// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:nil -*-
// vim: ts=8 sw=2 sts=2 expandtab

#ifndef CEPH_LIBRBD_OBJECT_MAP_SNAPSHOT_REMOVE_REQUEST_H
#define CEPH_LIBRBD_OBJECT_MAP_SNAPSHOT_REMOVE_REQUEST_H

#include "include/int_types.h"
#include "include/buffer.h"
#include "include/rados.h" // for CEPH_NOSNAP
#include "common/bit_vector.hpp"
#include "librbd/AsyncRequest.h"

namespace librbd {
namespace object_map {

class SnapshotRemoveRequest : public AsyncRequest<> {
public:
  /**
   * Snapshot rollback goes through the following state machine:
   *
   * @verbatim
   *
   * <start> -----------> STATE_LOAD_MAP ----\
   *    .                      *             |
   *    .                      * (error)     |
   *    . (invalid object map) v             |
   *    . . . > STATE_INVALIDATE_NEXT_MAP    |
   *    .                      |             |
   *    .                      |             |
   *    . (fast diff disabled) v             v
   *    . . . . . . . . . . > STATE_REMOVE_MAP
   *                                 |
   *                                 v
   *                             <finish>
   *
   * @endverbatim
   *
   * The _LOAD_MAP state is skipped if the fast diff feature is disabled.
   * If the fast diff feature is enabled and the snapshot is flagged as
   * invalid, the next snapshot / HEAD object mapis flagged as invalid;
   * otherwise, the state machine proceeds to remove the object map.
   */

  SnapshotRemoveRequest(ImageCtx &image_ctx, ceph::shared_mutex* object_map_lock,
                        ceph::BitVector<2> *object_map, uint64_t snap_id,
                        Context *on_finish)
    : AsyncRequest(image_ctx, on_finish),
      m_object_map_lock(object_map_lock), m_object_map(*object_map),
      m_snap_id(snap_id), m_next_snap_id(CEPH_NOSNAP) {
  }

  void send() override;

protected:
  bool should_complete(int r) override {
    return true;
  }

private:
  ceph::shared_mutex* m_object_map_lock;
  ceph::BitVector<2> &m_object_map;
  uint64_t m_snap_id;
  uint64_t m_next_snap_id;

  uint64_t m_flags = 0;

  ceph::BitVector<2> m_snap_object_map;
  bufferlist m_out_bl;

  void load_map();
  void handle_load_map(int r);

  void remove_snapshot();
  void handle_remove_snapshot(int r);

  void invalidate_next_map();
  void handle_invalidate_next_map(int r);

  void remove_map();
  void handle_remove_map(int r);

  void compute_next_snap_id();
  void update_object_map();
};

} // namespace object_map
} // namespace librbd

#endif // CEPH_LIBRBD_OBJECT_MAP_SNAPSHOT_REMOVE_REQUEST_H
