iox-eclipse-iceoryx#2301 PoC for 32-64 bit mixed mode

iceoryx_examples/mixed_mode_poc/CMakeLists.txt

@@ -0,0 +1,41 @@
+# Copyright (c) 2024 by ekxide IO GmbH. All rights reserved.
+#
+# 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
+#
+# 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.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.16)
+project(example_mixed_mode_poc)
+
+find_package(iceoryx_platform REQUIRED)
+find_package(iceoryx_hoofs CONFIG REQUIRED)
+
+include(IceoryxPackageHelper)
+include(IceoryxPlatform)
+include(IceoryxPlatformSettings)
+
+iox_add_executable(
+    TARGET      mixed-mode-poc-leader
+    FILES       mixed_mode_poc_leader.cpp
+    LIBS        iceoryx_hoofs::iceoryx_hoofs
+)
+
+iox_add_executable(
+    TARGET      mixed-mode-poc-follower
+    FILES       mixed_mode_poc_follower.cpp
+    LIBS        iceoryx_hoofs::iceoryx_hoofs
+)
+
+if(USE_EXPLICIT_ALIGNMENT)
+    target_compile_definitions(mixed-mode-poc-follower PUBLIC USE_EXPLICIT_ALIGNMENT)
+endif()

iceoryx_examples/mixed_mode_poc/mixed_mode_poc_common.hpp

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+// Copyright (c) 2024 by ekxide IO GmbH. All rights reserved.
+//
+// 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
+//
+// 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.
+//
+// SPDX-License-Identifier: Apache-2.0
+
+#ifndef IOX_MIXED_MODE_POC_COMMON_HPP
+#define IOX_MIXED_MODE_POC_COMMON_HPP
+
+#include "iox/logging.hpp"
+#include "iox/mutex.hpp"
+#include "iox/posix_shared_memory_object.hpp"
+#include "iox/unnamed_semaphore.hpp"
+
+#include <atomic>
+#include <cstdint>
+#include <thread>
+
+#ifdef USE_EXPLICIT_ALIGNMENT
+#define ALIGNAS(n) alignas(n)
+#else
+#define ALIGNAS(n)
+#endif
+
+constexpr uint64_t ITERATIONS{50000000};
+
+class PoorMansSpinSemaphore
+{
+  public:
+    void post()
+    {
+        counter++;
+    }
+
+    void wait()
+    {
+        while (counter == 0)
+        {
+            std::this_thread::yield();
+        }
+        counter--;
+    }
+
+  private:
+    std::atomic<int32_t> counter{0};
+};
+
+struct SharedData
+{
+    PoorMansSpinSemaphore leader_barrier;
+    PoorMansSpinSemaphore follower_barrier;
+    ALIGNAS(8) uint8_t dummy0{0};
+    uint8_t dummy1{0};
+    ALIGNAS(8) volatile uint64_t non_atomic_counter{0};
+    uint8_t dummy2{0};
+    ALIGNAS(8) std::atomic<uint64_t> atomic_counter{0};
+};
+
+auto print_sizes()
+{
+    IOX_LOG(INFO, "Size of shared data: " << sizeof(SharedData));
+    IOX_LOG(INFO, "Size of iox::UnnamedSemaphore: " << sizeof(iox::UnnamedSemaphore));
+    IOX_LOG(INFO, "Size of POSIX sem_t: " << sizeof(sem_t));
+    IOX_LOG(INFO, "Size of iox::mutex: " << sizeof(iox::mutex));
+    IOX_LOG(INFO, "Size of POSIX pthread_mutex_t: " << sizeof(pthread_mutex_t));
+}
+
+auto open_or_create_shm()
+{
+    constexpr uint64_t MEMORY_SIZE{4096};
+    return iox::PosixSharedMemoryObjectBuilder()
+        .name("iox-mixed-mode-poc")
+        .memorySizeInBytes(MEMORY_SIZE)
+        .openMode(iox::OpenMode::OPEN_OR_CREATE)
+        .accessMode(iox::AccessMode::READ_WRITE)
+        .permissions(iox::perms::owner_all)
+        .create();
+}
+
+#endif // IOX_MIXED_MODE_POC_COMMON_HPP

