Example of synchronous error handling

This example is specifically about a handler which fails to find a valid device. This should fix #105.

Author: RossBrunton

samples/sync-handler/CMakeLists.txt

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+set(SOURCE_NAME "sync-handler")
+add_executable(
+ ${SOURCE_NAME}
+ ${CMAKE_CURRENT_SOURCE_DIR}/${SOURCE_NAME}.cpp
+)
+add_sycl_to_target(
+ TARGET ${SOURCE_NAME}
+ SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/${SOURCE_NAME}.cpp
+)
+add_test(
+ NAME ${SOURCE_NAME}
+ COMMAND ${SOURCE_NAME}
+)
+install(
+ TARGETS ${SOURCE_NAME}
+ RUNTIME DESTINATION bin
+)

samples/sync-handler/sync-handler.cpp

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+/***************************************************************************
+ *
+ * Copyright (C) 2018 Codeplay Software Limited
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * For your convenience, a copy of the License has been included in this
+ * repository.
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Codeplay's ComputeCpp SDK
+ *
+ * sync-handler.cpp
+ *
+ * Description:
+ * Sample code that demonstrates the use of a synchronous error handler to
+ * demonstrate error handling.
+ *
+ **************************************************************************/
+
+#include <CL/sycl.hpp>
+
+#include <iostream>
+
+using namespace cl::sycl;
+
+namespace {
+class Worker;
+
+/* A custom device selector */
+class PickySelector : public device_selector {
+ int operator()(const device&) const final {
+ /* Here logic would exist to find a specific device to do our computation
+ * with. As this is just an example, it's hardcoded to find nothing. In a
+ * real program, it would inspect the device information and return priority
+ * numbers depending on that device's suitablity. */
+ return -1;
+ }
+};
+} // namespace
+
+int main() {
+ /* Our output array */
+ constexpr size_t number_of_sevens = 7;
+ std::array<size_t, number_of_sevens> sevens;
+
+ try {
+ /* Use our custom device selector to find a specific device. In this example
+ * we require a very specific piece of hardware. If that isn't present, the
+ * code should just run on the host. */
+ PickySelector selector;
+
+ /* Attempt to create a queue for this using this selector. If the selector
+ * fails to find a device, this will throw an exception. */
+ queue myQueue(selector);
+
+ /* If the selector couldn't find a suitable device, the following code
+ * will not run. */
+ buffer<size_t, 1> buf(sevens.data(), range<1>(number_of_sevens));
+ myQueue.submit([&](handler& cgh) {
+ auto ptr = buf.get_access<access::mode::discard_write>(cgh);
+ cgh.parallel_for<Worker>(range<1>(number_of_sevens),
+ [=](item<1> item) { ptr[item] = 7; });
+ });
+ } catch (const exception& e) {
+ /* Report the exception to the user. */
+ std::cerr << "SYCL exception caught: " << e.what() << "\n";
+ std::cerr << "Running on host...\n";
+
+ /* Can't find any suitable devices, so just run the code on the host
+ * system normally. */
+ sevens.fill(7);
+ }
+
+ /* Check the array has been populated with sevens correctly. */
+ if (std::any_of(sevens.begin(), sevens.end(),
+ [](const auto x) { return x != 7; })) {
+ std::cerr << "A seven was not set!\n";
+ return 1;
+ }
+
+ return 0;
+}