Inside the Sausage Factory: A Journey from PHP to C

Presented May 8, 2014 at OpenWest: https://joind.in/talk/view/11189

Presented September 18, 2013 at Web & PHP Conference: https://joind.in/talk/view/8869

Reveal.js presentation published at: http://jmikola.github.io/slides/from_php_to_c/

Transcript

1. INSIDE THE SAUSAGE FACTORY A JOURNEY FROM PHP TO C Jeremy Mikola jmikola
2. I work with these guys
3. At this place
4. I've done a bit of this TI-83 Basic Perl PHP JavaScript C++ Delphi Java Scheme C Assembly Ada95 Python
5. But let's talk about PHP C
6. More specifically… Finding C in PHP A crash course in C PHP internals Creating extensions
8. Finding C in PHP Standard IO: f o p e n ( ) , f w r i t e ( ) Strings functions: s p r i n t f ( ) , s t r c h r ( ) Date/Time functions: s t r f t i m e ( ) , t i m e ( ) Extensions modeled on C APIs c u r l , g d , g m p , m y s q l , p c n t l
9. Simple file IO in PHP $ f p = f o p e n ( " e x a m p l e . t x t " , " w " ) ; i f ( $ f p ) { f p u t s ( $ f p , " h e l l o " ) ; f c l o s e ( $ f p ) ; }
10. Simple file IO in C # i n c l u d e < s t d i o . h > i n t m a i n ( ) { F I L E * f p = f o p e n ( " e x a m p l e . t x t " , " w " ) ; i f ( f p ) { f p u t s ( " h e l l o " , f p ) ; f c l o s e ( f p ) ; } r e t u r n 0 ; }
11. Language differences PHP C Source Interpreted Compiled Typing Dynamic Static Scoping Function-level Block-level Memory Automatic Manual
13. A crash course in C Header files and compiling Static and dynamic linking Declarations and data types Stack and heap memory
14. Header files Included at compile time Type declarations Function prototypes Defined constants, macros
15. Compiling C → Preprocessor → Translation Unit Translation Unit → Compiler → Object File Object Files → Linker → Executable
16. Static and dynamic linking Static linking Monolithic binaries No external dependencies Dynamic linking (. s o , . d l l ) Modules loaded at run-time More flexibility, slight overhead
17. Declarations Declare it before you use it Functions, types, variables Block-level scoping Source and header files e x t e r n and s t a t i c
18. Data types Signed and unsigned integers c h a r , s h o r t , i n t , l o n g Floating point numbers f l o a t , d o u b l e Array and s t r u c t aggregates
20. Pointers  Memory
21. Pointers are a type i n t a = 3 ; i n t * p t r = N U L L ; Variable Address Value a 0 x 8 1 3 0 0 x 0 0 0 0 0 0 0 3 p t r 0 x 8 1 3 4 0 x 0 0 0 0 0 0 0 0
22. Pointer assignments p t r = & a ; Variable Address Value a 0 x 8 1 3 0 0 x 0 0 0 0 0 0 0 3 p t r 0 x 8 1 3 4 0 x 0 0 0 0 8 1 3 0
23. Dereferencing pointers * p t r = 6 ; Variable Address Value a 0 x 8 1 3 0 0 x 0 0 0 0 0 0 0 6 p t r 0 x 8 1 3 4 0 x 0 0 0 0 8 1 3 0
24. Pointers and arrays i n t a [ 4 ] = { 0 , 0 , 0 , 0 } ; i n t * p t r = a ; a [ 0 ] = 1 ; p t r [ 1 ] = 2 ; * ( a + 2 ) = 3 ; * ( p t r + 3 ) = 4 ; s i z e o f ( a ) ; / * 4 × s i z e o f ( i n t ) * / s i z e o f ( p t r ) ; / * s i z e o f ( i n t * ) * /
25. Stack and heap memory / * S t a c k a l l o c a t i o n * / i n t z e n d _ a t o i ( c o n s t c h a r * s t r , i n t s t r _ l e n ) ; / * S t a c k a l l o c a t i o n * / i n t f o o [ 1 0 ] ; / * H e a p a l l o c a t i o n * / i n t * f o o = m a l l o c ( 1 0 * s i z e o f ( i n t ) ) ;
