Refactor: faster SSE event data-lines creation

Author: JeremS

libraries/sdk/src/main/starfederation/datastar/clojure/api/common.clj

@@ -32,7 +32,7 @@
   "Add an option `v` line to the transient `data-lines!` vector.
 
   Args:
-  - `data-lines`: a transient vector of data-lines that will be written in a sse
+  - `data-lines!`: a transient vector of data-lines that will be written in a sse
     event
   - `prefix`: The Datastar specific preffix for that line
   - `v`: the value for that line
@@ -43,13 +43,13 @@
 
 (defn add-data-lines!
   "Add several data-lines to the `data-lines!` transient vector."
-  [data-lines! prefix text]
-  (reduce
-    (fn [acc part]
-      (conj! acc (str prefix part)))
-    data-lines!
-    (string/split-lines text)))
-
+  [data-lines! prefix ^String text]
+  (let [stream (.lines text)
+        i (.iterator stream)]
+    (loop [acc data-lines!]
+      (if (.hasNext i)
+        (recur (conj! acc (str prefix (.next i))))
+        acc))))
 
 (defn add-boolean-option?
   "Utility used to test whether an boolean option should result in a sse event

src/dev/bench/split.clj

@@ -0,0 +1,28 @@
+(ns bench.split
+  (:require
+    [clojure.string :as string]
+    [starfederation.datastar.clojure.api.common :as c]))
+
+
+(defn old-datalines [data-lines! prefix text]
+  (reduce
+    (fn [acc part]
+      (conj! acc (str prefix part)))
+    data-lines!
+    (string/split-lines text)))
+
+
+(def input "hello there\n wold !\r\n How are \ryou \ntoday")
+(def input-big (apply str (repeat 100 input)))
+
+(defn bench [f input]
+  (println "---------------------------------------")
+  (dotimes [_ 20]
+    (time
+      (dotimes [_ 10000]
+        (f (transient []) "elements " input)))))
+
+
+(comment
+  (bench old-datalines input-big)
+  (bench c/add-data-lines! input-big))