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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_SQLITE_PROTO_PROTO_TABLE_MANAGER_H_
#define COMPONENTS_SQLITE_PROTO_PROTO_TABLE_MANAGER_H_
#include <string>
#include <vector>
#include "base/component_export.h"
#include "base/containers/span.h"
#include "base/memory/scoped_refptr.h"
#include "base/task/sequenced_task_runner.h"
#include "components/sqlite_proto/table_manager.h"
namespace sqlite_proto {
// ProtoTableManager is the instance of TableManager intended to be used
// in the common case of storing string-to-proto tables (alongside
// KeyValueData<T> and KeyValueTable<T>).
//
// End-to-end use:
// 1. Initialize a database with sql::Database::Open.
// 2. Initialize a ProtoTableManager on top of this database.
// 3. For each table, construct a pair of KeyValueTable and KeyValueData
// on the main sequence; initialize the KeyValueData on the database sequence.
// 4. Now, initialization is finished and the KeyValueData objects can be
// used (on the main thread) for get/put/delete operations against the database.
//
// TODO(crbug.com/40671040): This interface is a bit complex and could do with
// a refactor.
class ProtoTableManager : public TableManager {
public:
// Constructor. |db_task_runner| must run tasks on the
// sequence that subsequently calls |InitializeOnDbSequence|.
explicit ProtoTableManager(
scoped_refptr<base::SequencedTaskRunner> db_task_runner);
// Initialization:
// - |table_names| specifies the names of the tables to initialize.
// These must be unique.
// - |db| must be null or point to an open sql::Database.
// - |schema_version|, which must be positive, will be compared to the version
// stored on disk if any; in case of a mismatch (either there's no version
// stored, or |schema_version| != the stored version), clears and
// reinitializes the tables and writes the new version. It generally makes
// sense to change the version whenever the database's layout changes in a
// backwards-incompatible manner, for instance when removing or renaming
// tables or columns.
//
// If |db| is null or initialization fails, subsequent calls to
// ExecuteTaskOnDBThread will silently no-op. (When this class provides the
// backing store for a collection of KeyValueData/KeyValueTable, this leads to
// reasonable fallback behavior of the KeyValueData objects caching data in
// memory.)
void InitializeOnDbSequence(sql::Database* db,
base::span<const std::string> table_names,
int schema_version);
void WillShutdown();
protected:
~ProtoTableManager() override;
private:
// TableManager implementation.
void CreateOrClearTablesIfNecessary() override;
// Currently unused.
void LogDatabaseStats() override {}
std::vector<std::string> table_names_;
int schema_version_;
};
} // namespace sqlite_proto
#endif // COMPONENTS_SQLITE_PROTO_PROTO_TABLE_MANAGER_H_
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