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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 WEBKIT_FILEAPI_SYNCABLE_LOCAL_FILE_SYNC_STATUS_H_
#define WEBKIT_FILEAPI_SYNCABLE_LOCAL_FILE_SYNC_STATUS_H_
#include <map>
#include <set>
#include "base/basictypes.h"
#include "base/compiler_specific.h"
#include "base/threading/non_thread_safe.h"
#include "webkit/fileapi/file_system_url.h"
namespace fileapi {
// Represents local file sync status.
// This class is supposed to run only on IO thread.
//
// This class manages two important synchronization flags: writing (counter)
// and syncing (flag). Writing counter keeps track of which URL is in
// writing and syncing flag indicates which URL is in syncing.
//
// An invariant of this class is: no FileSystem objects should be both
// in syncing_ and writing_ status, i.e. trying to increment writing
// while the target url is in syncing must fail and vice versa.
class WEBKIT_STORAGE_EXPORT LocalFileSyncStatus : public base::NonThreadSafe {
public:
LocalFileSyncStatus();
~LocalFileSyncStatus();
// Increment writing counter for |url|.
// This should not be called if the |url| is not writable.
void StartWriting(const FileSystemURL& url);
// Decrement writing counter for |url|.
void EndWriting(const FileSystemURL& url);
// Start syncing for |url| and disable writing.
// This should not be called if |url| is in writing.
void StartSyncing(const FileSystemURL& url);
// Clears the syncing flag for |url| and enable writing.
void EndSyncing(const FileSystemURL& url);
// Returns true if the |url| or its parent or child is in writing.
bool IsWriting(const FileSystemURL& url) const;
// Returns true if the |url| is enabled for writing (i.e. not in syncing).
bool IsWritable(const FileSystemURL& url) const;
private:
typedef std::map<FileSystemURL, int64, FileSystemURL::Comparator> URLCountMap;
typedef std::set<FileSystemURL, FileSystemURL::Comparator> URLSet;
bool IsChildOrParentWriting(const FileSystemURL& url) const;
bool IsChildOrParentSyncing(const FileSystemURL& url) const;
// If this count is non-zero positive there're ongoing write operations.
URLCountMap writing_;
// If this flag is set sync process is running on the file.
URLSet syncing_;
DISALLOW_COPY_AND_ASSIGN(LocalFileSyncStatus);
};
} // namespace fileapi
#endif // WEBKIT_FILEAPI_SYNCABLE_LOCAL_FILE_SYNC_STATUS_H_
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