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@wilkerlucio
Last active March 3, 2020 13:42
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Pathom cache extension example
(defn cache-resolver [resolver]
(update resolver ::pc/resolve
(fn [resolve]
(fn [{::keys [persistent-cache*] :as env} input]
(let [cache-key [(::pc/sym resolver) input (p/params env)]]
(if-let [[_ v] (find @persistent-cache* cache-key)]
v
(let [response (resolve env input)]
(swap! persistent-cache* assoc cache-key response)
response)))))))
(pc/defresolver cached-resolver [env {:keys []}]
{::pc/output [:some-value]
::pc/transform cache-resolver}
{:some-value (gensym "random")})
(def registry
[cached-resolver])
(def parser
(p/parser
{::p/env {::p/reader [p/map-reader
pc/reader2
pc/open-ident-reader
p/env-placeholder-reader]
::p/placeholder-prefixes #{">"}}
::p/mutate pc/mutate
::p/plugins [(pc/connect-plugin {::pc/register registry})
p/error-handler-plugin
p/trace-plugin]}))
(defonce global-atom-persistent-cache* (atom {}))
(comment
; re-create cache, will always get a fresh value
(parser {::persistent-cache* (atom {})}
[:some-value])
; with the persistent cache, the value will remain constant
(parser {::persistent-cache* global-atom-persistent-cache*}
[:some-value]))
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