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pollen/cache.rkt

58 lines
2.1 KiB
Racket

#lang racket/base
(require racket/rerequire racket/serialize racket/file "world.rkt")
;; The cache is a hash with paths as keys.
;; The cache values are also hashes, with key/value pairs for that path.
(provide reset-cache current-cache make-cache cached-require cache-ref)
(define (get-cache-file-path)
(build-path (world:current-project-root) (world:current-cache-filename)))
(define (make-cache)
(define cache-file-path (get-cache-file-path))
(if (file-exists? cache-file-path)
(deserialize (file->value cache-file-path))
(make-hash)))
(define current-cache (make-parameter (make-cache)))
(define (reset-cache)
(define cache-path (get-cache-file-path))
(when (file-exists? cache-path)
(delete-file cache-path))
(current-cache (make-cache)))
(define (->complete-path path-string)
(path->complete-path (if (string? path-string) (string->path path-string) path-string)))
(define (cache-ref path-string)
(hash-ref (current-cache) (->complete-path path-string)))
(define (cache-has-key? path)
(hash-has-key? (current-cache) path))
(define (cache path)
(dynamic-rerequire path)
(hash-set! (current-cache) path (make-hash))
(define cache-hash (cache-ref path))
(hash-set! cache-hash 'mod-time (file-or-directory-modify-seconds path))
(hash-set! cache-hash (world:current-main-export) (dynamic-require path (world:current-main-export)))
(hash-set! cache-hash (world:current-meta-export) (dynamic-require path (world:current-meta-export)))
(write-to-file (serialize (current-cache)) (get-cache-file-path) #:exists 'replace)
(void))
(define (cached-require path-string key)
(when (not (current-cache)) (error 'cached-require "No cache set up."))
(define path
(with-handlers ([exn:fail? (λ(exn) (error 'cached-require (format "~a is not a valid path" path-string)))])
(->complete-path path-string)))
(when (not (file-exists? path)) (error (format "cached-require: ~a does not exist" (path->string path))))
(when (or (not (cache-has-key? path))
(> (file-or-directory-modify-seconds path) (hash-ref (cache-ref path) 'mod-time)))
(cache path))
(hash-ref (cache-ref path) key))