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arangodb/arangod/Utils/OperationCursor.cpp

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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 Michael Hackstein
////////////////////////////////////////////////////////////////////////////////
#include "OperationCursor.h"
#include "OperationResult.h"
#include "Basics/Exceptions.h"
#include "Logger/Logger.h"
#include "VocBase/LogicalCollection.h"
#include "VocBase/ManagedDocumentResult.h"
using namespace arangodb;
void OperationCursor::reset() {
code = TRI_ERROR_NO_ERROR;
if (_indexIterator != nullptr) {
_indexIterator->reset();
_hasMore = true;
_limit = _originalLimit;
}
}
//////////////////////////////////////////////////////////////////////////////
/// @brief Get next batchSize many DocumentTokens.
/// Defaults to _batchSize
/// Check hasMore()==true before using this
/// NOTE: This will throw on OUT_OF_MEMORY
//////////////////////////////////////////////////////////////////////////////
std::vector<DocumentIdentifierToken> OperationCursor::getMoreTokens(uint64_t batchSize) {
std::vector<DocumentIdentifierToken> res;
getMoreTokens(res, batchSize);
return res;
}
//////////////////////////////////////////////////////////////////////////////
/// @brief Get next batchSize many DocumentTokens.
/// Defaults to _batchSize
/// Check hasMore()==true before using this
/// NOTE: This will throw on OUT_OF_MEMORY
/// NOTE: The result vector handed in is used to continue index lookups
/// The caller shall NOT modify it.
//////////////////////////////////////////////////////////////////////////////
void OperationCursor::getMoreTokens(std::vector<DocumentIdentifierToken>& result,
uint64_t batchSize) {
if (!hasMore()) {
TRI_ASSERT(false);
// You requested more even if you should have checked it before.
return;
}
if (batchSize == UINT64_MAX) {
batchSize = _batchSize;
}
size_t atMost = static_cast<size_t>(batchSize > _limit ? _limit : batchSize);
_indexIterator->nextBabies(result, atMost);
TRI_ASSERT(_limit >= atMost);
_limit -= atMost;
if (result.empty()) {
// Index is empty
_hasMore = false;
return;
}
}
//////////////////////////////////////////////////////////////////////////////
/// @brief Skip the next toSkip many elements.
/// skipped will be increased by the amount of skipped elements afterwards
/// Check hasMore()==true before using this
/// NOTE: This will throw on OUT_OF_MEMORY
//////////////////////////////////////////////////////////////////////////////
int OperationCursor::skip(uint64_t toSkip, uint64_t& skipped) {
if (!hasMore()) {
TRI_ASSERT(false);
// You requested more even if you should have checked it before.
return TRI_ERROR_FORBIDDEN;
}
if (toSkip > _limit) {
// Short-cut, we jump to the end
_limit = 0;
_hasMore = false;
return TRI_ERROR_NO_ERROR;
}
_indexIterator->skip(toSkip, skipped);
_limit -= skipped;
if (skipped != toSkip || _limit == 0) {
_hasMore = false;
}
return TRI_ERROR_NO_ERROR;
}