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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.
*/
#pragma once
#include "mongo/db/query/canonical_query.h"
#include "mongo/db/query/lite_parsed_query.h"
#include "mongo/db/query/plan_cache.h"
#include "mongo/db/query/plan_executor.h"
#include "mongo/db/query/runner.h"
#include "mongo/db/query/stage_builder.h"
namespace mongo {
/**
* CachedPlanRunner runs a plan retrieved from the cache.
*
* Cached plans are bundled with information describing why the plan is in the cache.
*
* If we run a plan from the cache and behavior wildly deviates from expected behavior, we may
* remove the plan from the cache. See plan_cache.h.
*/
class CachedPlanRunner : public Runner {
public:
/**
* Takes ownership of both arguments.
*/
CachedPlanRunner(CanonicalQuery* canonicalQuery, CachedSolution* cached,
PlanStage* root, WorkingSet* ws)
: _canonicalQuery(canonicalQuery), _cachedQuery(cached),
_exec(new PlanExecutor(ws, root)), _updatedCache(false) { }
Runner::RunnerState getNext(BSONObj* objOut, DiskLoc* dlOut) {
Runner::RunnerState state = _exec->getNext(objOut, dlOut);
if (Runner::RUNNER_EOF == state && !_updatedCache) {
updateCache();
}
return state;
}
virtual bool isEOF() { return _exec->isEOF(); }
virtual void saveState() { _exec->saveState(); }
virtual bool restoreState() { return _exec->restoreState(); }
virtual void invalidate(const DiskLoc& dl) { _exec->invalidate(dl); }
virtual void setYieldPolicy(Runner::YieldPolicy policy) {
_exec->setYieldPolicy(policy);
}
virtual const string& ns() { return _canonicalQuery->getParsed().ns(); }
virtual void kill() { _exec->kill(); }
private:
void updateCache() {
_updatedCache = true;
// We're done. Update the cache.
PlanCache* cache = PlanCache::get(_canonicalQuery->ns());
// TODO: Is this an error?
if (NULL == cache) { return; }
// TODO: How do we decide this?
bool shouldRemovePlan = false;
if (shouldRemovePlan) {
if (!cache->remove(*_canonicalQuery, *_cachedQuery->solution)) {
warning() << "Cached plan runner couldn't remove plan from cache. Maybe"
" somebody else did already?";
return;
}
}
// We're done running. Update cache.
auto_ptr<CachedSolutionFeedback> feedback(new CachedSolutionFeedback());
feedback->stats = _exec->getStats();
cache->feedback(*_canonicalQuery, *_cachedQuery->solution, feedback.release());
}
scoped_ptr<CanonicalQuery> _canonicalQuery;
scoped_ptr<CachedSolution> _cachedQuery;
scoped_ptr<PlanExecutor> _exec;
// Have we updated the cache with our plan stats yet?
bool _updatedCache;
};
} // namespace mongo
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