// pack action data
   string unpacked_action_data_account_string;
   string unpacked_action_data_name_string;
   string unpacked_action_data_string;
   auto pack_action_data = convert->add_subcommand("pack_action_data", localized("From json action data to packed form"));
   pack_action_data->add_option("account", unpacked_action_data_account_string, localized("The name of the account that hosts the contract"))->required();
   pack_action_data->add_option("name", unpacked_action_data_name_string, localized("The name of the function that's called by this action"))->required();
   pack_action_data->add_option("unpacked_action_data", unpacked_action_data_string, localized("The action data expressed as json"))->required();
   pack_action_data->set_callback([&] {
      fc::variant unpacked_action_data_json;
      try {
         unpacked_action_data_json = json_from_file_or_string(unpacked_action_data_string);
      } EOS_RETHROW_EXCEPTIONS(transaction_type_exception, "Fail to parse unpacked action data JSON")
      bytes packed_action_data_string = variant_to_bin(unpacked_action_data_account_string, unpacked_action_data_name_string, unpacked_action_data_json);
      std::cout << fc::to_hex(packed_action_data_string.data(), packed_action_data_string.size()) << std::endl;
   });

   // unpack action data
   string packed_action_data_account_string;
   string packed_action_data_name_string;
   string packed_action_data_string;
   auto unpack_action_data = convert->add_subcommand("unpack_action_data", localized("From packed to json action data form"));
   unpack_action_data->add_option("account", packed_action_data_account_string, localized("The name of the account that hosts the contract"))->required();
   unpack_action_data->add_option("name", packed_action_data_name_string, localized("The name of the function that's called by this action"))->required();
   unpack_action_data->add_option("packed_action_data", packed_action_data_string, localized("The action data expressed as packed hex string"))->required();
   unpack_action_data->set_callback([&] {
      EOS_ASSERT( packed_action_data_string.size() >= 2, transaction_type_exception, "No packed_action_data found" );
      vector<char> packed_action_data_blob(packed_action_data_string.size()/2);
      fc::from_hex(packed_action_data_string, packed_action_data_blob.data(), packed_action_data_blob.size());
      fc::variant unpacked_action_data_json = bin_to_variant(packed_action_data_account_string, packed_action_data_name_string, packed_action_data_blob);
      std::cout << fc::json::to_pretty_string(unpacked_action_data_json) << std::endl;
   });

https://github.com/EOSIO/eos/blob/686f0deb5dac097cc292f735ccb47c238e763de0/programs/cleos/main.cpp#L2401

https://github.com/EOSIO/eos/blob/686f0deb5dac097cc292f735ccb47c238e763de0/programs/cleos/main.cpp#L2418

context.add_ram_usage(
    l.account,
    (int64_t)(config::billable_size_v<permission_link_object>)
);

https://github.com/EOSIO/eos/blob/3fddb727b8f3615917707281dfd3dd3cc5d3d66d/libraries/chain/eosio_contract.cpp#L340

先简单记一下，后面再做补充

主要作用是判断下前后交易是不是在一个链上，也就是有没有分叉。

参考

https://github.com/EOSIO/eos/issues/4659
https://eos.live/detail/17094
https://github.com/EOSIO/eosjs/issues/151
http://www.zhongruitech.com/955126221.html

cleos -u https://api.eoslaomao.com get table eosheartbeat eosheartbeat hbstruct