dnn(ie): separate IECore for different devices

- HETERO plugin doesn't switch well between devices

modules/dnn/src/dnn.cpp

@@ -108,7 +108,7 @@ public:
     {
 #if INF_ENGINE_VER_MAJOR_GE(INF_ENGINE_RELEASE_2019R3)
         // Lightweight detection
-        const std::vector<std::string> devices = getCore().GetAvailableDevices();
+        const std::vector<std::string> devices = getCore("").GetAvailableDevices();
         for (std::vector<std::string>::const_iterator i = devices.begin(); i != devices.end(); ++i)
         {
             if (std::string::npos != i->find("MYRIAD") && target == DNN_TARGET_MYRIAD)
@@ -3253,7 +3253,7 @@ Net Net::readFromModelOptimizer(const String& xml, const String& bin)
 
     InferenceEngine::CNNNetwork ieNet = reader.getNetwork();
 #else
-    InferenceEngine::Core& ie = getCore();
+    InferenceEngine::Core& ie = getCore("");
     InferenceEngine::CNNNetwork ieNet = ie.ReadNetwork(xml, bin);
 #endif
 
@@ -3302,7 +3302,7 @@ Net Net::readFromModelOptimizer(
 
     InferenceEngine::CNNNetwork ieNet = reader.getNetwork();
 #else
-    InferenceEngine::Core& ie = getCore();
+    InferenceEngine::Core& ie = getCore("");
 
     std::string model; model.assign((char*)bufferModelConfigPtr, bufferModelConfigSize);
 

modules/dnn/src/ie_ngraph.cpp

@@ -524,7 +524,7 @@ void InfEngineNgraphNet::initPlugin(InferenceEngine::CNNNetwork& net)
     try
     {
         AutoLock lock(getInitializationMutex());
-        InferenceEngine::Core& ie = getCore();
+        InferenceEngine::Core& ie = getCore(device_name);
         {
             isInit = true;
             std::vector<std::string> candidates;

