From 9a61fa6bdc8724cc66eba532360e0e48b6b1a60e Mon Sep 17 00:00:00 2001
From: Matthew Bentham <Matthew.Bentham@arm.com>
Date: Tue, 4 Feb 2020 10:03:55 +0000
Subject: Github #273 Handle failure to initialise BackendContext in Runtime

Define CreateBackendContext to throw BackendUnavailableException
if necessary runtime components are missing.

Handle this in the constructor of Runtime by not adding those
backends to the internal DeviceSpec owned by the Runtime.

Signed-off-by: Matthew Bentham <Matthew.Bentham@arm.com>
Change-Id: Iadffb5240e32e1f105683c4d361276b92d1e720c
---
 src/armnn/DeviceSpec.hpp |  4 +++-
 src/armnn/Runtime.cpp    | 13 +++++++++----
 src/armnn/Runtime.hpp    |  2 --
 3 files changed, 12 insertions(+), 7 deletions(-)

(limited to 'src/armnn')

diff --git a/src/armnn/DeviceSpec.hpp b/src/armnn/DeviceSpec.hpp
index 703a4b123f..a1457cf80e 100644
--- a/src/armnn/DeviceSpec.hpp
+++ b/src/armnn/DeviceSpec.hpp
@@ -14,6 +14,9 @@ namespace armnn
 class DeviceSpec : public IDeviceSpec
 {
 public:
+    DeviceSpec()
+    {}
+
     DeviceSpec(const BackendIdSet& supportedBackends)
         : m_SupportedBackends{supportedBackends} {}
 
@@ -48,7 +51,6 @@ public:
     }
 
 private:
-    DeviceSpec() = delete;
     BackendIdSet m_SupportedBackends;
     BackendIdSet m_DynamicBackends;
 };
diff --git a/src/armnn/Runtime.cpp b/src/armnn/Runtime.cpp
index 2d7269a09c..47c998a6fd 100644
--- a/src/armnn/Runtime.cpp
+++ b/src/armnn/Runtime.cpp
@@ -153,7 +153,6 @@ const std::shared_ptr<IProfiler> Runtime::GetProfiler(NetworkId networkId) const
 
 Runtime::Runtime(const CreationOptions& options)
     : m_NetworkIdCounter(0)
-    , m_DeviceSpec{BackendRegistryInstance().GetBackendIds()}
 {
     ARMNN_LOG(info) << "ArmNN v" << ARMNN_VERSION << "\n";
 
@@ -164,12 +163,11 @@ Runtime::Runtime(const CreationOptions& options)
     // goes through the backend registry
     LoadDynamicBackends(options.m_DynamicBackendsPath);
 
+    BackendIdSet supportedBackends;
     for (const auto& id : BackendRegistryInstance().GetBackendIds())
     {
         // Store backend contexts for the supported ones
-        const BackendIdSet& supportedBackends = m_DeviceSpec.GetSupportedBackends();
-        if (supportedBackends.find(id) != supportedBackends.end())
-        {
+        try {
             auto factoryFun = BackendRegistryInstance().GetFactory(id);
             auto backend = factoryFun();
             BOOST_ASSERT(backend.get() != nullptr);
@@ -182,8 +180,15 @@ Runtime::Runtime(const CreationOptions& options)
             {
                 m_BackendContexts.emplace(std::make_pair(id, std::move(context)));
             }
+            supportedBackends.emplace(id);
+        }
+        catch (const BackendUnavailableException&)
+        {
+            // Ignore backends which are unavailable
         }
+
     }
+    m_DeviceSpec.AddSupportedBackends(supportedBackends);
 }
 
 Runtime::~Runtime()
diff --git a/src/armnn/Runtime.hpp b/src/armnn/Runtime.hpp
index e5debbf9ac..2ad3c9633c 100644
--- a/src/armnn/Runtime.hpp
+++ b/src/armnn/Runtime.hpp
@@ -73,8 +73,6 @@ public:
     virtual void RegisterDebugCallback(NetworkId networkId, const DebugCallbackFunction& func) override;
 
     /// Creates a runtime for workload execution.
-    /// May throw a ClRuntimeUnavailableException if @a defaultComputeDevice requires a CL runtime but
-    /// it cannot be setup for some reason.
     Runtime(const CreationOptions& options);
 
     ~Runtime();
-- 
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