include/iocore/utils/Machine.h

/** @file

  Machine

  @section license License

  Licensed to the Apache Software Foundation (ASF) under one
  or more contributor license agreements.  See the NOTICE file
  distributed with this work for additional information
  regarding copyright ownership.  The ASF licenses this file
  to you under the Apache License, Version 2.0 (the
  "License"); you may not use this file except in compliance
  with the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

  @section details Details

  Part of the utils library which contains classes that use multiple
  components of the IO-Core to implement some useful functionality. The
  classes also serve as good examples of how to use the IO-Core.

 */

#pragma once

#include "tscore/ink_inet.h"
#include "tscore/SnowflakeID.h"
#include "tscore/ink_uuid.h"

#include <unordered_set>
#include <memory>
#include <string_view>
#include <swoc/string_view_util.h>
#include <swoc/TextView.h>

namespace ts
{

/** Functor for STL containers that need caseless equality of standard string types.
 *
 * For example a @c std::set of strings with caseless comparison would be
 *
 * @code
 * std::set<std::string, ts::caseless_compare> strings;
 * @endcode
 */
struct caseless_equal {
  bool
  operator()(std::string_view const &lhs, std::string_view const &rhs) const
  {
    return strcasecmp(lhs, rhs) == 0;
  }
  bool
  operator()(swoc::TextView const &lhs, swoc::TextView const &rhs) const
  {
    return strcasecmp(lhs, rhs) == 0;
  }
  bool
  operator()(std::string const &lhs, std::string const &rhs) const
  {
    return strcasecmp(lhs, rhs) == 0;
  }
};

} // namespace ts
/**
  The Machine is a simple place holder for the hostname and the ip
  address of an internet host.

  If a hostname or an IP address is not provided in the constructor,
  the hostname defaults to the name of the current processor and the
  IP address is the address of the current host.  If the host has
  multiple IP addresses, the numerically lowest IP address is used.
  The IP address is stored in the network byte order.

  @internal This does not handle multi-homed systems. That should be
  fixed.

 */
struct Machine {
  using self_type = Machine; ///< Self reference type.

  IpEndpoint ip;  ///< Preferred IP address of the host (network order)
  IpEndpoint ip4; ///< IPv4 address if present.
  IpEndpoint ip6; ///< IPv6 address if present.

  std::string                            host_name;
  uint64_t                               host_fnv1a;    ///<  A 64 bit FNV-1a hash of the host name.
  std::string                            ip_hex_string; ///< IP address as hex string
  ATSUuid                                process_uuid;
  std::unique_ptr<SnowflakeIdNoSequence> process_snowflake_id;

  ~Machine();

  /** Initialize the singleton.
      If @a hostname or @a ip are @c nullptr then system defaults are used.

      @note This must be called before called @c instance so that the
      singleton is not @em inadvertently default initialized.
  */
  static self_type *init(char const     *name = nullptr, ///< Host name of the machine.
                         sockaddr const *addr = nullptr  ///< Primary IP address of the machine.
  );
  /// @return The global instance of this class.
  static self_type *instance();
  bool              is_self(std::string_view name);
  bool              is_self(char const *name);
  bool              is_self(std::string const &name);
  bool              is_self(IpAddr const &ipaddr);
  bool              is_self(struct sockaddr const *addr);
  void              insert_id(char const *id);
  void              insert_id(IpAddr const &ipaddr);

protected:
  Machine(char const *hostname, sockaddr const *addr);

  static self_type                                                           *_instance; ///< Singleton for the class.
  std::unordered_set<std::string, std::hash<std::string>, ts::caseless_equal> machine_id_strings;
  std::unordered_set<IpAddr, IpAddr::Hasher>                                  machine_id_ipaddrs;
};