Merge pull request #13851 from TolyaTalamanov:at/new-kernel-package-design

G-API: Kernel package design (#13851)

* Remove cv::unite_policy from API

* Add check that all id in kernel package are unique

* Refactor checker id procedure

* Remove cv::gapi::GLookupOrder from API

* Implement cv::gapi::use_only

* Fix samples

* Fix docs

* Fix comments to review

* Remove unite_policy

* Fix GKernelPackage::backends()

* Fix comments to review

* Fix all_unique

* Fix comments to review

* Fix comments to review

* Remove out of date tests

doc/tutorials/gapi/anisotropic_segmentation/porting_anisotropic_segmentation.markdown

@@ -306,25 +306,17 @@ G-API to utilize appropriate Fluid functions in our graph.
 
 Kernel packages are combinable -- in the above example, we take "Core"
 and "ImgProc" Fluid kernel packages and combine it into a single
-one. See documentation reference on cv::gapi::combine and
+one. See documentation reference on cv::gapi::combine.
-cv::unite_policy on package combination options.
 
 If no kernel packages are specified in options, G-API is using
 _default_ package which consists of default OpenCV implementations and
 thus G-API graphs are executed via OpenCV functions by default. OpenCV
 backend provides broader functional coverage than any other
 backend. If a kernel package is specified, like in this example, then
-it is being combined with the _default_ one with
+it is being combined with the _default_.
-cv::unite_policy::REPLACE. It means that user-specified
+It means that user-specified implementations will replace default implementations in case of
-implementations will replace default implementations in case of
 conflict.
 
-Kernel packages may contain a mix of kernels, in particular, multiple
-implementations of the same kernel. For example, a single kernel
-package may contain both OpenCV and Fluid implementations of kernel
-"Filter2D". In this case, the implementation selection preference can
-be specified with a special compilation parameter cv::gapi::lookup_order.
-
 <!-- FIXME Document this process better as a part of regular -->
 <!-- documentation, not a tutorial kind of thing -->
 

modules/gapi/include/opencv2/gapi/cpu/gcpukernel.hpp

@@ -43,13 +43,12 @@ namespace cpu
      * stack. Every backend is hardware-oriented and thus can run its
      * kernels efficiently on the target platform.
      *
-     * Backends are usually "back boxes" for G-API users -- on the API
+     * Backends are usually "black boxes" for G-API users -- on the API
      * side, all backends are represented as different objects of the
-     * same class cv::gapi::GBackend. User can manipulate with backends
+     * same class cv::gapi::GBackend.
-     * mainly by specifying which kernels to use or where to look up
+     * User can manipulate with backends by specifying which kernels to use.
-     * for kernels first.
      *
-     * @sa @ref gapi_hld, cv::gapi::lookup_order()
+     * @sa @ref gapi_hld
      */
 
     /**

modules/gapi/include/opencv2/gapi/gkernel.hpp

@@ -14,7 +14,6 @@
 #include <type_traits> // false_type, true_type
 #include <unordered_map> // map (for GKernelPackage)
 #include <utility> // tuple
-#include <vector>  // lookup order
 
 #include <opencv2/gapi/gcommon.hpp> // CompileArgTag
 #include <opencv2/gapi/util/util.hpp> // Seq
@@ -24,7 +23,6 @@
 #include <opencv2/gapi/gtype_traits.hpp> // GTypeTraits
 #include <opencv2/gapi/util/compiler_hints.hpp> //suppress_unused_warning
 
-
 namespace cv {
 
 using GShapes = std::vector<GShape>;
@@ -57,7 +55,6 @@ namespace detail
     //
     namespace
     {
-
         template<typename T> struct Yield;
         template<> struct Yield<cv::GMat>
         {
@@ -248,13 +245,6 @@ public:
 
 namespace cv
 {
-// Declare <unite> in cv:: namespace
-enum class unite_policy
-{
-    REPLACE,
-    KEEP
-};
-
 namespace gapi
 {
     // Prework: model "Device" API before it gets to G-API headers.
@@ -303,33 +293,6 @@ namespace gapi {
      * @{
      */
 
-    // Lookup order is in fact a vector of Backends to traverse during look-up
-    /**
-     * @brief Priority list of backends to use during kernel
-     *   resolution process.
-     *
-     * Priority is descending -- the first backend in the list has the
-     * top priority, and the last one has the lowest priority.
-     *
-     * If there's multiple implementations available for a kernel at
-     * the moment of graph compilation, a kernel (and thus a backend)
-     * will be selected according to this order (if the parameter is passed).
-     *
-     * Default order is not specified (and by default, only
-     * CPU(OpenCV) backend is involved in graph compilation).
-     */
-    using GLookupOrder = std::vector<GBackend>;
-    /**
-     * @brief Create a backend lookup order -- priority list of
-     * backends to use during graph compilation process.
-     *
-     * @sa GLookupOrder, @ref gapi_std_backends
-     */
-    inline GLookupOrder lookup_order(std::initializer_list<GBackend> &&list)
-    {
-        return GLookupOrder(std::move(list));
-    }
-
     // FIXME: Hide implementation
     /**
      * @brief A container class for heterogeneous kernel
@@ -353,20 +316,16 @@ namespace gapi {
      * one since G-API kernel implementations are _types_, not objects.
      *
      * Finally, two kernel packages can be combined into a new one
-     * with function cv::gapi::combine(). There are different rules
+     * with function cv::gapi::combine().
-     * apply to this process, see also cv::gapi::unite_policy for
-     * details.
      */
     class GAPI_EXPORTS GKernelPackage
     {
-        /// @private
-        using S = std::unordered_map<std::string, GKernelImpl>;
 
         /// @private
-        using M = std::unordered_map<GBackend, S>;
+        using M = std::unordered_map<std::string, std::pair<GBackend, GKernelImpl>>;
 
         /// @private
-        M m_backend_kernels;
+        M m_id_kernels;
 
     protected:
         /// @private
@@ -398,10 +357,9 @@ namespace gapi {
         template<typename KImpl>
         bool includes() const
         {
-            const auto set_iter = m_backend_kernels.find(KImpl::backend());
+            auto kernel_it = m_id_kernels.find(KImpl::API::id());
-            return (set_iter != m_backend_kernels.end())
+            return kernel_it != m_id_kernels.end() &&
-                ? (set_iter->second.count(KImpl::API::id()) > 0)
+                   kernel_it->second.first == KImpl::backend();
-                : false;
         }
 
         /**
@@ -439,47 +397,37 @@ namespace gapi {
         }
 
         /**
-         * @brief Find a kernel (by its API), given the look-up order.
+         * @brief Find a kernel (by its API)
          *
-         * If order is empty, returns first suitable implementation.
+         * Returns implementation corresponding id.
          * Throws if nothing found.
          *
          * @return Backend which hosts matching kernel implementation.
          *
-         * @sa cv::gapi::lookup_order
          */
         template<typename KAPI>
-        GBackend lookup(const GLookupOrder &order = {}) const
+        GBackend lookup() const
         {
-            return lookup(KAPI::id(), order).first;
+            return lookup(KAPI::id()).first;
         }
 
         /// @private
         std::pair<cv::gapi::GBackend, cv::GKernelImpl>
-        lookup(const std::string &id, const GLookupOrder &order = {}) const;
+        lookup(const std::string &id) const;
 
         // FIXME: No overwrites allowed?
         /**
          * @brief Put a new kernel implementation KImpl into package.
-         *
-         * @param up unite policy to use. If the package has already
-         * implementation for this kernel (probably from another
-         * backend), and cv::unite_policy::KEEP is passed, the
-         * existing implementation remains in package; on
-         * cv::unite_policy::REPLACE all other existing
-         * implementations are first dropped from the package.
          */
         template<typename KImpl>
-        void include(const cv::unite_policy up = cv::unite_policy::KEEP)
+        void include()
         {
             auto backend     = KImpl::backend();
             auto kernel_id   = KImpl::API::id();
             auto kernel_impl = GKernelImpl{KImpl::kernel()};
-            if (up == cv::unite_policy::REPLACE) removeAPI(kernel_id);
+            removeAPI(kernel_id);
-            else GAPI_Assert(up == cv::unite_policy::KEEP);
 
