ruruby

An alternative Ruby implementation by Rust.

Feature

• Purely implemented with Rust.
• No dependency on any other Ruby implementation such as CRuby(MRI), mruby, .. etc.
• Hand-written original parser.
• Virtual machine execution.

Related article (sorry, currently only in Japanese)

Qiita: Rust でつくる（つくれるかもしれない）Ruby

Implementation status

Attention: Still in alpha, so the implementation and builtin libraries are immature.
Please note that some of features listed below are functional but still currently incomplete.

• Literals
  • Bool
  • Integer
  • Float
  • String literal
  • String literal with interpolation
  • Array literal
  • Hash literal
  • Lambda literal
  • Block literal
  • Regular expression
• Builtin Class
  • Integer
  • Float
  • Symbol
  • String
  • Range
  • Array
  • Hash
  • Proc
  • Method
  • Regexp
  • Struct
  • Enumerator
  • Fiber
• Variables
  • Local variable
  • Instance variable
  • Class variable
  • Global variable
• Constants
  • Constant
• Branch and Loop
  • If-then-elsif-else
  • Unless-then-else
  • Postfix if / unless
  • For-in
  • Break / Continue
  • While
  • Until
  • Postfix while / until
  • Case-when
  • Return
• Methods
  • Instance Method
  • Class Method
  • Singleton Method
• Class and Module
  • Subclass / Inheritance
  • Initializer
  • Attribute accessor
  • Open class (Ad-hoc class definition)
  • Module

Performance

Currently, performance of ruruby in speed is not satisfactory. Here is a preliminary report:

benchmark	ruruby	CRuby(2.8.0)
so_mandelbrot.rb*	2.88 s	1.89 s
app_mandelbrot.rb*	6.83 s	2.35 s
app_aobench.rb*	27.96 s	9.01 s
app_fib.rb*	1.51 s	0.32 s
optcarrot**	19.68 s	4.05 s

(Run on WSL2 on Windows10 with Intel Corei7-7700 @ 3.60GHz.)
Execution time in seconds are shown.
The lower, the better.
*available on https://github.com/ruby/ruby/blob/master/benchmark/
**Optcarrot is NES emulator, and a semi-official benchmark program for Ruby, on https://github.com/mame/optcarrot

Optcarrot benchmark results

benchmark	ruruby	CRuby(2.8.0)
optcarrot	9.62 fps	48.8 fps

Frames per seconds are shown.
The higher, the better.

Memory consumption

To investigate memory consumption, maximum resident set size was measured using gnu-time.

app_aobench.rb

(this benchmark program produce and consume huge number of objects)

engine	max resident set size
CRuby(GC on)	15 MB
CRuby(GC off)	1649 MB
ruruby	3864 MB

fibo.rb

(producing almost no objects, huge number of method calls)

engine	max resident set size
CRuby(GC on)	13.7 MB
CRuby(GC off)	13.9 MB
ruruby	2.1 MB

optcarrot (benchmark mode)

(a lot of arithmetic and array operations)

engine	max resident set size
CRuby(GC on)	82.5 MB
CRuby(GC off)	85.5 MB
ruruby	355.6 MB

How to run ruruby

To build ruruby, You'll need installation of Rust. Please be aware that only nightly version of Rust works for ruruby.

To run ruby program file on ruruby,

% cargo run tests/sample.rb

or

% cargo run --release -- tests/sample.rb

You can launch irb-like interactive shell, omitting file name.

% cargo run

Option: Bytecode Trace execution

% cargo run --features trace -- tests/sample.rb
   Compiling ruruby v0.1.0
    Finished dev [unoptimized + debuginfo] target(s) in 1.83s
     Running `target/debug/ruruby tests/sample.rb`
---> MethodRef(198)
   0:PUSH_STRING     stack:0
   5:SET_LOCAL       stack:1
   e:PUSH_STRING     stack:0
  13:PUSH_STRING     stack:1
  18:CONCAT_STR      stack:2
  19:GET_LOCAL       stack:1
  22:TO_S            stack:2
  23:CONCAT_STR      stack:2
  24:PUSH_STRING     stack:1
  29:CONCAT_STR      stack:2
  2a:SEND_SELF       stack:1
Hello world!
  3b:END             stack:1
<--- Ok(nil)

Option: Emit ByteCode

% cargo run --features emit-iseq -- tests/sample.rb
   Compiling ruruby v0.1.0
    Finished dev [unoptimized + debuginfo] target(s) in 6.72s
     Running `target/debug/ruruby tests/sample.rb`
-----------------------------------------
MethodRef(198)
local var: 0:w
block: None
  00000 PUSH_STRING 181
  00005 SET_LOCAL outer:0 LvarId:0
  00014 PUSH_STRING 182
  00019 PUSH_STRING 183
  00024 CONCAT_STR
  00025 GET_LOCAL outer:0 LvarId:0
  00034 TO_S
  00035 CONCAT_STR
  00036 PUSH_STRING 184
  00041 CONCAT_STR
  00042 SEND_SELF 'puts' 1 items
  00059 END
Hello world!

Option: Performance analysis per VM instruction

% cargo run --features perf -- tests/sample.rb
   Compiling ruruby v0.1.0
    Finished dev [unoptimized + debuginfo] target(s) in 3.53s
     Running `target/debug/ruruby tests/sample.rb`
Hello world!
Performance analysis for Inst:
------------------------------------------
Inst name         count    %time     nsec
                                    /inst
------------------------------------------
PUSH_STRING           4     6.48    25993
SET_LOCAL             1     0.19     3756
GET_LOCAL             1     0.00      382
SEND_SELF             1     2.58    41261
CONCAT_STR            3     0.19     1166
TO_S                  1     0.25     4707
END                   1     0.06     1044
CODEGEN               1    87.48  1391588
EXTERN                1     2.45    39834
------------------------------------------