Generating Power with Yield

My talk for the Nashville PHP Users Group August 2013 meeting.

Transcript

1. Generating Power with Yield / Jason Myers @jasonamyers
2. Yield, a modern language love story Originally Proposed in 1995, the yield keyword became official via the RFP on June 20th 2013 with PHP 5.5. Generators Facebook said a Hip, Hop and Don't Stop, and did their own yield generators in HipHop PHP
3. They are HEAVILY BASED off of Python, with a nod towards the Mozilla JS implementation and the await C# concept.
6. Iterator An object that lets us traverse a container
8. PHP Iterator Interface I t e r a t o r e x t e n d s T r a v e r s a b l e { / * M e t h o d s * / a b s t r a c t p u b l i c m i x e d c u r r e n t ( v o i d ) a b s t r a c t p u b l i c s c a l a r k e y ( v o i d ) a b s t r a c t p u b l i c v o i d n e x t ( v o i d ) a b s t r a c t p u b l i c v o i d r e w i n d ( v o i d ) a b s t r a c t p u b l i c b o o l e a n v a l i d ( v o i d ) } For example checkout class ArrayIterator
9. ArrayIterator Example $ f r u i t s = a r r a y ( " a p p l e " = > " y u m m y " , " o r a n g e " = > " a h y a , n i c e " , " g r a p e " = > " w o w , I l o v e i t ! " , " p l u m " = > " n a h , n o t m e " ) ; $ o b j = n e w A r r a y O b j e c t ( $ f r u i t s ) ; $ i t = $ o b j - > g e t I t e r a t o r ( ) ; e c h o " I t e r a t i n g o v e r : " . $ o b j - > c o u n t ( ) . " v a l u e s \ n " ; w h i l e ( $ i t - > v a l i d ( ) ) { e c h o $ i t - > k e y ( ) . " = " . $ i t - > c u r r e n t ( ) . " \ n " ; $ i t - > n e x t ( ) ; } I t e r a t i n g o v e r : 4 v a l u e s a p p l e = y u m m y o r a n g e = a h y a , n i c e g r a p e = w o w , I l o v e i t ! p l u m = n a h , n o t m e
10. Generator a special routine that can be used to control the iteration behavior of a loop, and yields the values one at a time
11. TL;DR A generator looks like a function but behaves like an iterator
13. Performant? r a n g e ( 0 , 1 0 0 0 0 0 0 ) Uses over 100MB of RAM
15. Generator Version f u n c t i o n x r a n g e ( $ s t a r t , $ l i m i t , $ s t e p = 1 ) { i f ( $ s t a r t < $ l i m i t ) { i f ( $ s t e p < = 0 ) { t h r o w n e w L o g i c E x c e p t i o n ( ' S t e p m u s t b e + v e ' ) ; } f o r ( $ i = $ s t a r t ; $ i < = $ l i m i t ; $ i + = $ s t e p ) { y i e l d $ i ; } } e l s e { i f ( $ s t e p > = 0 ) { t h r o w n e w L o g i c E x c e p t i o n ( ' S t e p m u s t b e - v e ' ) ; } f o r ( $ i = $ s t a r t ; $ i > = $ l i m i t ; $ i + = $ s t e p ) { y i e l d $ i ; } } } uses less than 1KB!
