record_store_v1_repair_iterator.h

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#pragma once

#include <set>

#include "mongo/db/storage/mmap_v1/record_store_v1_base.h"
#include "mongo/db/storage/record_store.h"

namespace mongo {

class RecordStoreV1RepairCursor final : public RecordCursor {
public:
    RecordStoreV1RepairCursor(OperationContext* opCtx, const RecordStoreV1Base* recordStore);

    boost::optional<Record> next() final;
    void invalidate(OperationContext* opCtx, const RecordId& dl);
    void save() final {}
    bool restore() final {
        return true;
    }
    void detachFromOperationContext() final {
        _opCtx = nullptr;
    }
    void reattachToOperationContext(OperationContext* opCtx) final {
        _opCtx = opCtx;
    }

    // Explicitly not supporting fetcherForNext(). The expected use case for this class is a
    // special offline operation where there are no concurrent operations, so it would be better
    // to take the pagefault inline with the operation.

private:
    void advance();

    bool _advanceToNextValidExtent();

    // transactional context for read locks. Not owned by us
    OperationContext* _opCtx;

    // Reference to the owning RecordStore. The store must not be deleted while there are
    // active iterators on it.
    //
    const RecordStoreV1Base* _recordStore;

    DiskLoc _currExtent;
    DiskLoc _currRecord;

    enum Stage { FORWARD_SCAN = 0, BACKWARD_SCAN = 1, DONE = 2 };

    Stage _stage;

    // Used to find cycles within an extent. Cleared after each extent has been processed.
    //
    std::set<DiskLoc> _seenInCurrentExtent;
};

}  // namespace mongo