include/rocksdb/sst_file_manager.h
//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
//  This source code is licensed under the BSD-style license found in the
//  LICENSE file in the root directory of this source tree. An additional grant
//  of patent rights can be found in the PATENTS file in the same directory.

#pragma once

#include <memory>
#include <string>
#include <unordered_map>

#include "rocksdb/status.h"

namespace rocksdb {

class Env;
class Logger;

// SstFileManager is used to track SST files in the DB and control there
// deletion rate.
// All SstFileManager public functions are thread-safe.
class SstFileManager {
 public:
  virtual ~SstFileManager() {}

  // Update the maximum allowed space that should be used by RocksDB, if
  // the total size of the SST files exceeds max_allowed_space, writes to
  // RocksDB will fail.
  //
  // Setting max_allowed_space to 0 will disable this feature, maximum allowed
  // space will be infinite (Default value).
  //
  // thread-safe.
  virtual void SetMaxAllowedSpaceUsage(uint64_t max_allowed_space) = 0;

  // Return true if the total size of SST files exceeded the maximum allowed
  // space usage.
  //
  // thread-safe.
  virtual bool IsMaxAllowedSpaceReached() = 0;

  // Return the total size of all tracked files.
  // thread-safe
  virtual uint64_t GetTotalSize() = 0;

  // Return a map containing all tracked files and there corresponding sizes.
  // thread-safe
  virtual std::unordered_map<std::string, uint64_t> GetTrackedFiles() = 0;

  // Return delete rate limit in bytes per second.
  // thread-safe
  virtual int64_t GetDeleteRateBytesPerSecond() = 0;
};

// Create a new SstFileManager that can be shared among multiple RocksDB
// instances to track SST file and control there deletion rate.
//
// @param env: Pointer to Env object, please see "rocksdb/env.h".
// @param info_log: If not nullptr, info_log will be used to log errors.
//
// == Deletion rate limiting specific arguments ==
// @param trash_dir: Path to the directory where deleted files will be moved
//    to be deleted in a background thread while applying rate limiting. If this
//    directory dont exist, it will be created. This directory should not be
//    used by any other process or any other SstFileManager, Set to "" to
//    disable deletion rate limiting.
// @param rate_bytes_per_sec: How many bytes should be deleted per second, If
//    this value is set to 1024 (1 Kb / sec) and we deleted a file of size 4 Kb
//    in 1 second, we will wait for another 3 seconds before we delete other
//    files, Set to 0 to disable deletion rate limiting.
// @param delete_exisitng_trash: If set to true, the newly created
//    SstFileManager will delete files that already exist in trash_dir.
// @param status: If not nullptr, status will contain any errors that happened
//    during creating the missing trash_dir or deleting existing files in trash.
extern SstFileManager* NewSstFileManager(
    Env* env, std::shared_ptr<Logger> info_log = nullptr,
    std::string trash_dir = "", int64_t rate_bytes_per_sec = 0,
    bool delete_exisitng_trash = true, Status* status = nullptr);

}  // namespace rocksdb