modules/dnn/src/op_inf_engine.cpp

@@ -604,18 +604,31 @@ static bool init_IE_plugins()
     (void)init_core->GetAvailableDevices();
     return true;
 }
-static InferenceEngine::Core& create_IE_Core_instance()
+static InferenceEngine::Core& retrieveIECore(const std::string& id, std::map<std::string, std::shared_ptr<InferenceEngine::Core> >& cores)
 {
-    static InferenceEngine::Core core;
-    return core;
+    AutoLock lock(getInitializationMutex());
+    std::map<std::string, std::shared_ptr<InferenceEngine::Core> >::iterator i = cores.find(id);
+    if (i == cores.end())
+    {
+        std::shared_ptr<InferenceEngine::Core> core = std::make_shared<InferenceEngine::Core>();
+        cores[id] = core;
+        return *core.get();
+    }
+    return *(i->second).get();
 }
-static InferenceEngine::Core& create_IE_Core_pointer()
+static InferenceEngine::Core& create_IE_Core_instance(const std::string& id)
+{
+    static std::map<std::string, std::shared_ptr<InferenceEngine::Core> > cores;
+    return retrieveIECore(id, cores);
+}
+static InferenceEngine::Core& create_IE_Core_pointer(const std::string& id)
 {
     // load and hold IE plugins
-    static InferenceEngine::Core* core = new InferenceEngine::Core();  // 'delete' is never called
-    return *core;
+    static std::map<std::string, std::shared_ptr<InferenceEngine::Core> >* cores =
+            new std::map<std::string, std::shared_ptr<InferenceEngine::Core> >();
+    return retrieveIECore(id, *cores);
 }
-InferenceEngine::Core& getCore()
+InferenceEngine::Core& getCore(const std::string& id)
 {
     // to make happy memory leak tools use:
     // - OPENCV_DNN_INFERENCE_ENGINE_HOLD_PLUGINS=0
@@ -631,9 +644,10 @@ InferenceEngine::Core& getCore()
                 false
 #endif
             );
-    static InferenceEngine::Core& core = param_DNN_INFERENCE_ENGINE_CORE_LIFETIME_WORKAROUND
-            ? create_IE_Core_pointer()
-            : create_IE_Core_instance();
+
+    InferenceEngine::Core& core = param_DNN_INFERENCE_ENGINE_CORE_LIFETIME_WORKAROUND
+            ? create_IE_Core_pointer(id)
+            : create_IE_Core_instance(id);
     return core;
 }
 #endif
@@ -641,9 +655,10 @@ InferenceEngine::Core& getCore()
 #if !defined(OPENCV_DNN_IE_VPU_TYPE_DEFAULT)
 static bool detectMyriadX_()
 {
+    AutoLock lock(getInitializationMutex());
 #if INF_ENGINE_VER_MAJOR_GE(INF_ENGINE_RELEASE_2019R3)
     // Lightweight detection
-    InferenceEngine::Core& ie = getCore();
+    InferenceEngine::Core& ie = getCore("MYRIAD");
     const std::vector<std::string> devices = ie.GetAvailableDevices();
     for (std::vector<std::string>::const_iterator i = devices.begin(); i != devices.end(); ++i)
     {
@@ -687,7 +702,6 @@ static bool detectMyriadX_()
 #if INF_ENGINE_VER_MAJOR_LE(INF_ENGINE_RELEASE_2019R1)
     InferenceEngine::InferenceEnginePluginPtr enginePtr;
     {
-        AutoLock lock(getInitializationMutex());
         auto& sharedPlugins = getSharedPlugins();
         auto pluginIt = sharedPlugins.find("MYRIAD");
         if (pluginIt != sharedPlugins.end()) {
@@ -706,9 +720,9 @@ static bool detectMyriadX_()
     try
     {
 #if INF_ENGINE_VER_MAJOR_LE(INF_ENGINE_RELEASE_2019R3)
-        auto netExec = getCore().LoadNetwork(cnn, "MYRIAD", {{"VPU_PLATFORM", "VPU_2480"}});
+        auto netExec = getCore("MYRIAD").LoadNetwork(cnn, "MYRIAD", {{"VPU_PLATFORM", "VPU_2480"}});
 #else
-        auto netExec = getCore().LoadNetwork(cnn, "MYRIAD", {{"VPU_MYRIAD_PLATFORM", "VPU_MYRIAD_2480"}});
+        auto netExec = getCore("MYRIAD").LoadNetwork(cnn, "MYRIAD", {{"VPU_MYRIAD_PLATFORM", "VPU_MYRIAD_2480"}});
 #endif
 #endif
         auto infRequest = netExec.CreateInferRequest();
@@ -739,7 +753,7 @@ void InfEngineBackendNet::initPlugin(InferenceEngine::CNNNetwork& net)
         }
         else
 #else
-        InferenceEngine::Core& ie = getCore();
+        InferenceEngine::Core& ie = getCore(device_name);
 #endif
         {
 #if INF_ENGINE_VER_MAJOR_LE(INF_ENGINE_RELEASE_2019R1)
@@ -1124,7 +1138,7 @@ void resetMyriadDevice()
     getSharedPlugins().erase("MYRIAD");
 #else
     // Unregister both "MYRIAD" and "HETERO:MYRIAD,CPU" plugins
-    InferenceEngine::Core& ie = getCore();
+    InferenceEngine::Core& ie = getCore("MYRIAD");
     try
     {
         ie.UnregisterPlugin("MYRIAD");

modules/dnn/src/op_inf_engine.hpp

@@ -245,7 +245,7 @@ bool isMyriadX();
 
 CV__DNN_EXPERIMENTAL_NS_END
 
-InferenceEngine::Core& getCore();
+InferenceEngine::Core& getCore(const std::string& id);
 
 template<typename T = size_t>
 static inline std::vector<T> getShape(const Mat& mat)