gcs_xcom_synode.h

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/* Copyright (c) 2018, 2023, Oracle and/or its affiliates.
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.
 
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
#ifndef GCS_XCOM_SYNODE_H
#define GCS_XCOM_SYNODE_H
 
#include <sstream>
#include <unordered_set>
#include "plugin/group_replication/libmysqlgcs/src/bindings/xcom/xcom/synode_no.h"
 
/**
 Defines a message identifier so that joining members can fetch the associated
 packet from a remote node.
 
 See Gcs_xcom_communication_interface::recover_packets.
 
 It wraps synode_no so we can use it in hash-based containers.
 */
class Gcs_xcom_synode {
 public:
  Gcs_xcom_synode() noexcept;
  explicit Gcs_xcom_synode(synode_no synod) noexcept;
 
  ~Gcs_xcom_synode();
 
  Gcs_xcom_synode(Gcs_xcom_synode const &other) = default;
  Gcs_xcom_synode &operator=(Gcs_xcom_synode const &other) = default;
 
  Gcs_xcom_synode(Gcs_xcom_synode &&other) noexcept;
  Gcs_xcom_synode &operator=(Gcs_xcom_synode &&other) noexcept;
 
  bool operator==(const Gcs_xcom_synode &other) const;
 
  synode_no const &get_synod() const;
 
 private:
  synode_no synode_;
};
 
/*
 Specialization of std::hash<Gcs_xcom_synode> so we can use it in hash-based
 containers.
 */
namespace std {
template <>
struct hash<Gcs_xcom_synode> {
  std::size_t operator()(Gcs_xcom_synode const &s) const noexcept {
    /*
     Represent the synode as a string of the format g<gid>m<msg_nr>n<node_nr> to
     serve as the hash function argument.
     */
    std::hash<std::string> hash_function;
 
    std::ostringstream formatter;
    formatter << "g" << s.get_synod().group_id << "m" << s.get_synod().msgno
              << "n" << s.get_synod().node;
    auto representation = formatter.str();
 
    return hash_function(representation);
  }
};
}  // namespace std
 
using Gcs_xcom_synode_set = std::unordered_set<Gcs_xcom_synode>;
 
#endif  // GCS_XCOM_SYNODE_H