devnull_kv_engine.h

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// devnull_kv_engine.h

#pragma once

#include <memory>

#include "mongo/db/storage/kv/kv_engine.h"
#include "mongo/db/storage/recovery_unit_noop.h"

namespace mongo {

class JournalListener;

class DevNullKVEngine : public KVEngine {
public:
    virtual ~DevNullKVEngine() {}

    virtual RecoveryUnit* newRecoveryUnit() {
        return new RecoveryUnitNoop();
    }

    virtual Status createRecordStore(OperationContext* opCtx,
                                     StringData ns,
                                     StringData ident,
                                     const CollectionOptions& options) {
        return Status::OK();
    }

    virtual std::unique_ptr<RecordStore> getRecordStore(OperationContext* opCtx,
                                                        StringData ns,
                                                        StringData ident,
                                                        const CollectionOptions& options);

    virtual Status createSortedDataInterface(OperationContext* opCtx,
                                             StringData ident,
                                             const IndexDescriptor* desc) {
        return Status::OK();
    }

    virtual SortedDataInterface* getSortedDataInterface(OperationContext* opCtx,
                                                        StringData ident,
                                                        const IndexDescriptor* desc);

    virtual Status dropIdent(OperationContext* opCtx, StringData ident) {
        return Status::OK();
    }

    virtual bool supportsDocLocking() const {
        return true;
    }

    virtual bool supportsDirectoryPerDB() const {
        return false;
    }

    virtual bool isDurable() const {
        return false;
    }

    virtual bool isEphemeral() const {
        return true;
    }

    virtual bool isCacheUnderPressure(OperationContext* opCtx) const override;

    virtual void setCachePressureForTest(int pressure) override;

    virtual int64_t getIdentSize(OperationContext* opCtx, StringData ident) {
        return 1;
    }

    virtual Status repairIdent(OperationContext* opCtx, StringData ident) {
        return Status::OK();
    }

    virtual bool hasIdent(OperationContext* opCtx, StringData ident) const {
        return true;
    }

    std::vector<std::string> getAllIdents(OperationContext* opCtx) const {
        return std::vector<std::string>();
    }

    virtual void cleanShutdown(){};

    void setJournalListener(JournalListener* jl) final {}

    virtual Timestamp getAllCommittedTimestamp() const override {
        return Timestamp();
    }

private:
    std::shared_ptr<void> _catalogInfo;

    int _cachePressureForTest;
};
}