriveFileError error,
const FilePath& file_path,
const std::string& mime_type,
DriveFileType file_type);
// Creates the |queue_| from the list of files with |latest_| timestamps.
void ReconstructQueue();
// Helper methods to traverse over the file system.
void VisitFile(const DriveEntryProto& entry);
void VisitDirectory(const FilePath& directory_path);
void OnReadDirectory(const FilePath& directory_path,
DriveFileError error,
bool hide_hosted_documents,
scoped_ptr<DriveEntryProtoVector> entries);
void OnReadDirectoryFinished();
// Keeps the kNumberOfLatestFilesToKeepInCache latest files in the filesystem.
typedef bool (*PrefetchPriorityComparator)(const DriveEntryProto&,
const DriveEntryProto&);
typedef std::set<DriveEntryProto, PrefetchPriorityComparator> LatestFileSet;
LatestFileSet latest_files_;
// The queue of files to fetch. Files with higher priority comes front.
std::deque<std::string> queue_;
// Number of in-flight |ExecuteOnePrefetch| calls that has not finished yet.
int number_of_inflight_prefetches_;
// Number of in-flight |VisitDirectory| calls that has not finished yet.
int number_of_inflight_traversals_;
// Indicates whether or not prefetching should be suspended, depending on
// the command line flag and the SyncClient's activity.
bool should_suspend_prefetch_;
// Number of files to put into prefetch queue
int initial_prefetch_count_;
// The maximum file size for prefetched files. Files larger than the limit is
// ignored from the prefetcher.
int64 prefetch_file_size_limit_;
// File system is owned by DriveSystemService.
DriveFileSystemInterface* file_system_;
// Event logger is owned by DriveSystemService.
EventLogger* event_logger_;
// Note: This should remain the last member so it'll be destroyed and
// invalidate its weak pointers before any other members are destroyed.
base::WeakPtrFactory<DrivePrefetcher> weak_ptr_factory_;
DISALLOW_COPY_AND_ASSIGN(DrivePrefetcher);
};
} // namespace drive
#endif // CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_PREFETCHER_H_
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