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/**
* Copyright (C) 2021-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/pipeline/window_function/window_function_exec_removable_document.h"
namespace mongo {
WindowFunctionExecRemovableDocument::WindowFunctionExecRemovableDocument(
PartitionIterator* iter,
boost::intrusive_ptr<Expression> input,
std::unique_ptr<WindowFunctionState> function,
WindowBounds::DocumentBased bounds)
: WindowFunctionExecRemovable(iter,
PartitionAccessor::Policy::kDefaultSequential,
std::move(input),
std::move(function)) {
stdx::visit(
visit_helper::Overloaded{
[](const WindowBounds::Unbounded&) {
// If the window is left unbounded we should use the non-removable executor.
MONGO_UNREACHABLE_TASSERT(5339802);
},
[&](const WindowBounds::Current&) { _lowerBound = 0; },
[&](const int& lowerIndex) { _lowerBound = lowerIndex; },
},
bounds.lower);
stdx::visit(
visit_helper::Overloaded{
[](const WindowBounds::Unbounded&) {
// Pass. _upperBound defaults to boost::none which represents no upper
// bound.
},
[&](const WindowBounds::Current&) { _upperBound = 0; },
[&](const int& upperIndex) { _upperBound = upperIndex; },
},
bounds.upper);
_memUsageBytes = sizeof(*this);
}
void WindowFunctionExecRemovableDocument::initialize() {
int lowerBoundForInit = _lowerBound > 0 ? _lowerBound : 0;
// Run the loop until we hit the out of partition break (right unbounded) or we hit the upper
// bound.
for (int i = lowerBoundForInit; !_upperBound || i <= _upperBound.get(); ++i) {
// If this is false, we're over the end of the partition.
if (auto doc = (this->_iter)[i]) {
addValue(_input->evaluate(*doc, &_input->getExpressionContext()->variables));
} else {
break;
}
}
_initialized = true;
}
void WindowFunctionExecRemovableDocument::update() {
if (!_initialized) {
initialize();
return;
}
// If there is no upper bound, the whole partition is loaded by initialize.
if (_upperBound) {
// If this is false, we're over the end of the partition.
if (auto doc = (this->_iter)[_upperBound.get()]) {
addValue(_input->evaluate(*doc, &_input->getExpressionContext()->variables));
}
}
// For a positive lower bound the first pass loads the correct window, so subsequent passes
// must always remove a document if there is a document left to remove.
// For a negative lower bound we can start removing every time only after we have seen
// documents to fill the left side of the window.
if (_lowerBound >= 0 || _iter.getCurrentPartitionIndex() > abs(_lowerBound)) {
removeFirstValueIfExists();
}
}
} // namespace mongo
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