samples: fix OpenCL events leaks

samples/opencl/opencl-opencv-interop.cpp

@@ -468,7 +468,6 @@ private:
     cl_kernel                   m_kernelImg;
     cl_mem                      m_img_src; // used as src in case processing of cl image
     cl_mem                      m_mem_obj;
-    cl_event                    m_event;
 };
 
 
@@ -498,7 +497,6 @@ App::App(CommandLineParser& cmd)
     m_kernelImg  = 0;
     m_img_src    = 0;
     m_mem_obj    = 0;
-    m_event      = 0;
 } // ctor
 
 
@@ -529,11 +527,6 @@ App::~App()
         m_mem_obj = 0;
     }
 
-    if (m_event)
-    {
-        clReleaseEvent(m_event);
-    }
-
     if (m_kernelBuf)
     {
         clReleaseKernel(m_kernelBuf);
@@ -775,11 +768,13 @@ int App::process_frame_with_open_cl(cv::Mat& frame, bool use_buffer, cl_mem* mem
 
             size_t origin[] = { 0, 0, 0 };
             size_t region[] = { (size_t)frame.cols, (size_t)frame.rows, 1 };
-            res = clEnqueueCopyImage(m_queue, m_img_src, mem, origin, origin, region, 0, 0, &m_event);
+            cl_event asyncEvent = 0;
+            res = clEnqueueCopyImage(m_queue, m_img_src, mem, origin, origin, region, 0, 0, &asyncEvent);
             if (CL_SUCCESS != res)
                 return -1;
 
-            res = clWaitForEvents(1, &m_event);
+            res = clWaitForEvents(1, &asyncEvent);
+            clReleaseEvent(asyncEvent);
             if (CL_SUCCESS != res)
                 return -1;
 
@@ -795,19 +790,17 @@ int App::process_frame_with_open_cl(cv::Mat& frame, bool use_buffer, cl_mem* mem
         }
     }
 
-    m_event = clCreateUserEvent(m_context, &res);
-    if (0 == m_event || CL_SUCCESS != res)
-        return -1;
-
     // process left half of frame in OpenCL
     size_t size[] = { (size_t)frame.cols / 2, (size_t)frame.rows };
-    res = clEnqueueNDRangeKernel(m_queue, kernel, 2, 0, size, 0, 0, 0, &m_event);
+    cl_event asyncEvent = 0;
+    res = clEnqueueNDRangeKernel(m_queue, kernel, 2, 0, size, 0, 0, 0, &asyncEvent);
     if (CL_SUCCESS != res)
         return -1;
 
-    res = clWaitForEvents(1, &m_event);
+    res = clWaitForEvents(1, &asyncEvent);
+    clReleaseEvent(asyncEvent);
     if (CL_SUCCESS != res)
-        return - 1;
+        return -1;
 
     mem_obj[0] = mem;