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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.…
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Using Windows API – Understanding OS-Backed Event Queues, System Calls, and Cross-Platform Abstractions
On Windows, things work a bit differently. While UNIX models almost everything as “files” you interact with, Windows uses other abstractions. On Windows, you get a handle that represents some object you can interact with in specific ways depending on exactly what kind of handle you have. We will use the same main function as…
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CALLING CONVENTION – Understanding OS-Backed Event Queues, System Calls, and Cross-Platform Abstractions
This is the first time we’ve encountered this term, so I’ll go over a brief explanation, even though we dive deeper into this topic later in the book. A calling convention defines how function calls are performed and will, amongst other things, specify: – How arguments are passed into the function – What registers the…
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The next level of abstraction – Understanding OS-Backed Event Queues, System Calls, and Cross-Platform Abstractions
The next level of abstraction is to use the API, which all three operating systems provide for us. We’ll soon see that this abstraction helps us remove some code. In this specific example, the syscall is the same on Linux and on macOS, so we only need to worry if we’re on Windows. We can…
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Raw syscall on macOS – Understanding OS-Backed Event Queues, System Calls, and Cross-Platform Abstractions
Now, since we use instructions that are specific to the CPU architecture, we’ll need different functions depending on if you run an older Mac with an intel CPU or if you run a newer Mac with an Arm 64-based CPU. We only present the one working for the new M series of chips using an…
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The lowest level of abstraction – Understanding OS-Backed Event Queues, System Calls, and Cross-Platform Abstractions
System calls, FFI, and cross-platform abstractions We’ll implement a very basic syscall for the three architectures: BSD/macOS, Linux, and Windows. We’ll also see how this is implemented in three levels of abstraction. The syscall we’ll implement is the one used when we write something to the standard output (stdout) since that is such a common…
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Cross-platform event queues – Understanding OS-Backed Event Queues, System Calls, and Cross-Platform Abstractions
When creating a cross-platform event queue, you have to deal with the fact that you have to create one unified API that’s the same whether it’s used on Windows (IOCP), macOS (kqueue), or Linux (epoll). The most obvious difference is that IOCP is completion-based while kqueue and epoll are readiness-based. This fundamental difference means that…
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Completion-based event queues – Understanding OS-Backed Event Queues, System Calls, and Cross-Platform Abstractions
IOCP stands for input/output completion port. This is a completion-based event queue. This type of queue notifies you when events are completed. An example of this is when data has been read into a buffer. The following is a basic breakdown of what happens in this type of event queue: Figure 3.2 – A simplified…
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Event queuing via epoll/kqueue and IOCP – Understanding OS-Backed Event Queues, System Calls, and Cross-Platform Abstractions
This is a sort of hybrid of the previous approaches. In the case of a network call, the call itself will be non-blocking. However, instead of polling the handle regularly, we can add that handle to an event queue, and we can do that with thousands of handles with very little overhead. As programmers, we…
