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arangodb/arangod/Transaction/SmartContext.h

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C++

////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2018 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 Simon Grätzer
////////////////////////////////////////////////////////////////////////////////
#ifndef ARANGOD_TRANSACTION_GLOBAL_CONTEXT_H
#define ARANGOD_TRANSACTION_GLOBAL_CONTEXT_H 1
#include "Context.h"
#include "Basics/Common.h"
#include "VocBase/vocbase.h"
struct TRI_vocbase_t;
namespace arangodb {
class TransactionState;
namespace transaction {
/// transaction context that will manage the creation or acquisition of a TransactionState
/// for transaction::Methods instances for cluster wide transactions. Cluster wide transactions
/// essentially just mean that all operations will use a consistent transaction ID and
/// on the same server the same TransactionState instance will be used.
/// The class supports three different use-cases
/// (1) Constructor with TID and Type::Default can be used to share a TransactionState between
/// multiple transaction::Methods instances
/// (2) Constructor with TID and Type::Global will try to lease an already existing TransactionState
/// from the TransactionManager. This supports global transaction with explicit begin / end requests
/// (3) Construcor with TransactionState* is used to manage a global transaction
class SmartContext final : public Context {
public:
/// @brief create the context, with given TID
explicit SmartContext(TRI_vocbase_t& vocbase);
/// @brief destroy the context
~SmartContext() = default;
/// @brief order a custom type handler
std::shared_ptr<arangodb::velocypack::CustomTypeHandler>
orderCustomTypeHandler() override final;
/// @brief return the resolver
CollectionNameResolver const& resolver() override final;
/// @brief get parent transaction (if any) and increase nesting
TransactionState* getParentTransaction() const override;
/// @brief register the transaction,
void registerTransaction(TransactionState*) override;
/// @brief unregister the transaction
void unregisterTransaction() noexcept override;
/// @brief whether or not the transaction is embeddable
bool isEmbeddable() const override;
static std::shared_ptr<Context> Create(TRI_vocbase_t&);
private:
/// @brief managed TransactionState
TransactionState *_state;
};
}
}
#endif