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How to use the repository alongside the book – Creating Our Own Fibers
The recommended way to read this chapter is to have the repository open alongside the book. In the repository, you’ll find three different folders that correspond to the examples we go through in this chapter: In addition, you will get two more examples that I refer to in the book but that should be explored…
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Technical requirements – Creating Our Own Fibers
In this chapter, we take a deep dive into a very popular way of handling concurrency. There is no better way of getting a fundamental understanding of the subject than doing it yourself. Fortunately, even though the topic is a little complex, we only need around 200 lines of code to get a fully working…
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NOTE – Create Your Own Event Queue
For simplicity, we use the index the event will have in the streams collection as its ID. This ID will be the same as the i variable in our loop. For example, in the first loop, i will be 0; it will also be the first stream to be pushed to our streams collection, so…
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The main program – Create Your Own Event Queue
Let’s see how it all works in practice. Make sure that delayserver is up and running, because we’ll need it for these examples to work. The goal is to send a set of requests to delayserver with varying delays and then use epoll to wait for the responses. Therefore, we’ll only use epoll to track…
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WHAT ABOUT WAITING ON EPOLL_WAIT IN MULTIPLE THREADS? – Create Your Own Event Queue
As long as we only have one Poll instance, we avoid the problems and subtleties of having multiple threads calling epoll_wait on the same epoll instance. Using level-triggered events will wake up all threads that are waiting in the epoll_wait call, causing all of them to try to handle the event (this is often referred…
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The ffi module – Create Your Own Event Queue-2
The last part of the code in this file is the Event struct: ch04/a-epoll/src/ffi.rs#[derive(Debug)]#[repr(C, packed)]pub struct Event { pub(crate) events: u32, // Token to identify event pub(crate) epoll_data: usize,}impl Event { pub fn token(&self) -> usize { self.epoll_data }} This structure is used to communicate to the operating system in epoll_ctl, and the operating system uses the same structure to communicate…
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The ffi module – Create Your Own Event Queue-1
Note The reason for doing file I/O in a thread pool is that there have historically been poor cross-platform APIs for non-blocking file I/O. While it’s true that many runtimes choose to relegate this task to a thread pool making blocking calls to the OS, it might not be true in the future as the…
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MIO – Create Your Own Event Queue-2
We’ll also use the std::io::Result type as our own Result type. It’s convenient since most errors will stem from one of our calls into the operating system, and an operating system error can be mapped to an io::Error type. There are two main abstractions over epoll. One is a structure called Poll and the other…
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MIO – Create Your Own Event Queue-1
mio describes itself as a “fast, low-level I/O library for Rust focusing on non-blocking APIs and event notification for building performance I/O apps with as little overhead as possible over the OS abstractions.” mio drives the event queue in Tokio, which is one of the most popular and widely used asynchronous runtimes in Rust. This…
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The highest level of abstraction – Understanding OS-Backed Event Queues, System Calls, and Cross-Platform Abstractions
This is simple, but I wanted to add this just for completeness. Rust standard library wraps the calls to the underlying OS APIs for us, so we don’t have to care about what syscalls to invoke.fn main() { println!(“Hello world from the standard library”);} Congratulations! You’ve now written the same syscall using three levels of abstraction.…
