DataWriter fails to write message

[plament]

I am using 0.10.4 and have the following message.idl

struct Message
{
    @optional int32 a0;
    @optional int32 a1;
};

Then I generate the data types using: idlc -b . -l <path to libcycloneddsidlcxx> -x final message.idl

Then I create 2 messages and try to write them using DataWriter. However sending the second message fails with write failed exception.

Here is my code:

#include <iostream>
#include "dds/dds.hpp"
#include "gen/message.hpp"

using namespace org::eclipse::cyclonedds;

int main() {

    std::cout << "=== [Publisher] Create writer." << std::endl;

    dds::domain::DomainParticipant participant(0);
    dds::topic::Topic<Message> topic(participant, "TOPIC");
    dds::pub::Publisher publisher(participant);
    dds::pub::DataWriter<Message> writer(publisher, topic);

    Message m1;
    m1.a1() = 10;

    Message m2;
    m2.a0() = 10;

    try {
        std::cout << "=== Will write m1" << std::endl;
        writer.write(m1);

        std::cout << "=== Will write m2" << std::endl;
        writer.write(m2);

        std::cout << "=== Write done" << std::endl;
    } catch (const std::exception& ex) {
        std::cerr << "=== [Publisher] Exception: " << ex.what() << std::endl;
        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}

The output is:

=== [Publisher] Create writer.
=== Will write m1
=== Will write m2
=== [Publisher] Exception: Error Bad Parameter - write failed.
===============================================================================
Context     : void org::eclipse::cyclonedds::pub::AnyDataWriterDelegate::write
Node        : UnknownNode

So writing m2 fails. However if I first write m2 and then m1 then everything works fine.

The actual method which fails is:

bool cdr_stream::bytes_available(size_t N, bool peek)

For some reason there is no space left in the cdr_stream buffer to serialize the second message.

@eboasson

[plament]

Seems the issue is that the serialized size is not calculated properly.

template<typename T, class S>
bool get_serialized_size(const T& sample, bool as_key, size_t &sz)
{
  if (TopicTraits<T>::isSelfContained()) {
    if ((as_key && !get_serialized_fixed_size<T,S,true>(sample, sz)) ||
        (!as_key && !get_serialized_fixed_size<T,S,false>(sample, sz)))
      return false;
  } else {
    S str;
    if (!move(str, sample, as_key))
      return false;
    sz = str.position();
  }

  return true;
}

Here isSelfContained() is true and get_serialized_fixed_size() actually calculates and caches the size and from that moment cyclone uses that cached size value. However serialized size is different depending on which optionals are set.

Actually is it correct that my struct with all optionals is self contained? Because idlc does not detect it as non self contained and that's why it doesn't generate isSelfContained() { return false; }. Maybe an issue in idlc?