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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_FILE_CACHE_METADATA_H_
#define CHROME_BROWSER_CHROMEOS_DRIVE_FILE_CACHE_METADATA_H_
#include <string>
#include <vector>
#include "base/files/file_path.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "chrome/browser/chromeos/drive/drive.pb.h"
namespace base {
class SequencedTaskRunner;
} // namespace base
namespace leveldb {
class DB;
class Iterator;
} // namespace leveldb
namespace drive {
namespace internal {
// FileCacheMetadata maintains metadata of FileCache's cached files.
// This class only manages metadata. File operations are done by FileCache.
// All member access including ctor and dtor must be made on the blocking pool.
class FileCacheMetadata {
public:
// Database path.
static const base::FilePath::CharType* kCacheMetadataDBPath;
// Object to iterate over entries stored in the cache metadata.
class Iterator {
public:
explicit Iterator(scoped_ptr<leveldb::Iterator> it);
~Iterator();
// Returns true if this iterator cannot advance any more and does not point
// to a valid entry. GetKey(), GetValue() and Advance() should not be called
// in such cases.
bool IsAtEnd() const;
// Returns the key of the entry currently pointed by this object.
std::string GetKey() const;
// Returns the value of the entry currently pointed by this object.
const FileCacheEntry& GetValue() const;
// Advances to the next entry.
void Advance();
// Returns true if this object has encountered any error.
bool HasError() const;
private:
// Used to implement Advance().
void AdvanceInternal();
scoped_ptr<leveldb::Iterator> it_;
FileCacheEntry entry_;
DISALLOW_COPY_AND_ASSIGN(Iterator);
};
// Tests are allowed to pass NULL as |blocking_task_runner|.
explicit FileCacheMetadata(base::SequencedTaskRunner* blocking_task_runner);
~FileCacheMetadata();
// Initialize the cache metadata store. Returns true on success.
bool Initialize(const std::vector<base::FilePath>& cache_paths);
// Adds a new cache entry corresponding to |resource_id| if it doesn't
// exist, otherwise update the existing entry.
void AddOrUpdateCacheEntry(const std::string& resource_id,
const FileCacheEntry& cache_entry);
// Removes entry corresponding to |resource_id| from cache map.
void RemoveCacheEntry(const std::string& resource_id);
// Gets the cache entry for file corresponding to |resource_id| and |md5|
// and returns true if entry exists in cache map. Otherwise, returns false.
// |md5| can be empty if only matching |resource_id| is desired.
bool GetCacheEntry(const std::string& resource_id,
const std::string& md5,
FileCacheEntry* entry);
// Returns an object to iterate over entries.
scoped_ptr<Iterator> GetIterator();
private:
// Checks whether the current thread is on the right sequenced worker pool
// with the right sequence ID. If not, DCHECK will fail.
void AssertOnSequencedWorkerPool();
scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
scoped_ptr<leveldb::DB> level_db_;
DISALLOW_COPY_AND_ASSIGN(FileCacheMetadata);
};
} // namespace internal
} // namespace drive
#endif // CHROME_BROWSER_CHROMEOS_DRIVE_FILE_CACHE_METADATA_H_
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