blender/intern/cycles/render/session.cpp

/*
 * Copyright 2011-2013 Blender Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <string.h>
#include <limits.h>

#include "render/buffers.h"
#include "render/camera.h"
#include "device/device.h"
#include "render/graph.h"
#include "render/integrator.h"
#include "render/light.h"
#include "render/mesh.h"
#include "render/object.h"
#include "render/scene.h"
#include "render/session.h"
#include "render/bake.h"

#include "util/util_foreach.h"
#include "util/util_function.h"
#include "util/util_logging.h"
#include "util/util_math.h"
#include "util/util_opengl.h"
#include "util/util_task.h"
#include "util/util_time.h"

CCL_NAMESPACE_BEGIN

/* Note about  preserve_tile_device option for tile manager:
 * progressive refine and viewport rendering does requires tiles to
 * always be allocated for the same device
 */
Session::Session(const SessionParams &params_)
    : params(params_),
      tile_manager(params.progressive,
                   params.samples,
                   params.tile_size,
                   params.start_resolution,
                   params.background == false || params.progressive_refine,
                   params.background,
                   params.tile_order,
                   max(params.device.multi_devices.size(), 1),
                   params.pixel_size),
      stats(),
      profiler()
{
  device_use_gl = ((params.device.type != DEVICE_CPU) && !params.background);

  TaskScheduler::init(params.threads);

  device = Device::create(params.device, stats, profiler, params.background);

  if (params.background && !params.write_render_cb) {
    buffers = NULL;
    display = NULL;
  }
  else {
    buffers = new RenderBuffers(device);
    display = new DisplayBuffer(device, params.display_buffer_linear);
  }

  session_thread = NULL;
  scene = NULL;

  reset_time = 0.0;
  last_update_time = 0.0;

  delayed_reset.do_reset = false;
  delayed_reset.samples = 0;

  display_outdated = false;
  gpu_draw_ready = false;
  gpu_need_tonemap = false;
  pause = false;
  kernels_loaded = false;

  /* TODO(sergey): Check if it's indeed optimal value for the split kernel. */
  max_closure_global = 1;
}

Session::~Session()
{
  if (session_thread) {
    /* wait for session thread to end */
    progress.set_cancel("Exiting");

    gpu_need_tonemap = false;
    gpu_need_tonemap_cond.notify_all();

    {
      thread_scoped_lock pause_lock(pause_mutex);
      pause = false;
    }
    pause_cond.notify_all();

    wait();
  }

  if (params.write_render_cb) {
    /* tonemap and write out image if requested */
    delete display;

    display = new DisplayBuffer(device, false);
    display->reset(buffers->params);
    tonemap(params.samples);

    int w = display->draw_width;
    int h = display->draw_height;
    uchar4 *pixels = display->rgba_byte.copy_from_device(0, w, h);
    params.write_render_cb((uchar *)pixels, w, h, 4);
  }

  /* clean up */
  tile_manager.device_free();

  delete buffers;
  delete display;
  delete scene;
  delete device;

  TaskScheduler::exit();
}

void Session::start()
{
  if (!session_thread) {
    session_thread = new thread(function_bind(&Session::run, this));
  }
}

bool Session::ready_to_reset()
{
  double dt = time_dt() - reset_time;

  if (!display_outdated)
    return (dt > params.reset_timeout);
  else
    return (dt > params.cancel_timeout);
}

/* GPU Session */

void Session::reset_gpu(BufferParams &buffer_params, int samples)
{
  thread_scoped_lock pause_lock(pause_mutex);

  /* block for buffer access and reset immediately. we can't do this
   * in the thread, because we need to allocate an OpenGL buffer, and
   * that only works in the main thread */
  thread_scoped_lock display_lock(display_mutex);
  thread_scoped_lock buffers_lock(buffers_mutex);

  display_outdated = true;
  reset_time = time_dt();

  reset_(buffer_params, samples);

  gpu_need_tonemap = false;
  gpu_need_tonemap_cond.notify_all();

  pause_cond.notify_all();
}

bool Session::draw_gpu(BufferParams &buffer_params, DeviceDrawParams &draw_params)
{
  /* block for buffer access */
  thread_scoped_lock display_lock(display_mutex);