16. TL; DR f u n c t i o n x r a n g e ( $ m i n , $ m a x ) { f o r ( $ i = $ m i n ; $ i < $ m a x ; $ i + + ) { y i e l d $ i ; } }
17. Sequences f u n c t i o n c o l l a t z ( $ v a l ) { y i e l d $ v a l ; w h i l e ( $ v a l ! = 1 ) { i f ( $ v a l % 2 = = 0 ) { $ v a l / = 2 ; } e l s e { $ v a l = 3 * $ v a l + 1 ; } y i e l d $ v a l ; } } f o r e a c h ( c o l l a t z ( 1 1 ) a s $ c ) { e c h o $ c , " " ; } 1 1 3 4 1 7 5 2 2 6 1 3 4 0 2 0 1 0 5 1 6 8 4 2 1
19. Y U Only LOOPin? It will work for any function that takes an Iterator or a Traversable as argument $ a r r = i t e r a t o r _ t o _ a r r a y ( c o l l a t z ( 1 1 ) ) ;
20. Transformations f u n c t i o n m u l t i p l y _ s e q u e n c e ( $ a , $ f a c ) { f o r e a c h ( $ a a s $ v a l ) { y i e l d $ v a l * $ f a c ; } } f u n c t i o n t o _ h t m l _ l i s t ( $ i n p u t ) { f o r e a c h ( $ i n p u t a s $ v a l ) { y i e l d " < l i > " . $ v a l . " < / l i > " ; } }
21. Chaining f o r e a c h ( t o _ h t m l _ l i s t ( m u l t i p l y _ s e q u e n c e ( c o l l a t z ( 5 ) , 2 ) ) a s $ v a l ) { e c h o $ v a l , " \ n " ; } < l i > 1 0 < / l i > < l i > 3 2 < / l i > < l i > 1 6 < / l i > < l i > 8 < / l i > < l i > 4 < / l i > < l i > 2 < / l i >
22. Selections f u n c t i o n s e l e c t _ p a t t e r n ( $ i n p u t , $ p a t t e r n ) { f o r e a c h ( $ i n p u t a s $ v a l ) { i f ( p r e g _ m a t c h ( $ p a t t e r n , $ v a l ) ) { y i e l d $ v a l ; } } }
23. Breath In f u n c t i o n g e t L i n e s ( $ f i l e ) { $ f = f o p e n ( $ f i l e , ' r ' ) ; i f ( ! $ f ) { t h r o w n e w E x c e p t i o n ( ) ; } w h i l e ( $ l i n e = f g e t s ( $ f ) ) { y i e l d $ l i n e ; } f c l o s e ( $ f ) ; } f o r e a c h ( g e t L i n e s ( " s o m e F i l e " ) a s $ l i n e ) { d o S o m e t h i n g W i t h L i n e ( $ l i n e ) ; }
24. Breath Out f u n c t i o n c r e a t e L o g ( $ f i l e ) { $ f = f o p e n ( $ f i l e , ' a ' ) ; w h i l e ( t r u e ) { $ l i n e = y i e l d ; f w r i t e ( $ f , $ l i n e ) ; } } $ l o g = c r e a t e L o g ( $ f i l e ) ; $ l o g - > s e n d ( " F i r s t " ) ; $ l o g - > s e n d ( " S e c o n d " ) ; $ l o g - > s e n d ( " T h i r d " ) ;
26. Bro Remote Me! Fake the simultaneous processing of data
28. Green Threads threads that are scheduled by a virtual machine (VM/interperter?) instead of natively by the underlying operating system
29. f u n c t i o n s t e p 1 ( ) { $ f = f o p e n ( " f i l e . t x t " , ' r ' ) ; w h i l e ( $ l i n e = f g e t s ( $ f ) ) { p r o c e s s L i n e ( $ l i n e ) ; y i e l d t r u e ; } }
30. f u n c t i o n s t e p 2 ( ) { $ f = f o p e n ( " f i l e 2 . t x t " , ' r ' ) ; w h i l e ( $ l i n e = f g e t s ( $ f ) ) { p r o c e s s L i n e ( $ l i n e ) ; y i e l d t r u e ; } }
31. f u n c t i o n s t e p 3 ( ) { $ f = f s o c k o p e n ( " w w w . e x a m p l e . c o m " , 8 0 ) ; s t r e a m _ s e t _ b l o c k i n g ( $ f , f a l s e ) ; $ h e a d e r s = " G E T / H T T P / 1 . 1 \ r \ n " ; $ h e a d e r s . = " H o s t : w w w . e x a m p l e . c o m \ r \ n " ; $ h e a d e r s . = " C o n n e c t i o n : C l o s e \ r \ n \ r \ n " ; f w r i t e ( $ f , $ h e a d e r s ) ; $ b o d y = ' ' ; w h i l e ( ! f e o f ( $ f ) ) { $ b o d y . = f r e a d ( $ f , 8 1 9 2 ) ; y i e l d t r u e ; } p r o c e s s B o d y ( $ b o d y ) ; }
32. f u n c t i o n r u n n e r ( a r r a y $ s t e p s ) { w h i l e ( t r u e ) { f o r e a c h ( $ s t e p s a s $ k e y = > $ s t e p ) { $ s t e p - > n e x t ( ) ; i f ( ! $ s t e p - > v a l i d ( ) ) { u n s e t ( $ s t e p s [ $ k e y ] ) ; } } i f ( e m p t y ( $ s t e p s ) ) r e t u r n ; } } r u n n e r ( a r r a y ( s t e p 1 ( ) , s t e p 2 ( ) , s t e p 3 ( ) ) ) ;
