[#555] health monitoring example cxx

.github/workflows/build-test.yml

@@ -334,7 +334,7 @@ jobs:
       - name: Build language bindings
         # NOTE: the cmake command is in a single line since Windows complains about breaking up lines with '\'
         run: |
-          cmake -S . -B target/ffi/build -DBUILD_EXAMPLES=ON -DBUILD_TESTING=ON ${{ matrix.mode.cmake-build-type }} ${{ matrix.mode.cmake-cxx-flags }} ${{ matrix.cmake-build-system-generator }} -DCMAKE_INSTALL_PREFIX=target/ffi/install -DCMAKE_PREFIX_PATH="${{ github.workspace }}/target/iceoryx/install" -DRUST_BUILD_ARTIFACT_PATH="${{ github.workspace }}/target/${{ matrix.mode.name }}"
+          cmake -S . -B target/ffi/build -DBUILD_EXAMPLES=ON -DBUILD_TESTING=ON -DWARNING_AS_ERROR=ON ${{ matrix.mode.cmake-build-type }} ${{ matrix.mode.cmake-cxx-flags }} ${{ matrix.cmake-build-system-generator }} -DCMAKE_INSTALL_PREFIX=target/ffi/install -DCMAKE_PREFIX_PATH="${{ github.workspace }}/target/iceoryx/install" -DRUST_BUILD_ARTIFACT_PATH="${{ github.workspace }}/target/${{ matrix.mode.name }}"
           cmake --build target/ffi/build ${{ matrix.mode.cmake-build-config }}
           cmake --install target/ffi/build ${{ matrix.mode.cmake-build-config }}
 

CMakeLists.txt

@@ -75,6 +75,12 @@ add_option(
     DEFAULT_VALUE OFF
 )
 
+add_option(
+    NAME WARNING_AS_ERROR
+    DESCRIPTION "Fails if the compiler emits a warning"
+    DEFAULT_VALUE OFF
+)
+
 add_param(
     NAME RUST_BUILD_ARTIFACT_PATH
     DESCRIPTION "The path to the folder with the Rust build artifacts, e.g. '/full/path/to/iceoryx2/target/release'"
@@ -110,6 +116,16 @@ add_rust_feature(
     RUST_FEATURE "iceoryx2/logger_tracing"
 )
 
+if(WARNING_AS_ERROR)
+    if(WIN32)
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+    else()
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror -Wall -Wextra -Wpedantic")
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror -Wall -Wextra -Wpedantic")
+    endif()
+endif()
+
 if(SANITIZERS)
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=address -fsanitize=undefined")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address -fsanitize=undefined")

examples/README.md

@@ -79,7 +79,7 @@ These types are demonstrated in the complex data types example.
 | event                              | [C](c/event) [C++](cxx/event) [Rust](rust/event)                                                                                        | Push notifications - send event signals to wakeup processes that are waiting for them.                                                                                                                          |
 | event based communication          | [C++](cxx/event_based_communication) [Rust](rust/event_based_communication)                                                             | Define multiple events like publisher/subscriber created or removed, send sample, received sample, deliver history etc. and react on them for a fully event driven communication setup.                         |
 | event multiplexing                 | [C](c/event_multiplexing) [C++](cxx/event_multiplexing) [Rust](rust/event_multiplexing)                                                 | Wait on multiple listeners or sockets with a single call. The WaitSet demultiplexes incoming events and notifies the user.                                                                                      |
-| health monitoring                  | [Rust](rust/health_monitoring)                                                                                                          | A central daemon creates the communication resources and monitors all nodes. When the central daemon crashes other nodes can take over and use the decentral API to monitor the nodes.                          |
+| health monitoring                  | [C++](cxx/health_monitoring) [Rust](rust/health_monitoring)                                                                             | A central daemon creates the communication resources and monitors all nodes. When the central daemon crashes other nodes can take over and use the decentral API to monitor the nodes.                          |
 | publish subscribe                  | [C](c/publish_subscribe) [C++](cxx/publish_subscribe) [Rust](rust/publish_subscribe)                                                    | Communication between multiple processes with a [publish subscribe messaging pattern](https://en.wikipedia.org/wiki/Publish–subscribe_pattern).                                                                 |
 | publish subscribe dynamic data     | [C++](cxx/publish_subscribe_dynamic_data) [Rust](rust/publish_subscribe_dynamic_data)                                                   | Communication between multiple processes with a [publish subscribe messaging pattern](https://en.wikipedia.org/wiki/Publish–subscribe_pattern) and payload data that has a dynamic size.                        |
 | publish subscribe with user header | [C](c/publish_subscribe_with_user_header) [C++](cxx/publish_subscribe_with_user_header) [Rust](rust/publish_subscribe_with_user_header) | Add a user header to the payload (samples) to transfer additional information.                                                                                                                                  |