  /* first check we already rendered something */
  if (gpu_draw_ready) {
    /* then verify the buffers have the expected size, so we don't
     * draw previous results in a resized window */
    if (!buffer_params.modified(display->params)) {
      /* for CUDA we need to do tone-mapping still, since we can
       * only access GL buffers from the main thread. */
      if (gpu_need_tonemap) {
        thread_scoped_lock buffers_lock(buffers_mutex);
        tonemap(tile_manager.state.sample);
        gpu_need_tonemap = false;
        gpu_need_tonemap_cond.notify_all();
      }

      display->draw(device, draw_params);

      if (display_outdated && (time_dt() - reset_time) > params.text_timeout)
        return false;

      return true;
    }
  }

  return false;
}

void Session::run_gpu()
{
  bool tiles_written = false;

  reset_time = time_dt();
  last_update_time = time_dt();

  progress.set_render_start_time();

  while (!progress.get_cancel()) {
    /* advance to next tile */
    bool no_tiles = !tile_manager.next();

    DeviceKernelStatus kernel_state = DEVICE_KERNEL_UNKNOWN;
    if (no_tiles) {
      kernel_state = device->get_active_kernel_switch_state();
    }

    if (params.background) {
      /* if no work left and in background mode, we can stop immediately */
      if (no_tiles) {
        progress.set_status("Finished");
        break;
      }
    }

    /* Don't go in pause mode when image was rendered with preview kernels
     * When feature kernels become available the session will be resetted. */
    else if (no_tiles && kernel_state == DEVICE_KERNEL_WAITING_FOR_FEATURE_KERNEL) {
      time_sleep(0.1);
    }
    else if (no_tiles && kernel_state == DEVICE_KERNEL_FEATURE_KERNEL_AVAILABLE) {
      reset_gpu(tile_manager.params, params.samples);
    }

    else {
      /* if in interactive mode, and we are either paused or done for now,
       * wait for pause condition notify to wake up again */
      thread_scoped_lock pause_lock(pause_mutex);

      if (!pause && !tile_manager.done()) {
        /* reset could have happened after no_tiles was set, before this lock.
         * in this case we shall not wait for pause condition
         */
      }
      else if (pause || no_tiles) {
        update_status_time(pause, no_tiles);

        while (1) {
          scoped_timer pause_timer;
          pause_cond.wait(pause_lock);
          if (pause) {
            progress.add_skip_time(pause_timer, params.background);
          }

          update_status_time(pause, no_tiles);
          progress.set_update();

          if (!pause)
            break;
        }
      }

      if (progress.get_cancel())
        break;
    }

    if (!no_tiles) {
      /* update scene */
      scoped_timer update_timer;
      if (update_scene()) {
        profiler.reset(scene->shaders.size(), scene->objects.size());
      }
      progress.add_skip_time(update_timer, params.background);

      if (!device->error_message().empty())
        progress.set_error(device->error_message());

      if (progress.get_cancel())
        break;
    }

    if (!no_tiles) {
      /* buffers mutex is locked entirely while rendering each
       * sample, and released/reacquired on each iteration to allow
       * reset and draw in between */
      thread_scoped_lock buffers_lock(buffers_mutex);

      /* update status and timing */
      update_status_time();

      /* render */
      render();

      device->task_wait();

      if (!device->error_message().empty())
        progress.set_cancel(device->error_message());

      /* update status and timing */
      update_status_time();

      gpu_need_tonemap = true;
      gpu_draw_ready = true;
      progress.set_update();

      /* wait for tonemap */
      if (!params.background) {
        while (gpu_need_tonemap) {
          if (progress.get_cancel())
            break;

          gpu_need_tonemap_cond.wait(buffers_lock);
        }
      }

      if (!device->error_message().empty())
        progress.set_error(device->error_message());

      tiles_written = update_progressive_refine(progress.get_cancel());

      if (progress.get_cancel())
        break;
    }
  }

  if (!tiles_written)
    update_progressive_refine(true);
}

/* CPU Session */

void Session::reset_cpu(BufferParams &buffer_params, int samples)
{
  thread_scoped_lock reset_lock(delayed_reset.mutex);
  thread_scoped_lock pause_lock(pause_mutex);

  display_outdated = true;
  reset_time = time_dt();

  delayed_reset.params = buffer_params;
  delayed_reset.samples = samples;
  delayed_reset.do_reset = true;
  device->task_cancel();

  pause_cond.notify_all();
}

bool Session::draw_cpu(BufferParams &buffer_params, DeviceDrawParams &draw_params)
{
  thread_scoped_lock display_lock(display_mutex);

