swift-corelibs-libdispatch
express-c
swift-corelibs-libdispatch | express-c | |
---|---|---|
3 | 7 | |
2,426 | 16 | |
0.8% | - | |
6.5 | 6.3 | |
5 days ago | 3 months ago | |
C | C | |
Apache License 2.0 | MIT License |
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
swift-corelibs-libdispatch
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Is Parallel Programming Hard, and, If So, What Can You Do About It? v2023.06.11a
GCD/libdispatch is a fantastic approach to concurrency and you can build and install support for non-Apple operating systems:
https://github.com/apple/swift-corelibs-libdispatch
Here’s a simple echo server:
https://github.com/williamcotton/c_playground/blob/master/sr...
Here’s a simple multithreaded database pool:
https://github.com/williamcotton/express-c/blob/master/src/d...
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Cross-platform I/O built on io_uring and kqueue (in TigerBeetle)
One of the reasons is that libdispatch's I/O functions introduce extra dynamic allocations for internal queueing via `dispatch_async` ([0],[1],[2]) and from an API perspective of realloc-ing ([3]) an internally owned ([4]) buffer.
TigerBeetle, on the other hand, statically allocates all I/O buffers upfront ([5]), treats these buffers as intrusively-provided typed data ([6]) (no growing/owned buffers), and does internal queueing without synchronization or dynamic allocation ([7]).
[0]: https://github.com/apple/swift-corelibs-libdispatch/blob/469...
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What are the best books/courses for rigorous study of concurrency in iOS?
If you want iOS in particular, read the source of GCD itself.
express-c
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Is Parallel Programming Hard, and, If So, What Can You Do About It? v2023.06.11a
GCD/libdispatch is a fantastic approach to concurrency and you can build and install support for non-Apple operating systems:
https://github.com/apple/swift-corelibs-libdispatch
Here’s a simple echo server:
https://github.com/williamcotton/c_playground/blob/master/sr...
Here’s a simple multithreaded database pool:
https://github.com/williamcotton/express-c/blob/master/src/d...
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A highly intuitive visual guide on how memory allocation works, step by step
Apache does this! And I do this in my own C web framework:
https://github.com/williamcotton/express-c/blob/master/deps/...
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My favorite C compiler flags during development
Unfortunately not all of the sanitizers are working in clang for Apple Silicon machines. For my own CI pipeline I run both Darwin and Linux builds, leaks and valgrind respectively, along with the kitchen sink of compiler sanitizers:
Here’s the GitHub actions for those platforms and a link to the Makefile:
GitHub Action:
https://github.com/williamcotton/express-c/blob/master/.gith...
Makefile:
https://github.com/williamcotton/express-c/blob/f2e1dde2f5a7...
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The two types of C programmers (a provocative thesis)
Lol, yeah, the libdispatch runtime is probably about as big as the Go runtime!
I think this has a slight advantage in that it uses a memory arena for a per-request bump allocator so it should keep overall memory usage lower.
The slowest part of all this has to do with Block_copy and the places where I’m very much treating blocks/closures in an OOP type manner.
This could be fixed by writing a different function that did basically the same thing as Block_copy but for all the “methods” on an “object” in a single pass. But who has time for that? :D
Here’s more about those performance issues and some text code that show how slow the approach is:
https://github.com/williamcotton/express-c/tree/master/resea...
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Software Dark Matter Is the Enemy of Software Transparency
I’ve used an approach to copy only the shared libs from the build container to the production container. This not only gets rid of most of this “dark matter” but results in much smaller containers!
https://github.com/williamcotton/express-c/blob/master/demo/...
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Untangling Lifetimes: The Arena Allocator
I use arenas for HTTP request handlers. The JSON built or parsed is only going to be around for the lifetime of the request. It's much simpler and faster to use an arena than to do reference counting wrapped around malloc/free.
Here's an example where in a commit I swapped in an arena:
https://github.com/williamcotton/express-c/commit/4ae53f38e3...
What are some alternatives?
Hopac - http://hopac.github.io/Hopac/Hopac.html
c_playground - C Playground
multiplix - An operating system kernel for RISC-V and AArch64 SBCs
tigerbeetle - The distributed financial transactions database designed for mission critical safety and performance.
mandelbrot - Simple fractal generator
ThreadPool - A simple C++11 Thread Pool implementation
futhark - :boom::computer::boom: A data-parallel functional programming language
gcc
libcnabl
preemptible-thread - How to preempt threads in user space