record_store_v1_capped_iterator.h

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#pragma once

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

namespace mongo {

class CappedRecordStoreV1;

struct Extent;

class CappedRecordStoreV1Iterator final : public SeekableRecordCursor {
public:
    CappedRecordStoreV1Iterator(OperationContext* opCtx,
                                const CappedRecordStoreV1* collection,
                                bool forward);

    boost::optional<Record> next() final;
    boost::optional<Record> seekExact(const RecordId& id) final;
    void save() final;
    bool restore() final;
    void detachFromOperationContext() final {
        _opCtx = nullptr;
    }
    void reattachToOperationContext(OperationContext* opCtx) final {
        _opCtx = opCtx;
    }
    void invalidate(OperationContext* opCtx, const RecordId& dl) final;
    std::unique_ptr<RecordFetcher> fetcherForNext() const final;
    std::unique_ptr<RecordFetcher> fetcherForId(const RecordId& id) const final;

private:
    void advance();
    bool isEOF() {
        return _curr.isNull();
    }

    DiskLoc getNextCapped(const DiskLoc& dl);
    DiskLoc prevLoop(const DiskLoc& curr);
    DiskLoc nextLoop(const DiskLoc& prev);

    // some helpers - these move to RecordStore probably
    Extent* _getExtent(const DiskLoc& loc);
    DiskLoc _getNextRecord(const DiskLoc& loc);
    DiskLoc _getPrevRecord(const DiskLoc& loc);

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

    // The collection we're iterating over.
    const CappedRecordStoreV1* const _recordStore;

    // The result returned on the next call to getNext().
    DiskLoc _curr;

    const bool _forward;

    // If invalidate kills the DiskLoc we need to move forward, we kill the iterator.  See the
    // comment in the body of invalidate(...).
    bool _killedByInvalidate = false;
};

}  // namespace mongo