  /* first check we already rendered something */
  if (display->draw_ready()) {
    /* then verify the buffers have the expected size, so we don't
     * draw previous results in a resized window */
    if (!buffer_params.modified(display->params)) {
      display->draw(device, draw_params);

      if (display_outdated && (time_dt() - reset_time) > params.text_timeout)
        return false;

      return true;
    }
  }

  return false;
}

bool Session::acquire_tile(Device *tile_device, RenderTile &rtile)
{
  if (progress.get_cancel()) {
    if (params.progressive_refine == false) {
      /* for progressive refine current sample should be finished for all tiles */
      return false;
    }
  }

  thread_scoped_lock tile_lock(tile_mutex);

  /* get next tile from manager */
  Tile *tile;
  int device_num = device->device_number(tile_device);

  if (!tile_manager.next_tile(tile, device_num))
    return false;

  /* fill render tile */
  rtile.x = tile_manager.state.buffer.full_x + tile->x;
  rtile.y = tile_manager.state.buffer.full_y + tile->y;
  rtile.w = tile->w;
  rtile.h = tile->h;
  rtile.start_sample = tile_manager.state.sample;
  rtile.num_samples = tile_manager.state.num_samples;
  rtile.resolution = tile_manager.state.resolution_divider;
  rtile.tile_index = tile->index;
  rtile.task = (tile->state == Tile::DENOISE) ? RenderTile::DENOISE : RenderTile::PATH_TRACE;

  tile_lock.unlock();

  /* in case of a permanent buffer, return it, otherwise we will allocate
   * a new temporary buffer */
  if (buffers) {
    tile_manager.state.buffer.get_offset_stride(rtile.offset, rtile.stride);

    rtile.buffer = buffers->buffer.device_pointer;
    rtile.buffers = buffers;

    device->map_tile(tile_device, rtile);

    return true;
  }

  if (tile->buffers == NULL) {
    /* fill buffer parameters */
    BufferParams buffer_params = tile_manager.params;
    buffer_params.full_x = rtile.x;
    buffer_params.full_y = rtile.y;
    buffer_params.width = rtile.w;
    buffer_params.height = rtile.h;

    /* allocate buffers */
    tile->buffers = new RenderBuffers(tile_device);
    tile->buffers->reset(buffer_params);
  }

  tile->buffers->params.get_offset_stride(rtile.offset, rtile.stride);

  rtile.buffer = tile->buffers->buffer.device_pointer;
  rtile.buffers = tile->buffers;
  rtile.sample = tile_manager.state.sample;

  /* this will tag tile as IN PROGRESS in blender-side render pipeline,
   * which is needed to highlight currently rendering tile before first
   * sample was processed for it
   */
  update_tile_sample(rtile);

  return true;
}

void Session::update_tile_sample(RenderTile &rtile)
{
  thread_scoped_lock tile_lock(tile_mutex);

  if (update_render_tile_cb) {
    if (params.progressive_refine == false) {
      /* todo: optimize this by making it thread safe and removing lock */

      update_render_tile_cb(rtile, true);
    }
  }

  update_status_time();
}

void Session::release_tile(RenderTile &rtile)
{
  thread_scoped_lock tile_lock(tile_mutex);

  progress.add_finished_tile(rtile.task == RenderTile::DENOISE);

  bool delete_tile;

  if (tile_manager.finish_tile(rtile.tile_index, delete_tile)) {
    if (write_render_tile_cb && params.progressive_refine == false) {
      write_render_tile_cb(rtile);
    }

    if (delete_tile) {
      delete rtile.buffers;
      tile_manager.state.tiles[rtile.tile_index].buffers = NULL;
    }
  }
  else {
    if (update_render_tile_cb && params.progressive_refine == false) {
      update_render_tile_cb(rtile, false);
    }
  }

