FFI
MAKING CROSS ENGINE EXTENSIONS


  Jeremy Hinegardner
    jeremy@copiousfreetime.org
       twitter: copiousfreetime
COPIOUS FREE TIME
  Fedora           Ruby
 Packaging         Gems

•beanstalkd    •keybox
•haproxy       •rabal
•libtomcry...
I LOVE RUBY
I LIKE C
ANY
EXTENSION DEVELOPERS
    IN THE HOUSE ?
WHO HAS USED FFI?
WHO HAS HEARD OF FFI?
WHAT IS FFI?
LIBFFI
    http://sourceware.org/libffi/

 “A foreign function interface is the
popular name for the interface that
allows ...
e
              m
           i
    Application
         t
      n
      uses

    u
libsomething_foo()

R       FFI


libs...
App                                            App
JRuby                                          Rubinius
Interpreter    ...
 1   #ifndef __SIMPLE_METRICS_H__
 2   #define __SIMPLE_METRICS_H__
 3   #include <stdlib.h>
 4   #include <math.h>
 5
 6 ...
 1   class Metric
 2     attr_reader :name
 3     def initialize( name )
 4       @name
 5     end
 6
 7     def update( n...
142   void Init_simple_metrics_ext()
143   {
144       VALUE cSM_Common;
145
146       mSM  = rb_define_module( quot;Simpl...
7   module SimpleMetrics
 8     module FFI
 9
10       class Struct < ::FFI::ManagedStruct
11         layout :min, :double...
35   module SimpleMetrics
36     module FFI
37       class Metric < ::SimpleMetrics::Common
38         include ::SimpleMet...
10   class Struct < ::FFI::ManagedStruct                  6   typedef struct _simple_metrics{
11     layout :min, :double,...
21   extend ::FFI::Library
22   ffi_lib quot;libsimple_metricsquot;
23
24   attach_function   :simple_metrics_new,   [    ...
MEANINGLESS METRICS
                                  Traditional C
                        FFI
                          ...
% ruby ~/Projects/simple_metrics/example/bench.rb 1000000
generating 1000000 random numbers between 0 and 10,000
Rehearsal...
FFI GEMS
   ffi-ncurses                  tidy_ffi




                     4
ffi-swig-generator              ffi-zlib
GEMS WITH EXTENSIONS



   346
      Out of 4,501 gems
GET
 TO
WORK!!
THANKS

• Wayne   Meissner - adding libffi to JRuby and providing the
 ffi gem for MRI.