-            // Regardless of the policy, store new impl in its storage slot.
+            m_id_kernels[kernel_id] = std::make_pair(backend, kernel_impl);
-            m_backend_kernels[backend][kernel_id] = std::move(kernel_impl);
         }
 
         /**
@@ -492,23 +440,14 @@ namespace gapi {
         // TODO: Doxygen bug -- it wants me to place this comment
         // here, not below.
         /**
-         * @brief Create a new package based on `lhs` and `rhs`,
+         * @brief Create a new package based on `lhs` and `rhs`.
-         * with unity policy defined by `policy`.
          *
          * @param lhs "Left-hand-side" package in the process
          * @param rhs "Right-hand-side" package in the process
-         * @param policy Unite policy which is used in case of conflicts
-         * -- when the same kernel API is implemented in both packages by
-         * different backends; cv::unite_policy::KEEP keeps both
-         * implementation in the resulting package, while
-         * cv::unite_policy::REPLACE gives precedence two kernels from
-         * "Right-hand-side".
-         *
          * @return a new kernel package.
          */
         friend GAPI_EXPORTS GKernelPackage combine(const GKernelPackage  &lhs,
-                                                   const GKernelPackage  &rhs,
+                                                   const GKernelPackage  &rhs);
-                                                   const cv::unite_policy policy);
     };
 
     /**
@@ -540,6 +479,7 @@ namespace gapi {
         // and parentheses are used to hide function call in the expanded sequence.
         // Leading 0 helps to handle case when KK is an empty list (kernels<>()).
 
+        static_assert(detail::all_unique<typename KK::API...>::value, "Kernels API must be unique");
         int unused[] = { 0, (pkg.include<KK>(), 0)... };
         cv::util::suppress_unused_warning(unused);
         return pkg;
@@ -548,8 +488,17 @@ namespace gapi {
     /** @} */
 
     GAPI_EXPORTS GKernelPackage combine(const GKernelPackage  &lhs,
-                                        const GKernelPackage  &rhs,
+                                        const GKernelPackage  &rhs);
-                                        const cv::unite_policy policy);
+    /**
+     * @brief cv::use_only() is a special combinator which hints G-API to use only
+     * kernels specified in cv::GComputation::compile() (and not to extend kernels available by
+     * default with that package).
+     */
+    struct GAPI_EXPORTS use_only
+    {
+        GKernelPackage pkg;
+    };
+
 } // namespace gapi
 
 namespace detail
@@ -558,9 +507,10 @@ namespace detail
     {
         static const char* tag() { return "gapi.kernel_package"; }
     };
-    template<> struct CompileArgTag<cv::gapi::GLookupOrder>
+
+    template<> struct CompileArgTag<cv::gapi::use_only>
     {
-        static const char* tag() { return "gapi.lookup_order"; }
+        static const char* tag() { return "gapi.use_only"; }
     };
 } // namespace detail
 } // namespace cv

modules/gapi/include/opencv2/gapi/util/util.hpp

@@ -84,6 +84,19 @@ namespace detail
     {
         static constexpr const std::size_t value = S;
     };
+
+    template <typename...>
+    struct contains : std::false_type{};
+
+    template <typename T1, typename T2, typename... Ts>
+    struct contains<T1, T2, Ts...> : std::integral_constant<bool, std::is_same<T1, T2>::value ||
+                                                                  contains<T1, Ts...>::value> {};
+    template <typename...>
+    struct all_unique : std::true_type{};
+
+    template <typename T1, typename... Ts>
+    struct all_unique<T1, Ts...> : std::integral_constant<bool, !contains<T1, Ts...>::value &&
+                                                                 all_unique<Ts...>::value> {};
 } // namespace detail
 } // namespace cv
 

modules/gapi/samples/api_ref_snippets.cpp

@@ -49,8 +49,7 @@ int main(int argc, char *argv[])
     //! [apply_with_param]
     cv::gapi::GKernelPackage kernels = cv::gapi::combine
         (cv::gapi::core::fluid::kernels(),
-         cv::gapi::imgproc::fluid::kernels(),
+         cv::gapi::imgproc::fluid::kernels());
-         cv::unite_policy::KEEP);
     sobelEdge.apply(input, output, cv::compile_args(kernels));
     //! [apply_with_param]
 

modules/gapi/src/api/gkernel.cpp

@@ -20,128 +20,73 @@
 // GKernelPackage public implementation ////////////////////////////////////////
 void cv::gapi::GKernelPackage::remove(const cv::gapi::GBackend& backend)
 {
-    m_backend_kernels.erase(backend);
+    std::vector<std::string> id_deleted_kernels;
+    for (const auto& p : m_id_kernels)
+    {
+        if (p.second.first == backend)
+        {
+            id_deleted_kernels.push_back(p.first);
+        }
+    }
+
+    for (const auto& kernel_id : id_deleted_kernels)
+    {
+        m_id_kernels.erase(kernel_id);
+    }
 }
 
 bool cv::gapi::GKernelPackage::includesAPI(const std::string &id) const
 {
-    // In current form not very efficient (n * log n)
+    return ade::util::contains(m_id_kernels, id);
-    auto it = std::find_if(m_backend_kernels.begin(),
-                           m_backend_kernels.end(),
-                           [&id](const M::value_type &p) {
-                               return ade::util::contains(p.second, id);
-                           });
-    return (it != m_backend_kernels.end());
 }
 
 void cv::gapi::GKernelPackage::removeAPI(const std::string &id)
 {
-    for (auto &bk : m_backend_kernels)
+    m_id_kernels.erase(id);
-        bk.second.erase(id);
 }
 
 std::size_t cv::gapi::GKernelPackage::size() const
 {
-    return std::accumulate(m_backend_kernels.begin(),
+    return m_id_kernels.size();
-                           m_backend_kernels.end(),
-                           static_cast<std::size_t>(0u),
-                           [](std::size_t acc, const M::value_type& v) {
-                               return acc + v.second.size();
-                           });
 }
 
 cv::gapi::GKernelPackage cv::gapi::combine(const GKernelPackage  &lhs,
-                                           const GKernelPackage  &rhs,
+                                           const GKernelPackage  &rhs)
-                                           const cv::unite_policy policy)
 {
 
-    if (policy == cv::unite_policy::REPLACE)
+        // If there is a collision, prefer RHS to LHS
-    {
-        // REPLACE policy: if there is a collision, prefer RHS
-        // to LHS
         // since RHS package has a precedense, start with its copy
         GKernelPackage result(rhs);
         // now iterate over LHS package and put kernel if and only
         // if there's no such one
-        for (const auto &backend : lhs.m_backend_kernels)
+        for (const auto& kernel : lhs.m_id_kernels)
         {
-            for (const auto &kimpl : backend.second)
+            if (!result.includesAPI(kernel.first))
             {
-                if (!result.includesAPI(kimpl.first))
+                result.m_id_kernels.emplace(kernel.first, kernel.second);
-                    result.m_backend_kernels[backend.first].insert(kimpl);
             }
         }
         return result;
-    }
-    else if (policy == cv::unite_policy::KEEP)
-    {
-        // KEEP policy: if there is a collision, just keep two versions
-        // of a kernel
-        GKernelPackage result(lhs);
-        for (const auto &p : rhs.m_backend_kernels)
-        {
-            result.m_backend_kernels[p.first].insert(p.second.begin(),
-                                                     p.second.end());
-        }
-        return result;
-    }
-    else GAPI_Assert(false);
-    return GKernelPackage();
 }
 
