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/**
* Copyright (C) 2013 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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/db/exec/skip.h"
#include "mongo/db/exec/scoped_timer.h"
#include "mongo/db/exec/working_set_common.h"
#include "mongo/util/mongoutils/str.h"
namespace mongo {
using std::unique_ptr;
using std::vector;
// static
const char* SkipStage::kStageType = "SKIP";
SkipStage::SkipStage(int toSkip, WorkingSet* ws, PlanStage* child)
: _ws(ws), _child(child), _toSkip(toSkip), _commonStats(kStageType) {}
SkipStage::~SkipStage() {}
bool SkipStage::isEOF() {
return _child->isEOF();
}
PlanStage::StageState SkipStage::work(WorkingSetID* out) {
++_commonStats.works;
// Adds the amount of time taken by work() to executionTimeMillis.
ScopedTimer timer(&_commonStats.executionTimeMillis);
WorkingSetID id = WorkingSet::INVALID_ID;
StageState status = _child->work(&id);
if (PlanStage::ADVANCED == status) {
// If we're still skipping results...
if (_toSkip > 0) {
// ...drop the result.
--_toSkip;
_ws->free(id);
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
*out = id;
++_commonStats.advanced;
return PlanStage::ADVANCED;
} else if (PlanStage::FAILURE == status || PlanStage::DEAD == status) {
*out = id;
// If a stage fails, it may create a status WSM to indicate why it
// failed, in which case 'id' is valid. If ID is invalid, we
// create our own error message.
if (WorkingSet::INVALID_ID == id) {
mongoutils::str::stream ss;
ss << "skip stage failed to read in results from child";
Status status(ErrorCodes::InternalError, ss);
*out = WorkingSetCommon::allocateStatusMember(_ws, status);
}
return status;
} else if (PlanStage::NEED_TIME == status) {
++_commonStats.needTime;
} else if (PlanStage::NEED_YIELD == status) {
++_commonStats.needYield;
*out = id;
}
// NEED_TIME, NEED_YIELD, ERROR, IS_EOF
return status;
}
void SkipStage::saveState() {
++_commonStats.yields;
_child->saveState();
}
void SkipStage::restoreState(OperationContext* opCtx) {
++_commonStats.unyields;
_child->restoreState(opCtx);
}
void SkipStage::invalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) {
++_commonStats.invalidates;
_child->invalidate(txn, dl, type);
}
vector<PlanStage*> SkipStage::getChildren() const {
vector<PlanStage*> children;
children.push_back(_child.get());
return children;
}
PlanStageStats* SkipStage::getStats() {
_commonStats.isEOF = isEOF();
_specificStats.skip = _toSkip;
unique_ptr<PlanStageStats> ret(new PlanStageStats(_commonStats, STAGE_SKIP));
ret->specific.reset(new SkipStats(_specificStats));
ret->children.push_back(_child->getStats());
return ret.release();
}
const CommonStats* SkipStage::getCommonStats() const {
return &_commonStats;
}
const SpecificStats* SkipStage::getSpecificStats() const {
return &_specificStats;
}
} // namespace mongo
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