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#lang scribble/manual
@ ( require scribble/eval pollen/cache pollen/world ( for-label racket ( except-in pollen #%module-begin ) pollen/world pollen/cache pollen/render pollen/file-tools ) )
@ ( define my-eval ( make-base-eval ) )
@ ( my-eval ` ( require pollen ) )
@section { Cache }
@defmodule [ pollen/cache ]
The slowest part of a @racket [ render ] is parsing and decoding the source file. Often , previewing a single source file necessarily means decoding others ( for instance templates , or other source files that are linked into the main source file ) . But usually , only one source file is changing at a time. Therefore , Pollen stores copies of the exports of source files — , whatever is stored in @code [ ( format " '~a " world:main-pollen-export ) ] and @code [ ( format " '~a " world:meta-pollen-export ) ] — the cache so they can be reused.
@defproc [
( cached-require
[ source-path pathish? ]
[ key ( or/c ' doc ' metas ' mod-time ) ] )
( or/c txexpr? hash? integer? ) ]
Similar to @racket [ ( dynamic-require _source-path _key ) ] , except that it tries to get the requested value out of @racket [ current-cache ] . If it ' s not there , or out of date , @racket [ dynamic-require ] is used to update the value.
If you want the speed benefit of the cache , you should @bold { always } use @racket [ cached-require ] to get data from Pollen source files. That doesn ' t mean you can ' t still use functions like @racket [ require ] , @racket [ local-require ] , and @racket [ dynamic-require ] . They ' ll just be slower.
@defproc [
( current-cache )
( or/c #f hash? ) ]
A parameter that refers to the current cache. It starts with a value of @racket [ #f ] . It has to be initialized with @racket [ make-cache ] .
The cache is a hash table that uses the complete path of a source file as its keys. The value associated with each of these keys is another hash table with keys @code [ ( format " '~a " world:main-pollen-export ) ] , @code [ ( format " '~a " world:meta-pollen-export ) ] ( for storing the exports of the source file ) and @racket [ ' mod-time ] ( for storing the modification time ) .
@defproc [
( make-cache )
hash? ]
Initializes @racket [ current-cache ] .
@defproc [
( reset-cache )
void? ]
Clears @racket [ current-cache ] . When only the nuclear option will do.
@defproc [
( cache-ref
[ source-path pathish? ] )
hash? ]
Returns the cached value associated with the key @racket [ _source-path ] , which will itself be a hash table. See @racket [ current-cache ] .