From 8c4b5b6a70c97614460dd069496e30dad7f2414e Mon Sep 17 00:00:00 2001
From: Alexander Alekhin <alexander.alekhin@intel.com>
Date: Wed, 28 Mar 2018 15:51:07 +0300
Subject: [PATCH 1/2] core(test): parallel_for test with exception

---
 modules/core/test/test_misc.cpp | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/modules/core/test/test_misc.cpp b/modules/core/test/test_misc.cpp
index 4c120c9ef3..3f62ed199d 100644
--- a/modules/core/test/test_misc.cpp
+++ b/modules/core/test/test_misc.cpp
@@ -157,4 +157,36 @@ TEST(Core_Copy, repeat_regression_8972)
                      });
 }
 
+
+class ThrowErrorParallelLoopBody : public cv::ParallelLoopBody
+{
+public:
+    ThrowErrorParallelLoopBody(cv::Mat& dst, int i) : dst_(dst), i_(i) {}
+    ~ThrowErrorParallelLoopBody() {}
+    void operator()(const cv::Range& r) const
+    {
+        for (int i = r.start; i < r.end; i++)
+        {
+            CV_Assert(i != i_);
+            dst_.row(i).setTo(1);
+        }
+    }
+protected:
+    Mat dst_;
+    int i_;
+};
+
+TEST(Core_Parallel, propagate_exceptions)
+{
+    Mat dst1(1000, 100, CV_8SC1, Scalar::all(0));
+    ASSERT_NO_THROW({
+        parallel_for_(cv::Range(0, dst1.rows), ThrowErrorParallelLoopBody(dst1, -1));
+    });
+
+    Mat dst2(1000, 100, CV_8SC1, Scalar::all(0));
+    ASSERT_THROW({
+        parallel_for_(cv::Range(0, dst2.rows), ThrowErrorParallelLoopBody(dst2, dst2.rows / 2));
+    }, cv::Exception);
+}
+
 }} // namespace

From 6f69800d0cbdd07fe41b31574c8a62f89a710bf1 Mon Sep 17 00:00:00 2001
From: Alexander Alekhin <alexander.alekhin@intel.com>
Date: Fri, 30 Mar 2018 14:57:51 +0300
Subject: [PATCH 2/2] core: propagate parallel_for() exceptions

---
 modules/core/src/parallel.cpp | 88 +++++++++++++++++++++++++++++++++--
 1 file changed, 85 insertions(+), 3 deletions(-)

diff --git a/modules/core/src/parallel.cpp b/modules/core/src/parallel.cpp
index 5b5e859689..82ca50411a 100644
--- a/modules/core/src/parallel.cpp
+++ b/modules/core/src/parallel.cpp
@@ -129,6 +129,28 @@
 
 #include "parallel_impl.hpp"
 
+
+#ifndef CV__EXCEPTION_PTR
+#  ifdef CV_CXX11
+#    define CV__EXCEPTION_PTR 1
+#  elif defined(CV_ICC)
+#    define CV__EXCEPTION_PTR 1
+#  elif defined(_MSC_VER)
+#    define CV__EXCEPTION_PTR (_MSC_VER >= 1600)
+#  elif defined(__clang__)
+#    define CV__EXCEPTION_PTR 0  // C++11 only (see above)
+#  elif defined(__GNUC__) && defined(__GXX_EXPERIMENTAL_CXX0X__)
+#    define CV__EXCEPTION_PTR (__GXX_EXPERIMENTAL_CXX0X__ > 0)
+#  endif
+#endif
+#ifndef CV__EXCEPTION_PTR
+#  define CV__EXCEPTION_PTR 0
+#else
+#  include <exception>  // std::exception_ptr
+#endif
+
+
+
 using namespace cv;
 
 namespace cv
@@ -169,7 +191,7 @@ namespace
     {
     public:
         ParallelLoopBodyWrapperContext(const cv::ParallelLoopBody& _body, const cv::Range& _r, double _nstripes) :
-            is_rng_used(false)
+            is_rng_used(false), hasException(false)
         {
 
             body = &_body;
@@ -189,7 +211,7 @@ namespace
             pThreadRoot = cv::instr::getInstrumentTLSStruct().pCurrentNode;
 #endif
         }
-        ~ParallelLoopBodyWrapperContext()
+        void finalize()
         {
 #ifdef ENABLE_INSTRUMENTATION
             for(size_t i = 0; i < pThreadRoot->m_childs.size(); i++)
@@ -209,7 +231,17 @@ namespace
             if (traceRootRegion)
                 CV_TRACE_NS::details::parallelForFinalize(*traceRootRegion);
 #endif
+
+            if (hasException)
+            {
+#if CV__EXCEPTION_PTR
+                std::rethrow_exception(pException);
+#else
+                CV_ErrorNoReturn(Error::StsError, "Exception in parallel_for() body: " + exception_message);
+#endif
+            }
         }
+        ~ParallelLoopBodyWrapperContext() {}
 
         const cv::ParallelLoopBody* body;
         cv::Range wholeRange;
@@ -223,6 +255,32 @@ namespace
 #ifdef ENABLE_INSTRUMENTATION
         cv::instr::InstrNode *pThreadRoot;
 #endif
+        bool hasException;
+#if CV__EXCEPTION_PTR
+        std::exception_ptr pException;
+#else
+        cv::String exception_message;
+#endif
+#if CV__EXCEPTION_PTR
+        void recordException()
+#else
+        void recordException(const cv::String& msg)
+#endif
+        {
+            if (!hasException)
+            {
+                cv::AutoLock lock(cv::getInitializationMutex());
+                if (!hasException)
+                {
+                    hasException = true;
+#if CV__EXCEPTION_PTR
+                    pException = std::current_exception();
+#else
+                    exception_message = msg;
+#endif
+                }
+            }
+        }
     private:
         ParallelLoopBodyWrapperContext(const ParallelLoopBodyWrapperContext&); // disabled
         ParallelLoopBodyWrapperContext& operator=(const ParallelLoopBodyWrapperContext&); // disabled
@@ -273,7 +331,29 @@ namespace
             CV_TRACE_ARG_VALUE(range_end, "range.end", (int64)r.end);
 #endif
 
-            (*ctx.body)(r);
+            try
+            {
+                (*ctx.body)(r);
+            }
+#if CV__EXCEPTION_PTR
+            catch (...)
+            {
+                ctx.recordException();
+            }
+#else
+            catch (const cv::Exception& e)
+            {
+                ctx.recordException(e.what());
+            }
+            catch (const std::exception& e)
+            {
+                ctx.recordException(e.what());
+            }
+            catch (...)
+            {
+                ctx.recordException("Unknown exception");
+            }
+#endif
 
             if (!ctx.is_rng_used && !(cv::theRNG() == ctx.rng))
                 ctx.is_rng_used = true;
@@ -486,6 +566,8 @@ static void parallel_for_impl(const cv::Range& range, const cv::ParallelLoopBody
 #error You have hacked and compiling with unsupported parallel framework
 
 #endif
+
+        ctx.finalize();  // propagate exceptions if exists
     }
     else
     {