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arangodb/arangod/Utils/CollectionReadLocker.h

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C++

////////////////////////////////////////////////////////////////////////////////
/// 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 Jan Steemann
////////////////////////////////////////////////////////////////////////////////
#ifndef ARANGOD_UTILS_COLLECTION_READ_LOCKER_H
#define ARANGOD_UTILS_COLLECTION_READ_LOCKER_H 1
#include "Basics/Common.h"
#include "Basics/Exceptions.h"
#include "VocBase/document-collection.h"
#include "VocBase/transaction.h"
namespace arangodb {
class CollectionReadLocker {
public:
CollectionReadLocker(CollectionReadLocker const&) = delete;
CollectionReadLocker& operator=(CollectionReadLocker const&) = delete;
//////////////////////////////////////////////////////////////////////////////
/// @brief create the locker
//////////////////////////////////////////////////////////////////////////////
CollectionReadLocker(TRI_document_collection_t* document, bool doLock)
: _document(document), _doLock(false) {
if (doLock) {
int res = _document->beginReadTimed(0, TRI_TRANSACTION_DEFAULT_SLEEP_DURATION * 3);
if (res != TRI_ERROR_NO_ERROR) {
THROW_ARANGO_EXCEPTION(res);
}
_doLock = true;
}
}
//////////////////////////////////////////////////////////////////////////////
/// @brief destroy the locker
//////////////////////////////////////////////////////////////////////////////
~CollectionReadLocker() { unlock(); }
//////////////////////////////////////////////////////////////////////////////
/// @brief release the lock
//////////////////////////////////////////////////////////////////////////////
inline void unlock() {
if (_doLock) {
_document->endRead();
_doLock = false;
}
}
private:
//////////////////////////////////////////////////////////////////////////////
/// @brief collection pointer
//////////////////////////////////////////////////////////////////////////////
TRI_document_collection_t* _document;
//////////////////////////////////////////////////////////////////////////////
/// @brief lock flag
//////////////////////////////////////////////////////////////////////////////
bool _doLock;
};
}
#endif