  update_status_time();
}

void Session::map_neighbor_tiles(RenderTile *tiles, Device *tile_device)
{
  thread_scoped_lock tile_lock(tile_mutex);

  int center_idx = tiles[4].tile_index;
  assert(tile_manager.state.tiles[center_idx].state == Tile::DENOISE);
  BufferParams buffer_params = tile_manager.params;
  int4 image_region = make_int4(buffer_params.full_x,
                                buffer_params.full_y,
                                buffer_params.full_x + buffer_params.width,
                                buffer_params.full_y + buffer_params.height);

  for (int dy = -1, i = 0; dy <= 1; dy++) {
    for (int dx = -1; dx <= 1; dx++, i++) {
      int px = tiles[4].x + dx * params.tile_size.x;
      int py = tiles[4].y + dy * params.tile_size.y;
      if (px >= image_region.x && py >= image_region.y && px < image_region.z &&
          py < image_region.w) {
        int tile_index = center_idx + dy * tile_manager.state.tile_stride + dx;
        Tile *tile = &tile_manager.state.tiles[tile_index];
        assert(tile->buffers);

        tiles[i].buffer = tile->buffers->buffer.device_pointer;
        tiles[i].x = tile_manager.state.buffer.full_x + tile->x;
        tiles[i].y = tile_manager.state.buffer.full_y + tile->y;
        tiles[i].w = tile->w;
        tiles[i].h = tile->h;
        tiles[i].buffers = tile->buffers;

        tile->buffers->params.get_offset_stride(tiles[i].offset, tiles[i].stride);
      }
      else {
        tiles[i].buffer = (device_ptr)NULL;
        tiles[i].buffers = NULL;
        tiles[i].x = clamp(px, image_region.x, image_region.z);
        tiles[i].y = clamp(py, image_region.y, image_region.w);
        tiles[i].w = tiles[i].h = 0;
      }
    }
  }

  assert(tiles[4].buffers);
  device->map_neighbor_tiles(tile_device, tiles);

  /* The denoised result is written back to the original tile. */
  tiles[9] = tiles[4];
}

void Session::unmap_neighbor_tiles(RenderTile *tiles, Device *tile_device)
{
  thread_scoped_lock tile_lock(tile_mutex);
  device->unmap_neighbor_tiles(tile_device, tiles);
}

void Session::run_cpu()
{
  bool tiles_written = false;

  last_update_time = time_dt();

  {
    /* reset once to start */
    thread_scoped_lock reset_lock(delayed_reset.mutex);
    thread_scoped_lock buffers_lock(buffers_mutex);
    thread_scoped_lock display_lock(display_mutex);

    reset_(delayed_reset.params, delayed_reset.samples);
    delayed_reset.do_reset = false;
  }

  while (!progress.get_cancel()) {
    /* advance to next tile */
    bool no_tiles = !tile_manager.next();
    bool need_tonemap = false;

    DeviceKernelStatus kernel_state = DEVICE_KERNEL_UNKNOWN;
    if (no_tiles) {
      kernel_state = device->get_active_kernel_switch_state();
    }

    if (params.background) {
      /* if no work left and in background mode, we can stop immediately */
      if (no_tiles) {
        progress.set_status("Finished");
        break;
      }
    }

    /* Don't go in pause mode when preview kernels are used
     * When feature kernels become available the session will be resetted. */
    else if (no_tiles && kernel_state == DEVICE_KERNEL_WAITING_FOR_FEATURE_KERNEL) {
      time_sleep(0.1);
    }
    else if (no_tiles && kernel_state == DEVICE_KERNEL_FEATURE_KERNEL_AVAILABLE) {
      reset_cpu(tile_manager.params, params.samples);
    }

    else {
      /* if in interactive mode, and we are either paused or done for now,
       * wait for pause condition notify to wake up again */
      thread_scoped_lock pause_lock(pause_mutex);

      if (!pause && delayed_reset.do_reset) {
        /* reset once to start */
        thread_scoped_lock reset_lock(delayed_reset.mutex);
        thread_scoped_lock buffers_lock(buffers_mutex);
        thread_scoped_lock display_lock(display_mutex);

        reset_(delayed_reset.params, delayed_reset.samples);
        delayed_reset.do_reset = false;
      }
      else if (pause || no_tiles) {
        update_status_time(pause, no_tiles);

        while (1) {
          scoped_timer pause_timer;
          pause_cond.wait(pause_lock);
          if (pause) {
            progress.add_skip_time(pause_timer, params.background);
          }

          update_status_time(pause, no_tiles);
          progress.set_update();

          if (!pause)
            break;
        }
      }

      if (progress.get_cancel())
        break;
    }

    if (!no_tiles) {
      /* buffers mutex is locked entirely while rendering each
       * sample, and released/reacquired on each iteration to allow
       * reset and draw in between */
      thread_scoped_lock buffers_lock(buffers_mutex);

