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/**
* Copyright (C) 2022-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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/base/string_data.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/storage/wiredtiger/wiredtiger_index.h"
namespace mongo {
/**
* Common logic for a cursor over any WiredTiger index.
*/
class WiredTigerIndexCursorGeneric {
public:
WiredTigerIndexCursorGeneric(OperationContext* opCtx, bool forward)
: _opCtx(opCtx), _forward(forward) {}
virtual ~WiredTigerIndexCursorGeneric() = default;
void resetCursor() {
try {
if (_cursor)
_cursor->reset();
} catch (const WriteConflictException&) {
// Ignore since this is only called when we are about to kill our transaction
// anyway.
}
}
void detachFromOperationContext() {
_opCtx = nullptr;
if (!_saveStorageCursorOnDetachFromOperationContext) {
_cursor = boost::none;
}
}
void reattachToOperationContext(OperationContext* opCtx) {
_opCtx = opCtx;
// _cursor recreated in restore() to avoid risk of WT_ROLLBACK issues.
}
void setSaveStorageCursorOnDetachFromOperationContext(bool saveCursor) {
_saveStorageCursorOnDetachFromOperationContext = saveCursor;
}
protected:
/**
* Returns true if and only if the cursor advanced to EOF.
*/
[[nodiscard]] bool advanceWTCursor() {
WT_CURSOR* c = _cursor->get();
int ret = wiredTigerPrepareConflictRetry(
_opCtx, [&] { return _forward ? c->next(c) : c->prev(c); });
if (ret == WT_NOTFOUND) {
return true;
}
invariantWTOK(ret, c->session);
return false;
}
void setKey(WT_CURSOR* cursor, const WT_ITEM* item) {
cursor->set_key(cursor, item);
}
void getKey(WT_CURSOR* cursor, WT_ITEM* key) {
invariantWTOK(cursor->get_key(cursor, key), cursor->session);
auto& metricsCollector = ResourceConsumption::MetricsCollector::get(_opCtx);
metricsCollector.incrementOneIdxEntryRead(cursor->internal_uri, key->size);
}
OperationContext* _opCtx;
const bool _forward;
boost::optional<WiredTigerCursor> _cursor;
bool _saveStorageCursorOnDetachFromOperationContext = false;
};
} // namespace mongo
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