Single process🔗
Introduction🔗
This example demonstrates how iceoryx can be used in a single process for inter-thread communication. This is for instance helpful if you would like to establish a simple communication API in a 3D engine with a multitude of threads that are interacting without starting RouDi every time separately.
Run singleprocess🔗
The first lines until RouDi is ready for clients
are coming from the RouDi
startup in which the shared memory management segment and user data segment are
created.
Afterward, the publisher and subscriber thread are started and are beginning to transmit and receive data.
Code Walkthrough🔗
Creating a Single Process RouDi, Publisher and Subscriber🔗
- We start by setting the log level to error since we do not want to see all the debug messages.
iox::log::LogManager::GetLogManager().SetDefaultLogLevel(iox::log::LogLevel::kError);
- To start RouDi we have to create a configuration for him. We are choosing the
default config. Additionally, RouDi needs some other components like a memory
management unit which handles how the memory is created in which the transmission
data is stored. The
IceOryxRouDiComponents
class is handling them for us
iox::RouDiConfig_t defaultRouDiConfig = iox::RouDiConfig_t().setDefaults();
iox::roudi::IceOryxRouDiComponents roudiComponents(defaultRouDiConfig);
- We are starting RouDi, provide the required components and
disable monitoring. The last bool parameter
TERMINATE_APP_IN_ROUDI_DTOR_FLAG
states that RouDi does not terminate all registered processes when RouDi goes out of scope. If we would set it totrue
, our application would self terminate in the destructor ofroudi
.
constexpr bool TERMINATE_APP_IN_ROUDI_DTOR_FLAG = false;
iox::roudi::RouDi roudi(
roudiComponents.rouDiMemoryManager,
roudiComponents.portManager,
iox::roudi::RouDi::RoudiStartupParameters{iox::roudi::MonitoringMode::OFF, TERMINATE_APP_IN_ROUDI_DTOR_FLAG});
- Here comes a key difference to an inter-process application. If you would like
to communicate within one process, you have to use
PoshRuntimeSingleProcess
. You can create only one runtime at a time!
iox::runtime::PoshRuntimeSingleProcess runtime("singleProcessDemo");
- Now that everything is up and running, we can start the publisher and subscriber thread and wait until the user terminates the application.
std::thread publisherThread(publisher), subscriberThread(subscriber);
iox::posix::waitForTerminationRequest();
publisherThread.join();
subscriberThread.join();
std::cout << "Finished" << std::endl;
Implementation of Publisher and Subscriber🔗
Since there are no differences to the inter-process ports you can take a look at the icedelivery example for a detailed documentation. We only provide here a short overview.
Publisher🔗
We create a typed publisher with the following service description
(Service = Single
, Instance = Process
, Event = Demo
) and a historyCapacity
of 10.
iox::popo::PublisherOptions publisherOptions;
publisherOptions.historyCapacity = 10U;
iox::popo::Publisher<TransmissionData_t> publisher({"Single", "Process", "Demo"}, publisherOptions);
After that, we are sending numbers in ascending order with a 100ms interval in a while
loop.
uint64_t counter{0};
constexpr const char GREEN_RIGHT_ARROW[] = "\033[32m->\033[m ";
while (!iox::posix::hasTerminationRequested())
{
publisher.loan().and_then([&](auto& sample) {
sample->counter = counter++;
consoleOutput("Sending ", GREEN_RIGHT_ARROW, sample->counter);
sample.publish();
});
std::this_thread::sleep_for(CYCLE_TIME);
}
Subscriber🔗
We create a subscriber port with the same service description, a queueCapacity
of 10 and request to get the last 5 samples when we connect (historyRequest
).
iox::popo::SubscriberOptions options;
options.queueCapacity = 10U;
options.historyRequest = 5U;
iox::popo::Subscriber<TransmissionData_t> subscriber({"Single", "Process", "Demo"}, options);
Now we can receive the data in a while loop when our SubscribeState
is SUBSCRIBED
until someone terminates the application.
constexpr const char ORANGE_LEFT_ARROW[] = "\033[33m<-\033[m ";
while (!iox::posix::hasTerminationRequested())
{
if (iox::SubscribeState::SUBSCRIBED == subscriber.getSubscriptionState())
{
bool hasMoreSamples{true};
do
{
subscriber.take()
.and_then([&](auto& sample) { consoleOutput("Receiving ", ORANGE_LEFT_ARROW, sample->counter); })
.or_else([&](auto& result) {
hasMoreSamples = false;
if (result != iox::popo::ChunkReceiveResult::NO_CHUNK_AVAILABLE)
{
std::cout << "Error receiving chunk." << std::endl;
}
});
} while (hasMoreSamples);
}
std::this_thread::sleep_for(CYCLE_TIME);
}