// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROMEOS_ASH_COMPONENTS_FILE_MANAGER_INDEXING_INDEX_STORAGE_H_
#define CHROMEOS_ASH_COMPONENTS_FILE_MANAGER_INDEXING_INDEX_STORAGE_H_
#include <optional>
#include <set>
#include <string>
#include <vector>
#include "chromeos/ash/components/file_manager/indexing/file_info.h"
#include "chromeos/ash/components/file_manager/indexing/term.h"
#include "url/gurl.h"
namespace ash::file_manager {
// Represents an abstract interface that maintains information necessary
// for an inverted index. This class exists so that we can offer multiple
// implementation of the inverted index: ephemeral and persistent. The first
// type is implemented in RAM and offers the highest level of performance, but
// needs to be rebuilt every time before use. The other may be implemented on
// top of SQL. It offers a slower performance, but keeps the state between
// device restarts.
//
// Please note that this class is optimized for performance. Therefore it
// takes certain shortcuts. For example, when adding term IDs it
// allows us to specify the term_id of text_bytes() part of the term. This
// term_id must be the same as generated from text_bytes(). However, for
// performance reasons this task is left to the class that implements FileIndex.
class IndexStorage {
public:
IndexStorage();
virtual ~IndexStorage();
IndexStorage(const IndexStorage&) = delete;
IndexStorage& operator=(IndexStorage&) = delete;
// Initializes the storage. Returns whether or not the initialization was
// successful. No other public method may be called until this method finishes
// and returns true.
virtual bool Init();
// Closes the storage. Returns true if successful.
virtual bool Close();
// For the given `term_id` this method returns all known URL IDs
// that are associated with that term.
virtual const std::set<int64_t> GetUrlIdsForTermId(int64_t term_id) const = 0;
// Returns term IDs for the given URL.
virtual const std::set<int64_t> GetTermIdsForUrl(int64_t url_id) const = 0;
// Adds association between terms and the file. This method assumes that the
// term list is not empty. Returns the number of terms added.
virtual size_t AddTermIdsForUrl(const std::set<int64_t>& term_ids,
int64_t url_id) = 0;
// Removes association between terms and the file. Returns the number of
// terms deleted.
virtual size_t DeleteTermIdsForUrl(const std::set<int64_t>& term_ids,
int64_t url_id) = 0;
// Adds to the posting list of the given `term_id` the given
// `url_id`. This may be no-op if the `url_id` already is associated with the
// given term_id. Returns the number of URL Ids added (1 or 0).
virtual size_t AddToPostingList(int64_t term_id, int64_t url_id) = 0;
// This method removes the `url_id` from the posting lists of the specified
// `term_id`. This may be a no-op if the url_id is not present on
// the posting list for the given term. Returns the number of URLs removed.
virtual size_t DeleteFromPostingList(int64_t term_id, int64_t url_id) = 0;
// Returns the ID corresponding to the given term. If the term cannot be
// located, the method returns -1.
virtual int64_t GetTermId(const Term& term) const = 0;
// Returns the ID corresponding to the term. If the term cannot be located,
// a new ID is allocated and returned.
virtual int64_t GetOrCreateTermId(const Term& term) = 0;
// Returns the ID corresponding to the given term bytes. If the term bytes
// cannot be located, the method returns -1.
virtual int64_t GetTokenId(const std::string& term_bytes) const = 0;
// Returns the ID corresponding to the given term bytes. If the term bytes
// cannot be located, a new ID is allocated and returned.
virtual int64_t GetOrCreateTokenId(const std::string& term_bytes) = 0;
// Returns the ID corresponding to the given file URL. If this is the first
// time we see this file URL, we return -1.
virtual int64_t GetUrlId(const GURL& url) const = 0;
// Changes URL from `from` URL to `to` URL. This keeps the same URL ID, just
// changes the string associated with it.
virtual int64_t MoveUrl(const GURL& from, const GURL& to) = 0;
// Returns the ID corresponding to the given GURL. If this is the first
// time we see this URL, a new ID is created and returned.
virtual int64_t GetOrCreateUrlId(const GURL& url) = 0;
// Deletes the given URL and returns its ID. If the URL was not
// seen before, this method returns -1.
virtual int64_t DeleteUrl(const GURL& url) = 0;
// Stores FileInfo. If successful, returns the ID generated from `file_url`
// field of the `file_info`. Otherwise, it returns -1.
virtual int64_t PutFileInfo(const FileInfo& file_info) = 0;
// Attempts to retrieve the unique FileInfo associated with the given URL.
// If found, it is returned as the value of the optional object.
// NO CHECK is performed whether the url_id corresponds to the `file_url`
// field in the `info` object.
virtual std::optional<FileInfo> GetFileInfo(int64_t url_id) const = 0;
// Removes the given file info from the storage. If it was not stored, this
// method returns -1. Otherwise, it returns the ID of the `url` parameter.
virtual int64_t DeleteFileInfo(int64_t url_id) = 0;
};
} // namespace ash::file_manager
#endif // CHROMEOS_ASH_COMPONENTS_FILE_MANAGER_INDEXING_INDEX_STORAGE_H_
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