 std::pair<cv::gapi::GBackend, cv::GKernelImpl>
-cv::gapi::GKernelPackage::lookup(const std::string &id,
+cv::gapi::GKernelPackage::lookup(const std::string &id) const
-                                 const GLookupOrder &order) const
 {
-    if (order.empty())
+    auto kernel_it = m_id_kernels.find(id);
+    if (kernel_it != m_id_kernels.end())
     {
-        // If order is empty, return what comes first
+        return kernel_it->second;
-        auto it = std::find_if(m_backend_kernels.begin(),
-                               m_backend_kernels.end(),
-                               [&id](const M::value_type &p) {
-                                   return ade::util::contains(p.second, id);
-                               });
-        if (it != m_backend_kernels.end())
-        {
-            // FIXME: Two lookups!
-            return std::make_pair(it->first, it->second.find(id)->second);
-        }
     }
-    else
+    // If reached here, kernel was not found.
-    {
-        // There is order, so:
-        // 1. Limit search scope only to specified backends
-        //    FIXME: Currently it is not configurable if search can fall-back
-        //    to other backends (not listed in order) if kernel hasn't been found
-        //    in the look-up list
-        // 2. Query backends in the specified order
-        for (const auto &selected_backend : order)
-        {
-            const auto kernels_it = m_backend_kernels.find(selected_backend);
-            if (kernels_it == m_backend_kernels.end())
-            {
-                GAPI_LOG_WARNING(NULL,
-                                 "Backend "
-                                  << &selected_backend.priv() // FIXME: name instead
-                                  << " was listed in lookup list but was not found "
-                                     "in the package");
-                continue;
-            }
-            if (ade::util::contains(kernels_it->second, id))
-            {
-                // FIXME: two lookups!
-                return std::make_pair(selected_backend, kernels_it->second.find(id)->second);
-            }
-        }
-    }
-
-    // If reached here, kernel was not found among selected backends.
     util::throw_error(std::logic_error("Kernel " + id + " was not found"));
 }
 
 std::vector<cv::gapi::GBackend> cv::gapi::GKernelPackage::backends() const
 {
-    std::vector<cv::gapi::GBackend> result;
+    using kernel_type = std::pair<std::string, std::pair<cv::gapi::GBackend, cv::GKernelImpl>>;
-    for (const auto &p : m_backend_kernels) result.emplace_back(p.first);
+    std::unordered_set<cv::gapi::GBackend> unique_set;
-    return result;
+    ade::util::transform(m_id_kernels, std::inserter(unique_set, unique_set.end()),
+                                       [](const kernel_type& k) { return k.second.first; });
+
+    return std::vector<cv::gapi::GBackend>(unique_set.begin(), unique_set.end());
 }

modules/gapi/src/compiler/gcompiler.cpp

@@ -48,16 +48,19 @@ namespace
 {
     cv::gapi::GKernelPackage getKernelPackage(cv::GCompileArgs &args)
     {
+        auto has_use_only = cv::gimpl::getCompileArg<cv::gapi::use_only>(args);
+        if (has_use_only)
+            return has_use_only.value().pkg;
+
         static auto ocv_pkg =
 #if !defined(GAPI_STANDALONE)
             combine(cv::gapi::core::cpu::kernels(),
-                    cv::gapi::imgproc::cpu::kernels(),
+                    cv::gapi::imgproc::cpu::kernels());
-                    cv::unite_policy::KEEP);
 #else
             cv::gapi::GKernelPackage();
 #endif // !defined(GAPI_STANDALONE)
         auto user_pkg = cv::gimpl::getCompileArg<cv::gapi::GKernelPackage>(args);
-        return combine(ocv_pkg, user_pkg.value_or(cv::gapi::GKernelPackage{}), cv::unite_policy::REPLACE);
+        return combine(ocv_pkg, user_pkg.value_or(cv::gapi::GKernelPackage{}));
     }
 
     cv::util::optional<std::string> getGraphDumpDirectory(cv::GCompileArgs& args)
@@ -87,7 +90,6 @@ cv::gimpl::GCompiler::GCompiler(const cv::GComputation &c,
 {
     using namespace std::placeholders;
     m_all_kernels       = getKernelPackage(m_args);
-    auto lookup_order   = getCompileArg<gapi::GLookupOrder>(m_args).value_or(gapi::GLookupOrder());
     auto dump_path      = getGraphDumpDirectory(m_args);
 
     m_e.addPassStage("init");
@@ -107,8 +109,7 @@ cv::gimpl::GCompiler::GCompiler(const cv::GComputation &c,
 
     m_e.addPassStage("kernels");
     m_e.addPass("kernels", "resolve_kernels", std::bind(passes::resolveKernels, _1,
-                                                     std::ref(m_all_kernels), // NB: and not copied here
+                                              std::ref(m_all_kernels))); // NB: and not copied here
-                                                     lookup_order));
     m_e.addPass("kernels", "check_islands_content", passes::checkIslandsContent);
 
     m_e.addPassStage("meta");

modules/gapi/src/compiler/passes/kernels.cpp

@@ -101,8 +101,7 @@ namespace
 // This pass, given the kernel package, selects a kernel implementation
 // for every operation in the graph
 void cv::gimpl::passes::resolveKernels(ade::passes::PassContext   &ctx,
-                                       const gapi::GKernelPackage &kernels,
+                                       const gapi::GKernelPackage &kernels)
-                                       const gapi::GLookupOrder   &order)
 {
     std::unordered_set<cv::gapi::GBackend> active_backends;
 
@@ -114,8 +113,7 @@ void cv::gimpl::passes::resolveKernels(ade::passes::PassContext   &ctx,
             auto &op = gr.metadata(nh).get<Op>();
             cv::gapi::GBackend selected_backend;
             cv::GKernelImpl    selected_impl;
-            std::tie(selected_backend, selected_impl)
+            std::tie(selected_backend, selected_impl) = kernels.lookup(op.k.name);
-                = kernels.lookup(op.k.name, order);
 
             selected_backend.priv().unpackKernel(ctx.graph, nh, selected_impl);
             op.backend = selected_backend;

modules/gapi/src/compiler/passes/passes.hpp

@@ -44,9 +44,8 @@ void storeResultingMeta(ade::passes::PassContext &ctx);
 void expandKernels(ade::passes::PassContext &ctx,
                    const gapi::GKernelPackage& kernels);
 
-void resolveKernels(ade::passes::PassContext       &ctx,
+void resolveKernels(ade::passes::PassContext   &ctx,
-                    const gapi::GKernelPackage &kernels,
+                    const gapi::GKernelPackage &kernels);
-                    const gapi::GLookupOrder   &order);
 
 void fuseIslands(ade::passes::PassContext &ctx);
 void syncIslandTags(ade::passes::PassContext &ctx);

modules/gapi/test/common/gapi_compoundkernel_tests.cpp

@@ -235,7 +235,7 @@ TEST(GCompoundKernel, ReplaceDefaultKernel)
     cv::GMat in1, in2;
     auto out = cv::gapi::add(in1, in2);
     const auto custom_pkg = cv::gapi::kernels<GCompoundAddImpl>();
-    const auto full_pkg   = cv::gapi::combine(cv::gapi::core::cpu::kernels(), custom_pkg, cv::unite_policy::REPLACE);
+    const auto full_pkg   = cv::gapi::combine(cv::gapi::core::cpu::kernels(), custom_pkg);
     cv::GComputation comp(cv::GIn(in1, in2), cv::GOut(out));
     cv::Mat in_mat1 = cv::Mat::eye(3, 3, CV_8UC1),
             in_mat2 = cv::Mat::eye(3, 3, CV_8UC1),
@@ -257,7 +257,7 @@ TEST(GCompoundKernel, DoubleAddC)
     auto out       = cv::gapi::addC(super, s);
 
