batchExample.cpp

/**
 * @file
 * @copyright
 *   SPDX-FileCopyrightText: 2023-2023 European Southern Observatory (ESO)
 *
 *   SPDX-License-Identifier: LGPL-3.0-only
 */
#include <chrono>
 
#include <ipcq/adapter.hpp>
#include <ipcq/reader.hpp>
#include <ipcq/writer.hpp>
 
struct MyElement {
    std::array<uint8_t, 128> data;
};
 
/** Writer side */
void Writer() {
    auto capacity = 64u;
    ipcq::Writer<MyElement> writer("myqueue", capacity);
    MyElement element = {};
    // Prepare element
    auto err = writer.Write(element, ipcq::Notify::All);
    if (err) {
        // handle error
    }
}
 
/** Reader side */
void Reader() {
    using namespace std::chrono_literals;
    // Create reader, waiting up to 30s for the topic to be created if it does not exist.
    // If the topic is not created after that it will throw `std::system_error` with error
    // code `ipcq::Error::Timeout`
    auto reader = ipcq::Reader<MyElement>::MakeReader("myqueue", 30s);
 
    std::array<MyElement, 40> elements;
 
    // Read *up to* 40 elements, using the adapter utility that performs assignment
    // for each element into the array.
    // If there is no data at all yet we wait 2s before giving up (returning `ipcq::Error::Timeout`)
    auto [err, count] =
        reader.Read(ipcq::OutputIteratorAdapter(std::begin(elements)), elements.size(), 2s);
 
    if (err) {
        // Handle errors.
        // Particularly ipcq::Error::InconsistentState indicates that writer has broken the
        // sequential reads by `reader`. This is recovered by resetting the internal state to read
        // the next written element by invoking `ipcq::BasicReader::Reset()`.
    } else {
        // Success
        // `count` elements have been copied.
        // process result ...
    }
}