examples/c/discovery/src/main.c

@@ -14,6 +14,7 @@
 #include <stdio.h>
 
 iox2_callback_progression_e list_callback(const iox2_static_config_t* static_details, void* callback_context) {
+    (void) callback_context;
     printf("Found Service: %s, ServiceID: %s\n", static_details->name, static_details->id);
     return iox2_callback_progression_e_CONTINUE;
 }

examples/c/domains/src/discovery.c

@@ -14,6 +14,7 @@
 #include <stdio.h>
 
 iox2_callback_progression_e list_callback(const iox2_static_config_t* static_details, void* callback_context) {
+    (void) callback_context;
     printf("Found Service: %s, ServiceID: %s\n", static_details->name, static_details->id);
     return iox2_callback_progression_e_CONTINUE;
 }

examples/c/domains/src/subscriber.c

@@ -94,11 +94,8 @@ int main(int argc, char** argv) {
         goto drop_service;
     }
 
-    uint64_t counter = 0;
     printf("subscribed to: [domain: \"%s\", service: \"%s\"]\n", argv[1], argv[2]);
     while (iox2_node_wait(&node_handle, 1, 0) == IOX2_OK) {
-        counter += 1;
-
         // receive sample
         iox2_sample_h sample = NULL;
         if (iox2_subscriber_receive(&subscriber, NULL, &sample) != IOX2_OK) {

examples/c/event_multiplexing/src/notifier.c

@@ -56,7 +56,7 @@ int main(int argc, char** argv) {
     iox2_port_factory_event_h service = NULL;
     if (iox2_service_builder_event_open_or_create(service_builder_event, NULL, &service) != IOX2_OK) {
         printf("Unable to create service!\n");
-        goto drop_node;
+        goto drop_service_name;
     }
 
     // create notifier

examples/c/publish_subscribe/src/subscriber.c

@@ -73,10 +73,7 @@ int main(void) {
         goto drop_service;
     }
 
-    uint64_t counter = 0;
     while (iox2_node_wait(&node_handle, 1, 0) == IOX2_OK) {
-        counter += 1;
-
         // receive sample
         iox2_sample_h sample = NULL;
         if (iox2_subscriber_receive(&subscriber, NULL, &sample) != IOX2_OK) {

examples/c/publish_subscribe_with_user_header/src/subscriber.c

@@ -86,10 +86,7 @@ int main(void) {
         goto drop_service;
     }
 
-    uint64_t counter = 0;
     while (iox2_node_wait(&node_handle, 1, 0) == IOX2_OK) {
-        counter += 1;
-
         // receive sample
         iox2_sample_h sample = NULL;
         if (iox2_subscriber_receive(&subscriber, NULL, &sample) != IOX2_OK) {
@@ -107,7 +104,7 @@ int main(void) {
             printf("received: %lu, user_header: version = %d, timestamp = %lu\n",
                    (long unsigned) *payload,
                    user_header->version,
-                   user_header->timestamp);
+                   (long unsigned) user_header->timestamp);
             iox2_sample_drop(sample);
         }
     }

examples/cxx/CMakeLists.txt

@@ -22,6 +22,7 @@ add_subdirectory(domains)
 add_subdirectory(event)
 add_subdirectory(event_multiplexing)
 add_subdirectory(event_based_communication)
+add_subdirectory(health_monitoring)
 add_subdirectory(publish_subscribe)
 add_subdirectory(publish_subscribe_dynamic_data)
 add_subdirectory(publish_subscribe_with_user_header)

examples/cxx/event_based_communication/src/pubsub_event.hpp

@@ -26,7 +26,7 @@ enum class PubSubEvent : uint8_t {
     SentSample = 4,
     ReceivedSample = 5,
     SentHistory = 6,
-    Unknown
+    Unknown = 7
 };
 
 namespace iox {

examples/cxx/event_multiplexing/src/wait.cpp

@@ -22,8 +22,6 @@
 #include "iox2/service_type.hpp"
 #include "iox2/waitset.hpp"
 
-constexpr iox::units::Duration CYCLE_TIME = iox::units::Duration::fromSeconds(1);
-
 // NOLINTBEGIN
 struct Args {
     IOX_CLI_DEFINITION(Args);
@@ -42,7 +40,6 @@ auto main(int argc, char** argv) -> int {
     using namespace iox2;
     auto args = Args::parse(argc, argv, "Notifier of the event multiplexing example.");
 