      /* update scene */
      scoped_timer update_timer;
      if (update_scene()) {
        profiler.reset(scene->shaders.size(), scene->objects.size());
      }
      progress.add_skip_time(update_timer, params.background);

      if (!device->error_message().empty())
        progress.set_error(device->error_message());

      if (progress.get_cancel())
        break;

      /* update status and timing */
      update_status_time();

      /* render */
      render();

      /* update status and timing */
      update_status_time();

      if (!params.background)
        need_tonemap = true;

      if (!device->error_message().empty())
        progress.set_error(device->error_message());
    }

    device->task_wait();

    {
      thread_scoped_lock reset_lock(delayed_reset.mutex);
      thread_scoped_lock buffers_lock(buffers_mutex);
      thread_scoped_lock display_lock(display_mutex);

      if (delayed_reset.do_reset) {
        /* reset rendering if request from main thread */
        delayed_reset.do_reset = false;
        reset_(delayed_reset.params, delayed_reset.samples);
      }
      else if (need_tonemap) {
        /* tonemap only if we do not reset, we don't we don't
         * want to show the result of an incomplete sample */
        tonemap(tile_manager.state.sample);
      }

      if (!device->error_message().empty())
        progress.set_error(device->error_message());

      tiles_written = update_progressive_refine(progress.get_cancel());
    }

    progress.set_update();
  }

  if (!tiles_written)
    update_progressive_refine(true);
}

DeviceRequestedFeatures Session::get_requested_device_features()
{
  /* TODO(sergey): Consider moving this to the Scene level. */
  DeviceRequestedFeatures requested_features;
  requested_features.experimental = params.experimental;

  scene->shader_manager->get_requested_features(scene, &requested_features);

  /* This features are not being tweaked as often as shaders,
   * so could be done selective magic for the viewport as well.
   */
  bool use_motion = scene->need_motion() == Scene::MotionType::MOTION_BLUR;
  requested_features.use_hair = false;
  requested_features.use_object_motion = false;
  requested_features.use_camera_motion = use_motion && scene->camera->use_motion();
  foreach (Object *object, scene->objects) {
    Mesh *mesh = object->mesh;
    if (mesh->num_curves()) {
      requested_features.use_hair = true;
    }
    if (use_motion) {
      requested_features.use_object_motion |= object->use_motion() | mesh->use_motion_blur;
      requested_features.use_camera_motion |= mesh->use_motion_blur;
    }
#ifdef WITH_OPENSUBDIV
    if (mesh->subdivision_type != Mesh::SUBDIVISION_NONE) {
      requested_features.use_patch_evaluation = true;
    }
#endif
    if (object->is_shadow_catcher) {
      requested_features.use_shadow_tricks = true;
    }
    requested_features.use_true_displacement |= mesh->has_true_displacement();
  }

  requested_features.use_background_light = scene->light_manager->has_background_light(scene);

  BakeManager *bake_manager = scene->bake_manager;
  requested_features.use_baking = bake_manager->get_baking();
  requested_features.use_integrator_branched = (scene->integrator->method ==
                                                Integrator::BRANCHED_PATH);
  if (params.run_denoising) {
    requested_features.use_denoising = true;
    requested_features.use_shadow_tricks = true;
  }

  return requested_features;
}

bool Session::load_kernels(bool lock_scene)
{
  thread_scoped_lock scene_lock;
  if (lock_scene) {
    scene_lock = thread_scoped_lock(scene->mutex);
  }

  DeviceRequestedFeatures requested_features = get_requested_device_features();

  if (!kernels_loaded || loaded_kernel_features.modified(requested_features)) {
    progress.set_status("Loading render kernels (may take a few minutes the first time)");

    scoped_timer timer;

