sml
abseil-cpp
sml | abseil-cpp | |
---|---|---|
23 | 54 | |
1,081 | 13,955 | |
2.3% | 1.3% | |
6.8 | 9.5 | |
about 1 month ago | 4 days ago | |
C++ | C++ | |
Boost Software License 1.0 | Apache License 2.0 |
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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.
sml
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Sharing Saturday #496
Anyway the need is not complicated, I need both entry and exit functions from every state, optionally allowing these functions to be coroutines (that's special sauce but for later), and an explicit state transition table which also have a way to say that a state can be accessed at any point. Also allow states to be state machines, optional FSM hierarchies. If you ignore the coroutine stuff it's pretty standard features these days, except that - Boost.MSM is quite archaic now (it was so novel when it was first released...) although it allows most of the features I talked about, I just think it will complicate my code unneecessarilly; - Boost-Ext.SML (not Boost) is almost perfect except it doesnt have entry/exit functions on states for some reason. Also last time we (as in in livestream) tried it in prototypes it didnt compile on msvc XD - Boost-Ext.SML2 is even better but still doesnt have entry/exit functions although it's in the plans.
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State machines with C++20 coroutines and Asio/Boost Async
Hello all. Being a huge fan of state machine and coroutines, I have been browsing around for examples of what other people do combine these two. I have been using boost-ext/sml for quite many projects and are quite happy about that. But when transitioning to code that relies on coroutines, I would like to write entry/exit/actions/guard methods that uses coroutines and where I can co_await on awaitables from Asio and more recently "Boost Async".
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Looking for well written, modern C++ (17/20) example projects for microcontrollers
boost-ext/sml: quite modern way of doing state machines using a DSL
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When Debug Symbols Get Large
I recently was troubleshooting a crash that backtraced through the boost::sml library [0]. The crash didn't actually have anything to do with the library, but it was used as the core event loop.
The backtrace -- as in, just the output from running `bt` in GDB -- was over a thousand wrapped lines long. There were ~5 stack frames that took up 200 lines of console each to print just the function name. That product's debug builds recently hit the 2GB line, which is enough that old versions of binutils complain.
I don't know what the solution is. There's some really neat stuff you can do with template metaprogramming, and in stripped release builds it compiles down extremely tiny. Plus the code is very clean to read. But it does feel like there isn't any kind of central vision for the C++ debugging experience, and bad interactions between highly-complex modern C++ typing, the compiler, and the debugger are probably only going to get worse unless somebody (the ISO committee? Vendors?) thinks really hard about debugging support.
[0]: https://github.com/boost-ext/sml
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[Boost::MSM] Huge Memory Usage Issue During Compilation
I'm a big fan of MSM but what you're experiencing is pretty normal for template-heavy libraries built on C++03 machinery (emulation of variadic templates is the usual culprit). It's probably not the answer you're hoping for, but the real solution is to switch to a library with more modern foundations. (I've been happily using [Boost::ext].SML for a few years but I'm reluctant to strongly recommend anything in particular since I haven't re-explored the problem space since I found it.)
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State machine suggestion?
The Boost one that you mention, seems to be one that it's kinda old. A "successor" of sorts is Boost SML. I've not used it yet, but certainly the first impressions are very good.
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Specifications for an open source finite state machine library
Or Boost.Sml
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Facts about State Machines
At our company, we rely a lot on https://github.com/boost-ext/sml
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What are some cool modern libraries you enjoy using?
I'm a big fan of boost::sml for representing state machines.
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[C++20] New way of meta-programming?
https://github.com/boost-ext/sml (State Machine DSL and backend for perfomance)
abseil-cpp
- Sane C++ Libraries
- Open source collection of Google's C++ libraries
- Is Ada safer than Rust?
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Appending to an std:string character-by-character: how does the capacity grow?
Yeah, it's nice! And Abseil does it, IFF you use LLVM libc++.
https://github.com/abseil/abseil-cpp/blob/master/absl/string...
The standard adopted it as resize_and_overwrite. Which I think is a little clunky.
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Shaving 40% Off Google’s B-Tree Implementation with Go Generics
This may be confusing to those familiar with Google's libraries. The baseline is the Go BTree, which I personally never heard of until just now, not the C++ absl::btree_set. The benchmarks aren't directly comparable, but the C++ version also comes with good microbenchmark coverage.
https://github.com/google/btree
https://github.com/abseil/abseil-cpp/blob/master/absl/contai...
- Faster Sorting Beyond DeepMind’s AlphaDev
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“Once” one-time concurrent initialization with an integer
An implementation of call_once that accommodates callbacks that throw: https://github.com/abseil/abseil-cpp/blob/master/absl/base/c...
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[R] AlphaDev discovers faster sorting algorithms
I wouldn't say it's that cryptic. It's just a few bitwise rotations/shifts/xor operations.
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Deepmind Alphadev: Faster sorting algorithms discovered using deep RL
You can see hashing optimizations as well https://www.deepmind.com/blog/alphadev-discovers-faster-sort..., https://github.com/abseil/abseil-cpp/commit/74eee2aff683cc7d...
I was one of the members who reviewed expertly what has been done both in sorting and hashing. Overall it's more about assembly, finding missed compiler optimizations and balancing between correctness and distribution (in hashing in particular).
It was not revolutionary in a sense it hasn't found completely new approaches but converged to something incomprehensible for humans but relatively good for performance which proves the point that optimal programs are very inhuman.
Note that for instructions in sorting, removing them does not always lead to better performance, for example, instructions can run in parallel and the effect can be less profound. Benchmarks can lie and compiler could do something differently when recompiling the sort3 function which was changed. There was some evidence that the effect can come from the other side.
For hashing it was even funnier, very small strings up to 64 bit already used 3 instructions like add some constant -> multiply 64x64 -> xor upper/lower. For bigger ones the question becomes more complicated, that's why 9-16 was a better spot and it simplified from 2 multiplications to just one and a rotation. Distribution on real workloads was good, it almost passed smhasher and we decided it was good enough to try out in prod. We did not rollback as you can see from abseil :)
But even given all that, it was fascinating to watch how this system was searching and was able to find particular programs can be further simplified. Kudos to everyone involved, it's a great incremental change that can bring more results in the future.
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Backward compatible implementations of newer standards constructs?
Check out https://abseil.io. It offers absl::optional, which is a backport of std::optional.
What are some alternatives?
hsm - Finite state machine library based on the boost hana meta programming library. It follows the principles of the boost msm and boost sml libraries, but tries to reduce own complex meta programming code to a minimum.
Folly - An open-source C++ library developed and used at Facebook.
stm32plus - The C++ library for the STM32 F0, F100, F103, F107 and F4 microcontrollers
Boost - Super-project for modularized Boost
hana - Your standard library for metaprogramming
spdlog - Fast C++ logging library.
HFSM2 - High-Performance Hierarchical Finite State Machine Framework
Qt - Qt Base (Core, Gui, Widgets, Network, ...)
Experimental Boost.DI - C++14 Dependency Injection Library
EASTL - Obsolete repo, please go to: https://github.com/electronicarts/EASTL
Boost.Beast - HTTP and WebSocket built on Boost.Asio in C++11
BDE - Basic Development Environment - a set of foundational C++ libraries used at Bloomberg.