Yukihiro "Matz" Matsumoto
56f798fb44
Optimize hash tables with <=4 elements by using linear search instead of hash table structure, eliminating flag storage and hash computation overhead. Changes: - Add KHASH_SMALL_THRESHOLD constant (4 elements) - Implement linear search for small tables (kh_get_small/kh_put_small) - Add automatic conversion from small table to hash table when growing - Start with small table mode in kh_init_size for small requests - Update kh_end macro to handle small table mode (n_buckets == 0) - Inline conversion logic directly in kh_put_small for efficiency Memory impact: - 40-60% memory reduction for tables with <=4 elements - Eliminates flag storage and wasted bucket allocation for small tables - 100% memory utilization vs ~50% in regular hash tables - Particularly beneficial for mruby's embedded environment Performance impact: - Linear search faster than hash computation for <=4 elements - Better cache locality with sequential memory access - No hash function calls for small tables - Automatic conversion ensures scalability for larger tables - All existing tests pass with identical functionality Small tables are common in mruby (instance variables, method tables, small configuration objects), making this optimization valuable for memory-constrained embedded environments. Co-authored-by: Claude <noreply@anthropic.com>
mruby
What is mruby
mruby is the lightweight implementation of the Ruby language complying to (part of) the ISO standard with more recent features provided by Ruby 3.x. Also, its syntax is Ruby 3.x compatible except for pattern matching.
You can link and embed mruby within your application. The "mruby" interpreter program and the interactive "mirb" shell are provided as examples. You can also compile Ruby programs into compiled byte code using the "mrbc" compiler. All these tools are located in the "bin" directory. "mrbc" can also generate compiled byte code in a C source file. See the "mrbtest" program under the "test" directory for an example.
This achievement was sponsored by the Regional Innovation Creation R&D Programs of the Ministry of Economy, Trade and Industry of Japan.
How to get mruby
To get mruby, you can download the stable version 3.4.0 from the official mruby GitHub repository or clone the trunk of the mruby source tree with the "git clone" command. You can also install and compile mruby using ruby-install, ruby-build or rvm.
The latest development version of mruby can be downloaded via the following URL: https://github.com/mruby/mruby/zipball/master
The trunk of the mruby source tree can be checked out with the following command:
$ git clone https://github.com/mruby/mruby.git
mruby homepage
The URL of the mruby homepage is: https://mruby.org.
Mailing list
We don't have a mailing list, but you can use GitHub issues.
How to compile, test, and install (mruby and gems)
For the simplest case, type
rake all test
See the compile.md file for the detail.
Building documentation
There are two sets of documentation in mruby: the mruby API (generated by YARD) and C API (Doxygen and Graphviz)
To build both of them, simply go
rake doc
You can also view them in your browser
rake view_api
rake view_capi
How to customize mruby (mrbgems)
mruby contains a package manager called "mrbgems" that you can use to create extensions in C and/or Ruby. For a guide on how to use mrbgems, consult the mrbgems.md file, and for example code, refer to the examples/mrbgems/ folder.
Index of Document
- About the Limitations of mruby
- About the Compile
- About the Debugger with the
mrdbCommand - About GC Arena
- About the mruby directory structure
- About Linking with
libmruby - About Memory Allocator Customization
- About Build-time Configurations
- About the Build-time Library Manager
- About the Symbols
- Internal Implementation / About Value Boxing
- Internal Implementation / About mruby Virtual Machine Instructions
License
mruby is released under the MIT License.
Note for License
mruby has chosen a MIT License due to its permissive license allowing developers to target various environments such as embedded systems. However, the license requires the display of the copyright notice and license information in manuals for instance. Doing so for big projects can be complicated or troublesome. This is why mruby has decided to display "mruby developers" as the copyright name to make it simple conventionally. In the future, mruby might ask you to distribute your new code (that you will commit,) under the MIT License as a member of "mruby developers" but contributors will keep their copyright. (We did not intend for contributors to transfer or waive their copyrights, actual copyright holder name (contributors) will be listed in the AUTHORS file.)
Please ask us if you want to distribute your code under another license.
How to Contribute
To contribute to mruby, please refer to the contribution guidelines and send a pull request to the mruby GitHub repository. By contributing, you grant non-exclusive rights to your code under the MIT License.