immer
Seastar
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immer | Seastar | |
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25 | 25 | |
2,420 | 8,004 | |
- | 1.4% | |
6.7 | 9.7 | |
2 days ago | 4 days ago | |
C++ | C++ | |
Boost Software License 1.0 | Apache License 2.0 |
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.
immer
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Text Editor Data Structures: Rethinking Undo
I've been working on an editor (not text) in C++ and pretty early got into undo/redo. I went down the route of doIt/undoIt for commands but that quickly got old. There was both the extra work needed to implement undo separately for every operation, but also the nagging feeling that the undo operation for some operation wasn't implemented correctly.
In the end, I switched to representing the entire document state using persistent data structures (using the immer library). This vastly simplified things and implementing undo/redo becomes absolutely trivial when using persistent data structures. It's probably not something that is suitable for all domains, but worth checking out.
https://github.com/arximboldi/immer
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Show HN: A hash array-mapped trie implementation in C
How does this compare to https://github.com/arximboldi/immer (other than the C/C++ difference)?
Also, it's my understanding that, in practice, persistent data structures require a garbage collector in order to handle deallocation when used in a general-purpose way. How does your implementation handle that?
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Text Editor Data Structures
You might be interested in ewig and immer by Juan Pedro Bolivar Puente:
https://github.com/arximboldi/ewig
https://github.com/arximboldi/immer
See the author instantly opening a ~1GB text file with async loading, paging through, copying/pasting, and undoing/redoing in their prototype “ewig” text editor about 27 minutes into their talk here:
https://m.youtube.com/watch?v=sPhpelUfu8Q
It’s backed by a “vector of vectors” data structure called a relaxed radix balanced tree:
https://infoscience.epfl.ch/record/169879/files/RMTrees.pdf
That original paper has seen lots of attention and attempts at performance improvements, such as:
https://hypirion.com/musings/thesis
https://github.com/hyPiRion/c-rrb
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value semantics and spans/views
You’re absolutely right, however people have been putting in the “extra efforts” required for efficiency. Check out immer if you’re interested.
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How to synchronize access to application data in multithreaded asio?
The C++ immer library: https://github.com/arximboldi/immer
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Purely Functional Data Structure by Chris Okasaki [pdf]
For C++ check this one out - https://github.com/arximboldi/immer
- Persistent and immutable data structures written in C++14
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Introducing B++ Trees, a C++ B+ Tree library
Yeah I agree that I should link that wikipedia page in the docs, I'll do that as soon as I get a chance. immer (https://github.com/arximboldi/immer) also links that page in its docs, for the exact same reason I'm sure. Interestingly, there is a lot of overlap between persistent data structures in the functional programming sense and persistent data structures in the persisted-to-disk sense because persistent data structures in the FP sense are one of the best ways to guarantee atomic updates and safe failure recovery in a persisted-to-disk system! Btrfs and ZFS, as well as many databases, are at their core basically just copy-on-write B+ trees.
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What are some architectural patterns for creating a game editor.
I’ve never tried it, but I love the idea of implementing editor scene state using immutable data structures like https://github.com/arximboldi/immer With that, every edit would append a new node to a list of scene states. Undo/redo becomes iterating your view of the scene up and down through that list. Can’t screw up an undo function if there’s never any work to do :P
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TypeScript Without Side Effects
I have! I think it's related to the C++ immer library which I used several years ago in Vortex. It's kinda like the previous generation of ValueScript. 🍻
Seastar
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I want to share my latest hobby project, dbeel: A distributed thread-per-core nosql db written in rust
I used glommio as the async executor (instead of something like tokio), and it is wonderful. For people wondering whether it's "good enough" or to use C++ and seastar (as I have thought about a lot before starting this project), take the leap of faith, it's fast - both in terms of run time and to code.
