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improve image rendering performance by less waited locking #1164

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22 changes: 5 additions & 17 deletions image_view/include/image_view/image_view_node.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -15,34 +15,20 @@
#ifndef IMAGE_VIEW__IMAGE_VIEW_NODE_HPP_
#define IMAGE_VIEW__IMAGE_VIEW_NODE_HPP_

#include <condition_variable>
#include <memory>
#include <mutex>
#include <string>
#include <thread>
#include <vector>

#include "cv_bridge/cv_bridge.hpp"

#include <cv_bridge/cv_bridge.hpp>
#include <image_transport/image_transport.hpp>
#include <rclcpp/rclcpp.hpp>
#include <sensor_msgs/msg/image.hpp>
#include <image_transport/image_transport.hpp>

namespace image_view
{

class ThreadSafeImage
{
std::mutex mutex_;
std::condition_variable condition_;
cv_bridge::CvImageConstPtr image_;

public:
void set(cv_bridge::CvImageConstPtr image);
cv_bridge::CvImageConstPtr get();
cv_bridge::CvImageConstPtr pop();
};

class ImageViewNode
: public rclcpp::Node
{
Expand All @@ -55,7 +41,7 @@ class ImageViewNode
~ImageViewNode();

private:
ThreadSafeImage queued_image_, shown_image_;
cv_bridge::CvImageConstPtr queued_image_, shown_image_;
bool autosize_;
int window_height_, window_width_;
bool g_gui;
Expand All @@ -75,6 +61,8 @@ class ImageViewNode
void windowThread();
rcl_interfaces::msg::SetParametersResult paramCallback(const std::vector<rclcpp::Parameter> &);
std::mutex param_mutex_;
std::mutex image_mutex_;
std::binary_semaphore new_data_available_{0};
};

} // namespace image_view
Expand Down
74 changes: 27 additions & 47 deletions image_view/src/image_view_node.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -70,38 +70,6 @@
namespace image_view
{

void ThreadSafeImage::set(cv_bridge::CvImageConstPtr image)
{
std::lock_guard<std::mutex> lock(mutex_);
image_ = image;
condition_.notify_one();
}

cv_bridge::CvImageConstPtr ThreadSafeImage::get()
{
std::lock_guard<std::mutex> lock(mutex_);
return image_;
}

cv_bridge::CvImageConstPtr ThreadSafeImage::pop()
{
cv_bridge::CvImageConstPtr image;

{
std::unique_lock<std::mutex> lock(mutex_);

condition_.wait_for(
lock, std::chrono::milliseconds(100),
[this] {
return !image_;
});

image = std::move(image_);
}

return image;
}

ImageViewNode::ImageViewNode(const rclcpp::NodeOptions & options)
: rclcpp::Node("image_view_node", options)
{
Expand Down Expand Up @@ -180,6 +148,9 @@ ImageViewNode::ImageViewNode(const rclcpp::NodeOptions & options)

ImageViewNode::~ImageViewNode()
{
image_mutex_.unlock();
new_data_available_.release();

if (window_thread_.joinable()) {
window_thread_.join();
}
Expand Down Expand Up @@ -234,9 +205,10 @@ void ImageViewNode::imageCb(const sensor_msgs::msg::Image::ConstSharedPtr & msg)
encoding = "bgr8";
}

queued_image_.set(
cv_bridge::cvtColorForDisplay(
cv_bridge::toCvShare(msg), encoding, options));
image_mutex_.lock();
queued_image_ = cv_bridge::cvtColorForDisplay(cv_bridge::toCvShare(msg), encoding, options);
image_mutex_.unlock();
new_data_available_.release();
} catch (cv_bridge::Exception & e) {
RCLCPP_ERROR_EXPRESSION(
this->get_logger(), (static_cast<int>(this->now().seconds()) % 30 == 0),
Expand Down Expand Up @@ -264,16 +236,23 @@ void ImageViewNode::mouseCb(int event, int /* x */, int /* y */, int /* flags */
return;
}

cv_bridge::CvImageConstPtr image(this_->shown_image_.get());
const std::string filename = string_format(this_->filename_format_, this_->count_);

if (!image) {
this_->image_mutex_.lock();

if (!this_->shown_image_) {
this_->image_mutex_.unlock();
RCLCPP_WARN(this_->get_logger(), "Couldn't save image, no data!");
return;
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}

std::string filename = string_format(this_->filename_format_, this_->count_);
const cv::Mat image = this_->shown_image_->image;

this_->image_mutex_.unlock();

const bool suc = cv::imwrite(filename, image);

if (cv::imwrite(filename, image->image)) {
if (suc) {
RCLCPP_INFO(this_->get_logger(), "Saved image %s", filename.c_str());
this_->count_++;
} else {
Expand All @@ -294,19 +273,20 @@ void ImageViewNode::windowThread()
}

while (rclcpp::ok()) {
cv_bridge::CvImageConstPtr image(queued_image_.pop());

if (cv::getWindowProperty(window_name_, 1) < 0) {
break;
}

if (image) {
cv::imshow(window_name_, image->image);
shown_image_.set(image);
cv::waitKey(1);
} else {
rclcpp::sleep_for(std::chrono::milliseconds(20));
// wait for new image data;
new_data_available_.acquire();

image_mutex_.lock();
if (queued_image_) {
cv::imshow(window_name_, queued_image_->image);
shown_image_ = queued_image_;
}
image_mutex_.unlock();
cv::waitKey(1);
}

cv::destroyAllWindows();
Expand Down