Cap'n Proto
cppcoro
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Cap'n Proto | cppcoro | |
---|---|---|
66 | 24 | |
11,163 | 3,214 | |
1.2% | - | |
9.3 | 0.0 | |
2 days ago | 3 months ago | |
C++ | C++ | |
GNU General Public License v3.0 or later | 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.
Cap'n Proto
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Mysterious Moving Pointers
Yeah I pretty much only use my own alternate container implementations (from KJ[0]), which avoid these footguns, but the result is everyone complains our project is written in Kenton-Language rather than C++ and there's no Stack Overflow for it and we can't hire engineers who know how to write it... oops.
[0] https://github.com/capnproto/capnproto/blob/v2/kjdoc/tour.md
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Show HN: Comprehensive inter-process communication (IPC) toolkit in modern C++
- may massively reduce the latency involved.
Those sharing Cap'n Proto-encoded data may have particular interest. Cap'n Proto (https://capnproto.org) is fantastic at its core task - in-place serialization with zero-copy - and we wanted to make the IPC (inter-process communication) involving capnp-serialized messages be zero-copy, end-to-end.
That said, we paid equal attention to other varieties of payload; it's not limited to capnp-encoded messages. For example there is painless (<-- I hope!) zero-copy transmission of arbitrary combinations of STL-compliant native C++ data structures.
To help determine whether Flow-IPC is relevant to you we wrote an intro blog post. It works through an example, summarizes the available features, and has some performance results. https://www.linode.com/blog/open-source/flow-ipc-introductio...
Of course there's nothing wrong with going straight to the GitHub link and getting into the README and docs.
Currently Flow-IPC is for Linux. (macOS/ARM64 and Windows support could follow soon, depending on demand/contributions.)
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Condvars and atomics do not mix
FWIW, my C++ toolkit library, KJ, does the same thing.[0]
But presumably you could still write a condition predicate which looks at things which aren't actually part of the mutex-wrapped structure? Or does is the Rust type system able to enforce that the callback can only consider the mutex-wrapped value and values that are constant over the lifetime of the wait? (You need the latter e.g. if you are waiting for the mutex-wrapped value to compare equal to some local variable...)
[0] https://github.com/capnproto/capnproto/blob/e6ad6f919aeb381b...
- Cap'n'Proto: infinitely faster than Protobuf
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I don’t understand zero copy
The second one is to encode data in such a way that you can read it and operate on it directly from the buffer. You write data in a layout that is the same, or easily transformed as types in memory. To do that you usually need to encode with a known schema, only Sized types to efficiently compute fields locations as offsets in the buffer, and you usually represent pointers as offset into the encode. You can look at capnproto protocol for instance https://capnproto.org/
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OpenTF Renames Itself to OpenTofu
Worked well for Cap'n Proto (the cerealization protocol)! https://capnproto.org/
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A Critique of the Cap'n Proto Schema Language
With all due respect, you read completely wrong.
* The very first use case for which Cap'n Proto was designed was to be the protocol that Sandstorm.io used to talk between sandbox and supervisor -- an explicitly adversarial security scenario.
* The documentation explicitly calls out how implementations should manage resource exhaustion problems like deep recursion depth (stack overflow risk).
* The implementation has been fuzz-tested multiple ways, including as part of Google's oss-fuzz.
* When there are security bugs, I issue advisories like this:
https://github.com/capnproto/capnproto/tree/v2/security-advi...
* The primary aim of the entire project is to be a Capability-Based Security RPC protocol.
- Cap'n Proto: serialization/RPC system – core tools and C++ library
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Sandstorm: Open-source platform for self-hosting web app
I like how they use capability-based security [0] and use Cap'n Proto protocol. This is another technology that is slow to get broad adoption, but has many things going for when compared to e.g. Protocol Buffers (Cap'n Proto is created by the primary author of Protobuf v2, Kenton Varda).
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Flatty - flat message buffers with direct mapping to Rust types without packing/unpacking
Related but not Rust-specific: FlatBuffers, Cap'n Proto.
cppcoro
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Struggle with C++ 20 Coroutines
PS: Take a look at cppcoro; this might help as well, especially generator<>, if you're looking to generate numbers, and stuff;
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Does C++23 have a coroutine task promise type?
This is the only viable implementation.
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Stop Comparing Rust to Old C++
Kind of sounds like whatever library you were using provided leaky abstractions. Something like cppcoro provides really good abstractions for coroutines, the user really doesn't need to understand why any of it works.
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Sane coroutine imitation with macros; copyable, serializable, and with reflection
Is there a usecase for copying/serializing such coroutines? If not, I would use the normal C++20 coroutines (cppcoro?).
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Is Tokio::sync::Mutex lock-free?
C++ has the popular CppCoro library. Async_mutex is its equivalent of Tokio::sync::Mutex, providing exclusive access to data shared between tasks.
- My experience with C++ 20 coroutines
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My thoughts and dreams about a standard user-space I/O scheduler
Because the whole application is running under a single thread there is no need for atomic operations in synchronization primitives(which most of the time requires seq_cst memory order and CMPXCHG which is an expensive instruction in CPU). for example what async_mutex would look like if it knows it's running in a single-threaded scheduler (a non-atomic state variable and waiters queue).
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[Discussion] What are some old C++ open source projects you wish were still active?
Maybe not old, but I wish cppcoro was still updated. It was such a nice start!
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A high-level coroutine explanation
You can get generator<> from https://github.com/lewissbaker/cppcoro
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C++ Coroutines Do Not Spark Joy
It is possible to compose them more easily than described in the article; Lewis Baker's cppcoro library for example provides a recursive_generator<> type[0] that allows this without using any macros. It's up to the library part of coroutines to make things easy, end users are not expected to write low-level coroutine code themselves.
I wonder about the allocation elision. Return value optimization became mandatory, and some compilers can already elide calls to new/delete and malloc()/free() in normal code, so perhaps it will be possible to guarantee allocation elision in the future in the most used cases.
[0]: https://github.com/lewissbaker/cppcoro#recursive_generatort
What are some alternatives?
gRPC - The C based gRPC (C++, Python, Ruby, Objective-C, PHP, C#)
libunifex - Unified Executors
Protobuf - Protocol Buffers - Google's data interchange format
drogon - Drogon: A C++14/17/20 based HTTP web application framework running on Linux/macOS/Unix/Windows
FlatBuffers - FlatBuffers: Memory Efficient Serialization Library
Folly - An open-source C++ library developed and used at Facebook.
ZeroMQ - ZeroMQ core engine in C++, implements ZMTP/3.1
C-Coroutines - Coroutines for C.
Apache Thrift - Apache Thrift
Flow - Flow is a software framework focused on ease of use while maximizing performance in closed closed loop systems (e.g. robots). Flow is built on top of C++ 20 coroutines and utilizes modern C++ techniques.
MessagePack - MessagePack serializer implementation for Java / msgpack.org[Java]
coproto - A protocol framework based on coroutines