    VLOG(2) << "Requested features:\n" << requested_features;
    if (!device->load_kernels(requested_features)) {
      string message = device->error_message();
      if (message.empty())
        message = "Failed loading render kernel, see console for errors";

      progress.set_error(message);
      progress.set_status("Error", message);
      progress.set_update();
      return false;
    }

    progress.add_skip_time(timer, false);
    VLOG(1) << "Total time spent loading kernels: " << time_dt() - timer.get_start();

    kernels_loaded = true;
    loaded_kernel_features = requested_features;
    return true;
  }
  return false;
}

void Session::run()
{
  if (params.use_profiling && (params.device.type == DEVICE_CPU)) {
    profiler.start();
  }

  /* session thread loop */
  progress.set_status("Waiting for render to start");

  /* run */
  if (!progress.get_cancel()) {
    /* reset number of rendered samples */
    progress.reset_sample();

    if (device_use_gl)
      run_gpu();
    else
      run_cpu();
  }

  profiler.stop();

  /* progress update */
  if (progress.get_cancel())
    progress.set_status("Cancel", progress.get_cancel_message());
  else
    progress.set_update();
}

bool Session::draw(BufferParams &buffer_params, DeviceDrawParams &draw_params)
{
  if (device_use_gl)
    return draw_gpu(buffer_params, draw_params);
  else
    return draw_cpu(buffer_params, draw_params);
}

void Session::reset_(BufferParams &buffer_params, int samples)
{
  if (buffers && buffer_params.modified(tile_manager.params)) {
    gpu_draw_ready = false;
    buffers->reset(buffer_params);
    if (display) {
      display->reset(buffer_params);
    }
  }

  tile_manager.reset(buffer_params, samples);
  progress.reset_sample();

  bool show_progress = params.background || tile_manager.get_num_effective_samples() != INT_MAX;
  progress.set_total_pixel_samples(show_progress ? tile_manager.state.total_pixel_samples : 0);

  if (!params.background)
    progress.set_start_time();
  progress.set_render_start_time();
}

void Session::reset(BufferParams &buffer_params, int samples)
{
  if (device_use_gl)
    reset_gpu(buffer_params, samples);
  else
    reset_cpu(buffer_params, samples);
}

void Session::set_samples(int samples)
{
  if (samples != params.samples) {
    params.samples = samples;
    tile_manager.set_samples(samples);

    {
      thread_scoped_lock pause_lock(pause_mutex);
    }
    pause_cond.notify_all();
  }
}

void Session::set_pause(bool pause_)
{
  bool notify = false;

  {
    thread_scoped_lock pause_lock(pause_mutex);

    if (pause != pause_) {
      pause = pause_;
      notify = true;
    }
  }

  if (notify)
    pause_cond.notify_all();
}

void Session::wait()
{
  if (session_thread) {
    session_thread->join();
    delete session_thread;
  }

  session_thread = NULL;
}

bool Session::update_scene()
{
  thread_scoped_lock scene_lock(scene->mutex);

  /* update camera if dimensions changed for progressive render. the camera
   * knows nothing about progressive or cropped rendering, it just gets the
   * image dimensions passed in */
  Camera *cam = scene->camera;
  int width = tile_manager.state.buffer.full_width;
  int height = tile_manager.state.buffer.full_height;
  int resolution = tile_manager.state.resolution_divider;

  if (width != cam->width || height != cam->height) {
    cam->width = width;
    cam->height = height;
    cam->resolution = resolution;
    cam->tag_update();
  }

  /* number of samples is needed by multi jittered
   * sampling pattern and by baking */
  Integrator *integrator = scene->integrator;
  BakeManager *bake_manager = scene->bake_manager;

  if (integrator->sampling_pattern == SAMPLING_PATTERN_CMJ || bake_manager->get_baking()) {
    int aa_samples = tile_manager.num_samples;

    if (aa_samples != integrator->aa_samples) {
      integrator->aa_samples = aa_samples;
      integrator->tag_update(scene);
    }
  }

  /* update scene */
  if (scene->need_update()) {
    bool new_kernels_needed = load_kernels(false);

