perf(storage): get/delete webmention lazily

also done some refactoring and DRY

1 files changed, 30 insertions, 21 deletions

diff --git a/src/weepinbell/storage.clj b/src/weepinbell/storage.clj
index dbee6b5..859eca7 100644
--- a/src/weepinbell/storage.clj
+++ b/src/weepinbell/storage.clj
@@ -19,21 +19,38 @@
   (when-let [data-with-string (map pr-str data)]
     (spit data-file (join "\n" data-with-string))))
 
+;; predicates used for filtering webmention
+(defn- st-pair-equal-pred [source target wm]
+  (and (= source (get-in wm [:webmention :source]))
+       (= target (get-in wm [:webmention :target]))))
+(defn- id-equal-pred [id wm]
+  (= id (get-in wm [:webmention :id])))
+(defn- get-predicate [source target]
+  (if target
+    #(st-pair-equal-pred source target %)
+    #(id-equal-pred source %)))
+;; end predicates
+
+(defn with-webmentions
+  "Opens the data file and applies function f to a lazy sequence of parsed Webmentions."
+  [f]
+  (with-open [r (io/reader data-file)]
+    (->> (line-seq r)
+         (map edn/read-string)
+         f)))
+
 (defn get-wm
-  "Get a Webmention by source/target or by ID."
-  ([id]
-   (get-wm id nil))
+  ([id] (get-wm id nil))
   ([source target]
-   (with-open [r (io/reader data-file)]
-     (let [lines (line-seq r)
-           pred (if target
-                  (fn [wm] (and (= source (get-in wm [:webmention :source]))
-                                (= target (get-in wm [:webmention :target]))))
-                  (fn [wm] (= source (get-in wm [:webmention :id]))))]
-       (->> lines
-            (map edn/read-string)
-            (filter pred)
-            first)))))
+   (let [pred (get-predicate source target)]
+     (with-webmentions
+       #(first (filter pred %))))))
+(defn delete-wm
+  ([id] (delete-wm id nil))
+  ([source target]
+   (let [pred (get-predicate source target)]
+     (with-webmentions
+       #(->> % (remove pred) unload-data)))))
 
 (defn first-line-empty? [path]
   (with-open [rdr (io/reader path)]
@@ -47,14 +64,6 @@
         line (str newline? (pr-str data))]
     (spit data-file line :append true)))
 
-(defn delete-wm
-  "Delete a Webmention entry by source and target."
-  [source target]
-  (when-let [wm (get-wm source target)]
-     (->> (load-data)
-       (remove #(= wm %))
-       unload-data)))
-
 (defn update-wm
   "Update an existing webmention"
   [source target new-data]