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

/*
 * Ceph - scalable distributed file system
 *
 * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
 *
 * This is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License version 2.1, as published by the Free Software
 * Foundation.  See file COPYING.
 *
 */


#ifndef CEPH_MOSDREPOP_H
#define CEPH_MOSDREPOP_H

#include "MOSDFastDispatchOp.h"

/*
 * OSD sub op - for internal ops on pobjects between primary and replicas(/stripes/whatever)
 */

class MOSDRepOp final : public MOSDFastDispatchOp {
private:
  static constexpr int HEAD_VERSION = 3;
  static constexpr int COMPAT_VERSION = 1;

public:
  epoch_t map_epoch, min_epoch;

  // metadata from original request
  osd_reqid_t reqid;

  spg_t pgid;

  ceph::buffer::list::const_iterator p;
  // Decoding flags. Decoding is only needed for messages caught by pipe reader.
  bool final_decode_needed;

  // subop
  pg_shard_t from;
  hobject_t poid;

  __u8 acks_wanted;

  // transaction to exec
  ceph::buffer::list logbl;
  pg_stat_t pg_stats;

  // subop metadata
  eversion_t version;

  // piggybacked osd/og state
  eversion_t pg_trim_to;   // primary->replica: trim to here

  /**
   * pg_committed_to
   *
   * Used by the primary to propagate pg_committed_to to replicas for use in
   * serving replica reads.
   *
   * Because updates <= pg_committed_to cannot become divergent, replicas
   * may safely serve reads on objects which do not have more recent updates.
   *
   * See PeeringState::pg_committed_to, PeeringState::can_serve_read
   *
   * Historical note: Prior to early 2024, this field was named
   * min_last_complete_ondisk.  The replica, however, only actually relied on
   * a single property of this field -- that any objects not modified since
   * mlcod couldn't have uncommitted state.  Weakening the field to the condition
   * above is therefore safe -- mlcod is always <= pg_committed_to and
   * sending pg_committed_to to a replica expecting mlcod will work correctly
   * as it only actually uses mlcod to check replica reads. The primary difference
   * between mlcod and pg_committed_to is simply that mlcod doesn't advance past
   * objects missing on replicas, but we check for that anyway.  This note may be
   * removed in main after U is released.
   */
  eversion_t pg_committed_to;

  hobject_t new_temp_oid;      ///< new temp object that we must now start tracking
  hobject_t discard_temp_oid;  ///< previously used temp object that we can now stop tracking

  /// non-empty if this transaction involves a hit_set history update
  std::optional<pg_hit_set_history_t> updated_hit_set_history;

  bufferlist txn_payload;

  epoch_t get_map_epoch() const override {
    return map_epoch;
  }
  epoch_t get_min_epoch() const override {
    return min_epoch;
  }
  spg_t get_spg() const override {
    return pgid;
  }

  int get_cost() const override {
    return data.length();
  }

  void set_txn_payload(bufferlist bl)
  {
    txn_payload = bl;
  }

  void decode_payload() override {
    using ceph::decode;
    p = payload.cbegin();
    // split to partial and final
    decode(map_epoch, p);
    if (header.version >= 2) {
      decode(min_epoch, p);
      decode_trace(p);
    } else {
      min_epoch = map_epoch;
    }
    decode(reqid, p);
    decode(pgid, p);
  }

  void finish_decode() {
    using ceph::decode;
    if (!final_decode_needed)
      return; // Message is already final decoded
    decode(poid, p);

    decode(acks_wanted, p);
    decode(version, p);
    decode(logbl, p);
    decode(pg_stats, p);
    decode(pg_trim_to, p);


    decode(new_temp_oid, p);
    decode(discard_temp_oid, p);

    decode(from, p);
    decode(updated_hit_set_history, p);

    ceph_assert(header.version >= 3);
    decode(pg_committed_to, p);
    final_decode_needed = false;
  }

  void encode_payload(uint64_t features) override {
    using ceph::encode;
    encode(map_epoch, payload);
    assert(HAVE_FEATURE(features, SERVER_OCTOPUS));
    header.version = HEAD_VERSION;
    encode(min_epoch, payload);
    encode_trace(payload, features);
    encode(reqid, payload);
    encode(pgid, payload);
    encode(poid, payload);

    encode(acks_wanted, payload);
    encode(version, payload);
    encode(logbl, payload);
    encode(pg_stats, payload);
    encode(pg_trim_to, payload);
    encode(new_temp_oid, payload);
    encode(discard_temp_oid, payload);
    encode(from, payload);
    encode(updated_hit_set_history, payload);
    encode(pg_committed_to, payload);
    bufferlist middle(txn_payload);
    set_middle(middle);
  }

  MOSDRepOp()
    : MOSDFastDispatchOp{MSG_OSD_REPOP, HEAD_VERSION, COMPAT_VERSION},
      map_epoch(0),
      final_decode_needed(true), acks_wanted (0) {}
  MOSDRepOp(osd_reqid_t r, pg_shard_t from,
	    spg_t p, const hobject_t& po, int aw,
	    epoch_t mape, epoch_t min_epoch, ceph_tid_t rtid, eversion_t v)
    : MOSDFastDispatchOp{MSG_OSD_REPOP, HEAD_VERSION, COMPAT_VERSION},
      map_epoch(mape),
      min_epoch(min_epoch),
      reqid(r),
      pgid(p),
      final_decode_needed(false),
      from(from),
      poid(po),
      acks_wanted(aw),
      version(v) {
    set_tid(rtid);
  }

private:
  ~MOSDRepOp() final {}

public:
  std::string_view get_type_name() const override { return "osd_repop"; }
  void print(std::ostream& out) const override {
    out << "osd_repop(" << reqid
	<< " " << pgid << " e" << map_epoch << "/" << min_epoch;
    if (!final_decode_needed) {
      out << " " << poid << " v " << version;
      if (updated_hit_set_history)
        out << ", has_updated_hit_set_history";
      out << ", pct=" << pg_committed_to;
    }
    out << ")";
  }
private:
  template<class T, typename... Args>
  friend boost::intrusive_ptr<T> ceph::make_message(Args&&... args);
};

#endif
