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arangodb/arangod/Aql/QueryRegistry.h

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////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// 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.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Max Neunhoeffer
////////////////////////////////////////////////////////////////////////////////
#ifndef ARANGOD_AQL_QUERY_REGISTRY_H
#define ARANGOD_AQL_QUERY_REGISTRY_H 1
#include "Basics/Common.h"
#include "Basics/ReadWriteLock.h"
#include "Aql/Query.h"
#include "Aql/types.h"
namespace arangodb {
namespace aql {
class QueryRegistry {
public:
QueryRegistry() {}
~QueryRegistry();
//////////////////////////////////////////////////////////////////////////////
/// @brief insert, this inserts the query <query> for the vocbase <vocbase>
/// and the id <id> into the registry. It is in error if there is already
/// a query for this <vocbase> and <id> combination and an exception will
/// be thrown in that case. The time to live <ttl> is in seconds and the
/// query will be deleted if it is not opened for that amount of time.
//////////////////////////////////////////////////////////////////////////////
void insert(QueryId id, Query* query, double ttl = 3600.0);
//////////////////////////////////////////////////////////////////////////////
/// @brief open, find a query in the registry, if none is found, a nullptr
/// is returned, otherwise, ownership of the query is transferred to the
/// caller, however, the registry retains the entry and will open will
/// succeed only once. If an already open query with the given id is
/// found, an exception is thrown.
/// An open query can directly be destroyed by the destroy method.
/// Note that an open query will not expire, so users should please
/// protect against leaks. If an already open query is found, an exception
/// is thrown.
//////////////////////////////////////////////////////////////////////////////
Query* open(TRI_vocbase_t* vocbase, QueryId id);
//////////////////////////////////////////////////////////////////////////////
/// @brief close, return a query to the registry, if the query is not found,
/// an exception is thrown. If the ttl is negative (the default is), the
/// original ttl is taken again.
//////////////////////////////////////////////////////////////////////////////
void close(TRI_vocbase_t* vocbase, QueryId id, double ttl = -1.0);
//////////////////////////////////////////////////////////////////////////////
/// @brief destroy, this removes the entry from the registry and calls
/// delete on the Query*. It is allowed to call this regardless of whether
/// the query is open or closed. No check is performed that this call comes
/// from the same thread that has opened it!
//////////////////////////////////////////////////////////////////////////////
void destroy(std::string const& vocbase, QueryId id, int errorCode);
void destroy(TRI_vocbase_t* vocbase, QueryId id, int errorCode);
//////////////////////////////////////////////////////////////////////////////
/// @brief expireQueries, this deletes all expired queries from the registry
//////////////////////////////////////////////////////////////////////////////
void expireQueries();
private:
//////////////////////////////////////////////////////////////////////////////
/// @brief a struct for all information regarding one query in the registry
//////////////////////////////////////////////////////////////////////////////
struct QueryInfo {
TRI_vocbase_t* _vocbase; // the vocbase
QueryId _id; // id of the query
Query* _query; // the actual query pointer
bool _isOpen; // flag indicating whether or not the query
// is in use
double _timeToLive; // in seconds
double _expires; // UNIX UTC timestamp of expiration
};
//////////////////////////////////////////////////////////////////////////////
/// @brief _queries, the actual map of maps for the registry
//////////////////////////////////////////////////////////////////////////////
std::unordered_map<std::string, std::unordered_map<QueryId, QueryInfo*>>
_queries;
//////////////////////////////////////////////////////////////////////////////
/// @brief _lock, the read/write lock for access
//////////////////////////////////////////////////////////////////////////////
basics::ReadWriteLock _lock;
};
} // namespace arangodb::aql
} // namespace arangodb
#endif