ospShutdown incorrectly reports errors

[paulmelis]

While looking at #431 noticed that ospShutdown() gives errors when there's still alive ospray objects. E.g. running this

#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <vector>
#include <chrono>
#include <thread>

#include <ospray/ospray_cpp.h>

using namespace ospcommon::math;

int main(int argc, const char **argv)
{
  // initialize OSPRay
  OSPError init_error = ospInit(&argc, argv);
  if (init_error != OSP_NO_ERROR)
    return init_error;

  // four vertex positions:
  std::vector<vec3f> vertex = {
      vec3f(-1.0f, -1.0f, 3.0f),
      vec3f(-1.0f, 1.0f, 3.0f),
      vec3f(1.0f, -1.0f, 3.0f),
      vec3f(0.1f, 0.1f, 0.3f)};

  // four vertex colors:
  std::vector<vec4f> color = {
      vec4f(0.9f, 0.5f, 0.5f, 1.0f),
      vec4f(0.8f, 0.8f, 0.8f, 1.0f),
      vec4f(0.8f, 0.8f, 0.8f, 1.0f),
      vec4f(0.5f, 0.9f, 0.5f, 1.0f)};

  // one triangle:
  vec3ui triangle(0, 1, 2);

  // Replicate the triangle N times. 
  // To notice the memory leak, we need the geometry to be more than just a handful of bytes.
  std::vector<vec3ui> index(10000);
  for(auto &t : index)
    t = triangle;

  //{

  // create and setup model and mesh
  ospray::cpp::Geometry mesh("mesh");
  mesh.setParam("vertex.position", ospray::cpp::Data(vertex));
  mesh.setParam("vertex.color", ospray::cpp::Data(color));
  mesh.setParam("index", ospray::cpp::Data(index));
  mesh.commit();

  // put the mesh into a model
  ospray::cpp::GeometricModel model(mesh);
  model.commit();

  //}

  ospShutdown();

  return 0;
}

gives

melis@juggle 11:51:~$ ./t_shutdown 
#ospray: INITIALIZATION ERROR --> OSPRay not yet initialized (most likely this means you tried to call an ospray API function before first calling ospInit())(pid 17134)
#ospray: INITIALIZATION ERROR --> OSPRay not yet initialized (most likely this means you tried to call an ospray API function before first calling ospInit())(pid 17134)

Apparently one error line per still-alive object. Removing the comments on the braces to put the two objects in local scope makes the errors on shutdown disappear. This is with 2.1.

[johguenther]

We fixed many similar issues, but this one still persists. The reason is that the cpp-wrappers manage the handles of created objects, and those are ospReleased in the destructor. In your example mesh and model are still alive after ospShutdown . Then both are destroyed at exit, resulting in two ospRelease at a time when there is no OSPRay device anymore, hence the two error messages. The local scoping on the other hand releases mesh and model before shutdown and all is good.

[johguenther]

I think the printed hints are still warranted (because there are API calls without a valid OSPRay device), but the message is a bit misleading.