26. Heap memory needs to be freed i n t * f o o = m a l l o c ( 1 0 * s i z e o f ( i n t ) ) ; i f ( f o o = = N U L L ) { / * R e q u i s i t e e r r o r h a n d l i n g * / } f r e e ( f o o ) ; / * R e t u r n a l l o c a t e d m e m o r y t o t h e h e a p * / f o o = N U L L ; / * A v o i d a c c e s s i n g f r e e d m e m o r y l a t e r * /
28. php-internals
29. php-src
30. PHP core does the heavy lifting Language parsing, compiling Macros for code scaffolding Data structures, utility functions Memory management, persistence Thread safety
31. lxr.php.net
34. A place for everything Core source and syntax in Z e n d / Parser, types, internal API Extensions in e x t / and PECL Server APIs in s a p i / Tests live in t e s t s /
36. PHPT tests Name, code, and expected output Used by both core and extensions Single-purpose and debuggable Documentation on qa.php.net Why not PHPUnit, PHPSpec, etc?
37. An example PHPT test - - T E S T - - s t r r c h r ( ) t e s t s - - F I L E - - < ? p h p v a r _ d u m p ( s t r r c h r ( " " , " " ) ) ; v a r _ d u m p ( s t r r c h r ( " a b c " , " " ) ) ; v a r _ d u m p ( s t r r c h r ( " " , " a b c " ) ) ; v a r _ d u m p ( s t r r c h r ( " a b c " , " a b c " ) ) ; ? > - - E X P E C T F - - b o o l ( f a l s e ) b o o l ( f a l s e ) b o o l ( f a l s e ) s t r i n g ( 3 ) " a b c "
38. It looks like you're giving a presentation on PHP internals. Would you like help? Talk about zvals
39. PHP variables are zvals t y p e d e f u n i o n _ z v a l u e _ v a l u e { l o n g l v a l ; / * l o n g v a l u e * / d o u b l e d v a l ; / * d o u b l e v a l u e * / s t r u c t { / * s t r i n g v a l u e * / c h a r * v a l ; i n t l e n ; } s t r ; H a s h T a b l e * h t ; / * h a s h t a b l e v a l u e * / z e n d _ o b j e c t _ v a l u e o b j ; / * o b j e c t v a l u e * / } z v a l u e _ v a l u e ; t y p e d e f s t r u c t _ z v a l _ s t r u c t { z v a l u e _ v a l u e v a l u e ; / * v a l u e * / z e n d _ u i n t r e f c o u n t _ _ g c ; / * r e f e r e n c e c o u n t * / z e n d _ u c h a r t y p e ; / * a c t i v e t y p e * / z e n d _ u c h a r i s _ r e f _ _ g c ; / * i s a r e f e r e n c e ? * / } z v a l ;
40. Macros for accessing zval data z v a l z v a l * z v a l * * Z _ L V A L Z _ L V A L _ P Z _ L V A L _ P P Z _ B V A L Z _ B V A L _ P Z _ B V A L _ P P Z _ D V A L Z _ D V A L _ P Z _ D V A L _ P P Z _ S T R V A L Z _ S T R V A L _ P Z _ S T R V A L _ P P Z _ S T R L E N Z _ S T R L E N _ P Z _ S T R L E N _ P P Z _ A R R V A L Z _ A R R V A L _ P Z _ A R R V A L _ P P Z _ O B J V A L Z _ O B J V A L _ P Z _ O B J V A L _ P P Z _ T Y P E Z _ T Y P E _ P Z _ T Y P E _ P P
41. Macros for defining methods P H P _ M E T H O D ( M o n g o C u r s o r , l i m i t ) { l o n g l ; m o n g o _ c u r s o r * c u r s o r ; c u r s o r = ( m o n g o _ c u r s o r * ) z e n d _ o b j e c t _ s t o r e _ g e t _ o b j e c t ( g e t T h i s ( ) T S R M L S _ C C ) ; i f ( z e n d _ p a r s e _ p a r a m e t e r s ( Z E N D _ N U M _ A R G S ( ) T S R M L S _ C C , " l " , & l ) = = F A I L U R E ) { r e t u r n ; } p h p _ m o n g o _ c u r s o r _ s e t _ l i m i t ( c u r s o r , l ) ; R E T V A L _ Z V A L ( g e t T h i s ( ) , 1 , 0 ) ; }
