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arangodb/arangod/Aql/RemoteExecutor.h

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C++

////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2019 ArangoDB 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 Tobias Gödderz
////////////////////////////////////////////////////////////////////////////////
#ifndef ARANGOD_AQL_REMOTE_EXECUTOR_H
#define ARANGOD_AQL_REMOTE_EXECUTOR_H
#include "Aql/ClusterNodes.h"
#include "Aql/ExecutionBlockImpl.h"
#include "Basics/Mutex.h"
#include "Cluster/ClusterComm.h"
#include <lib/Rest/CommonDefines.h>
#include <lib/SimpleHttpClient/SimpleHttpResult.h>
namespace arangodb {
namespace aql {
// The RemoteBlock is actually implemented by specializing ExecutionBlockImpl,
// so this class only exists to identify the specialization.
class RemoteExecutor final {};
/**
* @brief See ExecutionBlockImpl.h for documentation.
*/
template <>
class ExecutionBlockImpl<RemoteExecutor> : public ExecutionBlock {
public:
// TODO Even if it's not strictly necessary here, for consistency's sake the
// non-standard arguments (server, ownName and queryId) should probably be
// moved into some RemoteExecutorInfos class.
ExecutionBlockImpl(ExecutionEngine* engine, RemoteNode const* node,
ExecutorInfos&& infos, std::string const& server,
std::string const& ownName, std::string const& queryId);
~ExecutionBlockImpl() override = default;
std::pair<ExecutionState, SharedAqlItemBlockPtr> getSome(size_t atMost) override;
std::pair<ExecutionState, size_t> skipSome(size_t atMost) override;
std::pair<ExecutionState, Result> initializeCursor(InputAqlItemRow const& input) override;
std::pair<ExecutionState, Result> shutdown(int errorCode) override;
/// @brief handleAsyncResult
bool handleAsyncResult(ClusterCommResult* result) override;
#ifdef ARANGODB_ENABLE_MAINTAINER_MODE
// only for asserts:
public:
std::string const& server() const { return _server; }
std::string const& ownName() const { return _ownName; }
std::string const& queryId() const { return _queryId; }
#endif
private:
std::pair<ExecutionState, SharedAqlItemBlockPtr> getSomeWithoutTrace(size_t atMost);
std::pair<ExecutionState, size_t> skipSomeWithoutTrace(size_t atMost);
ExecutorInfos const& infos() const { return _infos; }
Query const& getQuery() const { return _query; }
/**
* @brief Handle communication errors in Async case.
*
* @param result The network response we got from cluster comm.
*
* @return A wrapped Result Object, that is either ok() or contains
* the error information to be thrown in get/skip some.
*/
arangodb::Result handleCommErrors(ClusterCommResult* result) const;
/// @brief internal method to send a request. Will register a callback to be
/// reactivated
arangodb::Result sendAsyncRequest(rest::RequestType type, std::string const& urlPart,
std::shared_ptr<std::string const> body);
std::shared_ptr<velocypack::Builder> stealResultBody();
private:
/// @brief timeout
static double const defaultTimeOut;
ExecutorInfos _infos;
Query const& _query;
/// @brief our server, can be like "shard:S1000" or like "server:Claus"
std::string const _server;
/// @brief our own identity, in case of the coordinator this is empty,
/// in case of the DBservers, this is the shard ID as a string
std::string const _ownName;
/// @brief the ID of the query on the server as a string
std::string const _queryId;
/// @brief whether or not this block will forward initialize,
/// initializeCursor or shutDown requests
bool const _isResponsibleForInitializeCursor;
/// @brief the last unprocessed result. Make sure to reset it
/// after it is processed.
std::shared_ptr<httpclient::SimpleHttpResult> _lastResponse;
/// @brief the last remote response Result object, may contain an error.
arangodb::Result _lastError;
/// @brief Mutex to cover against the race, that a getSome request
/// is responded before the ticket id is registered.
arangodb::Mutex _communicationMutex;
std::atomic<std::thread::id> _communicationMutexOwner; // current thread owning '_communicationMutex' lock (workaround for non-recusrive MutexLocker)
OperationID _lastTicketId;
bool _hasTriggeredShutdown;
};
} // namespace aql
} // namespace arangodb
#endif // ARANGOD_AQL_REMOTE_EXECUTOR_H