IVGCVSW-1987 : registry for backend creation functions (factories)

Change-Id: I13d2d3dc763e1d05dffddb34472bd4f9e632c776

8 files changed, 196 insertions, 3 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 669c92fd3f..501da806ad 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -378,6 +378,7 @@ if(BUILD_UNIT_TESTS)
         src/armnn/test/InstrumentTests.cpp
         src/armnn/test/ObservableTest.cpp
         src/armnn/test/OptionalTest.cpp
+        src/backends/test/BackendRegistryTests.cpp
         src/backends/test/IsLayerSupportedTestImpl.hpp
         src/backends/test/WorkloadDataValidation.cpp
         src/backends/test/TensorCopyUtils.hpp
diff --git a/include/armnn/Types.hpp b/include/armnn/Types.hpp
index 12ecda0c39..b7ee9472a3 100644
--- a/include/armnn/Types.hpp
+++ b/include/armnn/Types.hpp
@@ -117,7 +117,8 @@ public:
     virtual const ILayerSupport& GetLayerSupport() const = 0;
 };
 
-using IBackendPtr = std::shared_ptr<IBackend>;
+using IBackendSharedPtr = std::shared_ptr<IBackend>;
+using IBackendUniquePtr = std::unique_ptr<IBackend, void(*)(IBackend* backend)>;
 
 /// Device specific knowledge to be passed to the optimizer.
 class IDeviceSpec
diff --git a/src/armnn/DeviceSpec.hpp b/src/armnn/DeviceSpec.hpp
index dbc04f0af6..34acbcbdec 100644
--- a/src/armnn/DeviceSpec.hpp
+++ b/src/armnn/DeviceSpec.hpp
@@ -17,9 +17,9 @@ public:
     DeviceSpec() {}
     virtual ~DeviceSpec() {}
 
-    virtual std::vector<IBackendPtr> GetBackends() const
+    virtual std::vector<IBackendSharedPtr> GetBackends() const
     {
-        return std::vector<IBackendPtr>();
+        return std::vector<IBackendSharedPtr>();
     }
 
     std::set<Compute> m_SupportedComputeDevices;
diff --git a/src/backends/BackendRegistry.cpp b/src/backends/BackendRegistry.cpp
new file mode 100644
index 0000000000..68336c45b9
--- /dev/null
+++ b/src/backends/BackendRegistry.cpp
@@ -0,0 +1,45 @@
+//
+// Copyright © 2017 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#include "BackendRegistry.hpp"
+#include <armnn/Exceptions.hpp>
+
+namespace armnn
+{
+
+BackendRegistry& BackendRegistry::Instance()
+{
+    static BackendRegistry instance;
+    return instance;
+}
+
+void BackendRegistry::Register(const std::string& name, FactoryFunction factory)
+{
+    if (m_BackendFactories.count(name) > 0)
+    {
+        throw InvalidArgumentException(name + " already registered as backend");
+    }
+
+    m_BackendFactories[name] = factory;
+}
+
+BackendRegistry::FactoryFunction BackendRegistry::GetFactory(const std::string& name) const
+{
+    auto it = m_BackendFactories.find(name);
+    if (it == m_BackendFactories.end())
+    {
+        throw InvalidArgumentException(name + " has no backend factory registered");
+    }
+
+    return it->second;
+}
+
+void BackendRegistry::Swap(BackendRegistry::FactoryStorage& other)
+{
+    BackendRegistry& instance = Instance();
+    std::swap(instance.m_BackendFactories, other);
+}
+
+}
diff --git a/src/backends/BackendRegistry.hpp b/src/backends/BackendRegistry.hpp
new file mode 100644
index 0000000000..ff01d21715
--- /dev/null
+++ b/src/backends/BackendRegistry.hpp
@@ -0,0 +1,52 @@
+//
+// Copyright © 2017 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+#pragma once
+
+#include <armnn/Types.hpp>
+#include <string>
+#include <functional>
+#include <memory>
+#include <unordered_map>
+
+namespace armnn
+{
+
+class IBackend;
+
+class BackendRegistry
+{
+public:
+    using FactoryFunction = std::function<IBackendUniquePtr()>;
+
+    static BackendRegistry& Instance();
+    void Register(const std::string& name, FactoryFunction factory);
+    FactoryFunction GetFactory(const std::string& name) const;
+
+    struct Helper
+    {
+        Helper(const std::string& name, FactoryFunction factory)
+        {
+            BackendRegistry::Instance().Register(name, factory);
+        }
+    };
+
+    size_t Size() const { return m_BackendFactories.size(); }
+
+protected:
+    using FactoryStorage = std::unordered_map<std::string, FactoryFunction>;
+
+    // For testing only
+    static void Swap(FactoryStorage& other);
+    BackendRegistry() {}
+    ~BackendRegistry() {}
+
+private:
+    BackendRegistry(const BackendRegistry&) = delete;
+    BackendRegistry& operator=(const BackendRegistry&) = delete;
+
+    FactoryStorage m_BackendFactories;
+};
+
+} // namespace armnn
diff --git a/src/backends/CMakeLists.txt b/src/backends/CMakeLists.txt
index ea5ad7814c..0bc6888899 100644
--- a/src/backends/CMakeLists.txt
+++ b/src/backends/CMakeLists.txt
@@ -4,6 +4,8 @@
 #
 