     const auto custom_pkg = cv::gapi::kernels<GCompoundDoubleAddCImpl>();
-    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels(), cv::unite_policy::KEEP);
+    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels());
     cv::GComputation comp(cv::GIn(in1, in2, s), cv::GOut(out));
 
     cv::Mat in_mat1 = cv::Mat::eye(3, 3, CV_8UC1),
@@ -282,7 +282,7 @@ TEST(GCompoundKernel, AddC)
     auto out       = cv::gapi::addC(super, s);
 
     const auto custom_pkg = cv::gapi::kernels<GCompoundAddCImpl>();
-    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels(), cv::unite_policy::KEEP);
+    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels());
     cv::GComputation comp(cv::GIn(in1, in2, s), cv::GOut(out));
 
     cv::Mat in_mat1 = cv::Mat::eye(3, 3, CV_8UC1),
@@ -308,7 +308,7 @@ TEST(GCompoundKernel, MergeWithSplit)
     auto out = cv::gapi::merge3(a2, b2, c2);
 
     const auto custom_pkg = cv::gapi::kernels<GCompoundMergeWithSplitImpl>();
-    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels(), cv::unite_policy::KEEP);
+    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels());
     cv::GComputation comp(cv::GIn(in), cv::GOut(out));
 
     cv::Mat in_mat = cv::Mat::eye(3, 3, CV_8UC3), out_mat, ref_mat;
@@ -325,7 +325,7 @@ TEST(GCompoundKernel, AddWithAddC)
     auto out = GCompoundAddWithAddC::on(in1, in2, s);
 
     const auto custom_pkg = cv::gapi::kernels<GCompoundAddWithAddCImpl>();
-    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels(), cv::unite_policy::KEEP);
+    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels());
     cv::GComputation comp(cv::GIn(in1, in2, s), cv::GOut(out));
 
     cv::Mat in_mat1 = cv::Mat::eye(3, 3, CV_8UC1),
@@ -347,7 +347,7 @@ TEST(GCompoundKernel, SplitWithAdd)
     std::tie(out1, out2) = GCompoundSplitWithAdd::on(in);
 
     const auto custom_pkg = cv::gapi::kernels<GCompoundSplitWithAddImpl>();
-    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels(), cv::unite_policy::KEEP);
+    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels());
     cv::GComputation comp(cv::GIn(in), cv::GOut(out1, out2));
 
     cv::Mat in_mat = cv::Mat::eye(3, 3, CV_8UC3),
@@ -375,7 +375,7 @@ TEST(GCompoundKernel, ParallelAddC)
     std::tie(out1, out2) = GCompoundParallelAddC::on(in1, in2);
 
     const auto custom_pkg = cv::gapi::kernels<GCompoundParallelAddCImpl>();
-    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels(), cv::unite_policy::KEEP);
+    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels());
     cv::GComputation comp(cv::GIn(in1, in2), cv::GOut(out1, out2));
 
     cv::Mat in_mat = cv::Mat::eye(3, 3, CV_8UC1),
@@ -402,7 +402,7 @@ TEST(GCompoundKernel, GCompundKernelAndDefaultUseOneData)
     auto out = cv::gapi::add(GCompoundAddWithAddC::on(in1, in2, s), cv::gapi::addC(in2, s));
 
     const auto custom_pkg = cv::gapi::kernels<GCompoundAddWithAddCImpl>();
-    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels(), cv::unite_policy::KEEP);
+    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels());
     cv::GComputation comp(cv::GIn(in1, in2, s), cv::GOut(out));
 
     cv::Mat in_mat1 = cv::Mat::eye(3, 3, CV_8UC1),
@@ -428,7 +428,7 @@ TEST(GCompoundKernel, CompoundExpandedToCompound)
                                               GCompoundAddWithAddCImpl,
                                               GCompoundDoubleAddCImpl>();
 
-    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels(), cv::unite_policy::KEEP);
+    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels());
     cv::GComputation comp(cv::GIn(in1, in2, s), cv::GOut(out));
 
     cv::Mat in_mat1 = cv::Mat::eye(3, 3, CV_8UC1),
@@ -449,7 +449,7 @@ TEST(GCompoundKernel, MaxInArray)
     GDoubleArray in;
     auto out = GCompoundMaxInArray::on(in);
     const auto custom_pkg = cv::gapi::kernels<GCompoundMaxInArrayImpl, GMaxInArrayImpl>();
-    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels(), cv::unite_policy::KEEP);
+    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels());
     cv::GComputation comp(cv::GIn(in), cv::GOut(out));
     std::vector<double> v = { 1, 5, -2, 3, 10, 2};
     cv::Scalar out_scl;
@@ -465,7 +465,7 @@ TEST(GCompoundKernel, NegateArray)
     GDoubleArray in;
     GDoubleArray out = GCompoundNegateArray::on(in);
     const auto custom_pkg = cv::gapi::kernels<GCompoundNegateArrayImpl, GNegateArrayImpl>();
-    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels(), cv::unite_policy::KEEP);
+    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels());
     cv::GComputation comp(cv::GIn(in), cv::GOut(out));
     std::vector<double> in_v = {1, 5, -2, -10, 3};
     std::vector<double> out_v;
@@ -483,7 +483,7 @@ TEST(GCompoundKernel, RightGArrayHandle)
     GDoubleArray a;
     cv::GMat out = GCompoundGMatGArrayGMat::on(in[0], a, in[1]);
     const auto custom_pkg = cv::gapi::kernels<GCompoundGMatGArrayGMatImpl, SetDiagKernelImpl>();
-    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels(), cv::unite_policy::KEEP);
+    const auto full_pkg   = cv::gapi::combine(custom_pkg, cv::gapi::core::cpu::kernels());
     cv::GComputation comp(cv::GIn(in[0], a, in[1]), cv::GOut(out));
     std::vector<double> in_v(3, 1.0);
     cv::Mat in_mat1 = cv::Mat::eye(cv::Size(3, 3), CV_8UC1),

modules/gapi/test/gapi_fluid_resize_test.cpp

@@ -381,7 +381,7 @@ static auto fluidResizeTestPackage = [](int interpolation, cv::Size szIn, cv::Si
     }break;
     default: CV_Assert(false);
     }
-    return combine(pkg, fluidTestPackage, unite_policy::KEEP);
+    return combine(pkg, fluidTestPackage);
 
 #undef RESIZE_SWITCH
 #undef RESIZE_CASE
@@ -743,7 +743,7 @@ TEST_P(NV12PlusResizeTest, Test)
     auto out = cv::gapi::resize(rgb, out_sz, 0, 0, interp);
     cv::GComputation c(cv::GIn(y, uv), cv::GOut(out));
 
-    auto pkg = cv::gapi::combine(fluidTestPackage, cv::gapi::core::fluid::kernels(), cv::unite_policy::KEEP);
+    auto pkg = cv::gapi::combine(fluidTestPackage, cv::gapi::core::fluid::kernels());
 
     c.apply(cv::gin(y_mat, uv_mat), cv::gout(out_mat)
            ,cv::compile_args(pkg, cv::GFluidOutputRois{{to_own(roi)}}));
@@ -822,8 +822,7 @@ TEST_P(Preproc4lpiTest, Test)
     cv::GComputation c(cv::GIn(y, uv), cv::GOut(out));
 
     auto pkg = cv::gapi::combine(cv::gapi::core::fluid::kernels(),
-                                 fluidResizeTestPackage(interp, in_sz, out_sz, 4),
+                                 fluidResizeTestPackage(interp, in_sz, out_sz, 4));
-                                 cv::unite_policy::REPLACE);
 
     c.apply(cv::gin(y_mat, uv_mat), cv::gout(out_mat)
            ,cv::compile_args(pkg, cv::GFluidOutputRois{{to_own(roi)}}));

modules/gapi/test/gapi_kernel_tests.cpp

@@ -9,25 +9,126 @@
 #include "opencv2/gapi/cpu/gcpukernel.hpp"
 #include "gapi_mock_kernels.hpp"
 
