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/**
* Copyright (C) 2022-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <iosfwd>
#include "mongo/db/catalog/index_catalog.h"
#include "mongo/db/storage/column_store.h"
#include "mongo/util/functional.h"
namespace mongo::column_keygen {
/**
* This is a representation of the cell prior to flattening it out into a buffer which is passed to
* visitor callbacks.
*
* All memory within the UnencodedCellView should only be assumed valid within the callback. If you
* need it longer, you must copy it yourself. Non-test callers will generally immediately encode
* this to a flat buffer, so this shouldn't be a problem.
*/
struct UnencodedCellView {
const std::vector<BSONElement>& vals;
StringData arrayInfo;
// If true, this path has multiple values in a single (possibly nested) object with the same
// field name. In this case, arrayInfo will be empty and this cell must not be used to
// reconstruct an object. We should probably not attempt to encode vals in the index either, and
// just put a marker that causes us to either skip the row (because it breaks the rules) or go
// to the row store.
//
// Note that this detection is best-effort and will only detect cases that would result in
// corrupt array info. We have decided that query results do not need to be precise for objects
// with duplicate fields, so it is OK if we don't detect every case, as long as we don't crash
// or cause corruption on the undetected cases.
bool hasDuplicateFields;
// If true, this cell omits values that are stored in subpaths.
bool hasSubPaths;
// If true, when reconstructing an object, you will need to visit the parent path in order to
// match current semantics for projections and field-path expressions.
bool isSparse;
// If true, at least one of the values in vals is inside of a directly-double-nested array, or
// the field name was encountered while already inside of a directly-double-nested array, so
// arrayInfo must be consulted to know which values to skip when matching. If false, simple
// matches can ignore the array info and just match against each value independently.
bool hasDoubleNestedArrays;
// These are only used in tests and for debugging.
friend bool operator==(const UnencodedCellView&, const UnencodedCellView&);
friend std::ostream& operator<<(std::ostream&, const UnencodedCellView&);
friend std::ostream& operator<<(std::ostream&, const UnencodedCellView*);
};
/**
* Visits all paths within obj and provides their cell values.
* Path visit order is unspecified.
*/
void visitCellsForInsert(const BSONObj& obj,
function_ref<void(PathView, const UnencodedCellView&)> cb);
/**
* Visits all paths within obj and provides their cell values.
* Visit order is completely unspecified, so callers should not assume anything, but this function
* will attempt to perform the visits in an order optimized for inserting into a tree.
*
* Current implementation will visit all cells for a given path before moving on to the next path.
* Additionally, within each path, the cells will be visited in an order matching the order of their
* corresponding entries in the input vector. This will typically be ordered by RecordId since
* callers will typically pass records in that order, but this function neither relies on nor
* ensures that.
*/
void visitCellsForInsert(
const std::vector<BsonRecord>& recs,
function_ref<void(PathView, const BsonRecord& record, const UnencodedCellView&)> cb);
/**
* Visits all paths within obj. When deleting, you do not need to know about values.
* Path visit order is unspecified.
*/
void visitPathsForDelete(const BSONObj& obj, function_ref<void(PathView)> cb);
/**
* See visitDiffForUpdate().
*/
enum DiffAction { kInsert, kUpdate, kDelete };
/**
* Computes differences between oldObj and newObj, and invokes cb() with the required actions to
* take to update the columnar index.
*
* For kInsert and kUpdate, the UnencodedCellView will point to the cell data for newObj (you
* don't need to know the value for oldObj).
*
* For kDelete, the UnencodedCellView pointer will be null.
*
* Path visit order is unspecified.
*/
void visitDiffForUpdate(const BSONObj& oldObj,
const BSONObj& newObj,
function_ref<void(DiffAction, PathView, const UnencodedCellView*)> cb);
} // namespace mongo::column_keygen
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