cmake-init
Folly
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cmake-init | Folly | |
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164 | 90 | |
1,805 | 27,008 | |
- | 0.7% | |
8.1 | 9.8 | |
5 days ago | 7 days ago | |
CMake | C++ | |
GNU General Public License v3.0 only | Apache License 2.0 |
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cmake-init
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CMake install schema for single- and multi-config generators
https://github.com/friendlyanon/cmake-init This is how you do CMake properly. If you deviate from its install rules you are highly likely to do something wrong.
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cgen: another declarative CMake configuration generator
CMake itself is as declarative as a build systems need to be. For anything nontrivial, these "declarative" solutions all fall apart. Just use https://github.com/friendlyanon/cmake-init, learn CMake and you won't have any issues.
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How does one actually build a C++ project
If you want something with a (mostly) Just Works experience then just use https://github.com/friendlyanon/cmake-init
- CMakeList.txt, add_executable vs. add_library vs. target_link_libraries vs. target_link_directories
- Check out my tasks.json for C++ of VScode
- Clang++ Halp
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Putting libraries in program folder
For CMake basics check out the official "Getting started" tutorial: https://cmake.org/cmake/help/latest/guide/tutorial/index.html, as well as Introduction to Modern CMake. You can also get inspired by the CMake project generator cmake-init
- Recourses to help understand libraries/projects and setting them up?
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How to Create a Modern C Project with CMake and Conan
You can just use https://github.com/friendlyanon/cmake-init to get a CMake + Conan C project ready to go with a short little command: cmake-init --c -e -p conan coolio
- CMake template
Folly
- Ask HN: How bad is the xz hack?
- Backdoor in upstream xz/liblzma leading to SSH server compromise
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A lock-free ring-buffer with contiguous reservations (2019)
To set a HP on Linux, Folly just does a relaxed load of the src pointer, release store of the HP, compiler-only barrier, and acquire load. (This prevents the compiler from reordering the 2nd load before the store, right? But to my understanding does not prevent a hypothetical CPU reordering of the 2nd load before the store, which seems potentially problematic!)
Then on the GC/reclaim side of things, after protected object pointers are stored, it does a more expensive barrier[0] before acquire-loading the HPs.
I'll admit, I am not confident I understand why this works. I mean, even on x86, loads can be reordered before earlier program-order stores. So it seems like the 2nd check on the protection side could be ineffective. (The non-Linux portable version just uses an atomic_thread_fence SeqCst on both sides, which seems more obviously correct.) And if they don't need the 2nd load on Linux, I'm unclear on why they do it.
[0]: https://github.com/facebook/folly/blob/main/folly/synchroniz...
(This uses either mprotect to force a TLB flush in process-relevant CPUs, or the newer Linux membarrier syscall if available.)
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Appending to an std:string character-by-character: how does the capacity grow?
folly provides functions to resize std::string & std::vector without initialization [0].
[0] https://github.com/facebook/folly/blob/3c8829785e3ce86cb821c...
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Can anyone explain feedback of a HFT firm regarding implementation of SPSC lock-free ring-buffer queue?
My implementation was quite similar to Boost's spsc_queue and Facebook's folly/ProducerConsumerQueue.h.
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A Compressed Indexable Bitset
> How is that relevant?
Roaring bitmaps and similar data structures get their speed from decoding together consecutive groups of elements, so if you do sequential decoding or decode a large fraction of the list you get excellent performance.
EF instead excels at random skipping, so if you visit a small fraction of the list you generally get better performance. This is why it works so well for inverted indexes, as generally the queries are very selective (otherwise why do you need an index?) and if you have good intersection algorithms you can skip a large fraction of documents.
I didn't follow the rest of your comment, select is what EF is good at, every other data structure needs a lot more scanning once you land on the right chunk. With BMI2 you can also use the PDEP instruction to accelerate the final select on a 64-bit block: https://github.com/facebook/folly/blob/main/folly/experiment...
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Defer for Shell
C++ with folly's SCOPE_EXIT {} construct:
https://github.com/facebook/folly/blob/main/folly/ScopeGuard...
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Is there any facebook/folly community for discussion and Q&A?
Seems like github issues taking a long time to get any response: https://github.com/facebook/folly
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How a Single Line of Code Made a 24-Core Server Slower Than a Laptop
Can't speak for abseil and tbb, but in folly there are a few solutions for the common problem of sharing state between a writer that updates it very infrequently and concurrent readers that read it very frequently (typical use case is configs).
The most performant solutions are RCU (https://github.com/facebook/folly/blob/main/folly/synchroniz...) and hazard pointers (https://github.com/facebook/folly/blob/main/folly/synchroniz...), but they're not quite as easy to use as a shared_ptr [1].
Then there is simil-shared_ptr implemented with thread-local counters (https://github.com/facebook/folly/blob/main/folly/experiment...).
If you absolutely need a std::shared_ptr (which can be the case if you're working with pre-existing interfaces) there is CoreCachedSharedPtr (https://github.com/facebook/folly/blob/main/folly/concurrenc...), which uses an aliasing trick to transparently maintain per-core reference counts, and scales linearly, but it works only when acquiring the shared_ptr, any subsequent copies of that would still cause contention if passed around in threads.
[1] Google has a proposal to make a smart pointer based on RCU/hazptr, but I'm not a fan of it because generally RCU/hazptr guards need to be released in the same thread that acquired them, and hiding them in a freely movable object looks like a recipe for disaster to me, especially if paired with coroutines https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p05...
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Ask HN: What are some of the most elegant codebases in your favorite language?
Not sure if it's still the case but about 6 years ago Facebook's folly C++ library was something I'd point to for my junior engineers to get a sense of "good" C++ https://github.com/facebook/folly
What are some alternatives?
meson - The Meson Build System
abseil-cpp - Abseil Common Libraries (C++)
w64devkit - Portable C and C++ Development Kit for x64 (and x86) Windows
Boost - Super-project for modularized Boost
xmake - 🔥 A cross-platform build utility based on Lua
Seastar - High performance server-side application framework
fastbuild - High performance build system for Windows, OSX and Linux. Supporting caching, network distribution and more.
parallel-hashmap - A family of header-only, very fast and memory-friendly hashmap and btree containers.
ModernCppStarter - 🚀 Kick-start your C++! A template for modern C++ projects using CMake, CI, code coverage, clang-format, reproducible dependency management and much more.
EASTL - Obsolete repo, please go to: https://github.com/electronicarts/EASTL
llvm-mingw - An LLVM/Clang/LLD based mingw-w64 toolchain
OpenFrameworks - openFrameworks is a community-developed cross platform toolkit for creative coding in C++.