-    auto event_id = EventId(args.event_id());
     auto service_name_1 = ServiceName::create(args.service1().c_str()).expect("valid service name");
     auto service_name_2 = ServiceName::create(args.service2().c_str()).expect("valid service name");
 

examples/cxx/health_monitoring/BUILD.bazel

@@ -0,0 +1,61 @@
+# Copyright (c) 2024 Contributors to the Eclipse Foundation
+#
+# See the NOTICE file(s) distributed with this work for additional
+# information regarding copyright ownership.
+#
+# This program and the accompanying materials are made available under the
+# terms of the Apache Software License 2.0 which is available at
+# https://www.apache.org/licenses/LICENSE-2.0, or the MIT license
+# which is available at https://opensource.org/licenses/MIT.
+#
+# SPDX-License-Identifier: Apache-2.0 OR MIT
+
+load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_library")
+
+cc_binary(
+    name = "example_cxx_health_monitoring_central_daemon",
+    srcs = [
+        "src/central_daemon.cpp",
+        "src/pubsub_event.hpp"
+    ],
+    deps = [
+        "@iceoryx//:iceoryx_hoofs",
+        "//:iceoryx2-cxx-static",
+    ],
+)
+
+cc_binary(
+    name = "example_cxx_health_monitoring_publisher_1",
+    srcs = [
+        "src/publisher_1.cpp",
+        "src/pubsub_event.hpp"
+    ],
+    deps = [
+        "@iceoryx//:iceoryx_hoofs",
+        "//:iceoryx2-cxx-static",
+    ],
+)
+
+cc_binary(
+    name = "example_cxx_health_monitoring_publisher_2",
+    srcs = [
+        "src/publisher_2.cpp",
+        "src/pubsub_event.hpp"
+    ],
+    deps = [
+        "@iceoryx//:iceoryx_hoofs",
+        "//:iceoryx2-cxx-static",
+    ],
+)
+
+cc_binary(
+    name = "example_cxx_health_monitoring_subscriber",
+    srcs = [
+        "src/subscriber.cpp",
+        "src/pubsub_event.hpp"
+    ],
+    deps = [
+        "@iceoryx//:iceoryx_hoofs",
+        "//:iceoryx2-cxx-static",
+    ],
+)

examples/cxx/health_monitoring/CMakeLists.txt

@@ -0,0 +1,28 @@
+# Copyright (c) 2024 Contributors to the Eclipse Foundation
+#
+# See the NOTICE file(s) distributed with this work for additional
+# information regarding copyright ownership.
+#
+# This program and the accompanying materials are made available under the
+# terms of the Apache Software License 2.0 which is available at
+# https://www.apache.org/licenses/LICENSE-2.0, or the MIT license
+# which is available at https://opensource.org/licenses/MIT.
+#
+# SPDX-License-Identifier: Apache-2.0 OR MIT
+
+cmake_minimum_required(VERSION 3.22)
+project(example_cxx_health_monitoring LANGUAGES CXX)
+
+find_package(iceoryx2-cxx 0.4.1 REQUIRED)
+
+add_executable(example_cxx_health_monitoring_central_daemon src/central_daemon.cpp)
+target_link_libraries(example_cxx_health_monitoring_central_daemon iceoryx2-cxx::static-lib-cxx)
+
+add_executable(example_cxx_health_monitoring_publisher_1 src/publisher_1.cpp)
+target_link_libraries(example_cxx_health_monitoring_publisher_1 iceoryx2-cxx::static-lib-cxx)
+
+add_executable(example_cxx_health_monitoring_publisher_2 src/publisher_2.cpp)
+target_link_libraries(example_cxx_health_monitoring_publisher_2 iceoryx2-cxx::static-lib-cxx)
+
+add_executable(example_cxx_health_monitoring_subscriber src/subscriber.cpp)
+target_link_libraries(example_cxx_health_monitoring_subscriber iceoryx2-cxx::static-lib-cxx)