• Evan   Phoenix - using libffi in R...
LINKS

    http://blog.headius.com/2008/10/ffi-for-ruby-now-available.html
•

    http://kenai.com/projects/ruby-ffi
•

    ...
QUESTIONS?
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Ffi

  1. 1. FFI MAKING CROSS ENGINE EXTENSIONS Jeremy Hinegardner jeremy@copiousfreetime.org twitter: copiousfreetime
  2. 2. COPIOUS FREE TIME Fedora Ruby Packaging Gems •beanstalkd •keybox •haproxy •rabal •libtomcrypt •launchy •libtommath •heel •nginx •htauth •ragel •amalgalite •tinyproxy •hitimes •stickler •crate
  3. 3. I LOVE RUBY
  4. 4. I LIKE C
  5. 5. ANY EXTENSION DEVELOPERS IN THE HOUSE ?
  6. 6. WHO HAS USED FFI?
  7. 7. WHO HAS HEARD OF FFI?
  8. 8. WHAT IS FFI?
  9. 9. LIBFFI http://sourceware.org/libffi/ “A foreign function interface is the popular name for the interface that allows code written in one language to call code written in another language.”
  10. 10. e m i Application t n uses u libsomething_foo() R FFI libsomething.so
  11. 11. App App JRuby Rubinius Interpreter Interpreter App Matz Ruby something-ffi (pure ruby) Interpreter ruby-somethingor ffi gem built-in libffi C extension libsomething.so
  12. 12.  1 #ifndef __SIMPLE_METRICS_H__  2 #define __SIMPLE_METRICS_H__  3 #include <stdlib.h>  4 #include <math.h>  5  6 typedef struct _simple_metrics{  7     double min;  8     double max;  9     double sum; 10     double sumsq; 11     long   count; 12 } simple_metrics ; 13 14 simple_metrics* simple_metrics_new(); 15 void            simple_metrics_free(   simple_metrics* sm ); 16 void            simple_metrics_update( simple_metrics* sm, double value ); 17 double          simple_metrics_mean(   simple_metrics* sm ); 18 double          simple_metrics_min(    simple_metrics* sm ); 19 double          simple_metrics_max(    simple_metrics* sm ); 20 double          simple_metrics_sum(    simple_metrics* sm ); 21 long            simple_metrics_count(  simple_metrics* sm ); 22 double          simple_metrics_stddev( simple_metrics* sm ); 23 double          simple_metrics_rate(   simple_metrics* sm ); 24 25 #endif
  13. 13.  1 class Metric  2   attr_reader :name  3   def initialize( name )  4     @name  5   end  6  7   def update( new_value) ... end  8   def count  ... end  9   def max    ... end 10   def mean   ... end 11   def min    ... end 12   def rate   ... end 13   def sum    ... end 14   def stddev ... end 15 end
  14. 14. 142 void Init_simple_metrics_ext() 143 { 144     VALUE cSM_Common; 145 146     mSM  = rb_define_module( quot;SimpleMetricsquot; ); 147     mSME = rb_define_module_under( mSM, quot;Extquot; ); 148 149     /* load the class we inherit from */ 150     rb_require(quot;simplemetrics/commonquot;); 151 152     cSM_Common = rb_const_get( mSM, rb_intern( quot;Commonquot; ) ); 153 154     cSME_Metric = rb_define_class_under( mSME, quot;Metricquot;, cSM_Common ); 155 156     rb_define_alloc_func(cSME_Metric, sm_alloc); 157     rb_define_method( cSME_Metric, quot;initializequot;, sm_initialize, 1 ); 158     rb_define_method( cSME_Metric, quot;updatequot;, sm_update, 1 ); 159     rb_define_method( cSME_Metric, quot;countquot;, sm_count, 0 ); 160     rb_define_method( cSME_Metric, quot;maxquot;, sm_max, 0 ); 161     rb_define_method( cSME_Metric, quot;minquot;, sm_min, 0 ); 162     rb_define_method( cSME_Metric, quot;meanquot;, sm_mean, 0 ); 163     rb_define_method( cSME_Metric, quot;ratequot;, sm_rate, 0 ); 164     rb_define_method( cSME_Metric, quot;sumquot;, sm_sum, 0 ); 165     rb_define_method( cSME_Metric, quot;stddevquot;, sm_stddev, 0 ); 166 167 }
  15. 15. 7 module SimpleMetrics  8   module FFI  9 10     class Struct < ::FFI::ManagedStruct 11       layout :min, :double, :max, :double, :sum, :double, 12              :sumsq, :double, :count, :long 13       def self.release( ptr ) 14         SimpleMetrics::FFI.simple_metrics_free( ptr ) 15       end library function parameters return type 16     end 17 18     extend ::FFI::Library 19     ffi_lib quot;libsimple_metricsquot; 20 21     attach_function :simple_metrics_new,   [          ], :pointer 22     attach_function :simple_metrics_free,  [ :pointer ], :void 23     attach_function :simple_metrics_update,[ :pointer, :double  ], :void 24     attach_function :simple_metrics_min,   [ :pointer ], :double 25     attach_function :simple_metrics_max,   [ :pointer ], :double 26     attach_function :simple_metrics_mean,  [ :pointer ], :double 27     attach_function :simple_metrics_sum,   [ :pointer ], :double 28     attach_function :simple_metrics_count, [ :pointer ], :long 29     attach_function :simple_metrics_stddev,[ :pointer ], :double 30     attach_function :simple_metrics_rate,  [ :pointer ], :double 31 32   end 33 end
