Add handle to configure async/sync infer mode

modules/gapi/include/opencv2/gapi/infer/ie.hpp

@@ -88,6 +88,9 @@ struct ParamDesc {
 
     cv::optional<cv::gapi::wip::onevpl::Device> vpl_preproc_device;
     cv::optional<cv::gapi::wip::onevpl::Context> vpl_preproc_ctx;
+
+    enum InferMode {Sync, Async};
+    InferMode mode;
 };
 } // namespace detail
 
@@ -132,7 +135,8 @@ public:
               , {}
               , {}
               , {}
-              , {}} {
+              , {}
+              , detail::ParamDesc::InferMode::Async} {
     };
 
     /** @overload
@@ -156,7 +160,8 @@ public:
               , {}
               , {}
               , {}
-              , {}} {
+              , {}
+              , detail::ParamDesc::InferMode::Async} {
     };
 
     /** @brief Specifies sequence of network input layers names for inference.
@@ -351,6 +356,22 @@ public:
         return *this;
     }
 
+    /** @brief Specifies which api will be used to run inference.
+
+    The function is used to specify mode for OpenVINO inference.
+    OpenVINO has two options to run inference:
+    1. Asynchronous (using StartAsync: https://docs.openvino.ai/latest/classInferenceEngine_1_1InferRequest.html#doxid-class-inference-engine-1-1-infer-request-1a405293e8423d82a5b45f642a3bef0d24)
+    2. Synchronous (using Infer: https://docs.openvino.ai/latest/classInferenceEngine_1_1InferRequest.html#doxid-class-inference-engine-1-1-infer-request-1a3391ce30894abde730523e9ca9371ce8)
+    By default asynchronous mode is used.
+
+    @param mode Inference mode which will be used.
+    @return reference to this parameter structure.
+    */
+    Params<Net>& cfgInferMode(detail::ParamDesc::InferMode mode) {
+        desc.mode = mode;
+        return *this;
+    }
+
     // BEGIN(G-API's network parametrization API)
     GBackend      backend()    const { return cv::gapi::ie::backend();  }
     std::string   tag()        const { return Net::tag(); }
@@ -385,7 +406,8 @@ public:
            const std::string &device)
         : desc{ model, weights, device, {}, {}, {}, 0u, 0u,
                 detail::ParamDesc::Kind::Load, true, {}, {}, {}, 1u,
-                {}, {}, {}, {}},
+                {}, {}, {}, {},
+                detail::ParamDesc::InferMode::Async },
           m_tag(tag) {
     };
 
@@ -403,7 +425,8 @@ public:
            const std::string &device)
         : desc{ model, {}, device, {}, {}, {}, 0u, 0u,
                 detail::ParamDesc::Kind::Import, true, {}, {}, {}, 1u,
-                {}, {}, {}, {}},
+                {}, {}, {}, {},
+                detail::ParamDesc::InferMode::Async },
           m_tag(tag) {
     };
 
@@ -476,6 +499,12 @@ public:
         return *this;
     }
 
+    /** @see ie::Params::cfgInferAPI */
+    Params& cfgInferMode(detail::ParamDesc::InferMode mode) {
+        desc.mode = mode;
+        return *this;
+    }
+
     // BEGIN(G-API's network parametrization API)
     GBackend      backend()    const { return cv::gapi::ie::backend();  }
     std::string   tag()        const { return m_tag; }

modules/gapi/src/backends/ie/giebackend.cpp

@@ -375,6 +375,12 @@ struct IEUnit {
                                     params.vpl_preproc_ctx.value());
             GAPI_LOG_INFO(nullptr, "VPP preproc created successfuly");
         }
+
+        if (params.mode == cv::gapi::ie::detail::ParamDesc::InferMode::Sync &&
+            params.nireq != 1u) {
+            throw std::logic_error(
+                    "Failed: ParamDesc::InferMode::Sync works only with nireq equal to 1.");
+        }
     }
 
     // This method is [supposed to be] called at Island compilation stage
@@ -911,7 +917,8 @@ void AsyncInferExecutor::callback(IInferExecutor::Task task,
 class cv::gimpl::ie::RequestPool {
 public:
 
-    explicit RequestPool(std::vector<InferenceEngine::InferRequest>&& requests);
+    explicit RequestPool(cv::gapi::ie::detail::ParamDesc::InferMode   mode,
+                         std::vector<InferenceEngine::InferRequest>&& requests);
 
     IInferExecutor::Ptr getIdleRequest();
     void waitAll();
@@ -929,11 +936,23 @@ void cv::gimpl::ie::RequestPool::release(const size_t id) {
 }
 
 // RequestPool implementation //////////////////////////////////////////////
-cv::gimpl::ie::RequestPool::RequestPool(std::vector<InferenceEngine::InferRequest>&& requests) {
+cv::gimpl::ie::RequestPool::RequestPool(cv::gapi::ie::detail::ParamDesc::InferMode   mode,
+                                        std::vector<InferenceEngine::InferRequest>&& requests) {
     for (size_t i = 0; i < requests.size(); ++i) {
-        m_requests.emplace_back(
-                std::make_shared<AsyncInferExecutor>(std::move(requests[i]),
-                                                     std::bind(&RequestPool::release, this, i)));
+        IInferExecutor::Ptr iexec = nullptr;
+        switch (mode) {
+            case cv::gapi::ie::detail::ParamDesc::InferMode::Async:
+                iexec = std::make_shared<AsyncInferExecutor>(std::move(requests[i]),
+                                                             std::bind(&RequestPool::release, this, i));
+                break;
+            case cv::gapi::ie::detail::ParamDesc::InferMode::Sync:
+                iexec = std::make_shared<SyncInferExecutor>(std::move(requests[i]),
+                                                             std::bind(&RequestPool::release, this, i));
+                break;
+            default:
+                GAPI_Assert(false && "Unsupported ParamDesc::InferMode");
+        }
+        m_requests.emplace_back(std::move(iexec));
     }
     setup();
 }
@@ -974,7 +993,7 @@ cv::gimpl::ie::GIEExecutable::GIEExecutable(const ade::Graph &g,
             if (this_nh == nullptr) {
                 this_nh = nh;
                 this_iec = iem.metadata(this_nh).get<IEUnit>().compile();
-                m_reqPool.reset(new RequestPool(this_iec.createInferRequests()));
+                m_reqPool.reset(new RequestPool(this_iec.params.mode, this_iec.createInferRequests()));
             }
             else
                 util::throw_error(std::logic_error("Multi-node inference is not supported!"));