Refactor SSE data lines creation (#14)

* Refactor: centralizing the line splitting of SSE datalines

* Chore: cleaned unused code

* Refactor: faster SSE event data-lines creation

* Chore: changelog

Author: JeremS

CHANGELOG.md

@@ -3,13 +3,20 @@
 ## 2025-11-27 - RC5
 
 ### Fixed
+
 - Fixed `starfederation.datastar.clojure.adapter.http-kit2/wrap-start-responding`,
   the async arity was improperly managed.
 
 ### Changes
+
 - The internals of the Ring SSE generator have been reworked. The SSE gen won't error
   if a user reuses it for different requests anymore. Documentation is in place to warn
   against such reuse and this change makes for much simpler code.
+- When creating SSE events we need to split on end of lines the text that will
+  constitute the data lines of the event. This can prevent SSE event injection
+  problems. The SSE machinery has been refactored so that this splitting happens
+  in a code path that all API functions go through instead of doing it in every
+  d* patch function. This way we can't forget that splitting.
 
 ## 2025-10-30 - RC4
 

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

@@ -1,4 +1,6 @@
-(ns starfederation.datastar.clojure.api.common)
+(ns starfederation.datastar.clojure.api.common
+  (:require
+   [clojure.string :as string]))
 
 ;; -----------------------------------------------------------------------------
 ;; Option names
@@ -30,7 +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
@@ -41,13 +43,13 @@
 
 (defn add-data-lines!
   "Add several data-lines to the `data-lines!` transient vector."
-  [data-lines! prefix lines-seq]
-  (reduce
-    (fn [acc part]
-      (conj! acc (str prefix part)))
-    data-lines!
-    lines-seq))
-
+  [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
@@ -56,6 +58,3 @@
   (and
     (boolean? val)
     (not= val default-val)))
-
-
-

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

@@ -30,7 +30,7 @@
     (cond-> data-lines!
       (and sel (valid-selector? sel))
       (common/add-opt-line! consts/selector-dataline-literal sel)
- 
+
       (and patch-mode (add-epm? patch-mode))
       (common/add-opt-line! consts/mode-dataline-literal patch-mode)
 
@@ -47,8 +47,7 @@
   [data-lines! element]
   (cond-> data-lines!
     (u/not-empty-string? element)
-    (common/add-data-lines! consts/elements-dataline-literal
-                            (string/split-lines element))))
+    (common/add-data-lines! consts/elements-dataline-literal element)))
 
 
 (defn ->patch-elements
@@ -91,13 +90,15 @@
 (defn conj-patch-elements-seq
   "Adds a the data-lines when patching a seq of strings elements."
   [data-lines! elements-seq]
-  (cond-> data-lines!
-    (seq elements-seq)
-    (common/add-data-lines! consts/elements-dataline-literal
-                            (eduction
-                              (comp (mapcat string/split-lines)
-                                    (remove string/blank?))
-                              elements-seq))))
+  (if (seq elements-seq)
+    (reduce
+      (fn [data-lines! elements]
+        (if (string/blank? elements)
+          data-lines!
+          (common/add-data-lines! data-lines! consts/elements-dataline-literal elements)))
+      data-lines!
+      elements-seq)
+    data-lines!))
 
 
 (defn ->patch-elements-seq
@@ -146,5 +147,3 @@
   (patch-elements! sse-gen "" (assoc opts
                                      common/selector selector
                                      common/patch-mode consts/element-patch-mode-remove)))
-
-

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

@@ -21,16 +21,15 @@
         (common/add-opt-line! consts/only-if-missing-dataline-literal oim)
 
         (u/not-empty-string? signals)
-        (common/add-data-lines! consts/signals-dataline-literal
-                                (string/split-lines signals))))))
+        (common/add-data-lines! consts/signals-dataline-literal signals)))))
 
 
 
 (comment
   (= (->patch-signals "{'some': \n 'json'}" {})
      ["signals {'some': "
       "signals  'json'}"]))
- 
+
 (defn patch-signals! [sse-gen signals-content opts]
   (try
     (sse/send-event! sse-gen
@@ -56,5 +55,3 @@
   (if (= :get (:request-method request))
     (get-in request [:query-params consts/datastar-key])
     (:body request)))
-
-

libraries/sdk/src/main/starfederation/datastar/clojure/consts.clj

@@ -2,8 +2,7 @@
 (ns starfederation.datastar.clojure.consts)
 
 
-(def datastar-key                  "datastar")
-(def version                       "1.0.0-RC.1")
+(def datastar-key "datastar")
 
 
 ;; -----------------------------------------------------------------------------
@@ -14,10 +13,6 @@
   1000)
 
 
-;; -----------------------------------------------------------------------------
-;; Default values
-;; -----------------------------------------------------------------------------
-
 ;; -----------------------------------------------------------------------------
 ;; Dataline literals
 ;; -----------------------------------------------------------------------------

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))