kvstore_api.h

#pragma once

#include <cstdint>
#include <string>

class KVStoreAPI {
public:
    /**
     * You should put all sstables under `dir`.
     * Please create one sub-directory for each level, and put sstables
     * there. Please refer to the c++ filesystem library
     * (https://en.cppreference.com/w/cpp/filesystem).
     */
    explicit KVStoreAPI(const std::string &dir) {}

    KVStoreAPI() = delete;

    /**
     * Insert/Update the key-value pair.
     * No return values for simplicity.
     */
    virtual void put(uint64_t key, const std::string &s) = 0;

    /**
     * Returns the (string) value of the given key.
     * An empty string indicates not found.
     */
    [[nodiscard]] virtual std::string get(uint64_t key) const = 0;

    /**
     * Gets the key-value pairs between [lower, upper].
     * @param lower the lower bound of the key range (inclusive)
     * @param upper the upper bound of the key range (inclusive)
     * @param result the result vector to be filled
     */
    virtual void
    scan(uint64_t lower, uint64_t upper, std::vector<std::pair<uint64_t, std::string>> &result) const = 0;

    /**
     * Delete the given key-value pair if it exists.
     * Returns false iff the key is not found.
     */
    virtual bool del(uint64_t key) = 0;

    /**
     * This resets the kvstore. All key-value pairs should be removed,
     * including memtable and all sstables files.
     */
    virtual void reset() = 0;
};