kvstore_api.h

#pragma once

#include <cstdint>
#include <list>
#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).
   */
  KVStoreAPI(const std::string &dir, const std::string &vlog) {}
  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.
   */
  virtual std::string get(uint64_t key) = 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;

  /**
   * Return a list including all the key-value pair between key1 and key2.
   * keys in the list should be in an ascending order.
   * An empty string indicates not found.
   */
  virtual void scan(uint64_t key1, uint64_t key2,
                    std::list<std::pair<uint64_t, std::string>> &list) = 0;

  /**
   * This reclaims space from vLog by moving valid value and discarding invalid
   * value. chunk_size is the size in byte you should AT LEAST recycle.
   */
  virtual void gc(uint64_t chunk_size) = 0;
};