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How much reason is there to be multi-threaded in the k8s environment
b) It's proven now e.g Seastar, Glommio that the fastest way to run a multi-threaded application is to have one instance with one thread pinned per CPU core. Then to have fibers/lightweight threads on top handling all of the asynchronous code. Your approach of lots of instances is the slowest so there will be a ton of unnecessary thread context-switching.
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Are You Sure You Want to Use MMAP in Your Database Management System?
The most common example is DPDK [1]. It's a framework for building bespoke networking stacks that are usable from userspace, without involving the kernel.
You'll find DPDK mentioned a lot in the networking/HPC/data center literature. An example of a backend framework that uses DPDK is the seastar framework [2]. Also, I recently stumbled upon a paper for efficient RPC networks in data centers [3].
If you want to learn more, the p99 conference by ScyllaDB has tons of speakers talking about some interesting challenges.
[1] https://www.dpdk.org/.
[2] https://github.com/scylladb/seastar
[3] https://github.com/erpc-io/eRPC
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Why does Actix-web's handler not require Send?
I assume Tokio itself, see e.g monoio or glommio, but also Seastar for C++.
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What is DPDK library in C and how to learn it?
https://core.dpdk.org/supported/ lists supported nics. You're best just reading material from the dpdk website for figuring out roughly what it is. It is used for a lot of different goals. For most web C++ stuff it's mainly used because you can avoid round trips of data passing through the kernel and can reference network data without tons of copying. For an example check out the SeaStar framework, https://seastar.io/, which is under the hood of ScyllaDB.
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How Numberly Replaced Kafka with a Rust-Based ScyllaDB Shard-Aware Application
As this is a Kafka sub, this may be a good opportunity to mention that Redpanda is based on the same framework (seastar) as Scylla. The idea of sharding work to CPU cores turns out to apply very well to the Kafka data model, too!
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What are some C++ projects with high quality code that I can read through?
Seastar which is a thread per core runtime written by the Scylla devs thats used in both Redpanda and Scylla as the underlying runtime. https://github.com/scylladb/seastar
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Abstraction Is Expensive
ScyllaDB is, ironically, maybe one of the worst examples the author could have come up with for "abstraction" in the article.
If folks aren't familiar with their work/internal tech, go check out some of their repos like Seastar. They have some of the most talented systems programmers on the planet writing thin veneers over kernel and hardware API's to squeeze every ounce out of performance.
https://github.com/scylladb/seastar
I know it's beside the point, but I just had to share because I thought that was funny
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Modern JVM Multithreading • Paweł Jurczenko • Devoxx Poland 2021
I’ve seen frameworks for c++ (https://seastar.io/) and rust (https://github.com/actix/actix) which support what you’re describing out of the box.
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Who is using C++ for web development?
If you're interested in scaling and asynchronous programming in c++ I highly recommend you investigate the SeaStar application framework. You wouldn't build a web service with SeaStar, rather you would build the infrastructure that you would use to build the web service on top of. https://github.com/scylladb/seastar
What are some alternatives?
babashka - Native, fast starting Clojure interpreter for scripting
Folly - An open-source C++ library developed and used at Facebook.
clj-kondo - Static analyzer and linter for Clojure code that sparks joy
glommio - Glommio is a thread-per-core crate that makes writing highly parallel asynchronous applications in a thread-per-core architecture easier for rustaceans.
graalvm-clojure - This project contains a set of "hello world" projects to verify which Clojure libraries do actually compile and produce native images under GraalVM.
Boost.Asio - Asio C++ Library
ewig - The eternal text editor — Didactic Ersatz Emacs to show immutable data-structures and the single-atom architecture
Boost - Super-project for modularized Boost
deprecated-coalton-prototype - Coalton is (supposed to be) a dialect of ML embedded in Common Lisp.
ffead-cpp - Framework for Enterprise Application Development in c++, HTTP1/HTTP2/HTTP3 compliant, Supports multiple server backends
awesome-modern-cpp - A collection of resources on modern C++
Qt - Qt Base (Core, Gui, Widgets, Network, ...)