Making the 'httpsrc' plugin asynchronous | GSoC 2019

GStreamer plugins are the building units of any GStreamer application. The plugins can be linked and arranged in a pipeline. This pipeline defines the flow of the data. 'souphttpsrc', aka HTTP source is a plugin which reads data from a remote location specified by a URI and the supported protocols are 'http', 'https'. This plugin is written in C. 'rshttpsrc' is the Rust version of the above said plugin. 

Although the Rust version of the plugin is working, it is not feature complete. So my task here is to finish 'rshttpsrc' plugin completely. Let me break the task into smaller branches.
  1. Switching to async IO (Currently it is making request synchronously). 
  2. Support for cookie/HTTP connection sharing between multiple instances. 
  3. Making 'rshttpsrc' feature equivalent to 'souphttpsrc' (the C version of the same plugin). There are properties missing in 'rshttpsrc' which are implemented in C version of the plugin. Here is the list of properties in C version of the plugin.
This is the Gitlab link to this issue. Let me dig in detail into the first part of the problem. 

 'rshttpsrc' is using 'reqwest' for making HTTP/HTTPS request. Our plugin was using the synchronous Client of the 'reqwest' crate which pretty much explain why the requests were synchronous. All I had to do to make it asynchronous was introducing async Client of the reqwest. But when doing this conversion I had to change the code that is wrapped around the method which makes the call to the specified URI and modify the methods which handle the request. 

 Basically 'do_request()' method makes the call specified by the URI and gets the response asynchronously while 'create()' method is called by Gstreamer when data is needed. So 'create()' is invoked with the data from the response. These were some of the places in the code that I had to modify.

 'wait()' is an interesting function introduced newly to cater asynchronous feature. It was previously implemented in 's3' plugin. This is what the function does. It gets a input of a Future (something that take time to resolve) which resolves either into an error or an item. Basically this gives you an API that allows to run some operation that takes time, but allows to cancel it at any time without having to wait until it finishes.
Switching to async IO for 'rshttpsrc' is done. Let's discuss the next part of the problem in the upcoming blogs :)

Comments

Post a Comment

Popular posts from this blog

The Journey Begins | Google Summer of Code

Image
Google Summer of Code (GSoC) is a global program focused on bringing more student developers into open source software development. Students work with an open source organization on a 3 month programming project during their break from school. It has always been a wish of mine to contribute to open source community. I was ecstatic would be an understatement when I got the opportunity to contribute Gnome foundation through GSoC 2019. We go through an organized and friendly environment during this period which makes GSoC a great way to enter the open source community. More importantly each student gets a mentor to guide him/her through out the GSoC period. And I am the luckiest to have gotten Sebastian Dröge as my mentor. I'm working on GStreamer based project of Gnome Foundation. GStreamer is a pipeline-based multimedia framework that links together a wide variety of media processing systems to complete complex workflows. The framework is based on plugins that will provide t...
Read more

Review | GSoC 2019

Image
I've been working on GStreamer based project of Gnome Foundation. GStreamer is a pipeline-based multimedia framework that links together a wide variety of media processing systems to complete complex workflows. The framework is based on plugins that will provide various codec and other functionality. The plugins can be linked and arranged in a pipeline. And most of the plugins are written in C. Now the developers are in an attempt to convert them to Rust which is more robust and easily maintainable. My task is to be a part of this conversion and to help fix issues related to this. Planned Tasks Implement Hyper-based HTTP source around async IO and make it feature-complete. (Explained in below section) GitLab issue: https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/issues/31 Tutorial for gst-plugin-tutorial crate. (Explained in below section) GitLab issue: https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/issues/44 Finish FLV demuxer. Conversion of FLV demuxer t...
Read more

I was there at GNOME.Asia Summit 2019

Image
I was there at Gnome Asia Summit 2019 in Gresik, Indonesia as a speaker. Since I am very new to open source community this was a great experience. I conducted the New comers workshop with my pal Gaurav Agarwal from India. We had our parallel class on day 0 (which is actually day 1) on the premises of University of Muhammadhiya. The expenses of me to attend the event was sponsored by Gnome Foundation. I'm so thankful for this great opportunity. Let me run through my experience in Gresik and in the conference. I and Guarav landed on 10th of October 2019 in Surabaya. Mr. Firdhous from local community came to pick us up and we had the hotel already booked in Gresik. They dropped us in Hotel Santika Gresik which was fabulous. On the next day I went to the conference and met with people from local community and open source community. I had my talk after lunch and It went very well. We used our personal experience and getting started with Gnome guide to steer the participants towa...
Read more