+#include "opencv2/gapi/cpu/gcpukernel.hpp"     // cpu::backend
+#include "opencv2/gapi/fluid/gfluidkernel.hpp" // fluid::backend
+
 namespace opencv_test
 {
 
 namespace
 {
-    G_TYPED_KERNEL(GClone, <GMat(GMat)>, "org.opencv.test.clone")
+    namespace I
     {
-        static GMatDesc outMeta(GMatDesc in) { return in;  }
+        G_TYPED_KERNEL(GClone, <GMat(GMat)>, "org.opencv.test.clone")
-
-    };
-
-    GAPI_OCV_KERNEL(GCloneImpl, GClone)
-    {
-        static void run(const cv::Mat& in, cv::Mat &out)
         {
-            out = in.clone();
+            static GMatDesc outMeta(GMatDesc in) { return in;  }
-        }
+        };
+    }
+
+    enum class KernelTags
+    {
+        CPU_CUSTOM_BGR2GRAY,
+        CPU_CUSTOM_CLONE,
+        CPU_CUSTOM_ADD,
+        FLUID_CUSTOM_BGR2GRAY,
+        FLUID_CUSTOM_CLONE,
+        FLUID_CUSTOM_ADD
     };
-}
+
+    class HeteroGraph: public ::testing::Test
+    {
+    public:
+        HeteroGraph()
+        {
+            auto tmp = I::GClone::on(cv::gapi::add(in[0], in[1]));
+            out = cv::gapi::imgproc::GBGR2Gray::on(tmp);
+        }
+
+        static void registerCallKernel(KernelTags kernel_tag) {
+            kernel_calls.insert(kernel_tag);
+        }
+
+        bool checkCallKernel(KernelTags kernel_tag) {
+            return ade::util::contains(kernel_calls, kernel_tag);
+        }
+
+    protected:
+        void SetUp() override
+        {
+            if (!kernel_calls.empty())
+                cv::util::throw_error(std::logic_error("Kernel call log has not been cleared!!!"));
+        }
+
+        void TearDown() override
+        {
+            kernel_calls.clear();
+        }
+
+    protected:
+        cv::GMat in[2], out;
+        static std::set<KernelTags> kernel_calls;
+    };
+
+    namespace cpu
+    {
+        GAPI_OCV_KERNEL(GClone, I::GClone)
+        {
+            static void run(const cv::Mat&, cv::Mat)
+            {
+                HeteroGraph::registerCallKernel(KernelTags::CPU_CUSTOM_CLONE);
+            }
+        };
+
+        GAPI_OCV_KERNEL(BGR2Gray, cv::gapi::imgproc::GBGR2Gray)
+        {
+            static void run(const cv::Mat&, cv::Mat&)
+            {
+                HeteroGraph::registerCallKernel(KernelTags::CPU_CUSTOM_BGR2GRAY);
+            }
+        };
+
+        GAPI_OCV_KERNEL(GAdd, cv::gapi::core::GAdd)
+        {
+            static void run(const cv::Mat&, const cv::Mat&, int, cv::Mat&)
+            {
+                HeteroGraph::registerCallKernel(KernelTags::CPU_CUSTOM_ADD);
+            }
+        };
+    }
+
+    namespace fluid
+    {
+        GAPI_FLUID_KERNEL(GClone, I::GClone, false)
+        {
+            static const int Window = 1;
+            static void run(const cv::gapi::fluid::View&, cv::gapi::fluid::Buffer)
+            {
+                HeteroGraph::registerCallKernel(KernelTags::FLUID_CUSTOM_CLONE);
+            }
+        };
+
+        GAPI_FLUID_KERNEL(BGR2Gray, cv::gapi::imgproc::GBGR2Gray, false)
+        {
+            static const int Window = 1;
+            static void run(const cv::gapi::fluid::View&, cv::gapi::fluid::Buffer&)
+            {
+                HeteroGraph::registerCallKernel(KernelTags::FLUID_CUSTOM_BGR2GRAY);
+            }
+        };
+
+        GAPI_FLUID_KERNEL(GAdd, cv::gapi::core::GAdd, false)
+        {
+            static const int Window = 1;
+            static void run(const cv::gapi::fluid::View&, const cv::gapi::fluid::View&,
+                            int, cv::gapi::fluid::Buffer&)
+            {
+                HeteroGraph::registerCallKernel(KernelTags::FLUID_CUSTOM_ADD);
+            }
+        };
+    }
+
+    std::set<KernelTags> HeteroGraph::kernel_calls;
+} // anonymous namespace
 
 TEST(KernelPackage, Create)
 {
@@ -57,17 +158,6 @@ TEST(KernelPackage, IncludesAPI)
     EXPECT_FALSE(pkg.includesAPI<I::Qux>());
 }
 
-TEST(KernelPackage, IncludesAPI_Overlapping)
-{
-    namespace J = Jupiter;
-    namespace S = Saturn;
-    auto pkg = cv::gapi::kernels<J::Foo, J::Bar, S::Foo, S::Bar>();
-    EXPECT_TRUE (pkg.includesAPI<I::Foo>());
-    EXPECT_TRUE (pkg.includesAPI<I::Bar>());
-    EXPECT_FALSE(pkg.includesAPI<I::Baz>());
-    EXPECT_FALSE(pkg.includesAPI<I::Qux>());
-}
-
 TEST(KernelPackage, Include_Add)
 {
     namespace J = Jupiter;
@@ -78,23 +168,6 @@ TEST(KernelPackage, Include_Add)
     EXPECT_TRUE(pkg.includes<J::Qux>());
 }
 
-TEST(KernelPackage, Include_KEEP)
-{
-    namespace J = Jupiter;
-    namespace S = Saturn;
-    auto pkg = cv::gapi::kernels<J::Foo, J::Bar>();
-    EXPECT_FALSE(pkg.includes<S::Foo>());
-    EXPECT_FALSE(pkg.includes<S::Bar>());
-
-    pkg.include<S::Bar>(); // default (KEEP)
-    EXPECT_TRUE(pkg.includes<J::Bar>());
-    EXPECT_TRUE(pkg.includes<S::Bar>());
-
-    pkg.include<S::Foo>(cv::unite_policy::KEEP); // explicit (KEEP)
-    EXPECT_TRUE(pkg.includes<J::Foo>());
-    EXPECT_TRUE(pkg.includes<S::Foo>());
-}
-
 TEST(KernelPackage, Include_REPLACE)
 {
     namespace J = Jupiter;
@@ -102,7 +175,7 @@ TEST(KernelPackage, Include_REPLACE)
     auto pkg = cv::gapi::kernels<J::Foo, J::Bar>();
     EXPECT_FALSE(pkg.includes<S::Bar>());
 
-    pkg.include<S::Bar>(cv::unite_policy::REPLACE);
+    pkg.include<S::Bar>();
     EXPECT_FALSE(pkg.includes<J::Bar>());
     EXPECT_TRUE(pkg.includes<S::Bar>());
 }
@@ -111,31 +184,27 @@ TEST(KernelPackage, RemoveBackend)
 {
     namespace J = Jupiter;
     namespace S = Saturn;
-    auto pkg = cv::gapi::kernels<J::Foo, J::Bar, S::Foo>();
+    auto pkg = cv::gapi::kernels<J::Foo, J::Bar, S::Baz>();
     EXPECT_TRUE(pkg.includes<J::Foo>());
     EXPECT_TRUE(pkg.includes<J::Bar>());
-    EXPECT_TRUE(pkg.includes<S::Foo>());
 
     pkg.remove(J::backend());
     EXPECT_FALSE(pkg.includes<J::Foo>());
     EXPECT_FALSE(pkg.includes<J::Bar>());
-    EXPECT_TRUE(pkg.includes<S::Foo>());
+    EXPECT_TRUE(pkg.includes<S::Baz>());
 };
 