examples/cxx/health_monitoring/README.md

@@ -0,0 +1,140 @@
+# Health Monitoring
+
+Before proceeding, all dependencies need to be installed. You can find
+instructions in the [C++ Examples Readme](../README.md).
+
+This example demonstrates how to create a robust system using iceoryx2.
+A central daemon pre-creates all communication resources to ensure that every
+required resource, such as memory, is available as soon as the application
+starts.
+Additionally, the subscriber is immediately informed if one of the processes
+it depends on has crashed. Even if the central daemon itself crashes,
+communication can continue without any restrictions. Thanks to the
+decentralized API of iceoryx2, the subscriber can take over the role of the
+central daemon and continue monitoring all processes.
+
+The communication must also be reliable, and we expect publishers to provide
+updates at regular intervals. If a publisher misses a deadline, we want to be
+informed immediately. This situation can occur if the system is under heavy
+load or if a process has crashed.
+
+This example is more advanced and consists of four components:
+
+* `central_daemon` - Must run first. It creates all communication resources and
+    monitors all nodes/processes.
+* `publisher_1` - Sends data at a specific frequency on `service_1`.
+* `publisher_2` - Sends data at a specific frequency on `service_2`.
+* `subscriber` - Connects to `service_1` and `service_2` and expects new samples
+    within a specific time. If no sample arrives, it proactively checks for dead
+    nodes.
+
+```ascii
++----------------+   creates   ...........................
+| central_daemon | ----------> : communication resources :
++----------------+             ...........................
+  |                               ^
+  |                   opens       |
+  |             +-----------------+--------------+
+  |             |                 |              |
+  |   +-------------+    +-------------+    +------------+
+  |   | publisher_1 |    | publisher_2 |    | subscriber |
+  |   +-------------+    +-------------+    +------------+
+  |             ^                   ^                 ^
+  |  monitores  |                   |                 |
+  +-------------+-------------------+-----------------+
+```
+
+## Running The Example
+
+> [!CAUTION]
+> Every payload you transmit with iceoryx2 must be compatible with shared
+> memory. Specifically, it must:
+>
+> * be self contained, no heap, no pointers to external sources
+> * have a uniform memory representation -> `#[repr(C)]`
+> * not use pointers to manage their internal structure
+>
+> Data types like `String` or `Vec` will cause undefined behavior and may
+> result in segmentation faults. We provide alternative data types that are
+> compatible with shared memory. See the
+> [complex data type example](../complex_data_types) for guidance on how to
+> use them.
+
+First you have to build the C++ examples:
+
+```sh
+cmake -S . -B target/ffi/build -DBUILD_EXAMPLES=ON
+cmake --build target/ffi/build
+```
+
+For this example, you need to open five separate terminals.
+
+## Terminal 1: Central Daemon - Create All Communication Resources
+
+Run the central daemon, which sets up all communication resources and monitors
+processes.
+
+```sh
+./target/ffi/build/examples/cxx/health_monitoring/example_cxx_health_monitoring_central_daemon
+```
+
+## Terminal 2: Publisher 1
+
+Run the first publisher, which sends data on `service_1`.
+
+```sh
+./target/ffi/build/examples/cxx/health_monitoring/example_cxx_health_monitoring_publisher_1
+```
+
+## Terminal 3: Publisher 2
+
+Run the second publisher, which sends data on `service_2`.
+
+```sh
+./target/ffi/build/examples/cxx/health_monitoring/example_cxx_health_monitoring_publisher_2
+```
+
+## Terminal 4: Subscriber
+
+Run the subscriber, which listens to both `service_1` and `service_2`.
+
+```sh
+./target/ffi/build/examples/cxx/health_monitoring/example_cxx_health_monitoring_subscriber
+```
+
+## Terminal 5: Simulate Process Crashes
+
+Send a `SIGKILL` signal to `publisher_1` to simulate a fatal crash. This
+ensures that the process is unable to clean up any resources.
+
+```sh
+killall -9 example_cxx_health_monitoring_publisher_1
+```
+
+After running this command:
+
+1. The `central_daemon` will detect that the process has crashed and print:
+   ```ascii
+   detected dead node: Some(NodeName { value: "publisher 1" })
+   ```
+   The event service is configured to emit a `PubSub::ProcessDied` event when a
+   process is identified as dead.
+
+2. On the `subscriber` side, you will see the message:
+   ```ascii
+   ServiceName { value: "service_1" }: process died!
+   ```
+
+3. Since `publisher_1` is no longer sending messages, the subscriber will also
+    regularly print another message indicating that `service_1` has violated
+    the contract because no new samples are being received.
+
+Feel free to run multiple instances of publisher or subscriber processes
+simultaneously to explore how iceoryx2 handles publisher-subscriber
+communication efficiently.
+
+You may hit the maximum supported number of ports when too many publisher or
+subscriber processes run. Take a look at the [iceoryx2 config](../../../config)
+to set the limits globally or at the
+[API of the Service builder](https://docs.rs/iceoryx2/latest/iceoryx2/service/index.html)
+to set them for a single service.