Post on 11-Nov-2014
description
Native Extensions Served 3 Ways
Tejas Dinkar
Nilenso Software
about.talk
• Expect to see lots of code
• Will have about 5 minutes for questions
• Please laugh at my jokes!
• Will cover C Extensions, FFI and SWIG
Native Extensions
• Integrate with new libraries
• Improve Performance of critical code
• Write code that works across languages
• Feel super 1337
Let’s talk about Python
• Pythonista’s in the house?
• Yes, I’m trolling you!
http://montgomeryq.blogspot.in/2011/05/random-illustration-tuesday-python-ruby.html
#include "Python.h" #include "ruby.h" !static PyObject *python_ruby_eval(PyObject *self, PyObject *string) { VALUE val = rb_eval_string(PyString_AsString(string)); switch(TYPE(val)) { case T_FIXNUM: return PyInt_FromLong(FIX2INT(val)); case T_STRING: return PyString_FromString(StringValuePtr(val)); default: return Py_None; // Can handle these cases later } } !static PyMethodDef module_functions[] = { { "eval", python_ruby_eval, METH_O, "Evaluate Ruby Code" }, { NULL } }; !void initruby(void) { ruby_init(); Py_InitModule3("ruby", module_functions, "A ruby module for python."); }
#include "Python.h" #include "ruby.h" !static PyObject *python_ruby_eval(PyObject *self, PyObject *string) { VALUE val = rb_eval_string(PyString_AsString(string)); switch(TYPE(val)) { case T_FIXNUM: return PyInt_FromLong(FIX2INT(val)); case T_STRING: return PyString_FromString(StringValuePtr(val)); default: return Py_None; // Can handle these cases later } } !static PyMethodDef module_functions[] = { { "eval", python_ruby_eval, METH_O, "Evaluate Ruby Code" }, { NULL } }; !void initruby(void) { ruby_init(); Py_InitModule3("ruby", module_functions, "A ruby module for python."); }
#include "Python.h" #include "ruby.h" !static PyObject *python_ruby_eval(PyObject *self, PyObject *string) { VALUE val = rb_eval_string(PyString_AsString(string)); switch(TYPE(val)) { case T_FIXNUM: return PyInt_FromLong(FIX2INT(val)); case T_STRING: return PyString_FromString(StringValuePtr(val)); default: return Py_None; // Can handle these cases later } } !static PyMethodDef module_functions[] = { { "eval", python_ruby_eval, METH_O, "Evaluate Ruby Code" }, { NULL } }; !void initruby(void) { ruby_init(); Py_InitModule3("ruby", module_functions, "A ruby module for python."); }
#include "Python.h" #include "ruby.h" !static PyObject *python_ruby_eval(PyObject *self, PyObject *string) { VALUE val = rb_eval_string(PyString_AsString(string)); switch(TYPE(val)) { case T_FIXNUM: return PyInt_FromLong(FIX2INT(val)); case T_STRING: return PyString_FromString(StringValuePtr(val)); default: return Py_None; // Can handle these cases later } } !static PyMethodDef module_functions[] = { { "eval", python_ruby_eval, METH_O, "Evaluate Ruby Code" }, { NULL } }; !void initruby(void) { ruby_init(); Py_InitModule3("ruby", module_functions, "A ruby module for python."); }
#include "Python.h" #include "ruby.h" !static PyObject *python_ruby_eval(PyObject *self, PyObject *string) { VALUE val = rb_eval_string(PyString_AsString(string)); switch(TYPE(val)) { case T_FIXNUM: return PyInt_FromLong(FIX2INT(val)); case T_STRING: return PyString_FromString(StringValuePtr(val)); default: return Py_None; // Can handle these cases later } } !static PyMethodDef module_functions[] = { { "eval", python_ruby_eval, METH_O, "Evaluate Ruby Code" }, { NULL } }; !void initruby(void) { ruby_init(); Py_InitModule3("ruby", module_functions, "A ruby module for python."); }
#include "Python.h" #include "ruby.h" !static PyObject *python_ruby_eval(PyObject *self, PyObject *string) { VALUE val = rb_eval_string(PyString_AsString(string)); switch(TYPE(val)) { case T_FIXNUM: return PyInt_FromLong(FIX2INT(val)); case T_STRING: return PyString_FromString(StringValuePtr(val)); default: return Py_None; // Can handle these cases later } } !static PyMethodDef module_functions[] = { { "eval", python_ruby_eval, METH_O, "Evaluate Ruby Code" }, { NULL } }; !void initruby(void) { ruby_init(); Py_InitModule3("ruby", module_functions, "A ruby module for python."); }
#include "Python.h" #include "ruby.h" !static PyObject *python_ruby_eval(PyObject *self, PyObject *string) { VALUE val = rb_eval_string(PyString_AsString(string)); switch(TYPE(val)) { case T_FIXNUM: return PyInt_FromLong(FIX2INT(val)); case T_STRING: return PyString_FromString(StringValuePtr(val)); default: return Py_None; // Can handle these cases later } } !static PyMethodDef module_functions[] = { { "eval", python_ruby_eval, METH_O, "Evaluate Ruby Code" }, { NULL } }; !void initruby(void) { ruby_init(); Py_InitModule3("ruby", module_functions, "A ruby module for python."); }
#include "Python.h" #include "ruby.h" !static PyObject *python_ruby_eval(PyObject *self, PyObject *string) { VALUE val = rb_eval_string(PyString_AsString(string)); switch(TYPE(val)) { case T_FIXNUM: return PyInt_FromLong(FIX2INT(val)); case T_STRING: return PyString_FromString(StringValuePtr(val)); default: return Py_None; // Can handle these cases later } } !static PyMethodDef module_functions[] = { { "eval", python_ruby_eval, METH_O, "Evaluate Ruby Code" }, { NULL } }; !void initruby(void) { ruby_init(); Py_InitModule3("ruby", module_functions, "A ruby module for python."); }
Require Files?
static PyObject *python_ruby_require(PyObject *self, PyObject *file) { rb_require(PyString_AsString(file)); return Py_True; }
Congrats!
