mirror of https://gitee.com/bigwinds/arangodb
122 lines
4.2 KiB
C++
122 lines
4.2 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// DISCLAIMER
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///
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/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
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/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
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///
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/// Licensed under the Apache License, Version 2.0 (the "License");
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/// you may not use this file except in compliance with the License.
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/// You may obtain a copy of the License at
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///
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/// http://www.apache.org/licenses/LICENSE-2.0
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///
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/// Unless required by applicable law or agreed to in writing, software
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/// distributed under the License is distributed on an "AS IS" BASIS,
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/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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/// See the License for the specific language governing permissions and
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/// limitations under the License.
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///
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/// Copyright holder is ArangoDB GmbH, Cologne, Germany
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///
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/// @author Max Neunhoeffer
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGOD_UTILS_OPERATION_CURSOR_H
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#define ARANGOD_UTILS_OPERATION_CURSOR_H 1
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#include "Basics/Common.h"
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#include "Indexes/IndexIterator.h"
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namespace arangodb {
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class LogicalCollection;
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struct OperationCursor {
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private:
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std::unique_ptr<IndexIterator> _indexIterator;
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bool _hasMore;
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public:
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/// @brief creates an empty cursor
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OperationCursor()
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: _hasMore(false) {}
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/// @brief creates a cursor using an IndexIterator (which must be valid)
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explicit OperationCursor(std::unique_ptr<IndexIterator> iterator);
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TEST_VIRTUAL ~OperationCursor() = default;
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/// @brief return a pointer to the cursor's current index iterator
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/// (note: this may be a nullptr in the beginning)
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IndexIterator* indexIterator() const { return _indexIterator.get(); }
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/// @brief inject a new iterator into the cursor. the cursor will
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/// take over the ownership
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void rearm(std::unique_ptr<IndexIterator> iterator) {
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_indexIterator = std::move(iterator);
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TRI_ASSERT(_indexIterator != nullptr);
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_hasMore = true;
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}
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/// @brief return the logical collection used by the iterator.
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/// note that the collection may be a nullptr in case we are dealing with
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/// an EmptyIndexIterator!
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LogicalCollection* collection() const;
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inline bool hasMore() const { return _hasMore; }
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bool hasExtra() const;
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bool hasCovering() const;
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/// @brief Reset the cursor
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TEST_VIRTUAL void reset();
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/// @brief Calls cb for the next batchSize many elements
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/// returns true if there are more documents (hasMore) and false
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/// if there are none
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bool next(IndexIterator::LocalDocumentIdCallback const& callback, uint64_t batchSize);
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/// @brief Calls cb for the next batchSize many elements
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/// returns true if there are more documents (hasMore) and false
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/// if there are none
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bool nextWithExtra(IndexIterator::ExtraCallback const& callback, uint64_t batchSize);
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/// @brief Calls cb for the next batchSize many elements, complete documents
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/// returns true if there are more documents (hasMore) and false
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/// if there are none
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bool nextDocument(IndexIterator::DocumentCallback const& callback, uint64_t batchSize);
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/// @brief Calls cb for the next batchSize many elements, index-only
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/// projections returns true if there are more documents (hasMore) and false
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/// if there are none
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bool nextCovering(IndexIterator::DocumentCallback const& callback, uint64_t batchSize);
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/// @brief convenience function to retrieve all results
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void all(IndexIterator::LocalDocumentIdCallback const& callback) {
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while (next(callback, 1000)) {
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}
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}
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/// @brief convenience function to retrieve all results with extra
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void allWithExtra(IndexIterator::ExtraCallback const& callback) {
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while (nextWithExtra(callback, 1000)) {
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}
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}
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/// @brief convenience function to retrieve all results
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void allDocuments(IndexIterator::DocumentCallback const& callback, uint64_t batchSize) {
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while (nextDocument(callback, batchSize)) {
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}
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}
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/// @brief skip the next toSkip many elements.
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/// skipped will be increased by the amount of skipped elements
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/// afterwards Check hasMore()==true before using this NOTE: This will
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/// throw on OUT_OF_MEMORY
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void skip(uint64_t toSkip, uint64_t& skipped);
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};
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} // namespace arangodb
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#endif
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