 TEST(KernelPackage, RemoveAPI)
 {
     namespace J = Jupiter;
     namespace S = Saturn;
-    auto pkg = cv::gapi::kernels<J::Foo, J::Bar, S::Foo, S::Bar>();
+    auto pkg = cv::gapi::kernels<J::Foo, J::Bar>();
     EXPECT_TRUE(pkg.includes<J::Foo>());
     EXPECT_TRUE(pkg.includes<J::Bar>());
-    EXPECT_TRUE(pkg.includes<S::Foo>());
 
     pkg.remove<I::Foo>();
     EXPECT_TRUE(pkg.includes<J::Bar>());
-    EXPECT_TRUE(pkg.includes<S::Bar>());
     EXPECT_FALSE(pkg.includes<J::Foo>());
-    EXPECT_FALSE(pkg.includes<S::Foo>());
 };
 
 TEST(KernelPackage, CreateHetero)
@@ -177,7 +246,7 @@ TEST(KernelPackage, Combine_REPLACE_Full)
     namespace S = Saturn;
     auto j_pkg = cv::gapi::kernels<J::Foo, J::Bar, J::Baz>();
     auto s_pkg = cv::gapi::kernels<S::Foo, S::Bar, S::Baz>();
-    auto u_pkg = cv::gapi::combine(j_pkg, s_pkg, cv::unite_policy::REPLACE);
+    auto u_pkg = cv::gapi::combine(j_pkg, s_pkg);
 
     EXPECT_EQ(3u, u_pkg.size());
     EXPECT_FALSE(u_pkg.includes<J::Foo>());
@@ -194,7 +263,7 @@ TEST(KernelPackage, Combine_REPLACE_Partial)
     namespace S = Saturn;
     auto j_pkg = cv::gapi::kernels<J::Foo, J::Bar>();
     auto s_pkg = cv::gapi::kernels<S::Bar>();
-    auto u_pkg = cv::gapi::combine(j_pkg, s_pkg, cv::unite_policy::REPLACE);
+    auto u_pkg = cv::gapi::combine(j_pkg, s_pkg);
 
     EXPECT_EQ(2u, u_pkg.size());
     EXPECT_TRUE (u_pkg.includes<J::Foo>());
@@ -208,38 +277,7 @@ TEST(KernelPackage, Combine_REPLACE_Append)
     namespace S = Saturn;
     auto j_pkg = cv::gapi::kernels<J::Foo, J::Bar>();
     auto s_pkg = cv::gapi::kernels<S::Qux>();
-    auto u_pkg = cv::gapi::combine(j_pkg, s_pkg, cv::unite_policy::REPLACE);
+    auto u_pkg = cv::gapi::combine(j_pkg, s_pkg);
-
-    EXPECT_EQ(3u, u_pkg.size());
-    EXPECT_TRUE(u_pkg.includes<J::Foo>());
-    EXPECT_TRUE(u_pkg.includes<J::Bar>());
-    EXPECT_TRUE(u_pkg.includes<S::Qux>());
-}
-
-TEST(KernelPackage, Combine_KEEP_AllDups)
-{
-    namespace J = Jupiter;
-    namespace S = Saturn;
-    auto j_pkg = cv::gapi::kernels<J::Foo, J::Bar, J::Baz>();
-    auto s_pkg = cv::gapi::kernels<S::Foo, S::Bar, S::Baz>();
-    auto u_pkg = cv::gapi::combine(j_pkg ,s_pkg, cv::unite_policy::KEEP);
-
-    EXPECT_EQ(6u, u_pkg.size());
-    EXPECT_TRUE(u_pkg.includes<J::Foo>());
-    EXPECT_TRUE(u_pkg.includes<J::Bar>());
-    EXPECT_TRUE(u_pkg.includes<J::Baz>());
-    EXPECT_TRUE(u_pkg.includes<S::Foo>());
-    EXPECT_TRUE(u_pkg.includes<S::Bar>());
-    EXPECT_TRUE(u_pkg.includes<S::Baz>());
-}
-
-TEST(KernelPackage, Combine_KEEP_Append_NoDups)
-{
-    namespace J = Jupiter;
-    namespace S = Saturn;
-    auto j_pkg = cv::gapi::kernels<J::Foo, J::Bar>();
-    auto s_pkg = cv::gapi::kernels<S::Qux>();
-    auto u_pkg = cv::gapi::combine(j_pkg, s_pkg, cv::unite_policy::KEEP);
 
     EXPECT_EQ(3u, u_pkg.size());
     EXPECT_TRUE(u_pkg.includes<J::Foo>());
@@ -252,7 +290,7 @@ TEST(KernelPackage, TestWithEmptyLHS)
     namespace J = Jupiter;
     auto lhs = cv::gapi::kernels<>();
     auto rhs = cv::gapi::kernels<J::Foo>();
-    auto pkg = cv::gapi::combine(lhs, rhs, cv::unite_policy::KEEP);
+    auto pkg = cv::gapi::combine(lhs, rhs);
 
     EXPECT_EQ(1u, pkg.size());
     EXPECT_TRUE(pkg.includes<J::Foo>());
@@ -263,22 +301,211 @@ TEST(KernelPackage, TestWithEmptyRHS)
     namespace J = Jupiter;
     auto lhs = cv::gapi::kernels<J::Foo>();
     auto rhs = cv::gapi::kernels<>();
-    auto pkg = cv::gapi::combine(lhs, rhs, cv::unite_policy::KEEP);
+    auto pkg = cv::gapi::combine(lhs, rhs);
 
     EXPECT_EQ(1u, pkg.size());
     EXPECT_TRUE(pkg.includes<J::Foo>());
 }
 
+TEST(KernelPackage, Return_Unique_Backends)
+{
+    auto pkg = cv::gapi::kernels<cpu::GClone, fluid::BGR2Gray, fluid::GAdd>();
+    EXPECT_EQ(2u, pkg.backends().size());
+}
+
 TEST(KernelPackage, Can_Use_Custom_Kernel)
 {
     cv::GMat in[2];
-    auto out = GClone::on(cv::gapi::add(in[0], in[1]));
+    auto out = I::GClone::on(cv::gapi::add(in[0], in[1]));
     const auto in_meta = cv::GMetaArg(cv::GMatDesc{CV_8U,1,cv::Size(32,32)});
 
-    auto pkg = cv::gapi::kernels<GCloneImpl>();
+    auto pkg = cv::gapi::kernels<cpu::GClone>();
 
     EXPECT_NO_THROW(cv::GComputation(cv::GIn(in[0], in[1]), cv::GOut(out)).
                         compile({in_meta, in_meta}, cv::compile_args(pkg)));
 }
 
