Folly
Vcpkg
Folly | Vcpkg | |
---|---|---|
90 | 147 | |
27,218 | 21,844 | |
1.0% | 2.4% | |
9.8 | 10.0 | |
1 day ago | about 7 hours ago | |
C++ | CMake | |
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.
Folly
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Ask HN: How bad is the xz hack?
https://github.com/facebook/folly/commit/b1391e1c57be71c1e2a...
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Backdoor in upstream xz/liblzma leading to SSH server compromise
https://github.com/facebook/folly/pull/2153
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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
Vcpkg
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Xmake: A modern C/C++ build tool
re: C/C++ development: anybody using conda/pixi for dependency management? Here's an example of compiling a C++ SDL program using pixi and the SDL dependency from conda-forge [1].
Seems viable as a replacement for things like vckpg [2] which only builds from source.
I'm still researching this but it seems like rattler [3] is the tool to use to build/publish packages. The supported repos are: prefix.dev's own hosting, anaconda.org, artifactory or a self-hosted server.
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1: https://github.com/prefix-dev/pixi/blob/main/examples/cpp-sd...
2: https://github.com/microsoft/vcpkg
3: https://prefix-dev.github.io/rattler-build/latest/authentica...
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Backdoor in upstream xz/liblzma leading to SSH server compromise
5.4.5 can be compromised
https://github.com/microsoft/vcpkg/issues/37197
- GitHub - microsoft/vcpkg: C++ Library Manager for Windows, Linux, and MacOS
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Dependencies Belong in Version Control
vcpkg may expire assets after 1.5 years, so achieve long-term reproducibility you will need to cache your dependencies.... Somewhere. Not sure what the expected solution is.
https://github.com/microsoft/vcpkg/pull/30546#issuecomment-1...
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My first Software Release using GitHub Release
There were various approaches recommended depending on our language and ecosystem. My classmates who developed using Node.js were recommended npm, and PyPI or poetry for Python. Since my program is written in C++, I was recommended to look into one of vcpkg or conan, but I ultimately did not use either package manager.
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Anyone else frustrated with Conan2?
Which dependencies are not in vcpkg? We can ask them to add it. It’s pretty easy just open an issue there https://github.com/microsoft/vcpkg/issues .
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How to install libraries for c++ on a Linux CentOS supercomputer where I'm not a sudoer
./vcpkg search netcdf gdal[netcdf] Enable NetCDF support minc 2.4.03#3 MINC - Medical Image NetCDF or MINC isn't netCDF minc[minc1] Support minc1 file format, requires NETCDF netcdf-c 4.8.1#2 A set of self-describing, machine-independent data formats that support th... netcdf-c[dap] Build with DAP remote access client support netcdf-c[hdf5] Build with HDF5 support netcdf-c[nczarr] Build with NCZarr cloud storage access support netcdf-c[nczarr-zip] Build with NCZarr ZIP support netcdf-c[netcdf-4] Build with netCDF-4 support netcdf-c[platform-default-features] Enable platform-dependent default features netcdf-c[tools] Build utilities netcdf-cxx4 4.3.1#4 a set of machine-independent data formats that support the creation, acces... The result may be outdated. Run `git pull` to get the latest results. If your port is not listed, please open an issue at and/or consider making a pull request. - https://github.com/Microsoft/vcpkg/issues
- Does anyone has a idea to read out dependencies out of c/cpp directories to create .sbom files?
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hypergrep: A new "fastest grep" to search directories recursively for a regex pattern
The hyperscan update to vcpkg seems to have happened from 5.4.0 to 5.4.2 in this commit on Apr 20.
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Configuring incomplete due to CMake Error(missing OpenCVConfig.cmake ProtobufConfig.cmake and TIFF etc.)
Dear Fictrac team, I am hoping to install Fictrac in our windows 11 x64 laptop (Visual Studio 2019, cMake 3.26.4). I followed the installation guideline on github page fictrac and used the latest vcpkg
What are some alternatives?
abseil-cpp - Abseil Common Libraries (C++)
conan - Conan - The open-source C and C++ package manager
Boost - Super-project for modularized Boost
CPM.cmake - 📦 CMake's missing package manager. A small CMake script for setup-free, cross-platform, reproducible dependency management.
Seastar - High performance server-side application framework
Boost.Program_options - Boost.org program_options module
parallel-hashmap - A family of header-only, very fast and memory-friendly hashmap and btree containers.
Ncurses - ncurses Git mirror
EASTL - Obsolete repo, please go to: https://github.com/electronicarts/EASTL
vulkan - Haskell bindings for Vulkan
OpenFrameworks - openFrameworks is a community-developed cross platform toolkit for creative coding in C++.
meson - The Meson Build System