Jungfraujoch/image_pusher/ZMQStream2PusherSocket.cpp

// SPDX-FileCopyrightText: 2024 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only

#include "ZMQStream2PusherSocket.h"

void zmq_socket_free(void *data, void *hint) {
    auto z = (ZeroCopyReturnValue *) hint;
    z->release();
}

ZMQStream2PusherSocket::ZMQStream2PusherSocket(const std::string &addr,
    std::optional<int32_t> send_buffer_high_watermark,
    std::optional<int32_t> send_buffer_size)
: s(ZMQSocketType::Push) {
    if (send_buffer_size)
        s.SendBufferSize(send_buffer_size.value());
    if (send_buffer_high_watermark)
        s.SendWaterMark(send_buffer_high_watermark.value());
    s.SendTimeout(std::chrono::seconds(1)); // 1 second should be more than enough to flush buffers and to still give fast response
    s.Bind(addr);
}

std::string ZMQStream2PusherSocket::GetEndpointName() {
    return s.GetEndpointName();
}

bool ZMQStream2PusherSocket::Send(const uint8_t *data, size_t size) {
    std::unique_lock ul(m);
    return s.Send(data, size, true);
}

void ZMQStream2PusherSocket::StartWriterThread() {
    std::unique_lock ul(m);
    active = true;
    send_future = std::async(std::launch::async, &ZMQStream2PusherSocket::WriterThread, this);
}

void ZMQStream2PusherSocket::StopWriterThread() {
    std::unique_lock ul(m);
    if (!active)
        return; // Not active so no need to stop anything

    active = false;

    if (send_future.valid()) {
        queue.PutBlocking({.end = true});
        send_future.get();
    } else
        throw JFJochException(JFJochExceptionCategory::WrongDAQState, "Image pusher wasn't sending images");
}

void ZMQStream2PusherSocket::WriterThread() {
    bool transmission_error = false;
    ImagePusherQueueElement e = queue.GetBlocking();
    while (!e.end) {
        // When hitting timeout on SendZeroCopy consider it a transmission error and switch to non-blocking communication
        bool blocking_send = !transmission_error;
        if (!s.SendZeroCopy(e.z->GetImage(), e.z->GetImageSize(), zmq_socket_free, e.z, blocking_send)) {
            transmission_error = true;
            e.z->release(); // Important: callback won't run on failed enqueue/send
        }
        e = queue.GetBlocking();
    }
}

void ZMQStream2PusherSocket::SendImage(ZeroCopyReturnValue &z) {
    queue.PutBlocking(ImagePusherQueueElement{
        .image_data = static_cast<uint8_t *>(z.GetImage()),
        .z = &z,
        .end = false
    });
}