Author Topic: Question about BTS2.0 code?  (Read 1094 times)

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Offline bytemaster

Looks like its creating copies of objects everywhere.. Why no const references?

Because these API calls are called with newly constructed objects.  No extra copies are made.  Also string is copy on write or small string optimized.

What about the string that is copied upon each call to "set_desired_witness_and_committee_member_count" for example? This should be a const & for strictness and performance reasons. Just an example, it should extend to any params.

With this design it's invoking the copy constructor instead of allocating memory directly into the object space of the variable you need. 1 Extra copy is made and cleaned up by the garbage collector every time. The string's that are passed by value are creating copies every time needlessly?

There are micro optimizations in the API interface that we could implement. If it were in the inner loop of validation I would be more concerned.  If you look at the ACTUAL call site for this method you will see that the string passed in is a temporary (RVALUE) and thus no extra copy is made.
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Offline jsidhu

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Looks like its creating copies of objects everywhere.. Why no const references?

Because these API calls are called with newly constructed objects.  No extra copies are made.  Also string is copy on write or small string optimized.

What about the string that is copied upon each call to "set_desired_witness_and_committee_member_count" for example? This should be a const & for strictness and performance reasons. Just an example, it should extend to any params.

With this design it's invoking the copy constructor instead of allocating memory directly into the object space of the variable you need. 1 Extra copy is made and cleaned up by the garbage collector every time. The string's that are passed by value are creating copies every time needlessly?
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Offline bytemaster

Looks like its creating copies of objects everywhere.. Why no const references?

Because these API calls are called with newly constructed objects.  No extra copies are made.  Also string is copy on write or small string optimized. 
For the latest updates checkout my blog: http://bytemaster.bitshares.org
Anything said on these forums does not constitute an intent to create a legal obligation or contract between myself and anyone else.   These are merely my opinions and I reserve the right to change them at any time.

Offline jsidhu

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Looks like its creating copies of objects everywhere.. Why no const references?
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Offline xeroc

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a transaction contains several operations in an array ...
the transaction including those operations is signed

There are some calls implemented that build operations into transactions an sign them directly, such as set_voting_proxy, but in theory you can construct all transaction manually.
See  http://docs.bitshares.eu/bitshares/tutorials/construct-transaction.html

Offline BTSdac

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I am a new learner of C++ , and try to leaning BTS code 
but there are so many questions. BM ,can you answer the question
there are many operations of BTS , but all operations use same function
Code: [Select]
return sign_transaction( tx, broadcast ); to finish sign.
Code: [Select]
   signed_transaction set_desired_witness_and_committee_member_count(string account_to_modify,
                                                             uint16_t desired_number_of_witnesses,
                                                             uint16_t desired_number_of_committee_members,
                                                             bool broadcast /* = false */)
   { try {
      account_object account_object_to_modify = get_account(account_to_modify);

      if (account_object_to_modify.options.num_witness == desired_number_of_witnesses &&
          account_object_to_modify.options.num_committee == desired_number_of_committee_members)
         FC_THROW("Account ${account} is already voting for ${witnesses} witnesses and ${committee_members} committee_members",
                  ("account", account_to_modify)("witnesses", desired_number_of_witnesses)("committee_members",desired_number_of_witnesses));
      account_object_to_modify.options.num_witness = desired_number_of_witnesses;
      account_object_to_modify.options.num_committee = desired_number_of_committee_members;

      account_update_operation account_update_op;
      account_update_op.account = account_object_to_modify.id;
      account_update_op.new_options = account_object_to_modify.options;

      signed_transaction tx;
      tx.operations.push_back( account_update_op );
      set_operation_fees( tx, _remote_db->get_global_properties().parameters.current_fees);
      tx.validate();

      return sign_transaction( tx, broadcast );
   } FC_CAPTURE_AND_RETHROW( (account_to_modify)(desired_number_of_witnesses)(desired_number_of_committee_members)(broadcast) ) }

Code: [Select]
   signed_transaction set_voting_proxy(string account_to_modify,
                                       optional<string> voting_account,
                                       bool broadcast /* = false */)
   { try {
      account_object account_object_to_modify = get_account(account_to_modify);
      if (voting_account)
      {
         account_id_type new_voting_account_id = get_account_id(*voting_account);
         if (account_object_to_modify.options.voting_account == new_voting_account_id)
            FC_THROW("Voting proxy for ${account} is already set to ${voter}", ("account", account_to_modify)("voter", *voting_account));
         account_object_to_modify.options.voting_account = new_voting_account_id;
      }
      else
      {
         if (account_object_to_modify.options.voting_account == GRAPHENE_PROXY_TO_SELF_ACCOUNT)
            FC_THROW("Account ${account} is already voting for itself", ("account", account_to_modify));
         account_object_to_modify.options.voting_account = GRAPHENE_PROXY_TO_SELF_ACCOUNT;
      }

      account_update_operation account_update_op;
      account_update_op.account = account_object_to_modify.id;
      account_update_op.new_options = account_object_to_modify.options;

      signed_transaction tx;
      tx.operations.push_back( account_update_op );
      set_operation_fees( tx, _remote_db->get_global_properties().parameters.current_fees);
      tx.validate();

      return sign_transaction( tx, broadcast );
   } FC_CAPTURE_AND_RETHROW( (account_to_modify)(voting_account)(broadcast) ) }

though  tx.operations is different . but how to finish this operation, I cannot find the  specific code

BM ,can you answer the question ,  +5% +5%
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BTS2.0 API :ws://139.196.37.179:8091
BTS2.0 API 数据源ws://139.196.37.179:8091