    /* Update max_closures. */
    KernelIntegrator *kintegrator = &scene->dscene.data.integrator;
    if (params.background) {
      kintegrator->max_closures = get_max_closure_count();
    }
    else {
      /* Currently viewport render is faster with higher max_closures, needs investigating. */
      kintegrator->max_closures = MAX_CLOSURE;
    }

    progress.set_status("Updating Scene");
    MEM_GUARDED_CALL(&progress, scene->device_update, device, progress);

    DeviceKernelStatus kernel_switch_status = device->get_active_kernel_switch_state();
    bool kernel_switch_needed = kernel_switch_status == DEVICE_KERNEL_FEATURE_KERNEL_AVAILABLE ||
                                kernel_switch_status == DEVICE_KERNEL_FEATURE_KERNEL_INVALID;
    if (kernel_switch_status == DEVICE_KERNEL_WAITING_FOR_FEATURE_KERNEL) {
      progress.set_kernel_status("Compiling render kernels");
    }
    if (new_kernels_needed || kernel_switch_needed) {
      progress.set_kernel_status("Compiling render kernels");
      device->wait_for_availability(loaded_kernel_features);
      progress.set_kernel_status("");
    }

    if (kernel_switch_needed) {
      reset(tile_manager.params, params.samples);
    }
    return true;
  }
  return false;
}

void Session::update_status_time(bool show_pause, bool show_done)
{
  int progressive_sample = tile_manager.state.sample;
  int num_samples = tile_manager.get_num_effective_samples();

  int tile = progress.get_rendered_tiles();
  int num_tiles = tile_manager.state.num_tiles;

  /* update status */
  string status, substatus;

  if (!params.progressive) {
    const bool is_cpu = params.device.type == DEVICE_CPU;
    const bool rendering_finished = (tile == num_tiles);
    const bool is_last_tile = (tile + 1) == num_tiles;

    substatus = string_printf("Rendered %d/%d Tiles", tile, num_tiles);

    if (!rendering_finished && (device->show_samples() || (is_cpu && is_last_tile))) {
      /* Some devices automatically support showing the sample number:
       * - CUDADevice
       * - OpenCLDevice when using the megakernel (the split kernel renders multiple
       *   samples at the same time, so the current sample isn't really defined)
       * - CPUDevice when using one thread
       * For these devices, the current sample is always shown.
       *
       * The other option is when the last tile is currently being rendered by the CPU.
       */
      substatus += string_printf(", Sample %d/%d", progress.get_current_sample(), num_samples);
    }
    if (params.full_denoising) {
      substatus += string_printf(", Denoised %d tiles", progress.get_denoised_tiles());
    }
    else if (params.run_denoising) {
      substatus += string_printf(", Prefiltered %d tiles", progress.get_denoised_tiles());
    }
  }
  else if (tile_manager.num_samples == INT_MAX)
    substatus = string_printf("Path Tracing Sample %d", progressive_sample + 1);
  else
    substatus = string_printf("Path Tracing Sample %d/%d", progressive_sample + 1, num_samples);

  if (show_pause) {
    status = "Rendering Paused";
  }
  else if (show_done) {
    status = "Rendering Done";
    progress.set_end_time(); /* Save end time so that further calls to get_time are accurate. */
  }
  else {
    status = substatus;
    substatus.clear();
  }

  progress.set_status(status, substatus);
}

void Session::render()
{
  /* Clear buffers. */
  if (buffers && tile_manager.state.sample == tile_manager.range_start_sample) {
    buffers->zero();
  }

  /* Add path trace task. */
  DeviceTask task(DeviceTask::RENDER);

  task.acquire_tile = function_bind(&Session::acquire_tile, this, _1, _2);
  task.release_tile = function_bind(&Session::release_tile, this, _1);
  task.map_neighbor_tiles = function_bind(&Session::map_neighbor_tiles, this, _1, _2);
  task.unmap_neighbor_tiles = function_bind(&Session::unmap_neighbor_tiles, this, _1, _2);
  task.get_cancel = function_bind(&Progress::get_cancel, &this->progress);
  task.update_tile_sample = function_bind(&Session::update_tile_sample, this, _1);
  task.update_progress_sample = function_bind(&Progress::add_samples, &this->progress, _1, _2);
  task.need_finish_queue = params.progressive_refine;
  task.integrator_branched = scene->integrator->method == Integrator::BRANCHED_PATH;
  task.requested_tile_size = params.tile_size;
  task.passes_size = tile_manager.params.get_passes_size();