42. Our method after pre-processing v o i d z i m _ M o n g o C u r s o r _ l i m i t ( i n t h t , z v a l * r e t u r n _ v a l u e , z v a l * * r e t u r n _ v a l u e _ p t r , z v a l * t h i s _ p t r , i n t r e t u r n _ v a l u e _ u s e d ) { l o n g l ; m o n g o _ c u r s o r * c u r s o r ; c u r s o r = ( m o n g o _ c u r s o r * ) z e n d _ o b j e c t _ s t o r e _ g e t _ o b j e c t ( t h i s _ p t r ) ; i f ( z e n d _ p a r s e _ p a r a m e t e r s ( h t , " l " , & l ) = = F A I L U R E ) { r e t u r n ; } p h p _ m o n g o _ c u r s o r _ s e t _ l i m i t ( c u r s o r , l ) ; z e n d _ u c h a r i s _ r e f = z v a l _ i s r e f _ p ( r e t u r n _ v a l u e ) ; z e n d _ u i n t r e f c o u n t = z v a l _ r e f c o u n t _ p ( r e t u r n _ v a l u e ) ; r e t u r n _ v a l u e - > v a l u e = t h i s _ p t r - > v a l u e ; ( * r e t u r n _ v a l u e ) . t y p e = ( * t h i s _ p t r ) . t y p e ; z v a l _ c o p y _ c t o r ( r e t u r n _ v a l u e ) ; z v a l _ s e t _ i s r e f _ t o _ p ( r e t u r n _ v a l u e , i s _ r e f ) ; z v a l _ s e t _ r e f c o u n t _ p ( r e t u r n _ v a l u e , r e f c o u n t ) ; }
43. Macros for… Memory allocation Working with hash tables Comparisons, casts, operations Defining class/function entries Other macros # d e f i n e Z _ T Y P E ( z v a l ) ( z v a l ) . t y p e # d e f i n e Z _ T Y P E _ P ( z v a l _ p ) Z _ T Y P E ( * z v a l _ p ) # d e f i n e Z _ T Y P E _ P P ( z v a l _ p p ) Z _ T Y P E ( * * z v a l _ p p )
44. MACROS MACROS EVERYWHERE
46. Ingredients for an extension Autoconf, p h p i z e , core libs c o n f i g . m 4 and c o n f i g . w 3 2 p h p _ m y e x t . c and p h p _ m y e x t . h and test coverage Coding standards Windows? Difficult but . not impossible
47. The recipe $ p h p i z e C o n f i g u r i n g f o r : P H P A p i V e r s i o n : 2 0 1 0 0 4 1 2 Z e n d M o d u l e A p i N o : 2 0 1 0 0 5 2 5 Z e n d E x t e n s i o n A p i N o : 2 2 0 1 0 0 5 2 5 $
48. The recipe $ . / c o n f i g u r e c h e c k i n g f o r g r e p t h a t h a n d l e s l o n g l i n e s a n d - e . . . / b i n / g r e p c h e c k i n g f o r e g r e p . . . / b i n / g r e p - E c h e c k i n g f o r a s e d t h a t d o e s n o t t r u n c a t e o u t p u t . . . / b i n / s e d c h e c k i n g f o r c c . . . c c c h e c k i n g w h e t h e r t h e C c o m p i l e r w o r k s . . . y e s . . . c h e c k i n g w h e t h e r t o b u i l d s t a t i c l i b r a r i e s . . . n o c o n f i g u r e : c r e a t i n g . / c o n f i g . s t a t u s c o n f i g . s t a t u s : c r e a t i n g c o n f i g . h c o n f i g . s t a t u s : e x e c u t i n g l i b t o o l c o m m a n d s $
49. The recipe $ m a k e . . . B u i l d c o m p l e t e . D o n ' t f o r g e t t o r u n ' m a k e t e s t ' . $
51. Recommended reading Developer blogs , , Kristina Chodorow's (2011) Marcus Börger's (2009) Zend Developer Zone articles (2009) Sara Golemon's (2005) PHP Internals Book Nikita Popov Sara Golemon Anthony Ferrara tutorial series conference talks Wrapping C++ Classes in a PHP Extension tutorial series
52. Perhaps the most informative slide in this entire presentation wiki.php.net/internals/references
53. THANKS! Questions?
54. Image Credits http://pbfcomics.com/153/ http://www.flickr.com/photos/phuson/4311168776/ http://www.esourceengine.com/downloads/minecraft/minecraft-library.png http://en.wikipedia.org/wiki/File:The_C_Programming_Language_cover.svg http://xkcd.com/138/ http://en.wikipedia.org/wiki/File:Pointers.svg http://www.flickr.com/photos/abmann/5286312715/ http://gifsoup.com/view/33383/kangaroo-boxing.html http://breakingbadamc.tumblr.com/post/36457804409/lets-cook http://xkcd.com/303/