  16. 16. 35 module SimpleMetrics 36   module FFI 37     class Metric < ::SimpleMetrics::Common 38       include ::SimpleMetrics::FFI 39       def initialize( name ) 40         super 41         @impl = FFI.simple_metrics_new 42       end 43 44       def update( v ) 45         simple_metrics_update( @impl, v ) 46       end 47 48       self.keys.each do |f| 49         module_eval <<-code 50         def #{f} 51           simple_metrics_#{f}( @impl ) 52         end 53         code 54       end 55     end 56   end 57 end
  17. 17. 10 class Struct < ::FFI::ManagedStruct  6 typedef struct _simple_metrics{ 11   layout :min, :double,  7     double min; 12          :max, :double,  8     double max; 13          :sum, :double,  9     double sum; 14          :sumsq, :double, 10     double sumsq; 15          :count, :long 11     long   count; 16   def self.release( ptr ) 12 } simple_metrics ; 17     SimpleMetrics::FFI.simple_metrics_free( ptr ) 18   end 19 end
  18. 18. 21 extend ::FFI::Library 22 ffi_lib quot;libsimple_metricsquot; 23 24 attach_function :simple_metrics_new,   [          ], :pointer 25 attach_function :simple_metrics_free,  [ :pointer ], :void 26 attach_function :simple_metrics_update,[ :pointer, :double  ], :void 27 attach_function :simple_metrics_mean,  [ :pointer ], :double 28 attach_function :simple_metrics_min,   [ :pointer ], :double 29 attach_function :simple_metrics_max,   [ :pointer ], :double 30 attach_function :simple_metrics_sum,   [ :pointer ], :double 31 attach_function :simple_metrics_count, [ :pointer ], :long 32 attach_function :simple_metrics_stddev,[ :pointer ], :double 33 attach_function :simple_metrics_rate,  [ :pointer ], :double 14 simple_metrics* simple_metrics_new(); 15 void            simple_metrics_free(   simple_metrics* sm ); 16 void            simple_metrics_update( simple_metrics* sm, double value ); 17 double          simple_metrics_mean(   simple_metrics* sm ); 18 double          simple_metrics_min(    simple_metrics* sm ); 19 double          simple_metrics_max(    simple_metrics* sm ); 20 double          simple_metrics_sum(    simple_metrics* sm ); 21 long            simple_metrics_count(  simple_metrics* sm ); 22 double          simple_metrics_stddev( simple_metrics* sm ); 23 double          simple_metrics_rate(   simple_metrics* sm );
  19. 19. MEANINGLESS METRICS Traditional C FFI Extension Jeremy’s Time 40 minutes 70 minutes 1 Million update() 1.16 sec 0.42 sec calls Will it Blend run Yes No on JRuby?
  20. 20. % ruby ~/Projects/simple_metrics/example/bench.rb 1000000 generating 1000000 random numbers between 0 and 10,000 Rehearsal ----------------------------------------------- ext 0.420000 0.000000 0.420000 ( 0.460806) ffi 1.160000 0.000000 1.160000 ( 1.171498) -------------------------------------- total: 1.580000sec user system total real ext 0.420000 0.010000 0.430000 ( 0.424809) ffi 1.160000 0.000000 1.160000 ( 1.182928) % ./bin/jruby ~/Projects/simple_metrics/example/bench.rb 1000000 generating 1000000 random numbers between 0 and 10,000 Skipping Ext Rehearsal ----------------------------------------------- ffi 0.922000 0.000000 0.922000 ( 0.922000) -------------------------------------- total: 0.922000sec user system total real ffi 0.834000 0.000000 0.834000 ( 0.834000)
  21. 21. FFI GEMS ffi-ncurses tidy_ffi 4 ffi-swig-generator ffi-zlib
  22. 22. GEMS WITH EXTENSIONS 346 Out of 4,501 gems
  23. 23. GET TO WORK!!
  24. 24. THANKS • Wayne Meissner - adding libffi to JRuby and providing the ffi gem for MRI. • Evan Phoenix - using libffi in Rubinius • Authors of the examples on the Project Kenai wiki
  25. 25. LINKS http://blog.headius.com/2008/10/ffi-for-ruby-now-available.html • http://kenai.com/projects/ruby-ffi • http://wmeissner.blogspot.com/ • http://www.igvita.com/2009/01/15/bridging-mri-jruby-rubinius-with-ffi/ • http://blog.segment7.net/articles/2008/01/15/rubinius-foreign-function- • interface
  26. 26. QUESTIONS?
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