Common Fears
MEMORY ALLOCATION!?
Memory Management
• Data_Wrap_Struct(klass, mark_cb, free_cb, *data)
• Data_Get_Struct( VALUE, data_type, data* )
Common Fears
Portability
http://geekandpoke.typepad.com/geekandpoke/2008/05/the-history-of.html
void Init_String(void) {! rb_cString = rb_define_class("String", rb_cObject);! // ...! rb_define_method(rb_cString, "eql?", rb_str_eql, 1);! rb_define_method(rb_cString, "==", rb_str_equal, 1);! // ...! rb_define_method(rb_cString, "insert", rb_str_insert, 2);! rb_define_method(rb_cString, "length", rb_str_length, 0);! // ...! }! ! static VALUE rb_str_eql(VALUE self, VALUE str2)! {! if (self == str2) return Qtrue;! if (!RB_TYPE_P(str2, T_STRING)) return Qfalse;! return str_eql(self, str2);! }!
string.c
void Init_String(void) {! rb_cString = rb_define_class("String", rb_cObject);! // ...! rb_define_method(rb_cString, "eql?", rb_str_eql, 1);! rb_define_method(rb_cString, "==", rb_str_equal, 1);! // ...! rb_define_method(rb_cString, "insert", rb_str_insert, 2);! rb_define_method(rb_cString, "length", rb_str_length, 0);! // ...! }! ! static VALUE rb_str_eql(VALUE str2, VALUE str2)! {! if (self == str2) return Qtrue;! if (!RB_TYPE_P(str2, T_STRING)) return Qfalse;! return str_eql(self, str2);! }!
string.c
void Init_String(void) {! rb_cString = rb_define_class("String", rb_cObject);! // ...! rb_define_method(rb_cString, "eql?", rb_str_eql, 1);! rb_define_method(rb_cString, "==", rb_str_equal, 1);! // ...! rb_define_method(rb_cString, "insert", rb_str_insert, 2);! rb_define_method(rb_cString, "length", rb_str_length, 0);! // ...! }! ! static VALUE rb_str_eql(VALUE str2, VALUE str2)! {! if (self == str2) return Qtrue;! if (!RB_TYPE_P(str2, T_STRING)) return Qfalse;! return str_eql(self, str2);! }!
string.c
C Extensions
Native Code Ruby CodeRuby Aware!Native Code
Foreign Function Interface
Native Code Ruby CodeNative Aware!Ruby Code
Foreign Function Interface
• A Ruby DSL
• Works across all Ruby Implementations
• Converts to and from C primitives for you
example
require 'ffi'!!module MyLib! extend FFI::Library! ffi_lib 'c'! attach_function :puts, [:string], :int!end!!MyLib.puts 'Hello, World using libc!'
another example
require 'ffi'!!module MyMathLib! extend FFI::Library! ffi_lib 'm'! attach_function :pow, [:double, :double],! :double!end!!MyMathLib.pow(4, 5) # => 1024.0
Lots of built in types
Numbers!! ! ! ! ! Character!! ! ! ! ! Other!:int! ! ! ! ! ! ! :char!! ! ! ! ! ! ! :pointer!:short! ! ! ! ! ! :string!:long!:double!:float!
Foreign Function Interface
• Probably your best solution
• It’s really easy
• Do your modelling in Ruby
• Still have to worry about GC
• Sadly, no C++ without wrapping
Memory in FFI
def run_query_which_will_crash! db_connection = MyFFIModule.database_connection("localhost")! MyFFIModule.database_query(db_connection, "select * from users")!end!
Memory in FFI
def run_query_which_will_crash! db_connection = MyFFIModule.database_connection("localhost")! MyFFIModule.database_query(db_connection, "select * from users")!end!
This will get GCed
SWIG
• Simplified Wrapper and Interface Generator
• Annotate your C/C++ header files
• It generates native extensions for languages
• About 20 languages currently supported
SWIG
Native Code
Ruby Code
Magic Python Code
The Magic• Takes an interface file
• Auto generates code to make it work
• For ruby, it’s a `regular’ C extension
• For python, it’s a a .c and .py file
• For Java it’s a JNI interface
• Still need to do your own GC
The Rectangle
class Rectangle!{! int length;! int breadth;!! public:! Rectangle(int length, int breadth);! int area();!};
The Rectangle
class Rectangle!{! int length;! int breadth;!! public:! Rectangle(int length, int breadth);! int area();!};
#ifdef SWIG %module shape %{
%}
SWIG Stuff Here
require 'shapes'!!rectangle = shapes.Rectangle.new(10, 12)!rectangle.area == 120!
Other Options
• DL (Dynamic Load)
• Fiddle(r)
TL;DR
• Native Extensions are fun and easy to build
• The three big tools
• You want to pick FFI if you don’t maintain the lib
• SWIG may be better if you are a maintainer
Thank You
Many Questions?
wow
so native
so extension
wow
no python
such easy
such performance
super integration
ruby = win