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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
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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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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WHAT DOES #[REPR(PACKED)] DO? – Create Your Own Event Queue
The #[repr(packed)] annotation is new to us. Usually, a struct will have padding either between fields or at the end of the struct. This happens even when we’ve specified #[repr(C)]. The reason has to do with efficient access to the data stored in the struct by not having to make multiple fetches to get the…
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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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IMPORTANT NOTE – Create Your Own Event Queue
By moving the concern of registering interests to a separate struct like this, users can call Registry::try_clone to get an owned Registry instance. This instance can be passed to, or shared through Arc<Registry> with, other threads, allowing multiple threads to register interest to the same Poll instance even when Poll is blocking another thread while…
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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…
