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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/collection_scan.h"
#include "mongo/db/catalog/database.h"
#include "mongo/db/exec/collection_scan_common.h"
#include "mongo/db/exec/filter.h"
#include "mongo/db/exec/working_set.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/util/fail_point_service.h"
#include "mongo/db/client.h" // XXX-ERH
namespace mongo {
// Some fail points for testing.
MONGO_FP_DECLARE(collscanInMemoryFail);
MONGO_FP_DECLARE(collscanInMemorySucceed);
// static
bool CollectionScan::diskLocInMemory(DiskLoc loc) {
if (MONGO_FAIL_POINT(collscanInMemoryFail)) {
return false;
}
if (MONGO_FAIL_POINT(collscanInMemorySucceed)) {
return true;
}
return _iter->recordFor(loc)->likelyInPhysicalMemory();
}
CollectionScan::CollectionScan(const CollectionScanParams& params,
WorkingSet* workingSet,
const MatchExpression* filter)
: _workingSet(workingSet),
_filter(filter),
_params(params),
_nsDropped(false) {
// We pre-allocate a WSID and use it to pass up fetch requests. It is only
// used to pass up fetch requests and we should never use it for anything else.
_wsidForFetch = _workingSet->allocate();
WorkingSetMember* member = _workingSet->get(_wsidForFetch);
// Kind of a lie since the obj isn't pointing to the data at loc. but the obj
// won't be used.
member->state = WorkingSetMember::LOC_AND_UNOWNED_OBJ;
}
PlanStage::StageState CollectionScan::work(WorkingSetID* out) {
++_commonStats.works;
if (_nsDropped) { return PlanStage::DEAD; }
// Do some init if we haven't already.
if (NULL == _iter) {
if ( _params.collection == NULL ) {
_nsDropped = true;
return PlanStage::DEAD;
}
_iter.reset( _params.collection->getIterator( _params.start,
_params.tailable,
_params.direction ) );
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
// See if the record we're about to access is in memory. If it's not, pass a fetch
// request up.
if (!isEOF()) {
DiskLoc curr = _iter->curr();
if (!curr.isNull() && !diskLocInMemory(curr)) {
WorkingSetMember* member = _workingSet->get(_wsidForFetch);
member->loc = curr;
*out = _wsidForFetch;
return PlanStage::NEED_FETCH;
}
}
// What we'll return to the user.
DiskLoc nextLoc;
// Should we try getNext() on the underlying _iter if we're EOF? Yes, if we're tailable.
if (isEOF()) {
if (!_params.tailable) {
return PlanStage::IS_EOF;
}
else {
// See if _iter gives us anything new.
nextLoc = _iter->getNext();
if (nextLoc.isNull()) {
// Nope, still EOF.
return PlanStage::IS_EOF;
}
}
}
else {
nextLoc = _iter->getNext();
}
WorkingSetID id = _workingSet->allocate();
WorkingSetMember* member = _workingSet->get(id);
member->loc = nextLoc;
member->obj = _params.collection->docFor(member->loc);
member->state = WorkingSetMember::LOC_AND_UNOWNED_OBJ;
++_specificStats.docsTested;
if (Filter::passes(member, _filter)) {
*out = id;
++_commonStats.advanced;
return PlanStage::ADVANCED;
}
else {
_workingSet->free(id);
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
}
bool CollectionScan::isEOF() {
if ((0 != _params.maxScan) && (_specificStats.docsTested >= _params.maxScan)) {
return true;
}
if (_nsDropped) { return true; }
if (NULL == _iter) { return false; }
return _iter->isEOF();
}
void CollectionScan::invalidate(const DiskLoc& dl, InvalidationType type) {
++_commonStats.invalidates;
// We don't care about mutations since we apply any filters to the result when we (possibly)
// return it.
if (INVALIDATION_DELETION != type) {
return;
}
// If we're here, 'dl' is being deleted.
// Deletions can harm the underlying RecordIterator so we must pass them down.
if (NULL != _iter) {
_iter->invalidate(dl);
}
// We might have 'dl' inside of the WSM that _wsidForFetch references. This is OK because
// the runner who handles the fetch request does so before releasing any locks (and allowing
// the DiskLoc to be deleted). We also don't use any data in the WSM referenced by
// _wsidForFetch so it's OK to leave the DiskLoc there.
}
void CollectionScan::prepareToYield() {
++_commonStats.yields;
if (NULL != _iter) {
_iter->prepareToYield();
}
}
void CollectionScan::recoverFromYield() {
++_commonStats.unyields;
if (NULL != _iter) {
if (!_iter->recoverFromYield()) {
warning() << "Collection dropped or state deleted during yield of CollectionScan";
_nsDropped = true;
}
}
}
PlanStageStats* CollectionScan::getStats() {
_commonStats.isEOF = isEOF();
auto_ptr<PlanStageStats> ret(new PlanStageStats(_commonStats, STAGE_COLLSCAN));
ret->specific.reset(new CollectionScanStats(_specificStats));
return ret.release();
}
} // namespace mongo
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