text: //
  // Copyright (c) 2020 The Khronos Group Inc.
  //
  // 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 "testBase.h"
  
  static volatile cl_int sDestructorIndex;
  
  void CL_CALLBACK context_destructor_callback(cl_context context, void *userData)
  {
      int *userPtr = (int *)userData;
  
      // ordering of callbacks is guaranteed, meaning we don't need to do atomic
      // operation here
      *userPtr = ++sDestructorIndex;
  }
  
  int test_context_destructor_callback(cl_device_id deviceID, cl_context context,
                                       cl_command_queue queue, int num_elements)
  {
      cl_int error;
      clContextWrapper localContext =
          clCreateContext(NULL, 1, &deviceID, NULL, NULL, &error);
      test_error(error, "Unable to create local context");
  
      // Set up some variables to catch the order in which callbacks are called
      volatile int callbackOrders[3] = { 0, 0, 0 };
      sDestructorIndex = 0;
  
      // Set up the callbacks
      error = clSetContextDestructorCallback(
          localContext, context_destructor_callback, (void *)&callbackOrders[0]);
      test_error(error, "Unable to set destructor callback");
  
      error = clSetContextDestructorCallback(
          localContext, context_destructor_callback, (void *)&callbackOrders[1]);
      test_error(error, "Unable to set destructor callback");
  
      error = clSetContextDestructorCallback(
          localContext, context_destructor_callback, (void *)&callbackOrders[2]);
      test_error(error, "Unable to set destructor callback");
  
      // Now release the context, which SHOULD call the callbacks
      localContext.reset();
  
      // At this point, all three callbacks should have already been called
      int numErrors = 0;
      for (int i = 0; i < 3; i++)
      {
          // Spin waiting for the release to finish.  If you don't call the
          // context_destructor_callback, you will not pass the test.
          log_info("\tWaiting for callback %d...\n", i);
          int wait = 0;
          while (0 == callbackOrders[i])
          {
              usleep(100000); // 1/10th second
              if (++wait >= 10 * 10)
              {
                  log_error("\tERROR: Callback %d was not called within 10 "
                            "seconds!  Assuming failure.\n",
                            i + 1);
                  numErrors++;
                  break;
              }
          }
  
          if (callbackOrders[i] != 3 - i)
          {
              log_error("\tERROR: Callback %d was called in the wrong order! "
                        "(Was called order %d, should have been order %d)\n",
                        i + 1, callbackOrders[i], 3 - i);
              numErrors++;
          }
      }
  
      return (numErrors > 0) ? TEST_FAIL : TEST_PASS;
  }
  