SIGSEGV on std::vector<Person>* persons

[louxiu]

Come for help again. 😭
hello.h is the interface. hello_impl.h and hello_impl.cc is the implement. The SIGSEGV happens on hello_impl.cc#SayHelloTo. I test the libhello.a in C++ and it is ok. I doubt that the problem is that the jvm has GCed the reference, but I can't solve it.

// hello.h
#ifndef HELLO_H_
#define HELLO_H_

#include <string>
#include <vector>

namespace louxiu {
struct Person {
  std::string name;
};

class HelloCallback {
 public:
  virtual void OnReply() = 0;
};

class Hello {

 public:

  static Hello* Create();
  virtual void SayHelloTo(std::vector<Person>* persons) = 0;

 protected:
  virtual ~Hello() {
  }
};
}

#endif /* HELLO_H_ */

// hello_impl.h
#ifndef HELLO_IMPL_H_
#define HELLO_IMPL_H_

#include "hello.h"

namespace louxiu {

class HelloImpl : public Hello {

public:

  HelloImpl();
  ~HelloImpl();

  virtual void SayHelloTo(std::vector<Person>* persons) override;
};

}

#endif /* HELLO_IMPL_H_ */

// hello_impl.cc
#include "hello_impl.h"
#include <iostream>

namespace louxiu {

Hello* Hello::Create() {
  return new HelloImpl();
}

HelloImpl::HelloImpl() {

}

HelloImpl::~HelloImpl() {

}

void HelloImpl::SayHelloTo(std::vector<Person>* persons) {
  for (auto it = persons->begin(); it != persons->end(); it++) {
    std::cout << "hello1: " << (*it).name << std::endl; // <------  SIGSEGV on (*it).name
  }
}

}

@Properties(target = "org.bytedeco.javacpp.libhello", value = {@Platform(include = "<hello.h>", link = "hello", library = "hello")})
public class libhello implements InfoMapper {

    public void map(InfoMap infoMap) {
        infoMap.put(new Info("louxiu::HelloCallback").virtualize())
                .put(new Info("std::vector<louxiu::Person>").pointerTypes("PersonVector").define())
                ;
    }
}

    public static void main(String[] args) {
        System.setProperty("java.library.path",
                System.getProperty("java.library.path") + File.pathSeparator
                        + "/Users/louxiu/projects/javacpp-presets/libhello/target/classes/org/bytedeco/javacpp/macosx-x86_64/");

        libhello.Hello hello = libhello.Hello.Create();
        libhello.Person person = new libhello.Person();
        BytePointer name = new BytePointer("123");
        person.name(name);

        libhello.PersonVector pointPersonVector = new libhello.PersonVector();
        pointPersonVector.put(person);
        hello.SayHelloTo(pointPersonVector);
    }

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x00000001299e1460, pid=73243, tid=0x0000000000001903
#
# JRE version: Java(TM) SE Runtime Environment (8.0_102-b14) (build 1.8.0_102-b14)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.102-b14 mixed mode bsd-amd64 compressed oops)
# Problematic frame:
# C  [libhello.dylib+0x7460]  louxiu::HelloImpl::SayHelloTo(std::__1::vector<louxiu::Person, std::__1::allocator<louxiu::Person> >*)+0x40
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# An error report file with more information is saved as:
# /Users/louxiu/projects/javacpp-test/hs_err_pid73243.log
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.java.com/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#
hello1: 
Process finished with exit code 134 (interrupted by signal 6: SIGABRT)

[saudet]

Yes, it's possible it gets deallocated prematurely. Try to call deallocate() on it at the end.

[louxiu]

Tried it without luck. Maybe there is another problem?

        hello.SayHelloTo(pointPersonVector);

        name.deallocate();
        person.deallocate();
        pointPersonVector.deallocate();

[saudet]

You're probably calling the generic put(Pointer) method, which isn't what you want...

[louxiu]

Wow, I see. 😃 Thanks!!!
IMHO, this is error prone. Can we improve this?

This works.

libhello.PersonVector pointPersonVector = new libhello.PersonVector(1);
pointPersonVector.put(0, person);

This doesn't work.

libhello.PersonVector pointPersonVector = new libhello.PersonVector();
pointPersonVector.put(0, person);

[saudet]

Yes, we can improve this, for example: bytedeco/javacv#659 Contributions welcome!

[saudet]

There, I fixed that in the commit above. We can now do new PersonVector(person) or new PersonVector().put(person) and it works as expected. Thanks for the feedback!