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/**
* Copyright 2013 MongoDB 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/query/idhack_runner.h"
#include "mongo/db/structure/btree/btree.h"
#include "mongo/db/catalog/index_catalog.h"
#include "mongo/db/diskloc.h"
#include "mongo/db/exec/projection_exec.h"
#include "mongo/db/index/index_descriptor.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/query/canonical_query.h"
#include "mongo/db/query/type_explain.h"
#include "mongo/db/query/plan_executor.h"
#include "mongo/db/structure/collection.h"
#include "mongo/s/d_logic.h"
namespace mongo {
IDHackRunner::IDHackRunner(Collection* collection, CanonicalQuery* query)
: _collection(collection),
_query(query),
_killed(false),
_done(false) { }
IDHackRunner::~IDHackRunner() { }
Runner::RunnerState IDHackRunner::getNext(BSONObj* objOut, DiskLoc* dlOut) {
if (_killed) { return Runner::RUNNER_DEAD; }
if (_done) { return Runner::RUNNER_EOF; }
// Use the index catalog to get the id index.
IndexCatalog* catalog = _collection->getIndexCatalog();
// Find the index we use.
IndexDescriptor* idDesc = catalog->findIdIndex();
if (NULL == idDesc) {
_done = true;
return Runner::RUNNER_EOF;
}
// Create the key that we need to perform a lookup.
IndexDetails& id = idDesc->getOnDisk();
BSONObj key = id.getKeyFromQuery(_query->getQueryObj());
// Look up the key by going directly to the Btree.
DiskLoc loc;
if (0 == id.version()) {
loc = id.head.btree<V0>()->findSingle(id, id.head, key);
} else {
loc = id.head.btree<V1>()->findSingle(id, id.head, key);
}
_done = true;
// Key not found.
if (loc.isNull()) {
return Runner::RUNNER_EOF;
}
// Set out parameters and note that we're done w/lookup.
if (NULL != objOut) {
Record* record = loc.rec();
// If the record isn't in memory...
if (!Record::likelyInPhysicalMemory(record->dataNoThrowing())) {
// And we're allowed to yield ourselves...
if (Runner::YIELD_AUTO == _policy) {
// Note what we're yielding to fetch so that we don't crash if the loc is
// deleted during a yield.
_locFetching = loc;
// Yield. TODO: Do we want to bother yielding if micros < 0?
int micros = ClientCursor::suggestYieldMicros();
ClientCursor::staticYield(micros, "", record);
// This can happen when we're yielded for various reasons (e.g. db/idx dropped).
if (_killed) {
return Runner::RUNNER_DEAD;
}
}
}
// Either the data was in memory or we paged it in.
*objOut = loc.obj();
// If we're sharded make sure the key belongs to us. We need the object to do this.
if (shardingState.needCollectionMetadata(_query->ns())) {
CollectionMetadataPtr m = shardingState.getCollectionMetadata(_query->ns());
if (m) {
KeyPattern kp(m->getKeyPattern());
if (!m->keyBelongsToMe( kp.extractSingleKey(*objOut))) {
// We have something with a matching _id but it doesn't belong to me.
return Runner::RUNNER_EOF;
}
}
}
// If there is a projection...
if (NULL != _query->getProj()) {
// Create something to execute it.
auto_ptr<ProjectionExec> projExec(new ProjectionExec(_query->getParsed().getProj(),
_query->root()));
projExec->transform(*objOut, objOut);
}
}
// Return the DiskLoc if the caller wants it.
if (NULL != dlOut) {
*dlOut = loc;
}
return Runner::RUNNER_ADVANCED;
}
bool IDHackRunner::isEOF() {
return _killed || _done;
}
void IDHackRunner::saveState() { }
bool IDHackRunner::restoreState() { return true; }
void IDHackRunner::setYieldPolicy(Runner::YieldPolicy policy) {
if (_done || _killed) { return; }
_policy = policy;
}
// Nothing to do here, holding no state.
void IDHackRunner::invalidate(const DiskLoc& dl) {
if (_done || _killed) { return; }
if (_locFetching == dl) {
_locFetching = DiskLoc();
_killed = true;
}
}
const std::string& IDHackRunner::ns() {
return _query->getParsed().ns();
}
void IDHackRunner::kill() {
_killed = true;
}
Status IDHackRunner::getExplainPlan(TypeExplain** explain) const {
// This shouldn't be called anyway as idhack is only used when there is no explain.
return Status(ErrorCodes::InternalError, "no stats available to explain plan");
}
} // namespace mongo
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