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/**
* Copyright (C) 2014 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.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kStorage
#include "mongo/db/storage/mmap_v1/record_store_v1_repair_iterator.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/storage/mmap_v1/extent.h"
#include "mongo/db/storage/mmap_v1/extent_manager.h"
#include "mongo/db/storage/mmap_v1/record_store_v1_simple.h"
#include "mongo/util/log.h"
namespace mongo {
using std::endl;
RecordStoreV1RepairCursor::RecordStoreV1RepairCursor(OperationContext* txn,
const RecordStoreV1Base* recordStore)
: _txn(txn), _recordStore(recordStore), _stage(FORWARD_SCAN) {
// Position the iterator at the first record
//
advance();
}
boost::optional<Record> RecordStoreV1RepairCursor::next() {
if (_currRecord.isNull())
return {};
auto out = _currRecord.toRecordId();
advance();
return {{out, _recordStore->dataFor(_txn, out)}};
}
boost::optional<Record> RecordStoreV1RepairCursor::seekExact(const RecordId& id) {
invariant(!"seekExact not supported");
}
void RecordStoreV1RepairCursor::advance() {
const ExtentManager* em = _recordStore->_extentManager;
while (true) {
if (_currRecord.isNull()) {
if (!_advanceToNextValidExtent()) {
return;
}
_seenInCurrentExtent.clear();
// Otherwise _advanceToNextValidExtent would have returned false
//
invariant(!_currExtent.isNull());
const Extent* e = em->getExtent(_currExtent, false);
_currRecord = (FORWARD_SCAN == _stage ? e->firstRecord : e->lastRecord);
} else {
switch (_stage) {
case FORWARD_SCAN:
_currRecord = _recordStore->getNextRecordInExtent(_txn, _currRecord);
break;
case BACKWARD_SCAN:
_currRecord = _recordStore->getPrevRecordInExtent(_txn, _currRecord);
break;
default:
invariant(!"This should never be reached.");
break;
}
}
if (_currRecord.isNull()) {
continue;
}
// Validate the contents of the record's disk location and deduplicate
//
if (!_seenInCurrentExtent.insert(_currRecord).second) {
error() << "infinite loop in extent, seen: " << _currRecord << " before" << endl;
_currRecord = DiskLoc();
continue;
}
if (_currRecord.getOfs() <= 0) {
error() << "offset is 0 for record which should be impossible" << endl;
_currRecord = DiskLoc();
continue;
}
return;
}
}
bool RecordStoreV1RepairCursor::_advanceToNextValidExtent() {
const ExtentManager* em = _recordStore->_extentManager;
while (true) {
if (_currExtent.isNull()) {
switch (_stage) {
case FORWARD_SCAN:
_currExtent = _recordStore->details()->firstExtent(_txn);
break;
case BACKWARD_SCAN:
_currExtent = _recordStore->details()->lastExtent(_txn);
break;
default:
invariant(DONE == _stage);
return false;
}
} else {
// If _currExtent is not NULL, then it must point to a valid extent, so no extra
// checks here.
//
const Extent* e = em->getExtent(_currExtent, false);
_currExtent = (FORWARD_SCAN == _stage ? e->xnext : e->xprev);
}
bool hasNextExtent = !_currExtent.isNull();
// Sanity checks for the extent's disk location
//
if (hasNextExtent && (!_currExtent.isValid() || (_currExtent.getOfs() < 0))) {
error() << "Invalid extent location: " << _currExtent << endl;
// Switch the direction of scan
//
hasNextExtent = false;
}
if (hasNextExtent) {
break;
}
// Swap the direction of scan and loop again
//
switch (_stage) {
case FORWARD_SCAN:
_stage = BACKWARD_SCAN;
break;
case BACKWARD_SCAN:
_stage = DONE;
break;
default:
invariant(!"This should never be reached.");
break;
}
_currExtent = DiskLoc();
}
// Check _currExtent's contents for validity, but do not count is as failure if they
// don't check out.
//
const Extent* e = em->getExtent(_currExtent, false);
if (!e->isOk()) {
warning() << "Extent not ok magic: " << e->magic << " going to try to continue" << endl;
}
log() << (FORWARD_SCAN == _stage ? "FORWARD" : "BACKWARD") << " Extent loc: " << _currExtent
<< ", length: " << e->length << endl;
return true;
}
void RecordStoreV1RepairCursor::invalidate(const RecordId& id) {
// If we see this record again it probably means it was reinserted rather than an infinite
// loop. If we do loop, we should quickly hit another seen record that hasn't been
// invalidated.
DiskLoc dl = DiskLoc::fromRecordId(id);
_seenInCurrentExtent.erase(dl);
if (_currRecord == dl) {
// The DiskLoc being invalidated is also the one pointed at by this iterator. We
// advance the iterator so it's not pointing at invalid data.
advance();
if (_currRecord == dl) {
// Even after advancing the iterator, we're still pointing at the DiskLoc being
// invalidated. This is expected when 'dl' is the last DiskLoc in the FORWARD scan,
// and the initial call to getNext() moves the iterator to the first loc in the
// BACKWARDS scan.
advance();
}
invariant(_currRecord != dl);
}
}
} // namespace mongo
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