iceoryx_examples/mixed_mode_poc/mixed_mode_poc_follower.cpp

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+// Copyright (c) 2024 by ekxide IO GmbH. All rights reserved.
+//
+// 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
+//
+// 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.
+//
+// SPDX-License-Identifier: Apache-2.0
+
+#include "mixed_mode_poc_common.hpp"
+
+int main()
+{
+    print_sizes();
+
+    IOX_LOG(INFO, "");
+
+    auto shm_result = open_or_create_shm();
+    if (shm_result.has_error())
+    {
+        IOX_LOG(ERROR, "Could not create shared memory");
+        return -1;
+    }
+    auto& shm = shm_result.value();
+
+    auto* shared_data = static_cast<SharedData*>(shm.getBaseAddress());
+
+    auto& leader_barrier = shared_data->leader_barrier;
+    auto& follower_barrier = shared_data->follower_barrier;
+
+    auto& non_atomic_counter = shared_data->non_atomic_counter;
+    auto& atomic_counter = shared_data->atomic_counter;
+
+    leader_barrier.post();
+    follower_barrier.wait();
+
+    IOX_LOG(INFO, "Racing on the non atomic counter!");
+
+    for (uint64_t i = 0; i < ITERATIONS; ++i)
+    {
+        non_atomic_counter++;
+    }
+
+    leader_barrier.post();
+    follower_barrier.wait();
+
+    IOX_LOG(INFO, "Non atomic counter value: " << non_atomic_counter);
+    IOX_LOG(INFO, "Expected any value below: " << 2 * ITERATIONS);
+    IOX_LOG(INFO, "");
+    IOX_LOG(INFO, "Racing on the atomic counter!");
+
+    for (uint64_t i = 0; i < ITERATIONS; ++i)
+    {
+        // this is intentional more complex than necessary in order to test the CAS loop
+        auto old_counter_value = atomic_counter.load(std::memory_order_relaxed);
+        while (!atomic_counter.compare_exchange_weak(
+            old_counter_value, old_counter_value + 1, std::memory_order_acq_rel, std::memory_order_relaxed))
+        {
+        }
+    }
+
+    leader_barrier.post();
+    follower_barrier.wait();
+
+    IOX_LOG(INFO, "Atomic counter value:     " << atomic_counter);
+    IOX_LOG(INFO, "Expected counter value:   " << 2 * ITERATIONS);
+
+    if (atomic_counter == 2 * ITERATIONS)
+    {
+        IOX_LOG(INFO, "Success! Data layout and atomics work!");
+    }
+    else
+    {
+        IOX_LOG(ERROR, "Failed! Either data layout issues or atomics do not work!");
+    }
+
+    return 0;
+}

iceoryx_examples/mixed_mode_poc/mixed_mode_poc_leader.cpp

@@ -0,0 +1,90 @@
+// Copyright (c) 2024 by ekxide IO GmbH. All rights reserved.
+//
+// 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
+//
+// 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.
+//
+// SPDX-License-Identifier: Apache-2.0
+
+#include "iox/logging.hpp"
+#include "mixed_mode_poc_common.hpp"
+#include <atomic>
+
+int main()
+{
+    print_sizes();
+
+    IOX_LOG(INFO, "");
+
+    auto shm_result = open_or_create_shm();
+    if (shm_result.has_error())
+    {
+        IOX_LOG(ERROR, "Could not create shared memory");
+        return -1;
+    }
+    auto& shm = shm_result.value();
+
+    auto* shared_data = new (shm.getBaseAddress()) SharedData();
+
+    auto& leader_barrier = shared_data->leader_barrier;
+    auto& follower_barrier = shared_data->follower_barrier;
+
+    auto& non_atomic_counter = shared_data->non_atomic_counter;
+    auto& atomic_counter = shared_data->atomic_counter;
+
+    IOX_LOG(INFO, "Initialization done! Please run mixed-mode-poc-follower!");
+    IOX_LOG(INFO, "");
+
+    leader_barrier.wait();
+    follower_barrier.post();
+
+    IOX_LOG(INFO, "Racing on the non atomic counter!");
+
+    for (uint64_t i = 0; i < ITERATIONS; ++i)
+    {
+        non_atomic_counter++;
+    }
+
+    leader_barrier.wait();
+    follower_barrier.post();
+
+    IOX_LOG(INFO, "Non atomic counter value: " << non_atomic_counter);
+    IOX_LOG(INFO, "Expected any value below: " << 2 * ITERATIONS);
+    IOX_LOG(INFO, "");
+    IOX_LOG(INFO, "Racing on the atomic counter!");
+
+    for (uint64_t i = 0; i < ITERATIONS; ++i)
+    {
+        // this is intentional more complex than necessary in order to test the CAS loop
+        auto old_counter_value = atomic_counter.load(std::memory_order_relaxed);
+        while (!atomic_counter.compare_exchange_weak(
+            old_counter_value, old_counter_value + 1, std::memory_order_acq_rel, std::memory_order_relaxed))
+        {
+        }
+    }
+
+    leader_barrier.wait();
+    follower_barrier.post();
+
+    IOX_LOG(INFO, "Atomic counter value:     " << atomic_counter);
+    IOX_LOG(INFO, "Expected counter value:   " << 2 * ITERATIONS);
+
+    if (atomic_counter == 2 * ITERATIONS)
+    {
+        IOX_LOG(INFO, "Success! Data layout and atomics work!");
+    }
+    else
+    {
+        IOX_LOG(ERROR, "Failed! Either data layout issues or atomics do not work!");
+    }
+
+    return 0;
+}