+TEST_F(HeteroGraph, Call_Custom_Kernel_Default_Backend)
+{
+    // in0 -> GCPUAdd -> tmp -> cpu::GClone -> GCPUBGR2Gray -> out
+    //            ^
+    //            |
+    // in1 -------`
+
+    cv::Mat in_mat1 = cv::Mat::eye(3, 3, CV_8UC3),
+            in_mat2 = cv::Mat::eye(3, 3, CV_8UC3),
+            out_mat;
+
+    auto pkg = cv::gapi::kernels<cpu::GClone>();
+    cv::GComputation(cv::GIn(in[0], in[1]), cv::GOut(out)).
+        apply(cv::gin(in_mat1, in_mat2), cv::gout(out_mat), cv::compile_args(pkg));
+
+    EXPECT_TRUE(checkCallKernel(KernelTags::CPU_CUSTOM_CLONE));
+}
+
+TEST_F(HeteroGraph, Call_Custom_Kernel_Not_Default_Backend)
+{
+    // in0 -> GCPUAdd -> tmp -> fluid::GClone -> GCPUBGR2Gray -> out
+    //            ^
+    //            |
+    // in1 -------`
+
+    cv::Mat in_mat1 = cv::Mat::eye(3, 3, CV_8UC3),
+            in_mat2 = cv::Mat::eye(3, 3, CV_8UC3),
+            out_mat;
+
+    auto pkg = cv::gapi::kernels<fluid::GClone>();
+    cv::GComputation(cv::GIn(in[0], in[1]), cv::GOut(out)).
+        apply(cv::gin(in_mat1, in_mat2), cv::gout(out_mat), cv::compile_args(pkg));
+
+    EXPECT_TRUE(checkCallKernel(KernelTags::FLUID_CUSTOM_CLONE));
+}
+
+TEST_F(HeteroGraph, Replace_Default_To_Same_Backend)
+{
+    // in0 -> GCPUAdd -> tmp -> cpu::GClone -> cpu::BGR2Gray -> out
+    //            ^
+    //            |
+    // in1 -------`
+
+    cv::Mat in_mat1 = cv::Mat::eye(3, 3, CV_8UC3),
+            in_mat2 = cv::Mat::eye(3, 3, CV_8UC3),
+            out_mat;
+
+    auto pkg = cv::gapi::kernels<cpu::GClone, cpu::BGR2Gray>();
+    cv::GComputation(cv::GIn(in[0], in[1]), cv::GOut(out)).
+        apply(cv::gin(in_mat1, in_mat2), cv::gout(out_mat), cv::compile_args(pkg));
+
+    EXPECT_TRUE(checkCallKernel(KernelTags::CPU_CUSTOM_BGR2GRAY));
+}
+
+TEST_F(HeteroGraph, Replace_Default_To_Another_Backend)
+{
+    //in0 -> GCPUAdd -> tmp -> cpu::GClone -> fluid::BGR2Gray -> out
+    //            ^
+    //            |
+    //in1 --------`
+
+    cv::Mat in_mat1(300, 300, CV_8UC3),
+            in_mat2(300, 300, CV_8UC3),
+            out_mat;
+
+    auto pkg = cv::gapi::kernels<cpu::GClone, fluid::BGR2Gray>();
+    cv::GComputation(cv::GIn(in[0], in[1]), cv::GOut(out)).
+        apply(cv::gin(in_mat1, in_mat2), cv::gout(out_mat), cv::compile_args(pkg));
+
+    EXPECT_TRUE(checkCallKernel(KernelTags::FLUID_CUSTOM_BGR2GRAY));
+}
+
+TEST_F(HeteroGraph, Use_Only_Same_Backend)
+{
+    //in0 -> cpu::GAdd -> tmp -> cpu::GClone -> cpu::BGR2Gray -> out
+    //            ^
+    //            |
+    //in1 --------`
+
+    cv::Mat in_mat1(300, 300, CV_8UC3),
+            in_mat2(300, 300, CV_8UC3),
+        out_mat;
+
+    auto pkg = cv::gapi::kernels<cpu::GAdd, cpu::GClone, cpu::BGR2Gray>();
+    cv::GComputation(cv::GIn(in[0], in[1]), cv::GOut(out)).
+        apply(cv::gin(in_mat1, in_mat2), cv::gout(out_mat), cv::compile_args(cv::gapi::use_only{pkg}));
+
+    EXPECT_TRUE(checkCallKernel(KernelTags::CPU_CUSTOM_ADD));
+    EXPECT_TRUE(checkCallKernel(KernelTags::CPU_CUSTOM_CLONE));
+    EXPECT_TRUE(checkCallKernel(KernelTags::CPU_CUSTOM_BGR2GRAY));
+}
+
+TEST_F(HeteroGraph, Use_Only_Another_Backend)
+{
+    //in0 -> fluid::GAdd -> tmp -> fluid::GClone -> fluid::BGR2Gray -> out
+    //            ^
+    //            |
+    //in1 --------`
+
+    cv::Mat in_mat1(300, 300, CV_8UC3),
+            in_mat2(300, 300, CV_8UC3),
+        out_mat;
+
+    auto pkg = cv::gapi::kernels<fluid::GAdd, fluid::GClone, fluid::BGR2Gray>();
+    cv::GComputation(cv::GIn(in[0], in[1]), cv::GOut(out)).
+        apply(cv::gin(in_mat1, in_mat2), cv::gout(out_mat), cv::compile_args(cv::gapi::use_only{pkg}));
+
+    EXPECT_TRUE(checkCallKernel(KernelTags::FLUID_CUSTOM_ADD));
+    EXPECT_TRUE(checkCallKernel(KernelTags::FLUID_CUSTOM_CLONE));
+    EXPECT_TRUE(checkCallKernel(KernelTags::FLUID_CUSTOM_BGR2GRAY));
+}
+
+TEST_F(HeteroGraph, Use_Only_Hetero_Backend)
+{
+    //in0 -> cpu::GAdd -> tmp -> fluid::GClone -> fluid::BGR2Gray -> out
+    //            ^
+    //            |
+    //in1 --------`
+
+    cv::Mat in_mat1(300, 300, CV_8UC3),
+            in_mat2(300, 300, CV_8UC3),
+        out_mat;
+
+    auto pkg = cv::gapi::kernels<cpu::GAdd, fluid::GClone, fluid::BGR2Gray>();
+    cv::GComputation(cv::GIn(in[0], in[1]), cv::GOut(out)).
+        apply(cv::gin(in_mat1, in_mat2), cv::gout(out_mat), cv::compile_args(cv::gapi::use_only{pkg}));
+
+    EXPECT_TRUE(checkCallKernel(KernelTags::CPU_CUSTOM_ADD));
+    EXPECT_TRUE(checkCallKernel(KernelTags::FLUID_CUSTOM_CLONE));
+    EXPECT_TRUE(checkCallKernel(KernelTags::FLUID_CUSTOM_BGR2GRAY));
+}
+
+TEST_F(HeteroGraph, Use_Only_Not_Found_Default)
+{
+    //in0 -> GCPUAdd -> tmp -> fluid::GClone -> fluid::BGR2Gray -> out
+    //            ^
+    //            |
+    //in1 --------`
+
+    cv::Mat in_mat1(300, 300, CV_8UC3),
+            in_mat2(300, 300, CV_8UC3),
+        out_mat;
+
+    auto pkg = cv::gapi::kernels<fluid::GClone, fluid::BGR2Gray>();
+    EXPECT_ANY_THROW(cv::GComputation(cv::GIn(in[0], in[1]), cv::GOut(out)).
+        apply(cv::gin(in_mat1, in_mat2), cv::gout(out_mat), cv::compile_args(cv::gapi::use_only{pkg})));
+}
+
+TEST_F(HeteroGraph, Use_Only_Not_Found_Custom)
+{
+    //in0 -> cpu::GAdd -> tmp -> fluid::GClone -> fluid::BGR2Gray -> out
+    //            ^
+    //            |
+    //in1 --------`
+
+    cv::Mat in_mat1(300, 300, CV_8UC3),
+            in_mat2(300, 300, CV_8UC3),
+        out_mat;
+
+    auto pkg = cv::gapi::kernels<cpu::GAdd, fluid::BGR2Gray>();
+    EXPECT_ANY_THROW(cv::GComputation(cv::GIn(in[0], in[1]), cv::GOut(out)).
+        apply(cv::gin(in_mat1, in_mat2), cv::gout(out_mat), cv::compile_args(cv::gapi::use_only{pkg})));
+}
+
+TEST_F(HeteroGraph, Use_Only_Other_Package_Ignored)
+{
+    //in0 -> cpu::GAdd -> tmp -> fluid::GClone -> fluid::BGR2Gray -> out
+    //            ^
+    //            |
+    //in1 --------`
+
+    cv::Mat in_mat1(300, 300, CV_8UC3),
+            in_mat2(300, 300, CV_8UC3),
+        out_mat;
+
+    auto pkg = cv::gapi::kernels<cpu::GAdd, fluid::BGR2Gray>();
+    auto clone_pkg = cv::gapi::kernels<cpu::GClone>();
+
+    EXPECT_ANY_THROW(cv::GComputation(cv::GIn(in[0], in[1]), cv::GOut(out)).
+        apply(cv::gin(in_mat1, in_mat2), cv::gout(out_mat),
+              cv::compile_args(clone_pkg, cv::gapi::use_only{pkg})));
+}
+
 } // namespace opencv_test