33. ZOMG... THERE BE DRAGONS! This relies on making sure we have no blocking IO
34. overREACTPHP much? event based, non-blocking IO - ReActPHP
35. One More Thing So if I can flip control, I can haz an Async?
36. c l a s s B u f f e r { p r o t e c t e d $ r e a d s , $ d a t a ; p u b l i c f u n c t i o n _ _ c o n s t r u c t ( ) { $ t h i s - > r e a d s = n e w S p l Q u e u e ( ) ; $ t h i s - > d a t a = n e w S p l Q u e u e ( ) ; } p u b l i c f u n c t i o n r e a d ( ) { i f ( $ t h i s - > d a t a - > i s E m p t y ( ) ) { $ d e f e r r e d = n e w \ R e a c t \ P r o m i s e \ D e f e r r e d ( ) ; $ t h i s - > r e a d s - > e n q u e u e ( $ d e f e r r e d - > r e s o l v e r ( ) ) ; r e t u r n $ d e f e r r e d - > p r o m i s e ( ) ; } e l s e { r e t u r n \ R e a c t \ P r o m i s e \ W h e n : : r e s o l v e ( $ t h i s - > d a t a - > d e q u e u e ( ) ) ; } } p u b l i c f u n c t i o n w r i t e ( $ s t r ) { i f ( $ t h i s - > r e a d s - > i s E m p t y ( ) ) { $ t h i s - > d a t a - > e n q u e u e ( $ s t r ) ; } e l s e { $ t h i s - > r e a d s - > d e q u e u e ( ) - > r e s o l v e ( $ s t r ) ; } } }
37. f u n c t i o n p r i n t e r ( B u f f e r $ b u f f e r ) { w h i l e ( t r u e ) { $ v a l u e = ( y i e l d U t i l : : a s y n c ( $ b u f f e r - > r e a d ( ) ) ) ; e c h o " P r i n t e r : " , $ v a l u e , P H P _ E O L ; y i e l d U t i l : : a s y n c ( n e s t e d _ p r i n t e r ( $ b u f f e r ) ) ; } }
38. f u n c t i o n n e s t e d _ p r i n t e r ( B u f f e r $ b u f f e r ) { f o r ( $ i = 0 ; $ i < 5 ; $ i + + ) { / / Y i e l d a p r o m i s e t a s k a n d w a i t f o r t h e r e s u l t - t h i s i s n o n - b l o c k i n g $ v a l u e = ( y i e l d U t i l : : a s y n c ( $ b u f f e r - > r e a d ( ) ) ) ; e c h o " N e s t e d p r i n t e r : " , $ v a l u e , P H P _ E O L ; } }
39. $ b u f f e r = n e w B u f f e r ( ) ; $ s c h e d u l e r = n e w \ A s y n c \ S c h e d u l e r ( ) ; $ s c h e d u l e r - > a d d ( n e w \ A s y n c \ T a s k \ G e n e r a t o r T a s k ( p r i n t e r ( $ b u f f e r ) ) ) ; $ i = 0 ; $ s c h e d u l e r - > a d d ( n e w \ A s y n c \ T a s k \ R e c u r r i n g T a s k ( f u n c t i o n ( ) u s e ( $ b u f f e r , & $ i ) { $ b u f f e r - > w r i t e ( + + $ i ) ; } ) ) ; $ s c h e d u l e r - > r u n ( ) ; P r i n t e r : 1 N e s t e d p r i n t e r : 2 N e s t e d p r i n t e r : 3 N e s t e d p r i n t e r : 4 N e s t e d p r i n t e r : 5 N e s t e d p r i n t e r : 6 P r i n t e r : 7 N e s t e d p r i n t e r : 8 N e s t e d p r i n t e r : 9 N e s t e d p r i n t e r : 1 0 N e s t e d p r i n t e r : 1 1 N e s t e d p r i n t e r : 1 2 . . .
40. $ l o o p = \ R e a c t \ E v e n t L o o p \ F a c t o r y : : c r e a t e ( ) ; $ s c h e d u l e r = n e w \ A s y n c \ S c h e d u l e r ( ) ; $ s c h e d u l e r - > a d d ( n e w \ A s y n c \ T a s k \ R e c u r r i n g T a s k ( [ $ l o o p , ' t i c k ' ] ) ) ; $ s c h e d u l e r - > r u n ( ) ;
41. Async Created by Matt Pryor, on Bitbucket
42. Thanks Huge thanks to Paul M. Jones and William Golden!
43. THE END @jasonamyers