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/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef SRC_TRACE_PROCESSOR_SQLITE_QUERY_CONSTRAINTS_H_
#define SRC_TRACE_PROCESSOR_SQLITE_QUERY_CONSTRAINTS_H_
#include <sqlite3.h>
#include <vector>
#include "perfetto/ext/base/scoped_file.h"
namespace perfetto {
namespace trace_processor {
// This class stores the constraints (including the order-by information) for
// a query on a sqlite3 virtual table and handles their de/serialization into
// strings.
// This is because the constraint columns and the order-by clauses are passed
// to the xBestIndex method but the constraint values are available only in the
// xFilter method. Unfortunately sqlite vtable API don't give any hint about
// the validity of the constraints (i.e. constraints passed to xBestIndex can
// be used by future xFilter calls in the far future). The only mechanism
// offered by sqlite is the idxStr string which is returned by the vtable
// in the xBestIndex call and passed to each corresponding xFilter call.
class QueryConstraints {
public:
using Constraint = sqlite3_index_info::sqlite3_index_constraint;
using OrderBy = sqlite3_index_info::sqlite3_index_orderby;
static int FreeSqliteString(char* resource);
using SqliteString = base::ScopedResource<char*, FreeSqliteString, nullptr>;
QueryConstraints();
~QueryConstraints();
QueryConstraints(QueryConstraints&&) noexcept;
QueryConstraints& operator=(QueryConstraints&&);
// Two QueryConstraints with the same constraint and orderby vectors
// are equal.
bool operator==(const QueryConstraints& other) const;
void AddConstraint(int column, unsigned char op);
void AddOrderBy(int column, unsigned char desc);
void ClearOrderBy() { order_by_.clear(); }
// Converts the constraints and order by information to a string for
// use by sqlite.
SqliteString ToNewSqlite3String() const;
// Deserializes the string into QueryConstraints. String given is in the form
// C{# of constraints},col1,op1,col2,op2...,O{# of order by},col1,desc1...
// For example C1,0,3,O2,1,0,4,1
static QueryConstraints FromString(const char* idxStr);
const std::vector<OrderBy>& order_by() const { return order_by_; }
const std::vector<Constraint>& constraints() const { return constraints_; }
private:
QueryConstraints(const QueryConstraints&) = delete;
QueryConstraints& operator=(const QueryConstraints&) = delete;
std::vector<OrderBy> order_by_;
std::vector<Constraint> constraints_;
};
} // namespace trace_processor
} // namespace perfetto
#endif // SRC_TRACE_PROCESSOR_SQLITE_QUERY_CONSTRAINTS_H_
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