modules/gapi/test/internal/gapi_int_recompilation_test.cpp

@@ -197,8 +197,7 @@ TEST(GComputationCompile, ReshapeRois)
     cv::randn(first_in_mat, cv::Scalar::all(127), cv::Scalar::all(40.f));
     cv::Mat first_out_mat;
     auto fluidKernels = cv::gapi::combine(gapi::imgproc::fluid::kernels(),
-                                          gapi::core::fluid::kernels(),
+                                          gapi::core::fluid::kernels());
-                                          cv::unite_policy::REPLACE);
     cc.apply(first_in_mat, first_out_mat, cv::compile_args(fluidKernels));
     auto first_comp = cc.priv().m_lastCompiled;
 

modules/gapi/test/internal/gapi_int_resolve_kernel_test.cpp

@@ -1,119 +0,0 @@
-// This file is part of OpenCV project.
-// It is subject to the license terms in the LICENSE file found in the top-level directory
-// of this distribution and at http://opencv.org/license.html.
-//
-// Copyright (C) 2018 Intel Corporation
-
-
-#include "../test_precomp.hpp"
-
-#include "../gapi_mock_kernels.hpp"
-
-namespace opencv_test
-{
-
-TEST(Lookup, CreateOrder)
-{
-    const auto order = cv::gapi::lookup_order({Jupiter::backend(),
-                                               Saturn::backend()});
-    EXPECT_EQ(2u, order.size());
-    EXPECT_EQ(Jupiter::backend(), order[0]);
-    EXPECT_EQ(Saturn ::backend(), order[1]);
-}
-
-TEST(Lookup, NoOrder)
-{
-    namespace J = Jupiter;
-    namespace S = Saturn;
-    const auto pkg = cv::gapi::kernels<J::Foo, J::Bar, J::Baz,
-                                       S::Foo, S::Bar, S::Baz>();
-
-    EXPECT_NO_THROW (pkg.lookup<I::Foo>());
-    EXPECT_NO_THROW (pkg.lookup<I::Bar>());
-    EXPECT_NO_THROW (pkg.lookup<I::Baz>());
-    EXPECT_ANY_THROW(pkg.lookup<I::Qux>());
-}
-
-TEST(Lookup, Only_Jupiter)
-{
-    namespace J = Jupiter;
-    namespace S = Saturn;
-    const auto pkg = cv::gapi::kernels<J::Foo, J::Bar, J::Baz,
-                                       S::Foo, S::Bar, S::Baz>();
-
-    auto order = cv::gapi::lookup_order({J::backend()});
-
-    EXPECT_EQ(J::backend(), pkg.lookup<I::Foo>(order));
-    EXPECT_EQ(J::backend(), pkg.lookup<I::Bar>(order));
-    EXPECT_EQ(J::backend(), pkg.lookup<I::Baz>(order));
-    EXPECT_ANY_THROW(pkg.lookup<I::Qux>(order));
-}
-
-TEST(Lookup, Only_Saturn)
-{
-    namespace J = Jupiter;
-    namespace S = Saturn;
-    const auto pkg = cv::gapi::kernels<J::Foo, J::Bar, J::Baz,
-                                       S::Foo, S::Bar, S::Baz>();
-
-    auto order = cv::gapi::lookup_order({S::backend()});
-
-    EXPECT_EQ(S::backend(), pkg.lookup<I::Foo>(order));
-    EXPECT_EQ(S::backend(), pkg.lookup<I::Bar>(order));
-    EXPECT_EQ(S::backend(), pkg.lookup<I::Baz>(order));
-    EXPECT_ANY_THROW(pkg.lookup<I::Qux>(order));
-}
-
-TEST(Lookup, With_Order)
-{
-    namespace J = Jupiter;
-    namespace S = Saturn;
-    const auto pkg = cv::gapi::kernels<J::Foo, J::Bar, J::Baz,
-                                       S::Foo, S::Bar, S::Baz>();
-
-    auto prefer_j = cv::gapi::lookup_order({J::backend(), S::backend()});
-    EXPECT_EQ(J::backend(), pkg.lookup<I::Foo>(prefer_j));
-    EXPECT_EQ(J::backend(), pkg.lookup<I::Bar>(prefer_j));
-    EXPECT_EQ(J::backend(), pkg.lookup<I::Baz>(prefer_j));
-    EXPECT_ANY_THROW(pkg.lookup<I::Qux>(prefer_j));
-
-    auto prefer_s = cv::gapi::lookup_order({S::backend(), J::backend()});
-    EXPECT_EQ(S::backend(), pkg.lookup<I::Foo>(prefer_s));
-    EXPECT_EQ(S::backend(), pkg.lookup<I::Bar>(prefer_s));
-    EXPECT_EQ(S::backend(), pkg.lookup<I::Baz>(prefer_s));
-    EXPECT_ANY_THROW(pkg.lookup<I::Qux>(prefer_s));
-}
-
-TEST(Lookup, NoOverlap)
-{
-    namespace J = Jupiter;
-    namespace S = Saturn;
-    const auto pkg = cv::gapi::kernels<J::Foo, J::Bar, S::Baz, S::Qux>();
-    EXPECT_EQ(J::backend(), pkg.lookup<I::Foo>());
-    EXPECT_EQ(J::backend(), pkg.lookup<I::Bar>());
-    EXPECT_EQ(S::backend(), pkg.lookup<I::Baz>());
-    EXPECT_EQ(S::backend(), pkg.lookup<I::Qux>());
-}
-
-TEST(Lookup, ExtraBackend)
-{
-    namespace J = Jupiter;
-    namespace S = Saturn;
-    const auto pkg = cv::gapi::kernels<J::Foo, J::Bar, J::Baz>();
-
-    // Even if pkg doesn't contain S kernels while S is preferable,
-    // it should work.
-    const auto prefer_sj = cv::gapi::lookup_order({S::backend(), J::backend()});
-    EXPECT_EQ(J::backend(), pkg.lookup<I::Foo>(prefer_sj));
-    EXPECT_EQ(J::backend(), pkg.lookup<I::Bar>(prefer_sj));
-    EXPECT_EQ(J::backend(), pkg.lookup<I::Baz>(prefer_sj));
-
-    // If search scope is limited to S only, neither J nor S  kernels
-    // shouldn't be found
-    const auto only_s = cv::gapi::lookup_order({S::backend()});
-    EXPECT_ANY_THROW(pkg.lookup<I::Foo>(only_s));
-    EXPECT_ANY_THROW(pkg.lookup<I::Bar>(only_s));
-    EXPECT_ANY_THROW(pkg.lookup<I::Baz>(only_s));
-}
-
-} // namespace opencv_test

samples/cpp/tutorial_code/gapi/porting_anisotropic_image_segmentation/porting_anisotropic_image_segmentation_gapi_fluid.cpp

@@ -65,8 +65,7 @@ int main()
     // Prepare the kernel package and run the graph
     cv::gapi::GKernelPackage fluid_kernels = cv::gapi::combine        // Define a custom kernel package:
         (cv::gapi::core::fluid::kernels(),                            // ...with Fluid Core kernels
-         cv::gapi::imgproc::fluid::kernels(),                         // ...and Fluid ImgProc kernels
+         cv::gapi::imgproc::fluid::kernels());                        // ...and Fluid ImgProc kernels
-         cv::unite_policy::KEEP);
     //! [kernel_pkg]
     //! [kernel_hotfix]
     fluid_kernels.remove<cv::gapi::imgproc::GBoxFilter>();            // Remove Fluid Box filter as unsuitable,