  if (params.run_denoising) {
    task.denoising = params.denoising;

    assert(!scene->film->need_update);
    task.pass_stride = scene->film->pass_stride;
    task.target_pass_stride = task.pass_stride;
    task.pass_denoising_data = scene->film->denoising_data_offset;
    task.pass_denoising_clean = scene->film->denoising_clean_offset;

    task.denoising_from_render = true;
    task.denoising_do_filter = params.full_denoising;
    task.denoising_write_passes = params.write_denoising_passes;
  }

  device->task_add(task);
}

void Session::tonemap(int sample)
{
  /* add tonemap task */
  DeviceTask task(DeviceTask::FILM_CONVERT);

  task.x = tile_manager.state.buffer.full_x;
  task.y = tile_manager.state.buffer.full_y;
  task.w = tile_manager.state.buffer.width;
  task.h = tile_manager.state.buffer.height;
  task.rgba_byte = display->rgba_byte.device_pointer;
  task.rgba_half = display->rgba_half.device_pointer;
  task.buffer = buffers->buffer.device_pointer;
  task.sample = sample;
  tile_manager.state.buffer.get_offset_stride(task.offset, task.stride);

  if (task.w > 0 && task.h > 0) {
    device->task_add(task);
    device->task_wait();

    /* set display to new size */
    display->draw_set(task.w, task.h);
  }

  display_outdated = false;
}

bool Session::update_progressive_refine(bool cancel)
{
  int sample = tile_manager.state.sample + 1;
  bool write = sample == tile_manager.num_samples || cancel;

  double current_time = time_dt();

  if (current_time - last_update_time < params.progressive_update_timeout) {
    /* if last sample was processed, we need to write buffers anyway  */
    if (!write && sample != 1)
      return false;
  }

  if (params.progressive_refine) {
    foreach (Tile &tile, tile_manager.state.tiles) {
      if (!tile.buffers) {
        continue;
      }

      RenderTile rtile;
      rtile.x = tile_manager.state.buffer.full_x + tile.x;
      rtile.y = tile_manager.state.buffer.full_y + tile.y;
      rtile.w = tile.w;
      rtile.h = tile.h;
      rtile.sample = sample;
      rtile.buffers = tile.buffers;

      if (write) {
        if (write_render_tile_cb)
          write_render_tile_cb(rtile);
      }
      else {
        if (update_render_tile_cb)
          update_render_tile_cb(rtile, true);
      }
    }
  }

  last_update_time = current_time;

  return write;
}

void Session::device_free()
{
  scene->device_free();

  tile_manager.device_free();

  /* used from background render only, so no need to
   * re-create render/display buffers here
   */
}

void Session::collect_statistics(RenderStats *render_stats)
{
  scene->collect_statistics(render_stats);
  if (params.use_profiling && (params.device.type == DEVICE_CPU)) {
    render_stats->collect_profiling(scene, profiler);
  }
}

int Session::get_max_closure_count()
{
  if (scene->shader_manager->use_osl()) {
    /* OSL always needs the maximum as we can't predict the
     * number of closures a shader might generate. */
    return MAX_CLOSURE;
  }

  int max_closures = 0;
  for (int i = 0; i < scene->shaders.size(); i++) {
    int num_closures = scene->shaders[i]->graph->get_num_closures();
    max_closures = max(max_closures, num_closures);
  }
  max_closure_global = max(max_closure_global, max_closures);

  if (max_closure_global > MAX_CLOSURE) {
    /* This is usually harmless as more complex shader tend to get many
     * closures discarded due to mixing or low weights. We need to limit
     * to MAX_CLOSURE as this is hardcoded in CPU/mega kernels, and it
     * avoids excessive memory usage for split kernels. */
    VLOG(2) << "Maximum number of closures exceeded: " << max_closure_global << " > "
            << MAX_CLOSURE;

    max_closure_global = MAX_CLOSURE;
  }

  return max_closure_global;
}

CCL_NAMESPACE_END