1 files changed, 49 insertions, 0 deletions
diff --git a/debbugs/cache.scm b/debbugs/cache.scm
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+++ b/debbugs/cache.scm
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+;;; Guile-Debbugs --- Guile bindings for Debbugs
+;;; Copyright © 2018 Ricardo Wurmus <rekado@elephly.net>
+;;;
+;;; This file is part of Guile-Debbugs.
+;;;
+;;; Guile-Debbugs is free software; you can redistribute it and/or
+;;; modify it under the terms of the GNU General Public License as
+;;; published by the Free Software Foundation; either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; Guile-Debbugs is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with Guile-Debbugs.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (debbugs cache)
+  #:use-module (debbugs config)
+  #:use-module (ice-9 match)
+  #:export (cached? cache! forget! forget-all!))
+
+(define %cache (make-hash-table))
+
+(define (cached? key)
+  "Return the value matching KEY from the cache if it has not yet
+expired or return #F."
+  (let ((t (current-time)))
+    (match (hash-ref %cache key)
+      ((#:expires time #:value value)
+       (if (< t time) value #f))
+      (_ #f))))
+
+(define* (cache! key value
+                 #:optional (ttl (config 'cache-ttl)))
+  "Store VALUE for the given KEY and mark it to expire after TTL
+seconds."
+  (let ((t (current-time)))
+    (hash-set! %cache key `(#:expires ,(+ t ttl) #:value ,value))
+    value))
+
+(define (forget! key)
+  "Delete KEY from the cache."
+  (hash-remove! %cache key))
+
+(define (forget-all!)
+  "Reset the cache."
+  (set! %cache (make-hash-table)))