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Summary – Create Your Own Event Queue
The concept of epoll, kqueue, and IOCP is pretty simple at a high level, but the devil is in the details. It’s just not that easy to understand and get it working correctly. Even programmers who work on these things will often specialize in one platform (epoll/kqueue or Windows). It’s rare that one person will…
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BE CAREFUL WITH USING TCPSTREAM::READ_TO_END – Create Your Own Event Queue
You should be careful with using TcpStream::read_to_end or any other function that fully drains the buffer for you when using non-blocking buffers. If you get an error of the io::WouldBlock type, it will report that as an error even though you had several successful reads before you got that error. You have no way of…
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TCPSTREAM IN RUST AND NAGLE’S ALGORITHM – Create Your Own Event Queue-2
The last part of main is simply to write FINISHED to the console to let us know we exited main at that point. The last bit of code in this chapter is the handle_events function. This function takes two arguments, a slice of Event structs and a mutable slice of TcpStream objects. Let’s take a…
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TCPSTREAM IN RUST AND NAGLE’S ALGORITHM – Create Your Own Event Queue-1
Here is a little fact for you (I originally intended to call it a “fun fact,” but realized that’s stretching the concept of “fun” just a little too far!). In Rust’s TcpStream, and, more importantly, most APIs that aim to mimic the standard library’s TcpStream such as mio or Tokio, the stream is created with…
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NOTE – Create Your Own Event Queue
We would get a value of 0 if a timeout elapses before an event has happened. The last thing we do is to make an unsafe call to events.set_len(res as usize). This function is unsafe since we could potentially set the length so that we would access memory that’s not been initialized yet in safe…
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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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Is all I/O blocking? – Create Your Own Event Queue
Finally, a question that’s easy to answer. The answer is a big, resounding… maybe. The thing is that not all I/O operations will block in the sense that the operating system will park the calling thread and it will be more efficient to switch to another task. The reason for this is that the operating…
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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…