 list(APPEND armnnBackendsCommon_sources
+    BackendRegistry.cpp
+    BackendRegistry.hpp
     CpuTensorHandle.cpp
     CpuTensorHandleFwd.hpp
     CpuTensorHandle.hpp
diff --git a/src/backends/common.mk b/src/backends/common.mk
index e65281a1a4..99c6e12a3e 100644
--- a/src/backends/common.mk
+++ b/src/backends/common.mk
@@ -8,6 +8,7 @@
 # file in the root of ArmNN
 
 COMMON_SOURCES := \
+    BackendRegistry.cpp \
     CpuTensorHandle.cpp \
     MemCopyWorkload.cpp \
     OutputHandler.cpp \
diff --git a/src/backends/test/BackendRegistryTests.cpp b/src/backends/test/BackendRegistryTests.cpp
new file mode 100644
index 0000000000..e895df63a6
--- /dev/null
+++ b/src/backends/test/BackendRegistryTests.cpp
@@ -0,0 +1,91 @@
+//
+// Copyright © 2017 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+#include <boost/test/unit_test.hpp>
+
+#include <backends/BackendRegistry.hpp>
+#include <armnn/Types.hpp>
+
+namespace
+{
+
+class SwapRegistryStorage : public armnn::BackendRegistry
+{
+public:
+    SwapRegistryStorage() : armnn::BackendRegistry()
+    {
+        Swap(m_TempStorage);
+    }
+
+    ~SwapRegistryStorage()
+    {
+        Swap(m_TempStorage);
+    }
+
+private:
+    BackendRegistry::FactoryStorage m_TempStorage;
+};
+
+}
+
+BOOST_AUTO_TEST_SUITE(BackendRegistryTests)
+
+BOOST_AUTO_TEST_CASE(SwapRegistry)
+{
+    using armnn::BackendRegistry;
+    auto nFactories = BackendRegistry::Instance().Size();
+    {
+        SwapRegistryStorage helper;
+        BOOST_TEST(BackendRegistry::Instance().Size() == 0);
+    }
+    BOOST_TEST(BackendRegistry::Instance().Size() == nFactories);
+}
+
+BOOST_AUTO_TEST_CASE(TestRegistryHelper)
+{
+    using armnn::BackendRegistry;
+    SwapRegistryStorage helper;
+
+    bool called = false;
+    BackendRegistry::Helper factoryHelper("HelloWorld", [&called]() {
+        called = true;
+        return armnn::IBackendUniquePtr(nullptr, nullptr);
+    } );
+
+    // sanity check: the factory has not been called yet
+    BOOST_TEST(called == false);
+
+    auto factoryFunction = BackendRegistry::Instance().GetFactory("HelloWorld");
+
+    // sanity check: the factory still not called
+    BOOST_TEST(called == false);
+
+    factoryFunction();
+    BOOST_TEST(called == true);
+}
+
+BOOST_AUTO_TEST_CASE(TestDirectCallToRegistry)
+{
+    using armnn::BackendRegistry;
+    SwapRegistryStorage helper;
+
+    bool called = false;
+    BackendRegistry::Instance().Register("HelloWorld", [&called]() {
+        called = true;
+        return armnn::IBackendUniquePtr(nullptr, nullptr);
+    } );
+
+    // sanity check: the factory has not been called yet
+    BOOST_TEST(called == false);
+
+    auto factoryFunction = BackendRegistry::Instance().GetFactory("HelloWorld");
+
+    // sanity check: the factory still not called
+    BOOST_TEST(called == false);
+
+    factoryFunction();
+    BOOST_TEST(called == true);
+}
+
+BOOST_AUTO_TEST_SUITE_END()